Mechanical testing of internal fixation devices: A theoretical and practical examination of current methods.

PubMed

Grant, Caroline A; Schuetz, Michael; Epari, Devakar

2015-11-26

Successful healing of long bone fractures is dependent on the mechanical environment created within the fracture, which in turn is dependent on the fixation strategy. Recent literature reports have suggested that locked plating devices are too stiff to reliably promote healing. However, in vitro testing of these devices has been inconsistent in both method of constraint and reported outcomes, making comparisons between studies and the assessment of construct stiffness problematic. Each of the methods previously used in the literature were assessed for their effect on the bending of the sample and concordant stiffness. The choice of outcome measures used in in vitro fracture studies was also assessed. Mechanical testing was conducted on seven hole locked plated constructs in each method for comparison. Based on the assessment of each method the use of spherical bearings, ball joints or similar is suggested at both ends of the sample. The use of near and far cortex movement was found to be more comprehensive and more accurate than traditional centrally calculated interfragmentary movement values; stiffness was found to be highly susceptible to the accuracy of deformation measurements and constraint method, and should only be used as a within study comparison method. The reported stiffness values of locked plate constructs from in vitro mechanical testing is highly susceptible to testing constraints and output measures, with many standard techniques overestimating the stiffness of the construct. This raises the need for further investigation into the actual mechanical behaviour within the fracture gap of these devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

The orbiter mate/demate device

NASA Technical Reports Server (NTRS)

Miller, A. J.; Binkley, W. H.

1985-01-01

The numerous components and systems of the space shuttle orbiter mate/demate device (MDD) are discussed. Special emphasis is given, mechanisms and mechanical systems to discuss in general their requirements, functions, and design; and, where applicable, to relate any unusual problems encountered during the initial concept studies, final design, and construction are discussed. The MDD and its electrical, machinery, and mechanical systems, including the main hoisting system, power operated access service platform, wind restrain and adjustment mechanism, etc., were successfully designed and constructed. The MDD was used routinely during the initial orbiter-747 approach and landing test and the more recent orbiter flight tests recovery and mate operations.

On-track testing of a power harvesting device for railroad track health monitoring

NASA Astrophysics Data System (ADS)

Hansen, Sean E.; Pourghodrat, Abolfazl; Nelson, Carl A.; Fateh, Mahmood

2010-03-01

A considerable proportion of railroad infrastructure exists in regions which are comparatively remote. With regard to the cost of extending electrical infrastructure into these areas, road crossings in these areas do not have warning light systems or crossing gates and are commonly marked with reflective signage. For railroad track health monitoring purposes, distributed sensor networks can be applicable in remote areas, but the same limitation regarding electrical infrastructure is the hindrance. This motivated the development of an energy harvesting solution for remote railroad deployment. This paper describes on-track experimental testing of a mechanical device for harvesting mechanical power from passing railcar traffic, in view of supplying electrical power to warning light systems at crossings and to remote networks of sensors. The device is mounted to and spans two rail ties and transforms the vertical rail displacement into electrical energy through mechanical amplification and rectification into a PMDC generator. A prototype was tested under loaded and unloaded railcar traffic at low speeds. Stress analysis and speed scaling analysis are presented, results of the on-track tests are compared and contrasted to previous laboratory testing, discrepancies between the two are explained, and conclusions are drawn regarding suitability of the device for illuminating high-efficiency LED lights at railroad crossings and powering track-health sensor networks.

A high throughput mechanical screening device for cartilage tissue engineering.

PubMed

Mohanraj, Bhavana; Hou, Chieh; Meloni, Gregory R; Cosgrove, Brian D; Dodge, George R; Mauck, Robert L

2014-06-27

Articular cartilage enables efficient and near-frictionless load transmission, but suffers from poor inherent healing capacity. As such, cartilage tissue engineering strategies have focused on mimicking both compositional and mechanical properties of native tissue in order to provide effective repair materials for the treatment of damaged or degenerated joint surfaces. However, given the large number design parameters available (e.g. cell sources, scaffold designs, and growth factors), it is difficult to conduct combinatorial experiments of engineered cartilage. This is particularly exacerbated when mechanical properties are a primary outcome, given the long time required for testing of individual samples. High throughput screening is utilized widely in the pharmaceutical industry to rapidly and cost-effectively assess the effects of thousands of compounds for therapeutic discovery. Here we adapted this approach to develop a high throughput mechanical screening (HTMS) system capable of measuring the mechanical properties of up to 48 materials simultaneously. The HTMS device was validated by testing various biomaterials and engineered cartilage constructs and by comparing the HTMS results to those derived from conventional single sample compression tests. Further evaluation showed that the HTMS system was capable of distinguishing and identifying 'hits', or factors that influence the degree of tissue maturation. Future iterations of this device will focus on reducing data variability, increasing force sensitivity and range, as well as scaling-up to even larger (96-well) formats. This HTMS device provides a novel tool for cartilage tissue engineering, freeing experimental design from the limitations of mechanical testing throughput. © 2013 Published by Elsevier Ltd.

A field-emission based vacuum device for the generation of THz waves

NASA Astrophysics Data System (ADS)

Lin, Ming-Chieh

2005-03-01

Terahertz waves have been used to characterize the electronic, vibrational and compositional properties of solid, liquid and gas phase materials during the past decade. More and more applications in imaging science and technology call for the well development of THz wave sources. Amplification and generation of a high frequency electromagnetic wave are a common interest of field emission based devices. In the present work, we propose a vacuum electronic device based on field emission mechanism for the generation of THz waves. To verify our thinking and designs, the cold tests and the hot tests have been studied via the simulation tools, SUPERFISH and MAGIC. In the hot tests, two types of electron emission mechanisms are considered. One is the field emission and the other is the explosive emission. The preliminary design of the device is carried out and tested by the numerical simulations. The simulation results show that an electronic efficiency up to 4% can be achieved without employing any magnetic circuits.

Large - scale Rectangular Ruler Automated Verification Device

NASA Astrophysics Data System (ADS)

Chen, Hao; Chang, Luping; Xing, Minjian; Xie, Xie

2018-03-01

This paper introduces a large-scale rectangular ruler automated verification device, which consists of photoelectric autocollimator and self-designed mechanical drive car and data automatic acquisition system. The design of mechanical structure part of the device refer to optical axis design, drive part, fixture device and wheel design. The design of control system of the device refer to hardware design and software design, and the hardware mainly uses singlechip system, and the software design is the process of the photoelectric autocollimator and the automatic data acquisition process. This devices can automated achieve vertical measurement data. The reliability of the device is verified by experimental comparison. The conclusion meets the requirement of the right angle test procedure.

A new device to test cutting efficiency of mechanical endodontic instruments

PubMed Central

Rubini, Alessio Giansiracusa; Plotino, Gianluca; Al-Sudani, Dina; Grande, Nicola M.; Putorti, Ermanno; Sonnino, GianPaolo; Cotti, Elisabetta; Testarelli, Luca; Gambarini, Gianluca

2014-01-01

Background The purpose of the present study was to introduce a new device specifically designed to evaluate the cutting efficiency of mechanically driven endodontic instruments. Material/Methods Twenty new Reciproc R25 (VDW, Munich, Germany) files were used to be investigated in the new device developed to test the cutting ability of endodontic instruments. The device consists of a main frame to which a mobile plastic support for the hand-piece is connected and a stainless-steel block containing a Plexiglas block against which the cutting efficiency of the instruments was tested. The length of the block cut in 1 minute was measured in a computerized program with a precision of 0.1mm. The instruments were activated by using a torque-controlled motor (Silver Reciproc; VDW, Munich, Germany) in a reciprocating movement by the “Reciproc ALL” program (Group 1) and in counter-clockwise rotation at 300 rpm (Group 2). Mean and standard deviations of each group were calculated and data were statistically analyzed with a one-way ANOVA test (P<0.05). Results Reciproc in reciprocation (Group 1) mean cut in the Plexiglas block was 8.6 mm (SD=0.6 mm), while Reciproc in rotation mean cut was 8.9 mm (SD=0.7 mm). There was no statistically significant difference between the 2 groups investigated (P>0.05). Conclusions The cutting testing device evaluated in the present study was reliable and easy to use and may be effectively used to test cutting efficiency of both rotary and reciprocating mechanical endodontic instruments. PMID:24603777

Efficient, flexible and mechanically robust perovskite solar cells on inverted nanocone plastic substrates.

PubMed

Tavakoli, Mohammad Mahdi; Lin, Qingfeng; Leung, Siu-Fung; Lui, Ga Ching; Lu, Hao; Li, Liang; Xiang, Bin; Fan, Zhiyong

2016-02-21

Utilization of nanostructures on photovoltaic devices can significantly improve the device energy conversion efficiency by enhancing the device light harvesting capability as well as carrier collection efficiency. However, improvements in device mechanical robustness and reliability, particularly for flexible devices, have rarely been reported with in-depth understanding. In this work, we fabricated efficient, flexible and mechanically robust organometallic perovskite solar cells on plastic substrates with inverted nanocone (i-cone) structures. Compared with the reference cell that was fabricated on a flat substrate, it was shown that the device power conversion efficiency could be improved by 37%, and reached up to 11.29% on i-cone substrates. More interestingly, it was discovered that the performance of an i-cone device remained more than 90% of the initial value even after 200 mechanical bending cycles, which is remarkably better than for the flat reference device, which degraded down to only 60% in the same test. Our experiments, coupled with mechanical simulation, demonstrated that a nanostructured template can greatly help in relaxing stress and strain upon device bending, which suppresses crack nucleation in different layers of a perovskite solar cell. This essentially leads to much improved device reliability and robustness and will have significant impact on practical applications.

High-risk medical devices, children and the FDA: regulatory challenges facing pediatric mechanical circulatory support devices.

PubMed

Almond, Christopher S D; Chen, Eric A; Berman, Michael R; Less, Joanne R; Baldwin, J Timothy; Linde-Feucht, Sarah R; Hoke, Tracey R; Pearson, Gail D; Jenkins, Kathy; Duncan, Brian W; Zuckerman, Bram D

2007-01-01

Pediatric mechanical circulatory support is a critical unmet need in the United States. Infant- and child-sized ventricular assist devices are currently being developed largely through federal contracts and grants through the National Heart, Lung, and Blood Institute (NHLBI). Human testing and marketing of high-risk devices for children raises epidemiologic and regulatory issues that will need to be addressed. Leaders from the US Food and Drug Administration (FDA), NHLBI, academic pediatric community, and industry convened in January 2006 for the first FDA Workshop on the Regulatory Process for Pediatric Mechanical Circulatory Support Devices. The purpose was to provide the pediatric community with an overview of the federal regulatory process for high-risk medical devices and to review the challenges specific to the development and regulation of pediatric mechanical circulatory support devices. Pediatric mechanical circulatory support present significant epidemiologic, logistic, and financial challenges to industry, federal regulators, and the pediatric community. Early interactions with the FDA, shared appreciation of challenges, and careful planning will be critical to avoid unnecessary delays in making potentially life-saving devices available for children. Collaborative efforts to address these challenges are warranted.

Radiation Testing, Characterization and Qualification Challenges for Modern Microelectronics and Photonics Devices and Technologies

NASA Technical Reports Server (NTRS)

LaBel, Kenneth A.; Cohn, Lewis M.

2008-01-01

At GOMAC 2007, we discussed a selection of the challenges for radiation testing of modern semiconductor devices focusing on state-of-the-art memory technologies. This included FLASH non-volatile memories (NVMs) and synchronous dynamic random access memories (SDRAMs). In this presentation, we extend this discussion in device packaging and complexity as well as single event upset (SEU) mechanisms using several technology areas as examples including: system-on-a-chip (SOC) devices and photonic or fiber optic systems. The underlying goal is intended to provoke thought for understanding the limitations and interpretation of radiation testing results.

Quantitative Accelerated Life Testing of MEMS Accelerometers.

PubMed

Bâzu, Marius; Gălăţeanu, Lucian; Ilian, Virgil Emil; Loicq, Jerome; Habraken, Serge; Collette, Jean-Paul

2007-11-20

Quantitative Accelerated Life Testing (QALT) is a solution for assessing thereliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shownin this paper and an attempt to assess the reliability level for a batch of MEMSaccelerometers is reported. The testing plan is application-driven and contains combinedtests: thermal (high temperature) and mechanical stress. Two variants of mechanical stressare used: vibration (at a fixed frequency) and tilting. Original equipment for testing at tiltingand high temperature is used. Tilting is appropriate as application-driven stress, because thetilt movement is a natural environment for devices used for automotive and aerospaceapplications. Also, tilting is used by MEMS accelerometers for anti-theft systems. The testresults demonstrated the excellent reliability of the studied devices, the failure rate in the"worst case" being smaller than 10 -7 h -1 .

Quantitative Accelerated Life Testing of MEMS Accelerometers

PubMed Central

Bâzu, Marius; Gălăţeanu, Lucian; Ilian, Virgil Emil; Loicq, Jerome; Habraken, Serge; Collette, Jean-Paul

2007-01-01

Quantitative Accelerated Life Testing (QALT) is a solution for assessing the reliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shown in this paper and an attempt to assess the reliability level for a batch of MEMS accelerometers is reported. The testing plan is application-driven and contains combined tests: thermal (high temperature) and mechanical stress. Two variants of mechanical stress are used: vibration (at a fixed frequency) and tilting. Original equipment for testing at tilting and high temperature is used. Tilting is appropriate as application-driven stress, because the tilt movement is a natural environment for devices used for automotive and aerospace applications. Also, tilting is used by MEMS accelerometers for anti-theft systems. The test results demonstrated the excellent reliability of the studied devices, the failure rate in the “worst case” being smaller than 10-7h-1. PMID:28903265

Mars Science Laboratory CHIMRA: A Device for Processing Powdered Martian Samples

NASA Technical Reports Server (NTRS)

Sunshine, Daniel

2010-01-01

The CHIMRA is an extraterrestrial sample acquisition and processing device for the Mars Science Laboratory that emphasizes robustness and adaptability through design configuration. This work reviews the guidelines utilized to invent the initial CHIMRA and the strategy employed in advancing the design; these principles will be discussed in relation to both the final CHIMRA design and similar future devices. The computational synthesis necessary to mature a boxed-in impact-generating mechanism will be presented alongside a detailed mechanism description. Results from the development testing required to advance the design for a highly-loaded, long-life and high-speed bearing application will be presented. Lessons learned during the assembly and testing of this subsystem as well as results and lessons from the sample-handling development test program will be reviewed.

21 CFR 862.2570 - Instrumentation for clinical multiplex test systems.

Code of Federal Regulations, 2010 CFR

2010-04-01

... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical... hardware components, as well as raw data storage mechanisms, data acquisition software, and software to...

Strand development and splice device : final report, February 3, 2009.

DOT National Transportation Integrated Search

2010-02-01

"A new device for gripping prestressing strands was developed and tested. The device could provide a means of anchoring the terminal end of a strand in order to provide a mechanism for developing bonded strand at the service limit state, to provide t...

Investigation of Basic Mechanisms of Radiation Effects in Carbon-Based Electronic Materials

DTIC Science & Technology

2017-06-01

materials characterization, and carbon nanotube diodes, FET, and PZT-memory test device structures for electrical measurements. Pre - and post -irradiation...definition (Radiation exposure) Task 2) The grantee shall perform testing to include: - Radiation testing . May be multiple types. - Pre and post -rad...technologies for electronic devices. Experiential radiation testing has included exposure to 10 keV X-rays, 4 MeV protons, heavy ions, and Ultra

Mechanical CPR: Who? When? How?

PubMed

Poole, Kurtis; Couper, Keith; Smyth, Michael A; Yeung, Joyce; Perkins, Gavin D

2018-05-29

In cardiac arrest, high quality cardiopulmonary resuscitation (CPR) is a key determinant of patient survival. However, delivery of effective chest compressions is often inconsistent, subject to fatigue and practically challenging.Mechanical CPR devices provide an automated way to deliver high-quality CPR. However, large randomised controlled trials of the routine use of mechanical devices in the out-of-hospital setting have found no evidence of improved patient outcome in patients treated with mechanical CPR, compared with manual CPR. The limited data on use during in-hospital cardiac arrest provides preliminary data supporting use of mechanical devices, but this needs to be robustly tested in randomised controlled trials.In situations where high-quality manual chest compressions cannot be safely delivered, the use of a mechanical device may be a reasonable clinical approach. Examples of such situations include ambulance transportation, primary percutaneous coronary intervention, as a bridge to extracorporeal CPR and to facilitate uncontrolled organ donation after circulatory death.The precise time point during a cardiac arrest at which to deploy a mechanical device is uncertain, particularly in patients presenting in a shockable rhythm. The deployment process requires interruptions in chest compression, which may be harmful if the pause is prolonged. It is recommended that use of mechanical devices should occur only in systems where quality assurance mechanisms are in place to monitor and manage pauses associated with deployment.In summary, mechanical CPR devices may provide a useful adjunct to standard treatment in specific situations, but current evidence does not support their routine use.

Grips for testing of electrical characteristics of a specimen under a mechanical load

DOE Office of Scientific and Technical Information (OSTI.GOV)

Briggs, Timothy; Loyola, Bryan

Various technologies to facilitate coupled electrical and mechanical measurement of conductive materials are disclosed herein. A gripping device simultaneously holds a specimen in place and causes contact to be made between the specimen and a plurality of electrodes connected to an electrical measuring device. An electrical characteristic of the specimen is then measured while a mechanical load is applied to the specimen, and a relationship between the mechanical load and changes in the electrical characteristic can be identified.

MCTs and IGBTs - A comparison of performance in power electronic circuits

NASA Technical Reports Server (NTRS)

Sul, S. K.; Profumo, F.; Cho, G. H.; Lipo, T. A.

1989-01-01

There is a continuous demand for improvements in the quality of switching power devices, such as higher switching frequency, higher withstand voltage capability, larger current-handling capability, and lower conduction losses. However, for single-conduction-mechanism devices (SCRs, GTOs, BJTs, FETs), possessing all these features is probably unrealizable for physical reasons. An attractive solution appears to be double-mechanism devices, in which the features of both a minority carrier device (BJT or SCR) and a majority carrier device (MOSFET) are embedded. Both IGBTs (insulated-gate bipolar transistors) and MCTs (MOS-controlled thyristors) belong to this family of double-mechanism devices and promise to have a major impact on converter circuit signs. The authors deal with the major features of these two devices, pointing out those that are most critical to the design of converter topologies. In particular, the two devices have been tested both in a chopper and in two resonant link converter topologies, and the experimental results are reported.

Enabling reliability assessments of pre-commercial perovskite photovoltaics with lessons learned from industrial standards

NASA Astrophysics Data System (ADS)

Snaith, Henry J.; Hacke, Peter

2018-06-01

Photovoltaic modules are expected to operate in the field for more than 25 years, so reliability assessment is critical for the commercialization of new photovoltaic technologies. In early development stages, understanding and addressing the device degradation mechanisms are the priorities. However, any technology targeting large-scale deployment must eventually pass industry-standard qualification tests and undergo reliability testing to validate the module lifetime. In this Perspective, we review the methodologies used to assess the reliability of established photovoltaics technologies and to develop standardized qualification tests. We present the stress factors and stress levels for degradation mechanisms currently identified in pre-commercial perovskite devices, along with engineering concepts for mitigation of those degradation modes. Recommendations for complete and transparent reporting of stability tests are given, to facilitate future inter-laboratory comparisons and to further the understanding of field-relevant degradation mechanisms, which will benefit the development of accelerated stress tests.

In-flight friction and wear mechanism

NASA Technical Reports Server (NTRS)

Devine, E. J.; Evans, H. E.

1975-01-01

A unique mechanism developed for conducting friction and wear experiments in orbit is described. The device is capable of testing twelve material samples simultaneously. Parameters considered critical include: power, weight, volume, mounting, cleanliness, and thermal designs. The device performed flawlessly in orbit over an eighteen month period and demonstrated the usefulness of this design for future unmanned spacecraft or shuttle applications.

The Resonating Arm Exerciser: design and pilot testing of a mechanically passive rehabilitation device that mimics robotic active assistance

PubMed Central

2013-01-01

Background Robotic arm therapy devices that incorporate actuated assistance can enhance arm recovery, motivate patients to practice, and allow therapists to deliver semi-autonomous training. However, because such devices are often complex and actively apply forces, they have not achieved widespread use in rehabilitation clinics or at home. This paper describes the design and pilot testing of a simple, mechanically passive device that provides robot-like assistance for active arm training using the principle of mechanical resonance. Methods The Resonating Arm Exerciser (RAE) consists of a lever that attaches to the push rim of a wheelchair, a forearm support, and an elastic band that stores energy. Patients push and pull on the lever to roll the wheelchair back and forth by about 20 cm around a neutral position. We performed two separate pilot studies of the device. In the first, we tested whether the predicted resonant properties of RAE amplified a user’s arm mobility by comparing his or her active range of motion (AROM) in the device achieved during a single, sustained push and pull to the AROM achieved during rocking. In a second pilot study designed to test the therapeutic potential of the device, eight participants with chronic stroke (35 ± 24 months since injury) and a mean, stable, initial upper extremity Fugl-Meyer (FM) score of 17 ± 8 / 66 exercised with RAE for eight 45 minute sessions over three weeks. The primary outcome measure was the average AROM measured with a tilt sensor during a one minute test, and the secondary outcome measures were the FM score and the visual analog scale for arm pain. Results In the first pilot study, we found people with a severe motor impairment after stroke intuitively found the resonant frequency of the chair, and the mechanical resonance of RAE amplified their arm AROM by a factor of about 2. In the second pilot study, AROM increased by 66% ± 20% (p = 0.003). The mean FM score increase was 8.5 ± 4 pts (p = 0.009). Subjects did not report discomfort or an increase in arm pain with rocking. Improvements were sustained at three months. Conclusions These results demonstrate that a simple mechanical device that snaps onto a manual wheelchair can use resonance to assist arm training, and that such training shows potential for safely increasing arm movement ability for people with severe chronic hemiparetic stroke. PMID:23597303

The Resonating Arm Exerciser: design and pilot testing of a mechanically passive rehabilitation device that mimics robotic active assistance.

PubMed

Zondervan, Daniel K; Palafox, Lorena; Hernandez, Jorge; Reinkensmeyer, David J

2013-04-18

Robotic arm therapy devices that incorporate actuated assistance can enhance arm recovery, motivate patients to practice, and allow therapists to deliver semi-autonomous training. However, because such devices are often complex and actively apply forces, they have not achieved widespread use in rehabilitation clinics or at home. This paper describes the design and pilot testing of a simple, mechanically passive device that provides robot-like assistance for active arm training using the principle of mechanical resonance. The Resonating Arm Exerciser (RAE) consists of a lever that attaches to the push rim of a wheelchair, a forearm support, and an elastic band that stores energy. Patients push and pull on the lever to roll the wheelchair back and forth by about 20 cm around a neutral position. We performed two separate pilot studies of the device. In the first, we tested whether the predicted resonant properties of RAE amplified a user's arm mobility by comparing his or her active range of motion (AROM) in the device achieved during a single, sustained push and pull to the AROM achieved during rocking. In a second pilot study designed to test the therapeutic potential of the device, eight participants with chronic stroke (35 ± 24 months since injury) and a mean, stable, initial upper extremity Fugl-Meyer (FM) score of 17 ± 8 / 66 exercised with RAE for eight 45 minute sessions over three weeks. The primary outcome measure was the average AROM measured with a tilt sensor during a one minute test, and the secondary outcome measures were the FM score and the visual analog scale for arm pain. In the first pilot study, we found people with a severe motor impairment after stroke intuitively found the resonant frequency of the chair, and the mechanical resonance of RAE amplified their arm AROM by a factor of about 2. In the second pilot study, AROM increased by 66% ± 20% (p = 0.003). The mean FM score increase was 8.5 ± 4 pts (p = 0.009). Subjects did not report discomfort or an increase in arm pain with rocking. Improvements were sustained at three months. These results demonstrate that a simple mechanical device that snaps onto a manual wheelchair can use resonance to assist arm training, and that such training shows potential for safely increasing arm movement ability for people with severe chronic hemiparetic stroke.

A tensile machine with a novel optical load cell for soft biological tissues application.

PubMed

Faturechi, Rahim; Hashemi, Ata; Abolfathi, Nabiollah

2014-11-01

The uniaxial tensile testing machine is the most common device used to measure the mechanical properties of industrial and biological materials. The need for a low-cost uniaxial tension testing device for small research centers has always been the subject of research. To address this need, a novel uniaxial tensile testing machine was designed and fabricated to measure the mechanical properties of soft biological tissues. The device is equipped with a new low-cost load cell which works based on the linear displacement/force relationship of beams. The deflection of the beam load cell is measured optically by a digital microscope with an accuracy of 1 µm. The stiffness of the designed load cell was experimentally and theoretically determined at 100 N mm(-1). The stiffness of the load cell can be easily adjusted according to the tissue's strength. The force-time behaviour of soft tissue specimens was obtained by an in-house image processing program. To demonstrate the efficiency of the fabricated device, the mechanical properties of amnion tissue was measured and compared with available data. The obtained results indicate a strong agreement with that of previous studies.

Performance of three different artificial swimmers in Newtonian and complex fluids

NASA Astrophysics Data System (ADS)

Godinez, F.; Zenit, R.; Lauga, E.

2012-11-01

We present an experimental investigation of three simple swimming devices at low Reynolds number. Each swimmer is composed of a magnetic head attached to a propulsive tail. The robots are driven by an external magnetic field and three different kinds of tails are used: (i) a flexible filament periodically oscillated (the flexible oar mechanism); (ii) a rigid helical filament rotated by the external field (the corkscrew mechanism); (iii) a flexible filament that, when rotated by the field, acquires a conical helical shape (a hybrid case). Each swimmer is tested in two different fluids with the same shear viscosity, a Newtonian and a Boger fluid. Surprisingly, even though the tests were conducted with the same fluid, the results for the viscoelastic fluid are contrastingly different. The device based on flexible oar mechanism swims faster in the Boger fluid than in the Newtonian one; on the contrary, the hybrid device swims at lower speeds in the Boger fluid than in the Newtonian one. And unexpectedly, the device based on the corkscrew mechanism practically swims at the same velocity in both fluids. These results, suggest that the swimming performance of a biomimetic device strongly depends on the details of the swimming actuation. We can conclude that a general viscoelastic effect.

Degradation Mechanisms for GaN and GaAs High Speed Transistors

PubMed Central

Cheney, David J.; Douglas, Erica A.; Liu, Lu; Lo, Chien-Fong; Gila, Brent P.; Ren, Fan; Pearton, Stephen J.

2012-01-01

We present a review of reliability issues in AlGaN/GaN and AlGaAs/GaAs high electron mobility transistors (HEMTs) as well as Heterojunction Bipolar Transistors (HBTs) in the AlGaAs/GaAs materials systems. Because of the complex nature and multi-faceted operation modes of these devices, reliability studies must go beyond the typical Arrhenius accelerated life tests. We review the electric field driven degradation in devices with different gate metallization, device dimensions, electric field mitigation techniques (such as source field plate), and the effect of device fabrication processes for both DC and RF stress conditions. We summarize the degradation mechanisms that limit the lifetime of these devices. A variety of contact and surface degradation mechanisms have been reported, but differ in the two device technologies: For HEMTs, the layers are thin and relatively lightly doped compared to HBT structures and there is a metal Schottky gate that is directly on the semiconductor. By contrast, the HBT relies on pn junctions for current modulation and has only Ohmic contacts. This leads to different degradation mechanisms for the two types of devices.

Testing of mechanical ventilators and infant incubators in healthcare institutions.

PubMed

Badnjevic, Almir; Gurbeta, Lejla; Jimenez, Elvira Ruiz; Iadanza, Ernesto

2017-01-01

The medical device industry has grown rapidly and incessantly over the past century. The sophistication and complexity of the designed instrumentation is nowadays rising and, with it, has also increased the need to develop some better, more effective and efficient maintenance processes, as part of the safety and performance requirements. This paper presents the results of performance tests conducted on 50 mechanical ventilators and 50 infant incubators used in various public healthcare institutions. Testing was conducted in accordance to safety and performance requirements stated in relevant international standards, directives and legal metrology policies. Testing of output parameters for mechanical ventilators was performed in 4 measuring points while testing of output parameters for infant incubators was performed in 7 measuring points for each infant incubator. As performance criteria, relative error of output parameters for mechanical ventilators and absolute error of output parameters for infant incubators was calculated. The ranges of permissible error, for both groups of devices, are regulated by the Rules on Metrological and Technical Requirements published in the Official Gazette of Bosnia and Herzegovina No. 75/14, which are defined based on international recommendations, standards and guidelines. All ventilators and incubators were tested by etalons calibrated in an ISO 17025 accredited laboratory, which provides compliance to international standards for all measured parameters.The results show that 30% of the tested medical devices are not operating properly and should be serviced, recalibrated and/or removed from daily application.

Effects of mobile phone use on specific intensive care unit devices.

PubMed

Hans, Nidhi; Kapadia, Farhad N

2008-10-01

To observe the effects of mobile phone use in the vicinity of medical devices used in a critical care setting. Electromagnetic interference (EMI) was tested by using two types of mobile phones - GSM and CDMA. Mobile phones were placed at a distance of one foot from three medical devices - syringe pump, mechanical ventilator, and the bedside monitor - in switch off, standby, and talking modes of the phone. Medical devices were observed for any interference caused by the electromagnetic radiations (EMR) from the mobile phones. Out of the three medical devices that were tested, EMI occurred while using the mobile phone in the vicinity of the syringe pump, in the 'talk mode.' The mean variation observed in the calculated and delivered volume of the syringe pump was 2.66 ml. Mechanical ventilator did not show any specific adverse effects with mobile phone use in the one-foot vicinity. No other adverse effects or unexplained malfunctions or shutdown of the syringe pump, mechanical ventilator, or the bedside monitor was noted during the study period of 36 hours. EMI from mobile phones have an adverse effect on the medical devices used in critical care setup. They should be used at least one foot away from the diameter of the syringe pump.

Laser Scanner Tests For Single-Event Upsets

NASA Technical Reports Server (NTRS)

Kim, Quiesup; Soli, George A.; Schwartz, Harvey R.

1992-01-01

Microelectronic advanced laser scanner (MEALS) is opto/electro/mechanical apparatus for nondestructive testing of integrated memory circuits, logic circuits, and other microelectronic devices. Multipurpose diagnostic system used to determine ultrafast time response, leakage, latchup, and electrical overstress. Used to simulate some of effects of heavy ions accelerated to high energies to determine susceptibility of digital device to single-event upsets.

Design of a novel telerehabilitation system with a force-sensing mechanism.

PubMed

Zhang, Songyuan; Guo, Shuxiang; Gao, Baofeng; Hirata, Hideyuki; Ishihara, Hidenori

2015-05-19

Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist-patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist's motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients' safety is guaranteed by monitoring the motor's current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients' safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

Design of a Novel Telerehabilitation System with a Force-Sensing Mechanism

PubMed Central

Zhang, Songyuan; Guo, Shuxiang; Gao, Baofeng; Hirata, Hideyuki; Ishihara, Hidenori

2015-01-01

Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist–patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist’s motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients’ safety is guaranteed by monitoring the motor’s current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients’ safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication. PMID:25996511

Data processing device test apparatus and method therefor

DOEpatents

Wilcox, Richard Jacob; Mulig, Jason D.; Eppes, David; Bruce, Michael R.; Bruce, Victoria J.; Ring, Rosalinda M.; Cole, Jr., Edward I.; Tangyunyong, Paiboon; Hawkins, Charles F.; Louie, Arnold Y.

2003-04-08

A method and apparatus mechanism for testing data processing devices are implemented. The test mechanism isolates critical paths by correlating a scanning microscope image with a selected speed path failure. A trigger signal having a preselected value is generated at the start of each pattern vector. The sweep of the scanning microscope is controlled by a computer, which also receives and processes the image signals returned from the microscope. The value of the trigger signal is correlated with a set of pattern lines being driven on the DUT. The trigger is either asserted or negated depending the detection of a pattern line failure and the particular line that failed. In response to the detection of the particular speed path failure being characterized, and the trigger signal, the control computer overlays a mask on the image of the device under test (DUT). The overlaid image provides a visual correlation of the failure with the structural elements of the DUT at the level of resolution of the microscope itself.

A Mechanomodulatory Device to Minimize Incisional Scar Formation

PubMed Central

Wong, Victor W.; Beasley, Bill; Zepeda, John; Dauskardt, Reinhold H.; Yock, Paul G.; Longaker, Michael T.; Gurtner, Geoffrey C.

2013-01-01

Objective To mechanically control the wound environment and prevent cutaneous scar formation. Approach We subjected various material substrates to biomechanical testing to investigate their ability to modulate skin behavior. Combinations of elastomeric materials, adhesives, and strain applicators were evaluated to develop topical stress-shielding devices. Noninvasive imaging modalities were utilized to characterize anatomic site-specific differences in skin biomechanical properties in humans. The devices were tested in a validated large animal model of hypertrophic scarring. Phase I within-patient controlled clinical trials were conducted to confirm their safety and efficacy in scar reduction in patients undergoing abdominoplasty surgery. Results Among the tested materials and device applicators, a polymer device was developed that effectively off-loaded high tension wounds and blocked pro-fibrotic pathways and excess scar formation in red Duroc swine. In humans, different anatomic sites exhibit unique biomechanical properties that may correlate with the propensity to form scars. In the clinical trial, utilization of this device significantly reduced incisional scar formation and improved scar appearance for up to 12 months compared with control incisions that underwent routine postoperative care. Innovation This is the first device that is able to precisely control the mechanical environment of incisional wounds and has been demonstrated in multiple clinical trials to significantly reduce scar formation after surgery. Conclusion Mechanomodulatory strategies to control the incisional wound environment can significantly reduce pathologic scarring and fibrosis after surgery. PMID:24527342

The effect of steam sterilization on the accuracy of spring-style mechanical torque devices for dental implants

PubMed Central

Mahshid, Minoo; Saboury, Aboulfazl; Fayaz, Ali; Sadr, Seyed Jalil; Lampert, Friedrich; Mir, Maziar

2012-01-01

Background Mechanical torque devices (MTDs) are one of the most commonly recommended devices used to deliver optimal torque to the screw of dental implants. Recently, high variability has been reported about the accuracy of spring-style mechanical torque devices (S-S MTDs). Joint stability and survival rate of fixed implant supported prosthesis depends on the accuracy of these devices. Currently, there is limited information on the steam sterilization influence on the accuracy of MTDs. The purpose of this study was to assess the effect of steam sterilization on the accuracy (±10% of the target torque) of spring-style mechanical torque devices for dental implants. Materials and methods Fifteen new S-S MTDs and their appropriate drivers from three different manufacturers (Nobel Biocare, Straumann [ITI], and Biomet 3i [3i]) were selected. Peak torque of devices (5 in each subgroup) was measured before and after autoclaving using a Tohnichi torque gauge. Descriptive statistical analysis was used and a repeated-measures ANOVA with type of device as a between-subject comparison was performed to assess the difference in accuracy among the three groups of spring-style mechanical torque devices after sterilization. A Bonferroni post hoc test was used to assess pairwise comparisons. Results Before steam sterilization, all the tested devices stayed within 10% of their target values. After 100 sterilization cycles, results didn’t show any significant difference between raw and absolute error values in the Nobel Biocare and ITI devices; however the results demonstrated an increase of error values in the 3i group (P < 0.05). Raw error values increased with a predictable pattern in 3i devices and showed more than a 10% difference from target torque values (maximum difference of 14% from target torque was seen in 17% of peak torque measurements). Conclusion Within the limitation of this study, steam sterilization did not affect the accuracy (±10% of the target torque) of the Nobel Biocare and ITI MTDs. Raw error values increased with a predictable pattern in 3i devices and showed more than 10% difference from target torque values. Before expanding upon the clinical implications, the controlled and combined effect of aging (frequency of use) and steam sterilization needs more investigation. PMID:23674923

A flexible pressure responsive device based on the interaction between silver nanoparticles and an aluminum reflector

NASA Astrophysics Data System (ADS)

Rankin, Alasdair; McGarry, Steven

2018-01-01

The unique and tunable optical properties of metal nanoparticles have attracted intense and sustained academic attention in recent years. In tandem with the demand for low-cost responsive materials, one particular topic of interest is the development of mechanically responsive device structures. This work describes the design, fabrication, and testing of a mechanically responsive plasmonic device structure that has been integrated onto a standard commercial plastic substrate. With a low actuation force and a visually perceivable color shift, this device would be attractive for applications requiring responsive features that can be activated by the human hand.

Method and system for automated on-chip material and structural certification of MEMS devices

DOEpatents

Sinclair, Michael B.; DeBoer, Maarten P.; Smith, Norman F.; Jensen, Brian D.; Miller, Samuel L.

2003-05-20

A new approach toward MEMS quality control and materials characterization is provided by a combined test structure measurement and mechanical response modeling approach. Simple test structures are cofabricated with the MEMS devices being produced. These test structures are designed to isolate certain types of physical response, so that measurement of their behavior under applied stress can be easily interpreted as quality control and material properties information.

A durability study of a paracorporeal pulsatile electro-mechanical pneumatic biventricular assist device.

PubMed

Choi, Hyuk; Lee, Heung-Man; Nam, Kyoung Won; Choi, Jaesoon; Lee, Jung-Joo; Kim, Ho Chul; Song, Seung Joon; Ahn, Chi Bum; Son, Ho Sung; Lim, Choon Hak; Son, Kuk Hui; Park, Yong Doo; Jeong, Gi Seok; Sun, Kyung

2011-06-01

In 2002, the paracorporeal pulsatile electro-mechanical pneumatic ventricular assist device (VAD) began to be developed by the Korea Artificial Organ Center at Korea University under a Health & Medical Technology Research and Development program which finished in 2008. In vitro durability testing was conducted on the paracorporeal pulsatile pneumatic VAD to determine device durability and to evaluate device failures. The 1- and 2-year reliability of the paracorporeal pulsatile pneumatic VAD was shown to be 91.2% and 54.9%, respectively, with an 80% confidence level. Failure modes were analyzed using fault tree analysis, with customized software continuously acquiring data during the test period. After this period, 21 in vivo animal tests were done, with 14 cases of left atrium to left ventricle (LV) inflow cannulation (36Fr)/outflow grafting to descending aorta, and seven cases of apex cannulation of LV to descending aorta (12 mm). The longest postoperative day (182 days) in Korea was recently recorded in in vivo animal testing (bovine, 90 kg, male, 3.5-4.0 L/min flow rate, and 55 bpm). © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

International Conference on the Mechanical Technology of Inertial Devices, University of Newcastle-upon-Tyne, England, Apr. 7-9, 1987, Proceedings

NASA Astrophysics Data System (ADS)

Various papers on the mechanical technology of inertial devices are presented. The topics addressed include: development of a directional gyroscope for remotely piloted vehicles and similar applications; a two-degree-of-freedom gyroscope with frictionless inner and outer gimbal pickoffs; oscillogyro design, manufacture, and performance; development of miniature two-axis rate gyroscope; mechanical design aspects of the electrostatically suspended gyroscope; role of gas-lubricated bearings in current and future sensors; development of a new microporous retainer material for precision ball bearings; design study for a high-stability, large-centrifuge test bed; evaluation of a two-axis rate gyro; operating principles of a two-axis angular rate transducer; and nutation frequency analysis. Also considered are: triaxial laser gyro; mechanical design considerations for a ring laser gyro dither mechanism; environmental considerations in the design of fiberoptic gyroscopes; manufacturing aspects of some critical high-precision mechanical components of inertial devices; dynamics and control of a gyroscopic force measurement system; high precision and high performance motion systems; use of multiple acceleration references to obtain high precision centrifuge data at low cost; gyro testing and evaluation at the Communications Research Centre; review of the mechanical design and development of a high-performance accelerometer; and silicon microengineering for accelerometers.

Initial stages of cavitation damage and erosion on copper and brass tested in a rotating disk device

NASA Technical Reports Server (NTRS)

Rao, P. V.; Rao, B. C. S.; Rao, N. S. L.

1982-01-01

In view of the differences in flow and experimental conditions, there has been a continuing debate as to whether or not the ultrasonic method of producing cavitation damage is similar to the damage occurring in cavitating flow systems, namely, venturi and rotating disk devices. In this paper, the progress of cavitation damage during incubation periods on polycrystalline copper and brass tested in a rotating disk device is presented. The results indicate several similarities and differences in the damage mechanism encountered in a rotating disk device (which simulates field rotary devices) and a magnetostriction apparatus. The macroscopic erosion appears similar to that in the vibratory device except for nonuniform erosion and apparent plastic flow during the initial damage phase.

Experimental research on a modular miniaturization nanoindentation device

NASA Astrophysics Data System (ADS)

Huang, Hu; Zhao, Hongwei; Mi, Jie; Yang, Jie; Wan, Shunguang; Yang, Zhaojun; Yan, Jiwang; Ma, Zhichao; Geng, Chunyang

2011-09-01

Nanoindentation technology is developing toward the in situ test which requires miniaturization of indentation instruments. This paper presents a miniaturization nanoindentation device based on the modular idea. It mainly consists of macro-adjusting mechanism, x-y precise positioning platform, z axis precise driving unit, and the load-depth measuring unit. The device can be assembled with different forms and has minimum dimensions of 200 mm × 135 mm × 200 mm. The load resolution is about 0.1 mN and the displacement resolution is about 10 nm. A new calibration method named the reference-mapping method is proposed to calibrate the developed device. Output performance tests and indentation experiments indicate the feasibility of the developed device and calibration method. This paper gives an example that combining piezoelectric actuators with flexure hinge to realize nanoindentation tests. Integrating a smaller displacement sensor, a more compact nanoindentation device can be designed in the future.

Characterization of quantum well structures using a photocathode electron microscope

NASA Technical Reports Server (NTRS)

Spencer, Michael G.; Scott, Craig J.

1989-01-01

Present day integrated circuits pose a challenge to conventional electronic and mechanical test methods. Feature sizes in the submicron and nanometric regime require radical approaches in order to facilitate electrical contact to circuits and devices being tested. In addition, microwave operating frequencies require careful attention to distributed effects when considering the electrical signal paths within and external to the device under test. An alternative testing approach which combines the best of electrical and optical time domain testing is presented, namely photocathode electron microscope quantitative voltage contrast (PEMQVC).

PERFORMANCE EVALUATION OF TYPE I MARINE SANITATION DEVICES

EPA Science Inventory

This performance test was designed to evaluate the effectiveness of two Type I Marine Sanitation Devices (MSDs): the Electro Scan Model EST 12, manufactured by Raritan Engineering Company, Inc., and the Thermopure-2, manufactured by Gross Mechanical Laboratories, Inc. Performance...

The 13th Aerospace Mechanisms Symposium

NASA Technical Reports Server (NTRS)

Bond, A. C.

1979-01-01

Technological areas covered include propulsion, motion compensation, instrument pointing and adjustment, centrifuge testing, bearing design, vehicle braking, and cargo handling. Devices for satellite, missile, and hypersonic-wind-tunnel applications; space shuttle mechanical and thermal protection systems; and techniques for building large space structures are described. In addition, a fluid drop injector device for a Spacelab experiment, a helical grip for cable cars, and applications of rare earth permanent magnets are discussed.

Mechanical phenotyping of tumor cells using a microfluidic cell squeezer device

NASA Astrophysics Data System (ADS)

Khan, Zeina S.; Kamyabi, Nabiollah; Vanapalli, Siva A.

2013-03-01

Studies have indicated that cancer cells have distinct mechanical properties compared to healthy cells. We are investigating the potential of cell mechanics as a biophysical marker for diagnostics and prognosis of cancer. To establish the significance of mechanical properties for cancer diagnostics, a high throughput method is desired. Although techniques such as atomic force microscopy are very precise, they are limited in throughput for cellular mechanical property measurements. To develop a device for high throughput mechanical characterization of tumor cells, we have fabricated a microfludic cell squeezer device that contains narrow micrometer-scale pores. Fluid flow is used to drive cells into these pores mimicking the flow-induced passage of circulating tumor cells through microvasculature. By integrating high speed imaging, the device allows for the simultaneous characterization of five different parameters including the blockage pressure, cell velocity, cell size, elongation and the entry time into squeezer. We have tested a variety of in vitro cell lines, including brain and prostate cancer cell lines, and have found that the entry time is the most sensitive measurement capable of differentiating between cell lines with differing invasiveness.

Mechanical performance of cervical intervertebral body fusion devices: A systematic analysis of data submitted to the Food and Drug Administration.

PubMed

Peck, Jonathan H; Sing, David C; Nagaraja, Srinidhi; Peck, Deepa G; Lotz, Jeffrey C; Dmitriev, Anton E

2017-03-21

Cervical intervertebral body fusion devices (IBFDs) are utilized to provide stability while fusion occurs in patients with cervical pathology. For a manufacturer to market a new cervical IBFD in the United States, substantial equivalence to a cervical IBFD previously cleared by FDA must be established through the 510(k) regulatory pathway. Mechanical performance data are typically provided as part of the 510(k) process for IBFDs. We reviewed all Traditional 510(k) submissions for cervical IBFDs deemed substantially equivalent and cleared for marketing from 2007 through 2014. To reduce sources of variability in test methods and results, analysis was restricted to cervical IBFD designs without integrated fixation, coatings, or expandable features. Mechanical testing reports were analyzed and results were aggregated for seven commonly performed tests (static and dynamic axial compression, compression-shear, and torsion testing per ASTM F2077, and subsidence testing per ASTM F2267), and percentile distributions of performance measurements were calculated. Eighty-three (83) submissions met the criteria for inclusion in this analysis. The median device yield strength was 10,117N for static axial compression, 3680N for static compression-shear, and 8.6Nm for static torsion. Median runout load was 2600N for dynamic axial compression, 1400N for dynamic compression-shear, and ±1.5Nm for dynamic torsion. In subsidence testing, median block stiffness (Kp) was 424N/mm. The mechanical performance data presented here will aid in the development of future cervical IBFDs by providing a means for comparison for design verification purposes. Published by Elsevier Ltd.

[Research progress on mechanical performance evaluation of artificial intervertebral disc].

PubMed

Li, Rui; Wang, Song; Liao, Zhenhua; Liu, Weiqiang

2018-03-01

The mechanical properties of artificial intervertebral disc (AID) are related to long-term reliability of prosthesis. There are three testing methods involved in the mechanical performance evaluation of AID based on different tools: the testing method using mechanical simulator, in vitro specimen testing method and finite element analysis method. In this study, the testing standard, testing equipment and materials of AID were firstly introduced. Then, the present status of AID static mechanical properties test (static axial compression, static axial compression-shear), dynamic mechanical properties test (dynamic axial compression, dynamic axial compression-shear), creep and stress relaxation test, device pushout test, core pushout test, subsidence test, etc. were focused on. The experimental techniques using in vitro specimen testing method and testing results of available artificial discs were summarized. The experimental methods and research status of finite element analysis were also summarized. Finally, the research trends of AID mechanical performance evaluation were forecasted. The simulator, load, dynamic cycle, motion mode, specimen and test standard would be important research fields in the future.

Space Qualification Issues in Acousto-optic and Electro-optic Devices

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Taylor, Edward W.; Trivedi, Sudhir; Kutcher, Sue; Soos, Jolanta

2007-01-01

Satellite and space-based applications of photonic devices and systems require operational reliability in the harsh environment of space for extended periods of time. This in turn requires every component of the systems and their packaging to meet space qualifications. Acousto- and electro-optical devices form the major components of many current space based optical systems, which is the focus of this paper. The major space qualification issues are related to: mechanical stability, thermal effects and operation of the devices in the naturally occurring space radiation environment. This paper will discuss acousto- and electro-optic materials and devices with respect to their stability against mechanical vibrations, thermal cycling in operating and non-operating conditions and device responses to space ionizing and displacement radiation effects. Selection of suitable materials and packaging to meet space qualification criteria will also be discussed. Finally, a general roadmap for production and testing of acousto- and electro-optic devices will be discussed.

Design of a pulsatile flow facility to evaluate thrombogenic potential of implantable cardiac devices.

PubMed

Arjunon, Sivakkumar; Ardana, Pablo Hidalgo; Saikrishnan, Neelakantan; Madhani, Shalv; Foster, Brent; Glezer, Ari; Yoganathan, Ajit P

2015-04-01

Due to expensive nature of clinical trials, implantable cardiac devices should first be extensively characterized in vitro. Prosthetic heart valves (PHVs), an important class of these devices, have been shown to be associated with thromboembolic complications. Although various in vitro systems have been designed to quantify blood-cell damage and platelet activation caused by nonphysiological hemodynamic shear stresses in these PHVs, very few systems attempt to characterize both blood damage and fluid dynamics aspects of PHVs in the same test system. Various numerical modeling methodologies are also evolving to simulate the structural mechanics, fluid mechanics, and blood damage aspects of these devices. This article presents a completely hemocompatible small-volume test-platform that can be used for thrombogenicity studies and experimental fluid mechanics characterization. Using a programmable piston pump to drive freshly drawn human blood inside a cylindrical column, the presented system can simulate various physiological and pathophysiological conditions in testing PHVs. The system includes a modular device-mounting chamber, and in this presented case, a 23 mm St. Jude Medical (SJM) Regents® mechanical heart valve (MHV) in aortic position was used as the test device. The system was validated for its capability to quantify blood damage by measuring blood damage induced by the tester itself (using freshly drawn whole human blood). Blood damage levels were ascertained through clinically relevant assays on human blood while fluid dynamics were characterized using time-resolved particle image velocimetry (PIV) using a blood-mimicking fluid. Blood damage induced by the tester itself, assessed through Thrombin-anti-Thrombin (TAT), Prothrombin factor 1.2 (PF1.2), and hemolysis (Drabkins assay), was within clinically accepted levels. The hydrodynamic performance of the tester showed consistent, repeatable physiological pressure and flow conditions. In addition, the system contains proximity sensors to accurately capture leaflet motion during the entire cardiac cycle. The PIV results showed skewing of the leakage jet, caused by the asymmetric closing of the two leaflets. All these results are critical to characterizing the blood damage and fluid dynamics characteristics of the SJM Regents® MHV, proving the utility of this tester as a precise system for assessing the hemodynamics and thrombogenicity for various PHVs.

Functional Interrupts and Destructive Failures from Single Event Effect Testing of Point-Of-Load Devices

NASA Technical Reports Server (NTRS)

Chen, Dakai; Phan, Anthony; Kim, Hak; Swonger, James; Musil, Paul; LaBel, Kenneth

2013-01-01

We show examples of single event functional interrupt and destructive failure in modern POL devices. The increasing complexity and diversity of the design and process introduce hard SEE modes that are triggered by various mechanisms.

Total Dose Effects in Conventional Bipolar Transistors

NASA Technical Reports Server (NTRS)

Johnston, A. H.; Swift, G. W.; Rax, B. G.

1994-01-01

This paper examines various factors in bipolar device construction and design, and discusses their impact on radiation hardness. The intent of the paper is to improve understanding of the underlying mechanisms for practical devices without special test structures, and to provide (1) guidance in ways to select transistor designs that are more resistant to radiation damage, and (2) methods to estimate the maximum amount of damage that might be expected from a basic transistor design. The latter factor is extremely important in assessing the risk that future lots of devices will be substantially below design limits, which are usually based on test data for older devices.

Validation of a Portable Low-Power Deep Brain Stimulation Device Through Anxiolytic Effects in a Laboratory Rat Model.

PubMed

Kouzani, Abbas Z; Kale, Rajas P; Zarate-Garza, Pablo Patricio; Berk, Michael; Walder, Ken; Tye, Susannah J

2017-09-01

Deep brain stimulation (DBS) devices deliver electrical pulses to neural tissue through an electrode. To study the mechanisms and therapeutic benefits of deep brain stimulation, murine preclinical research is necessary. However, conducting naturalistic long-term, uninterrupted animal behavioral experiments can be difficult with bench-top systems. The reduction of size, weight, power consumption, and cost of DBS devices can assist the progress of this research in animal studies. A low power, low weight, miniature DBS device is presented in this paper. This device consists of electronic hardware and software components including a low-power microcontroller, an adjustable current source, an n-channel metal-oxide-semiconductor field-effect transistor, a coin-cell battery, electrode wires and a software program to operate the device. Evaluation of the performance of the device in terms of battery lifetime and device functionality through bench and in vivo tests was conducted. The bench test revealed that this device can deliver continuous stimulation current pulses of strength [Formula: see text], width [Formula: see text], and frequency 130 Hz for over 22 days. The in vivo tests demonstrated that chronic stimulation of the nucleus accumbens (NAc) with this device significantly increased psychomotor activity, together with a dramatic reduction in anxiety-like behavior in the elevated zero-maze test.

Novel scanning electron microscope bulge test technique integrated with loading function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chuanwei; Xie, Huimin, E-mail: liuzw@bit.edu.cn, E-mail: xiehm@mail.tsinghua.edu.cn; Liu, Zhanwei, E-mail: liuzw@bit.edu.cn, E-mail: xiehm@mail.tsinghua.edu.cn

2014-10-15

Membranes and film-on-substrate structures are critical elements for some devices in electronics industry and for Micro Electro Mechanical Systems devices. These structures are normally at the scale of micrometer or even nanometer. Thus, the measurement for the mechanical property of these membranes poses a challenge over the conventional measurements at macro-scales. In this study, a novel bulge test method is presented for the evaluation of mechanical property of micro thin membranes. Three aspects are discussed in the study: (a) A novel bulge test with a Scanning Electron Microscope system realizing the function of loading and measuring simultaneously; (b) a simplifiedmore » Digital Image Correlation method for a height measurement; and (c) an imaging distortion correction by the introduction of a scanning Moiré method. Combined with the above techniques, biaxial modulus as well as Young's modulus of the polyimide film can be determined. Besides, a standard tensile test is conducted as an auxiliary experiment to validate the feasibility of the proposed method.« less

The design and development of a high-throughput magneto-mechanostimulation device for cartilage tissue engineering.

PubMed

Brady, Mariea A; Vaze, Reva; Amin, Harsh D; Overby, Darryl R; Ethier, C Ross

2014-02-01

To recapitulate the in vivo environment and create neo-organoids that replace lost or damaged tissue requires the engineering of devices, which provide appropriate biophysical cues. To date, bioreactors for cartilage tissue engineering have focused primarily on biomechanical stimulation. There is a significant need for improved devices for articular cartilage tissue engineering capable of simultaneously applying multiple biophysical (electrokinetic and mechanical) stimuli. We have developed a novel high-throughput magneto-mechanostimulation bioreactor, capable of applying static and time-varying magnetic fields, as well as multiple and independently adjustable mechanical loading regimens. The device consists of an array of 18 individual stations, each of which uses contactless magnetic actuation and has an integrated Hall Effect sensing system, enabling the real-time measurements of applied field, force, and construct thickness, and hence, the indirect measurement of construct mechanical properties. Validation tests showed precise measurements of thickness, within 14 μm of gold standard calliper measurements; further, applied force was measured to be within 0.04 N of desired force over a half hour dynamic loading, which was repeatable over a 3-week test period. Finally, construct material properties measured using the bioreactor were not significantly different (p=0.97) from those measured using a standard materials testing machine. We present a new method for articular cartilage-specific bioreactor design, integrating combinatorial magneto-mechanostimulation, which is very attractive from functional and cost viewpoints.

Accelerated battery-life testing - A concept

NASA Technical Reports Server (NTRS)

Mccallum, J.; Thomas, R. E.

1971-01-01

Test program, employing empirical, statistical and physical methods, determines service life and failure probabilities of electrochemical cells and batteries, and is applicable to testing mechanical, electrical, and chemical devices. Data obtained aids long-term performance prediction of battery or cell.

Fiber optic tracheal detection device

NASA Astrophysics Data System (ADS)

Souhan, Brian E.; Nawn, Corinne D.; Shmel, Richard; Watts, Krista L.; Ingold, Kirk A.

2017-02-01

Poorly performed airway management procedures can lead to a wide variety of adverse events, such as laryngeal trauma, stenosis, cardiac arrest, hypoxemia, or death as in the case of failed airway management or intubation of the esophagus. Current methods for confirming tracheal placement, such as auscultation, direct visualization or capnography, may be subjective, compromised due to clinical presentation or require additional specialized equipment that is not always readily available during the procedure. Consequently, there exists a need for a non-visual detection mechanism for confirming successful airway placement that can give the provider rapid feedback during the procedure. Based upon our previously presented work characterizing the reflectance spectra of tracheal and esophageal tissue, we developed a fiber-optic prototype to detect the unique spectral characteristics of tracheal tissue. Device performance was tested by its ability to differentiate ex vivo samples of tracheal and esophageal tissue. Pig tissue samples were tested with the larynx, trachea and esophagus intact as well as excised and mounted on cork. The device positively detected tracheal tissue 18 out of 19 trials and 1 false positive out of 19 esophageal trials. Our proof of concept device shows great promise as a potential mechanism for rapid user feedback during airway management procedures to confirm tracheal placement. Ongoing studies will investigate device optimizations of the probe for more refined sensing and in vivo testing.

Spectral (optical) and mechanical responses of fresh and cryopreserved issued arteries

NASA Astrophysics Data System (ADS)

Pery, Emilie; Blondel, Walter C.; Goebel, Jean-Christophe; Didelon, Jacques; Guillemin, Francois

2005-04-01

Cryopreservation is the only method for conserving blood vessels as future allografts with biological immunity controls. Although it affects vessels mechanical structure, no biomechanical integrity simple test is available today. Biological tissues optical properties characterization by spectroscopic methods is of interest due to their types or natures variations. Collected data complementarity contributes to "photodiagnosis" applicative prospects (cancer, vascular...). Pig carotid artery rings were tested after excision and after one month cryopreservation. An uniaxial mechanical testing device was used for ring stretching, and elongation and axial forces measurement. Circumferential large strains and stresses were calculated. Simultaneously, each artery ring optical characteristics was measured using fibered autofluorescence and elastic scattering spectrometers. Mechanical results showed nonlinear strain/stress curves and large deformations in good agreement with other referenced works. Significant differences (p<0.05) between fresh and cryopreserved rings mechanical properties were noticed. Elastic scattering spectra intensity variations were well correlated with artery mechanical properties. The standardized autofluorescence spectra were more clearly correlated with anatomo-histological changes due to cryopreservation, providing rather accurate differentiation between fresh and cryopreserved samples. This study offers a new perspective to detect changes of cryopreserved arterial samples mechanical properties. Coupling mechanical tests (uniaxial traction of arterial rings) and optical spectroscopic measurements (autofluorescence, elastic scattering) is the driving point: it allows correlating mechanical modifications and spectral variations of artery rings before and after cryopreservation. Ultimately, this new approach could help developping a device allowing non-invasive, atraumatic and contactless optical examinations of arterial graft to assess its mechanical state before reimplantation.

SPILL ALERT DEVICE FOR EARTH DAM FAILURE WARNING

EPA Science Inventory

A spill alert device for determining earth dam safety based on the monitoring of the acoustic emissions generated in a deforming soil mass was developed and field-tested. The acoustic emissions are related to the basic mechanisms from which soils derive their strength. Laboratory...

Molecular switches and motors on surfaces.

PubMed

Pathem, Bala Krishna; Claridge, Shelley A; Zheng, Yue Bing; Weiss, Paul S

2013-01-01

Molecular switches and motors respond structurally, electronically, optically, and/or mechanically to external stimuli, testing and potentially enabling extreme miniaturization of optoelectronic devices, nanoelectromechanical systems, and medical devices. The assembly of motors and switches on surfaces makes it possible both to measure the properties of individual molecules as they relate to their environment and to couple function between assembled molecules. In this review, we discuss recent progress in assembling molecular switches and motors on surfaces, measuring static and dynamic structures, understanding switching mechanisms, and constructing functional molecular materials and devices. As demonstrative examples, we choose a representative molecule from three commonly studied classes including molecular switches, photochromic molecules, and mechanically interlocked molecules. We conclude by offering perspectives on the future of molecular switches and motors on surfaces.

Smart Materials for Electromagnetic and Optical Applications

NASA Astrophysics Data System (ADS)

Ramesh, Prashanth

The research presented in this dissertation focuses on the development of solid-state materials that have the ability to sense, act, think and communicate. Two broad classes of materials, namely ferroelectrics and wideband gap semiconductors were investigated for this purpose. Ferroelectrics possess coupled electromechanical behavior which makes them sensitive to mechanical strains and fluctuations in ambient temperature. Use of ferroelectrics in antenna structures, especially those subject to mechanical and thermal loads, requires knowledge of the phenomenological relationship between the ferroelectric properties of interest (especially dielectric permittivity) and the external physical variables, viz. electric field(s), mechanical strains and temperature. To this end, a phenomenological model of ferroelectric materials based on the Devonshire thermodynamic theory was developed. This model was then used to obtain a relationship expressing the dependence of the dielectric permittivity on the mechanical strain, applied electric field and ambient temperature. The relationship is shown to compare well with published experimental data and other related models in literature. A model relating ferroelectric loss tangent to the applied electric field and temperature is also discussed. Subsequently, relationships expressing the dependence of antenna operating frequency and radiation efficiency on those external physical quantities are described. These relationships demonstrate the tunability of load-bearing antenna structures that integrate ferroelectrics when they are subjected to mechanical and thermal loads. In order to address the inability of ferroelectrics to integrate microelectronic devices, a feature needed in a material capable of sensing, acting, thinking and communicating, the material Gallium Nitride (GaN) is pursued next. There is an increasing utilization of GaN in the area of microelectronics due to the advantages it offers over other semiconductors. This dissertation demonstrates GaN as a candidate material well suited for novel microelectromechanical systems. The potential of GaN for MEMS is demonstrated via the design, analysis, fabrication, testing and characterization of an optical microswitch device actuated by piezoelectric and electrostrictive means. The piezoelectric and electrostrictive properties of GaN and its differences from common piezoelectrics are discussed before elaborating on the device configuration used to implement the microswitch device. Next, the development of two recent fabrication technologies, Photoelectrochemical etch and Bias-enabled Dark Electrochemical etch, used to realize the 3-dimensional device structure in GaN are described in detail. Finally, an ultra-low-cost, laser-based, non-contact approach to test and characterize the microswitch device is described, followed by the device testing results.

Human and bovine spinal disc mechanics subsequent to trypsin injection.

PubMed

Alsup, Jeremy; Bishop, Timothy; Eggett, Dennis; Bowden, Anton E

2017-10-01

To investigate the biomechanical effects of injections of a protease on the characteristics of bovine coccygeal and human lumbar disc motion segments. Mechanics of treated tissues were measured immediately after injection and 3 h after injection. Motion segments underwent axial rotation and flexion-extension loading. Stiffness and neutral zone parameters experienced significant changes over time, with bovine tissues more strongly affected than human cadaver tissues. This was true in both axial rotation and flexion-extension. The treatment type significantly affected the neutral zone measurements in axial rotation. Hysteresis parameters were impacted by control injections. The extrapolation of bovine coccygeal motion testing results to human lumbar disc mechanics is not yet practical. The injected treatment may have a smaller impact on disc mechanics than time in testing. Viscoelasticity of human lumbar discs may be impacted by any damage to the annulus fibrosis induced by needlestick. Preclinical testing of novel spinal devices is essential to the design validation and regulatory processes, but current testing techniques rely on cadaveric testing of primarily older spines with essentially random amounts of disc degeneration. The present work investigates the viability of using trypsin injections to create a more uniform preclinical model of disc degeneration from a mechanics perspective, for the purpose of testing spinal devices. Such a model would facilitate translation of new spinal technologies to clinical practice.

Determining the structure-mechanics relationships of dense microtubule networks with confocal microscopy and magnetic tweezers-based microrheology.

PubMed

Yang, Yali; Valentine, Megan T

2013-01-01

The microtubule (MT) cytoskeleton is essential in maintaining the shape, strength, and organization of cells. Its spatiotemporal organization is fundamental for numerous dynamic biological processes, and mechanical stress within the MT cytoskeleton provides an important signaling mechanism in mitosis and neural development. This raises important questions about the relationships between structure and mechanics in complex MT structures. In vitro, reconstituted cytoskeletal networks provide a minimal model of cell mechanics while also providing a testing ground for the fundamental polymer physics of stiff polymer gels. Here, we describe our development and implementation of a broad tool kit to study structure-mechanics relationships in reconstituted MT networks, including protocols for the assembly of entangled and cross-linked MT networks, fluorescence imaging, microstructure characterization, construction and calibration of magnetic tweezers devices, and mechanical data collection and analysis. In particular, we present the design and assembly of three neodymium iron boron (NdFeB)-based magnetic tweezers devices optimized for use with MT networks: (1) high-force magnetic tweezers devices that enable the application of nano-Newton forces and possible meso- to macroscale materials characterization; (2) ring-shaped NdFeB-based magnetic tweezers devices that enable oscillatory microrheology measurements; and (3) portable magnetic tweezers devices that enable direct visualization of microscale deformation in soft materials under applied force. Copyright © 2013 Elsevier Inc. All rights reserved.

Tunable Microfluidic Devices for Hydrodynamic Fractionation of Cells and Beads: A Review

PubMed Central

Alvankarian, Jafar; Majlis, Burhanuddin Yeop

2015-01-01

The adjustable microfluidic devices that have been developed for hydrodynamic-based fractionation of beads and cells are important for fast performance tunability through interaction of mechanical properties of particles in fluid flow and mechanically flexible microstructures. In this review, the research works reported on fabrication and testing of the tunable elastomeric microfluidic devices for applications such as separation, filtration, isolation, and trapping of single or bulk of microbeads or cells are discussed. Such microfluidic systems for rapid performance alteration are classified in two groups of bulk deformation of microdevices using external mechanical forces, and local deformation of microstructures using flexible membrane by pneumatic pressure. The main advantage of membrane-based tunable systems has been addressed to be the high capability of integration with other microdevice components. The stretchable devices based on bulk deformation of microstructures have in common advantage of simplicity in design and fabrication process. PMID:26610519

Micro Electromechanical Systems (MEMS) Based Microfluidic Devices for Biomedical Applications

PubMed Central

Ashraf, Muhammad Waseem; Tayyaba, Shahzadi; Afzulpurkar, Nitin

2011-01-01

Micro Electromechanical Systems (MEMS) based microfluidic devices have gained popularity in biomedicine field over the last few years. In this paper, a comprehensive overview of microfluidic devices such as micropumps and microneedles has been presented for biomedical applications. The aim of this paper is to present the major features and issues related to micropumps and microneedles, e.g., working principles, actuation methods, fabrication techniques, construction, performance parameters, failure analysis, testing, safety issues, applications, commercialization issues and future prospects. Based on the actuation mechanisms, the micropumps are classified into two main types, i.e., mechanical and non-mechanical micropumps. Microneedles can be categorized according to their structure, fabrication process, material, overall shape, tip shape, size, array density and application. The presented literature review on micropumps and microneedles will provide comprehensive information for researchers working on design and development of microfluidic devices for biomedical applications. PMID:21747700

Electrorheological Fluid Based Force Feedback Device

NASA Technical Reports Server (NTRS)

Pfeiffer, Charles; Bar-Cohen, Yoseph; Mavroidis, Constantinos; Dolgin, Benjamin

1999-01-01

Parallel to the efforts to develop fully autonomous robots, it is increasingly being realized that there are applications where it is essential to have a fully controlled robot and "feel" its operating conditions, i.e. telepresence. This trend is a result of the increasing efforts to address tasks where humans can perform significantly better but, due to associated hazards, distance, physical limitations and other causes, only robots can be employed to perform these tasks. Such robots need to be assisted by a human that remotely controls the operation. To address the goal of operating robots as human surrogates, the authors launched a study of mechanisms that provide mechanical feedback. For this purpose, electrorheological fluids (ERF) are being investigated for the potential application as miniature haptic devices. This family of electroactive fluids has the property of changing the viscosity during electrical stimulation. Consequently, ERF can be used to produce force feedback haptic devices for tele-operated control of medical and space robotic systems. Forces applied at the robot end-effector due to a compliant environment are reflected to the user using an ERF device where a change in the system viscosity will occur proportionally to the transmitted force. Analytical model and control algorithms are being developed taking into account the non-linearities of these type of devices. This paper will describe the concept and the developed mechanism of ERF based force feedback. The test process and the physical properties of this device will be described and the results of preliminary tests will be presented.

A flexible, planar energy harvesting device for scavenging road side waste mechanical energy via the synergistic piezoelectric response of K0.5Na0.5NbO3-BaTiO3/PVDF composite films.

PubMed

Vivekananthan, Venkateswaran; Alluri, Nagamalleswara Rao; Purusothaman, Yuvasree; Chandrasekhar, Arunkumar; Kim, Sang-Jae

2017-10-12

Flexible, planar composite piezoelectric nanogenerators (C-PNGs) were developed to harness waste mechanical energy using cost-effective composite films (CFs) prepared via a probe-sonication technique. CFs, made up of highly crystalline, randomly oriented lead free piezoelectric nanoparticles (1 - x)K 0.5 Na 0.5 NbO 3 -xBaTiO 3 , where x = 0.02, 0.04, 0.06, or 0.08 [designated as KNN-xBTO], were impregnated in a polyvinylidene fluoride (PVDF) matrix. The KNN piezoelectric properties were tuned via the substitution of BTO nanoparticles, without altering the orthorhombic phase. A C-PNG device (x ≈ 0.02) generates a maximum open circuit voltage ≈160 V, and the instantaneous area power density is ≈14 mW m -2 upon a low mechanical force ≈0.4 N. The effects of BTO concentration in the KNN lattice, electrical poling effects, the fixed weight ratio of nanoparticles in the PVDF matrix, switching polarity tests, and load resistance analysis of C-PNG devices were investigated with constant mechanical force. Furthermore, the experimentally demonstrated C-PNG device output is sufficient to drive commercial blue light emitting diodes. The C-PNG device was placed on a road side, and the maximum energy generation and stability under real time harsh conditions, such as vehicle motion (motorcycle and bicycle) and human walking, were tested. C-PNG generates a peak-to-peak output voltage ≈16 V, when motorcycle forward/backward motion acts on it. This result indicates that the C-PNG device is a potential candidate to power road side sensors, speed tachometers, light indicators, etc. on highways.

Reliability Testing of NASA Piezocomposite Actuators

NASA Technical Reports Server (NTRS)

Wilkie, W.; High, J.; Bockman, J.

2002-01-01

NASA Langley Research Center has developed a low-cost piezocomposite actuator which has application for controlling vibrations in large inflatable smart space structures, space telescopes, and high performance aircraft. Tests show the NASA piezocomposite device is capable of producing large, directional, in-plane strains on the order of 2000 parts-per-million peak-to-peak, with no reduction in free-strain performance to 100 million electrical cycles. This paper describes methods, measurements, and preliminary results from our reliability evaluation of the device under externally applied mechanical loads and at various operational temperatures. Tests performed to date show no net reductions in actuation amplitude while the device was moderately loaded through 10 million electrical cycles. Tests were performed at both room temperature and at the maximum operational temperature of the epoxy resin system used in manufacture of the device. Initial indications are that actuator reliability is excellent, with no actuator failures or large net reduction in actuator performance.

A Wearable Body Controlling Device for Application of Functional Electrical Stimulation

PubMed Central

Jeffery, Nicholas D.

2018-01-01

In this research, we describe a new balancing device used to stabilize the rear quarters of a patient dog with spinal cord injuries. Our approach uses inertial measurement sensing and direct leg actuation to lay a foundation for eventual muscle control by means of direct functional electrical stimulation (FES). During this phase of development, we designed and built a mechanical test-bed to develop the control and stimulation algorithms before we use the device on our animal subjects. We designed the bionic test-bed to mimic the typical walking gait of a dog and use it to develop and test the functionality of the balancing device for stabilization of patient dogs with hindquarter paralysis. We present analysis for various muscle stimulation and balancing strategies, and our device can be used by veterinarians to tailor the stimulation strength and temporal distribution for any individual patient dog. We develop stabilizing muscle stimulation strategies using the robotic test-bed to enhance walking stability. We present experimental results using the bionic test-bed to demonstrate that the balancing device can provide an effective sensing strategy and deliver the required motion control commands for stabilizing an actual dog with a spinal cord injury. PMID:29670039

A Wearable Body Controlling Device for Application of Functional Electrical Stimulation.

PubMed

Taghavi, Nazita; Luecke, Greg R; Jeffery, Nicholas D

2018-04-18

In this research, we describe a new balancing device used to stabilize the rear quarters of a patient dog with spinal cord injuries. Our approach uses inertial measurement sensing and direct leg actuation to lay a foundation for eventual muscle control by means of direct functional electrical stimulation (FES). During this phase of development, we designed and built a mechanical test-bed to develop the control and stimulation algorithms before we use the device on our animal subjects. We designed the bionic test-bed to mimic the typical walking gait of a dog and use it to develop and test the functionality of the balancing device for stabilization of patient dogs with hindquarter paralysis. We present analysis for various muscle stimulation and balancing strategies, and our device can be used by veterinarians to tailor the stimulation strength and temporal distribution for any individual patient dog. We develop stabilizing muscle stimulation strategies using the robotic test-bed to enhance walking stability. We present experimental results using the bionic test-bed to demonstrate that the balancing device can provide an effective sensing strategy and deliver the required motion control commands for stabilizing an actual dog with a spinal cord injury.

Analysis of a Memory Device Failure

NASA Technical Reports Server (NTRS)

Nicolas, David P.; Devaney, John; Gores, Mark; Dicken, Howard

1998-01-01

The recent failure of a vintage memory device presented a unique challenge to failure analysts. Normally device layouts, fabrication parameters and other technical information were available to assist the analyst in the analysis. However, this device was out of production for many years and the manufacturer was no longer in business, so the information was not available. To further complicate this analysis, the package leads were all but removed making additional electrical testing difficult. Under these conditions, new and innovative methods were used to analyze the failure. The external visual exam, radiography, PIND, and leak testing were performed with nominal results. Since electrical testing was precluded by the short lead lengths, the device was delidded to expose the internal structures for microscopic examination. No failure mechanism was identified. The available electrical data suggested an ESD or low level EOS type mechanism which left no visible surface damage. Due to parallel electrical paths, electrical probing on the chip failed to locate the failure site. Two non-destructive Scanning Electron Microscopy techniques, CIVA (Charge Induced Voltage Alteration) and EBIC (Electron Beam Induced Current), and a liquid crystal decoration technique which detects localized heating were employed to aid in the analysis. CIVA and EBIC isolated two faults in the input circuitry, and the liquid crystal technique further localized two hot spots in regions on two input gates. Removal of the glassivation and metallization revealed multiple failure sites located in the gate oxide of two input transistors suggesting machine (testing) induced damage.

Characterization of deformable materials in the THOR dummy

DOT National Transportation Integrated Search

2000-01-01

Methodologies used to characterize the mechanical behavior of various materials used in the construction of the crash test dummy called THOR (Test device for Human Occupant Restraint) are described. These materials include polyurethane, neoprene, and...

Bulk and surface loss in superconducting transmon qubits

NASA Astrophysics Data System (ADS)

Dial, Oliver; McClure, Douglas T.; Poletto, Stefano; Keefe, G. A.; Rothwell, Mary Beth; Gambetta, Jay M.; Abraham, David W.; Chow, Jerry M.; Steffen, Matthias

2016-04-01

Decoherence of superconducting transmon qubits is purported to be consistent with surface loss from two-level systems on the substrate surface. Here, we present a study of surface loss in transmon devices, explicitly designed to have varying sensitivities to different surface loss contributors. Our experiments also encompass two particular different sapphire substrates, which reveal the onset of a yet unknown additional loss mechanism outside of surface loss for one of the substrates. Tests across different wafers and devices demonstrate substantial variation, and we emphasize the importance of testing large numbers of devices for disentangling different sources of decoherence.

A bio-inspired design of a hand robotic exoskeleton for rehabilitation

NASA Astrophysics Data System (ADS)

Ong, Aira Patrice R.; Bugtai, Nilo T.

2018-02-01

This paper presents the methodology for the design of a five-degree of freedom wearable robotic exoskeleton for hand rehabilitation. The design is inspired by the biological structure and mechanism of the human hand. One of the distinct features of the device is the cable-driven actuation, which provides the flexion and extension motion. A prototype of the orthotic device has been developed to prove the model of the system and has been tested in a 3D printed mechanical hand. The result showed that the proposed device was consistent with the requirements of bionics and was able to demonstrate the flexion and extension of the system.

Laser-machined piezoelectric cantilevers for mechanical energy harvesting.

PubMed

Kim, HyunUk; Bedekar, Vishwas; Islam, Rashed Adnan; Lee, Woo-Ho; Leo, Don; Priya, Shashank

2008-09-01

In this study, we report results on a piezoelectric- material-based mechanical energy-harvesting device that was fabricated by combining laser machining with microelectronics packaging technology. It was found that the laser-machining process did not have significant effect on the electrical properties of piezoelectric material. The fabricated device was tested in the low-frequency regime of 50 to 1000 Hz at constant force of 8 g (where g = 9.8 m/s(2)). The device was found to generate continuous power of 1.13 microW at 870 Hz across a 288.5 kOmega load with a power density of 301.3 microW/cm(3).

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee.

PubMed

Prabhala, Sai Krishna; Chien, Stanley; Yokota, Hiroki; Anwar, Sohel

2016-09-29

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force. The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality. The results reveal that the device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments.

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee

PubMed Central

Prabhala, Sai Krishna; Chien, Stanley; Yokota, Hiroki; Anwar, Sohel

2016-01-01

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force. The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality. The results reveal that the device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments. PMID:27690057

Flight Investigation of a Mechanical Feel Device in an Irreversible Elevator Control System of a Large Airplane

NASA Technical Reports Server (NTRS)

Brown, B Porter; Chilton, Robert G; Whitten, James B

1952-01-01

Report presents the results of measurements of the longitudinal stability and control characteristics of a large airplane using a mechanical feel device in combination with a booster incorporated in the elevator-control system. Tests were made to investigate the feasibility of eliminating the aerodynamic control forces through use of a booster and of providing control-feel forces mechanically. The feel device consisted of a centering spring which restrained the control stick through a linkage which was changed as a function of the dynamic pressure. Provisions were made for trimming and for manual adjustment of the force gradient. The system was designed to approximate the control-force characteristics that would result with a conventional elevator control with linear hinge-moment characteristics.

Comparison of mechanical properties of multi-walled carbon nanotube and graphene nanosheet/polyethylene oxide composites plasticized with lithium triflate

NASA Astrophysics Data System (ADS)

Jurkane, A.; Gaidukov, S.

2017-10-01

A strong engineering interest in nanostructured conducting polymers and its composite materials have been widely used to build various sensor devices, electronic interconnect devices, fuel cells and batteries. Preparation of polymeric nano-composites with finely controlled structure, especially, at nano-scale, is still one of the most perspective modification ways of the properties of polymeric composites. Multi-walled carbon nanotube (MWCNT)/polyethylene oxide (PEO) and graphene nanosheets (GR)/PEO composites and composite of MWCNT/GR/PEO were prepared by solution casting and hot-pressing method. Composites were plasticized by 5% of Lithium triflate (LiTrifl), which play role of additional ion source in conducting polymer composite. Mechanical tensile tests were performed to evaluate nanoparticles influence on the mechanical strength of the conductive polymer composite materials. Difference of tensile tests of prepared composition can be seen from tensile tests data curves. The results of tensile tests indicated that the nanoparticles can provide PEO/5%LiTrifl composite with stiffening effects at rather low filler content (at least 0.05% by volume).

Handcrafted cuff manometers do not accurately measure endotracheal tube cuff pressure

PubMed Central

Annoni, Raquel; de Almeida, Antonio Evanir

2015-01-01

Objective To test the agreement between two handcrafted devices and a cuff-specific manometer. Methods The agreement between two handcrafted devices adapted to measure tracheal tube cuff pressure and a cuff-specific manometer was tested on 79 subjects. The cuff pressure was measured with a commercial manometer and with two handcrafted devices (HD) assembled with aneroid sphygmomanometers (HD1 and HD2). The data were compared using Wilcoxon and Spearman tests, the intraclass correlation coefficient (ICC) and limit-of-agreement analysis. Results Cuff pressures assessed with handcrafted devices were significantly different from commercial device measurements (pressures were higher when measured with HD1 and lower with HD2). The ICCs between the commercial device and HD1 and HD2 were excellent (ICC = 0.8 p < 0.001) and good (ICC = 0.66, p < 0.001), respectively. However, the Bland- Altman plots showed wide limits of agreement between HD1 and HD2 and the commercial device. Conclusion The handcrafted manometers do not provide accurate cuff pressure measurements when compared to a cuff-specific device and should not be used to replace the commercial cuff manometers in mechanically ventilated patients. PMID:26376160

Methods of measuring water levels in deep wells

USGS Publications Warehouse

Garber, M.S.; Koopman, F. C.

1968-01-01

Accurate measurement of water levels deeper than 1,000 feet in wells requires specialized equipment. Corrections for stretch and thermal expansion of measuring tapes must be considered, and other measuring devices must be calibrated periodically. Bore-hole deviation corrections also must be made. Devices for recording fluctuation of fluid level usually require mechanical modification for use at these depths. A multichannel recording device utilizing pressure transducers has been constructed. This device was originally designed to record aquifer response to nearby underground nuclear explosions but can also be used for recording data from multi-well pumping tests. Bottom-hole recording devices designed for oil-field use have been utilized in a limited manner. These devices were generally found to lack the precision required, in ground-water investigations at the Nevada Test Site but may be applicable in other areas. A newly developed bottom-hole recording pressure gauge of improved accuracy has been used with satisfactory results.

Design and development of a biomimetic device for micro air vehicles

NASA Astrophysics Data System (ADS)

Bohorquez, Felipe; Pines, Darryll J.

2002-07-01

This paper presents the design and development of a pitching and plunging (flapping) mechanism for small-scale flight. In order to harness the unsteady lift mechanisms, used by most insects, a biologically inspired flapping/pitching device in conjunction with a rotary wing concept was developed and built. This mechanism attempts to replicate some of the aerodynamic phenomena that enhance the performance of small fliers, replacing the periodic translational motion with a unidirectional circular motion while actively flapping and pitching the rotor blades. In order to find the appropriate combination of phase, amplitude, frequency and rotational speed that leads to enhancement in lift, the device requires uncoupled independent pitch and flap actuation systems to permit the complete mapping of the parameter space. In the device under consideration the phase shift between the flapping and the pitching oscillations can be adjusted from 0 to 360 degrees over a wide range of rotational speeds. Maximum flapping and pitching amplitudes of +/- 23 degree(s) and +/- 20 degree(s) respectively can be attained. Linear displacements of two coaxial shafts are translated into the flapping and pitching motion of the rotor blades. The mechanism was designed to minimize the actuation stroke so that smart materials and conventional actuators such as motors and cams could be used. Kinematic analysis as well as experimental tests were performed. Using a customized test stand thrust and torque produced by the rotor were measured at different angles of attack, in steady-state and under periodical pitching actuation. The results showed that hover efficiency was considerably increased for a range of thrust coefficients. The device was developed based on the University of Maryland's rotary wing Micro Air vehicle (MAV) the MICOR (MIcro COaxial Rotorcraft), an electrically driven 100 g coaxial helicopter. It is anticipated that active flapping and/or pitching could be implemented in the prototype to improve its aerodynamic performance. The present paper will discuss the design and development process of a rotating/pitching/flapping mechanism for MAVs. Test results indicate that unsteady pitching motion can be used to include the aerodynamic effect of delayed stall. Performance measurements confirm that unsteady pitching motion improves efficiency in hover.

Design, Fabrication, Processing, and Testing of Micro-Electro-Mechanical Chemical Sensors

DTIC Science & Technology

1995-12-01

sensor ...... .......................... 118 71. Resonating bridge parameter curves ...... ......................... 119 72. Low frequency oscillations...131 82. Heater V-I curve .. .. .. .. ... ... ... ... ... ... ... ... ..... 132 83. Frequency response of heated chemoresistor...devices, including devices that may be pre-stressed due to fabrication procedures (i.e. curve out of the plane after being released)? Due to their

Mechanical Characterization of Polysilicon MEMS: A Hybrid TMCMC/POD-Kriging Approach.

PubMed

Mirzazadeh, Ramin; Eftekhar Azam, Saeed; Mariani, Stefano

2018-04-17

Microscale uncertainties related to the geometry and morphology of polycrystalline silicon films, constituting the movable structures of micro electro-mechanical systems (MEMS), were investigated through a joint numerical/experimental approach. An on-chip testing device was designed and fabricated to deform a compliant polysilicon beam. In previous studies, we showed that the scattering in the input–output characteristics of the device can be properly described only if statistical features related to the morphology of the columnar polysilicon film and to the etching process adopted to release the movable structure are taken into account. In this work, a high fidelity finite element model of the device was used to feed a transitional Markov chain Monte Carlo (TMCMC) algorithm for the estimation of the unknown parameters governing the aforementioned statistical features. To reduce the computational cost of the stochastic analysis, a synergy of proper orthogonal decomposition (POD) and kriging interpolation was adopted. Results are reported for a batch of nominally identical tested devices, in terms of measurement error-affected probability distributions of the overall Young’s modulus of the polysilicon film and of the overetch depth.

Mechanical Properties of Polymers Used for Anatomical Components in the Warrior Injury Assessment Manikin (WIAMan) Technology Demonstrator

DTIC Science & Technology

2016-07-01

14. ABSTRACT The Warrior Injury Assessment Manikin was developed to provide an instrumented anthropomorphic test device (ATD) specifically...underbody blasts . To achieve that goal, the ATD used numerous polymeric materials for component parts that simulate human tissue and enable compliance in...strain rate, underbody blast , mechanical testing, tension, compression 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT

Considerations for ex vivo thermal tissue testing exemplified using the fresh porcine longissimus muscle model for endometrial ablation

NASA Astrophysics Data System (ADS)

Fugett, James H.; Bennett, Haydon E.; Shrout, Joshua L.; Coad, James E.

2017-02-01

Expansions in minimally invasive medical devices and technologies with thermal mechanisms of action are continuing to advance the practice of medicine. These expansions have led to an increasing need for appropriate animal models to validate and quantify device performance. The planning of these studies should take into consideration a variety of parameters, including the appropriate animal model (test system - ex vivo or in vivo; species; tissue type), treatment conditions (test conditions), predicate device selection (as appropriate, control article), study timing (Day 0 acute to more than Day 90 chronic survival studies), and methods of tissue analysis (tissue dissection - staining methods). These considerations are discussed and illustrated using the fresh extirpated porcine longissimus muscle model for endometrial ablation.

In-situ photopolymerization and monitoring device for controlled shaping of tissue fillers, replacements, or implants

NASA Astrophysics Data System (ADS)

Schmocker, Andreas M.; Khoushabi, Azadeh; Bourban, Pierre-Etienne; Schizas, Constantin; Pioletti, Dominique; Moser, Christophe

2015-03-01

Photopolymerization is a common tool to harden materials initially in a liquid state. A surgeon can directly trigger the solidification of a dental implant or a bone or tissue filler simply by illumination. Traditionally, photopolymerization has been used mainly in dentistry. Over the last decade advances in material development including a wide range of biocompatible gel- and cement-systems open up a new avenue for in-situ photopolymerization. However, at the device level, surgical endoscopic probes are required. We present a miniaturized light probe where a photoactive material can be 1) mixed, pressurized and injected 2) photopolymerized or photoactivated and 3) monitored during the chemical reaction. The device enables surgeries to be conducted through a hole smaller than 1 mm in diameter. Beside basic injection mechanics, the tool consists of an optical fiber guiding the light required for photopolymerization and for chemical analysis. Combining photorheology and fluorescence spectroscopy, the current state of the photopolymerization is inferred and monitored in real time. Biocompatible and highly tuneable Poly-Ethylene-Glycol (PEG) hydrogels were used as the injection material. The device was tested on a model for intervertebral disc replacement. Gels were successfully implanted into a bovine caudal model and mechanically tested in-vitro during two weeks. The photopolymerized gel was evaluated at the tissue level (adherence and mechanical properties of the implant), at the cellular level (biocompatibility and cytotoxicity) and ergonomic level (sterilization procedure and feasibility study). This paper covers the monitoring aspect of the device.

Use of patient specific 3D printed (3DP) neurovascular phantoms for mechanical assessment of devices used in image guided minimally invasive procedures

NASA Astrophysics Data System (ADS)

Tabaczynski, Janelle R.; Stoll, Thomas; Shepard, Lauren; Siddiqui, Mohamed I. G.; Karkhanis, Nitant V.; Sommer, Kelsey; Siddiqui, Adnan H.; Ionita, Ciprian N.

2018-03-01

Patient-specific 3D printed phantoms (3DP) can reproduce accurate patient geometry and provide precise tools for Endovascular Image Guided Interventions (EIGI) simulations. We propose to build and test 3DP phantoms which mimic the arterial wall elasticity and surface properties and demonstrate their utility in comprehensive EIGI simulations. 3DP idealized and patient specific vascular phantoms were manufactured using Stratasys Objet 500 Connex 3. The idealized phantoms were created using a sine wave shape, patient specific phantoms were based on CT- angiography volumes. The phantoms were coated with a hydrophilic material to mimic vascular surface properties. We tested various endovascular procedures using an Interventional Device Testing Equipment (IDTE) 2000 and measured push/pull force used to actuate endovascular devices during EIGIs. The force needed to advance devices in neurovascular phantoms varied based on tortuosity, material and coating, ranging from -3 to 21 grams-force. Hydrophilic coating reduced maximum force from 21 to 4.8 grams-force in the same model. IDTE 2000 results of neurovascular models were compared to hand manipulation of guidewire access using a six-axis force sensor with forces ranging from -50 to 440 grams. The clot retriever tested in carotid models experienced most friction around tortuous bends ranging from -65 to -90 grams-force, with increasing rigidity of materials creating increased friction. Sine wave model forces varied from -2 to 105 grams. 3DP allows manufacturing of vascular phantoms with precise mechanical and surface properties which can be used for EIGI simulations for imaging protocol optimization and device behavior assessment.

Efficacy of anti-retraction devices in preventing bacterial contamination of dental unit water lines.

PubMed

Berlutti, Francesca; Testarelli, Luca; Vaia, Francesco; De Luca, Massimo; Dolci, Giovanni

2003-02-01

In this study we examine the efficacy of anti-retraction devices in preventing microbial contamination of dental unit water lines (DUWLs). The study was performed on 54 randomly selected DUs in use at private and public institutions for over six months. The selected DUs were all currently commercially available. To evaluate the efficiency of anti-retraction devices, two different methods were employed, mechanical and microbiological. The ADA/ANSI specification #47 (corresponding to a water retraction of less than 40.3 microl) was used for the evaluation of the retraction determined using the mechanical method; the presence/absence of test microorganisms in DUWLs upstream the turbine after the test was used for evaluating the microbiological assay. Both evaluation methods indicated correct amounts of retraction and prevention of DUWL contamination occurred in only two cases (3.7%). Correct retraction was noted in six other dental units (DUs), but their DUWLs became contaminated during testing. Six other produced the opposite results-improper retraction, yet no contamination. The remaining 40 DUs (74.0%) failed both evaluations. The results showed that the overwhelming majority of the anti-retraction devices did not prevent retraction when the turbine stopped running, leading to a contamination of the water lines, and to a consequent possible cross-contamination of the patients.

Effect of Electrostatic Discharge on Electrical Characteristics of Discrete Electronic Components

NASA Technical Reports Server (NTRS)

Wysocki, Phil; Vashchenko, Vladislav; Celaya, Jose; Saha, Sankalita; Goebel, Kai

2009-01-01

This article reports on preliminary results of a study conducted to examine how temporary electrical overstress seed fault conditions in discrete power electronic components that cannot be detected with reliability tests but impact longevity of the device. These defects do not result in formal parametric failures per datasheet specifications, but result in substantial change in the electrical characteristics when compared with pristine device parameters. Tests were carried out on commercially available 600V IGBT devices using transmission line pulse (TLP) and system level ESD stress. It was hypothesized that the ESD causes local damage during the ESD discharge which may greatly accelerate degradation mechanisms and thus reduce the life of the components. This hypothesis was explored in simulation studies where different types of damage were imposed to different parts of the device. Experimental results agree qualitatively with the simulation for a number of tests which will motivate more in-depth modeling of the damage.

Free-Standing Organic Transistors and Circuits with Sub-Micron Thicknesses

PubMed Central

Fukuda, Kenjiro; Sekine, Tomohito; Shiwaku, Rei; Morimoto, Takuya; Kumaki, Daisuke; Tokito, Shizuo

2016-01-01

The realization of wearable electronic devices with extremely thin and flexible form factors has been a major technological challenge. While substrates typically limit the thickness of thin-film electronic devices, they are usually necessary for their fabrication and functionality. Here we report on ultra-thin organic transistors and integrated circuits using device components whose substrates that have been removed. The fabricated organic circuits with total device thicknesses down to 350 nm have electrical performance levels close to those fabricated on conventional flexible substrates. Moreover, they exhibit excellent mechanical robustness, whereby their static and dynamic electrical characteristics do not change even under 50% compressive strain. Tests using systematically applied compressive strains reveal that these free-standing organic transistors possess anisotropic mechanical stability, and a strain model for a multilayer stack can be used to describe the strain in this sort of ultra-thin device. These results show the feasibility of ultimate-thin organic electronic devices using free-standing constructions. PMID:27278828

Very high-cycle fatigue failure in micron-scale polycrystalline silicon films: Effects of environment and surface oxide thickness

NASA Astrophysics Data System (ADS)

Alsem, D. H.; Timmerman, R.; Boyce, B. L.; Stach, E. A.; De Hosson, J. Th. M.; Ritchie, R. O.

2007-01-01

Fatigue failure in micron-scale polycrystalline silicon structural films, a phenomenon that is not observed in bulk silicon, can severely impact the durability and reliability of microelectromechanical system devices. Despite several studies on the very high-cycle fatigue behavior of these films (up to 1012cycles), there is still an on-going debate on the precise mechanisms involved. We show here that for devices fabricated in the multiuser microelectromechanical system process (MUMPs) foundry and Sandia Ultra-planar, Multi-level MEMS Technology (SUMMiT V™) process and tested under equi-tension/compression loading at ˜40kHz in different environments, stress-lifetime data exhibit similar trends in fatigue behavior in ambient room air, shorter lifetimes in higher relative humidity environments, and no fatigue failure at all in high vacuum. The transmission electron microscopy of the surface oxides in the test samples shows a four- to sixfold thickening of the surface oxide at stress concentrations after fatigue failure, but no thickening after overload fracture in air or after fatigue cycling in vacuo. We find that such oxide thickening and premature fatigue failure (in air) occur in devices with initial oxide thicknesses of ˜4nm (SUMMiT V™) as well as in devices with much thicker initial oxides ˜20nm (MUMPs). Such results are interpreted and explained by a reaction-layer fatigue mechanism. Specifically, moisture-assisted subcritical cracking within a cyclic stress-assisted thickened oxide layer occurs until the crack reaches a critical size to cause catastrophic failure of the entire device. The entirety of the evidence presented here strongly indicates that the reaction-layer fatigue mechanism is the governing mechanism for fatigue failure in micron-scale polycrystalline silicon thin films.

Mechanical shear and tensile characteristics of selected biomass stems

USDA-ARS?s Scientific Manuscript database

Mechanical characteristics (stress and energy of tensile and shear modes) of selected biomass stems, such as big bluestem, bromegrass, and Barlow wheat were determined. A high capacity MTI-100K universal testing machine attached with standard tensile clamps and designed fabricated double-shear devic...

Phonon-tunnelling dissipation in mechanical resonators

PubMed Central

Cole, Garrett D.; Wilson-Rae, Ignacio; Werbach, Katharina; Vanner, Michael R.; Aspelmeyer, Markus

2011-01-01

Microscale and nanoscale mechanical resonators have recently emerged as ubiquitous devices for use in advanced technological applications, for example, in mobile communications and inertial sensors, and as novel tools for fundamental scientific endeavours. Their performance is in many cases limited by the deleterious effects of mechanical damping. In this study, we report a significant advancement towards understanding and controlling support-induced losses in generic mechanical resonators. We begin by introducing an efficient numerical solver, based on the 'phonon-tunnelling' approach, capable of predicting the design-limited damping of high-quality mechanical resonators. Further, through careful device engineering, we isolate support-induced losses and perform a rigorous experimental test of the strong geometric dependence of this loss mechanism. Our results are in excellent agreement with the theory, demonstrating the predictive power of our approach. In combination with recent progress on complementary dissipation mechanisms, our phonon-tunnelling solver represents a major step towards accurate prediction of the mechanical quality factor. PMID:21407197

Bathed, Strained, Attenuated, Annihilated: Towards Quantum Optomechanics

NASA Astrophysics Data System (ADS)

Pepper, Brian Jeffrey

The field of optomechanics studies tiny devices that can be pushed mechanically by light. It is an extremely promising avenue towards tests of quantum mechanics on a macroscopic scale, by transferring quantum states of light to nano- or micromechanical objects. This dissertation concerns a long term research program to create quantum superpositions of a macroscopic mirror in an optomechanical cavity. This dissertation has two broad thrusts. The first focuses on microfabrication of a new type of device called optomechanical trampoline resonators, consisting of a small mirror on a cross-shaped tensed silicon nitride membrane. Devices have been fabricated with high mechanical and optical quality, including a 300 kHz device with quality factor 480,000, as well as a device of optical finesse 107,000. These devices are well into the sideband-resolved regime and suitable for optical cooling to the quantum ground state. One such device has been optically cooled to approximately 10 phonons. The second major thrust is theoretical. Creating a macroscopic superposition is a challenging problem, requiring optical cooling to the ground state, strong coupling, extremely high optical finesse and extremely low frequency. A realistic assessment of achievable parameters indicates that it is possible to achieve ground state cooling or strong coupling, but not both. This dissertation proposes a new technique using postselection to achieve macroscopic superpositions with only weak coupling. This relaxes some of the required parameters by orders of magnitude. Prospects for observing hypothetical novel decoherence mechanisms are also discussed.

High-resolution optical polarimetric elastography for measuring the mechanical properties of tissue

NASA Astrophysics Data System (ADS)

Hudnut, Alexa W.; Armani, Andrea M.

2018-02-01

Traditionally, chemical and molecular markers have been the predominate method in diagnostics. Recently, alternate methods of determining tissue and disease characteristics have been proposed based on testing the mechanical behavior of biomaterials. Existing methods for performing elastography measurements, such as atomic force microscopy, compression testing, and ultrasound elastography, require either extensive sample processing or have poor resolution. In the present work, we demonstrate an optical polarimetric elastography device to characterize the mechanical properties of salmon skeletal muscle. A fiber-coupled 1550nm laser paired with an optical polarizer is used to create a fiber optic sensing region. By measuring the change in polarization from the initial state to the final state within the fiber sensing region with a polarimeter, the loading-unloading curves can be determined for the biomaterial. The device is used to characterize the difference between samples with a range of collagen membranes. The loading-unloading curves are used to determine the change in polarization phase and energy loss of the samples at 10%, 20% and 30% strain. As expected, the energy loss is a better metric for measuring the mechanical properties of the tissues because it incorporates the entire loading-unloading curve rather than a single point. Using this metric, it is demonstrated the device can repeatedly differentiate between the different membrane configurations.

Fundamental aspects of polyimide dry film and composite lubrication: A review

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1982-01-01

The tribological properties of polyimide dry films and composites are reviewed. Friction coefficients, wear rates, transfer film characteristics, wear surface morphology, and possible wear mechanisms of several different polyimide films, polyimide-bonded solid lubricants, polyimide solid bodies, and polyimide composites are discussed. Such parameters as temperature, type of atmosphere, load, contact stress, and specimen configuration are investigated. Data from an accelerated test device (Pin-on-Disk) are compared to similar data obtained from an end use application test device (plain spherical bearing).

The effect of fatigue on the corrosion resistance of common medical alloys.

PubMed

Di Prima, Matthew; Gutierrez, Erick; Weaver, Jason D

2017-10-01

The effect of mechanical fatigue on the corrosion resistance of medical devices has been a concern for devices that experience significant fatigue during their lifespan and devices made from metallic alloys. The Food and Drug Administration had recommended in some instances for corrosion testing to be performed on post-fatigued devices [Non-clinical tests and recommended labeling for intravascular stents and associated delivery systems: guidance for industry and FDA staff. 2005: Food and Drug Administration, Center for Devices and Radiological Health], although the need for this has been debated [Nagaraja S, et al., J Biomed Mater Res Part B: Appl Biomater 2016, 8.] This study seeks to evaluate the effect of fatigue on the corrosion resistance of 5 different materials commonly used in medical devices: 316 LVM stainless steel, MP35N cobalt chromium, electropolished nitinol, mechanically polished nitinol, and black oxide nitinol. Prior to corrosion testing per ASTM F2129, wires of each alloy were split into subgroups and subjected to either nothing (that is, as received); high strain fatigue for less than 8 min; short-term phosphate buffered saline (PBS) soak for less than 8 min; low strain fatigue for 8 days; or long-term PBS soak for 8 days. Results from corrosion testing showed that the rest potential trended to an equilibrium potential with increasing time in PBS and that there was no statistical (p > 0.05) difference in breakdown potential between the fatigued and matching PBS soak groups for 9 out of 10 test conditions. Our results suggest that under these nonfretting conditions, corrosion susceptibility as measured by breakdown potential per ASTM F2129 was unaffected by the fatigue condition. 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2019-2026, 2017. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Metal-oxide-metal point contact junction detectors. [detection mechanism and mechanical stability

NASA Technical Reports Server (NTRS)

Baird, J.; Havemann, R. H.; Fults, R. D.

1973-01-01

The detection mechanism(s) and design of a mechanically stable metal-oxide-metal point contact junction detector are considered. A prototype for a mechanically stable device has been constructed and tested. A technique has been developed which accurately predicts microwave video detector and heterodyne mixer SIM (semiconductor-insulator-metal) diode performance from low dc frequency volt-ampere curves. The difference in contact potential between the two metals and geometrically induced rectification constitute the detection mechanisms.

Lifetime evaluation of large format CMOS mixed signal infrared devices

NASA Astrophysics Data System (ADS)

Linder, A.; Glines, Eddie

2015-09-01

New large scale foundry processes continue to produce reliable products. These new large scale devices continue to use industry best practice to screen for failure mechanisms and validate their long lifetime. The Failure-in-Time analysis in conjunction with foundry qualification information can be used to evaluate large format device lifetimes. This analysis is a helpful tool when zero failure life tests are typical. The reliability of the device is estimated by applying the failure rate to the use conditions. JEDEC publications continue to be the industry accepted methods.

Accuracy of torque-limiting devices: A comparative evaluation.

PubMed

Albayrak, Haydar; Gumus, Hasan Onder; Tursun, Funda; Kocaagaoglu, Hasan Huseyin; Kilinc, Halil Ibrahim

2017-01-01

To prevent the loosening of implant screws, clinicians should be aware of the output torque values needed to achieve the desired preload. Accurate torque-control devices are crucial in this regard; however, little information is currently available comparing the accuracy of mechanical with that of electronic torque-control devices. The purpose of this in vitro study was to identify and compare the accuracy of different types of torque-control devices. Devices from 5 different dental implant manufacturers were evaluated, including 2 spring-type (Straumann, Implance) mechanical devices (MTLD), 2 friction-type (Biohorizons, Dyna) MTLDs, and 1 (Megagen) electronic torque-control device (ETLD). For each manufacturer, 5 devices were tested 5 times with a digital torque tester, and the average for each device was calculated and recorded. The percentage of absolute deviations from the target torque values (PERDEV) were calculated and compared by using 1-way ANOVA. A 1-sample t test was used to evaluate the ability of each device to achieve its target torque value within a 95% confidence interval for the true population mean of measured values (α=.05 for all statistical analyses). One-way ANOVAs revealed statistically significant differences among torque-control devices (P<.001). ETLD showed higher PERDEVs (28.33 ±9.53) than MTLDs (P<.05), whereas PERDEVS of friction-type (7.56 ±3.64) and spring-type (10.85 ±4.11) MTLDs did not differ significantly. In addition, devices produced by Megagen had a significantly higher (P<.05) PERDEV (28.33 ±9.53) other devices, whereas no differences were found in devices manufactured by Biohorizons (7.31 ±5.34), Dyna (7.82 ±1.08), Implance (8.43 ±4.77), and Straumann (13.26 ±0.79). However, 1-sample t tests showed none of the torque-control devices evaluated in this study were capable of achieving their target torque values (P<.05). Within the limitations of this in vitro study, MTLDs were shown to be significantly more accurate than ETLDs. However, none of the torque-control devices evaluated were able to meet their target torque values successfully. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Alphabus Mechanical Validation Plan and Test Campaign

NASA Astrophysics Data System (ADS)

Calvisi, G.; Bonnet, D.; Belliol, P.; Lodereau, P.; Redoundo, R.

2012-07-01

A joint team of the two leading European satellite companies (Astrium and Thales Alenia Space) worked with the support of ESA and CNES to define a product line able to efficiently address the upper segment of communications satellites : Alphabus Starting in 2009 and up to 2011 the mechanical validation of the Alphabus platform has been obtained thanks to static tests performed on dedicated static model and to environmental test performed on the first satellite based on Alphabus: Alphasat I-XL. The mechanical validation of the Alphabus platform presented an excellent opportunity to improve the validation and qualification process, with respect to static, sine vibrations, acoustic and L/V shock environment, minimizing recurrent cost of manufacturing, integration and testing. A main driver on mechanical testing is that mechanical acceptance testing at satellite level will be performed with empty tanks due to technical constraints (limitation of existing vibration devices) and programmatic advantages (test risk reduction, test schedule minimization). In this paper the impacts that such testing logic have on validation plan are briefly recalled and its actual application for Alphasat PFM mechanical test campaign is detailed.

TID Effects of High-Z Material Spot Shields on FPGA Using MPTB Data

NASA Technical Reports Server (NTRS)

Hardage, Donna (Technical Monitor); Crain, S. H.; Mazur, J. E.; Looper, M. D.

2003-01-01

An experiment on the Microelectronics and Photonics Test Bed (MPTB) was testing lield programmable gate arrays using spot shields to extend the life of some of the devices being tested. It was expected that the unshielded parts would fail from a total ionizing dose (TID) and yet the opposite occurred. The data show that the devices failing from the TID effects are those with the spot shields attached. This effort is to determine the mechanism by which the environment is interacting with the high-Z material to enhance the TID in these field programmable gate arrays.

Development of an experimental setup for testing the properties of γ/γ' superalloys

NASA Astrophysics Data System (ADS)

Christophe, Siret; Bernard, Viguier; Claude, Salabura Jean; Eric, Andrieu; Sandrine, Lesterlin

2010-07-01

Certification tests on turboshaft engines for helicopters can expose components as high pressure turbine blades to very high temperature during short time periods. To simulate these complex temperature and mechanical stress loadings and to study dimensional and microstructural stability under severe testing conditions, an experimental set-up has been recently developed. In this paper, we first present this new device and describe its performances. Then, the device is used to study the effect of heating procedure on creep results at 1200°C and rafting during primary creep on the single crystal nickel-based superalloy MC2.

Integration of a mechanical forebody vortex control system into the F-15

NASA Technical Reports Server (NTRS)

Boalbey, Richard E.; Citurs, Kevin D.; Ely, Wayne L.; Harbaugh, Stephen P.; Hollingsworth, William B.; Phillips, Ronald L.

1994-01-01

The goal of the F-15 Forebody Vortex Control (FVC) program is to develop a production FVC system for the F-15. The system may consist of either a mechanically actuated device such as the strakes developed for the HARV program, or a pneumatic device such as the port blowing system being tested on the X-29. Both types of systems are being evaluated under this program. Background information on the F-15 and a description and overview of forebody vortex controls (FVC) will be presented.

FY12 End of Year Report for NEPP DDR2 Reliability

NASA Technical Reports Server (NTRS)

Guertin, Steven M.

2013-01-01

This document reports the status of the NASA Electronic Parts and Packaging (NEPP) Double Data Rate 2 (DDR2) Reliability effort for FY2012. The task expanded the focus of evaluating reliability effects targeted for device examination. FY11 work highlighted the need to test many more parts and to examine more operating conditions, in order to provide useful recommendations for NASA users of these devices. This year's efforts focused on development of test capabilities, particularly focusing on those that can be used to determine overall lot quality and identify outlier devices, and test methods that can be employed on components for flight use. Flight acceptance of components potentially includes considerable time for up-screening (though this time may not currently be used for much reliability testing). Manufacturers are much more knowledgeable about the relevant reliability mechanisms for each of their devices. We are not in a position to know what the appropriate reliability tests are for any given device, so although reliability testing could be focused for a given device, we are forced to perform a large campaign of reliability tests to identify devices with degraded reliability. With the available up-screening time for NASA parts, it is possible to run many device performance studies. This includes verification of basic datasheet characteristics. Furthermore, it is possible to perform significant pattern sensitivity studies. By doing these studies we can establish higher reliability of flight components. In order to develop these approaches, it is necessary to develop test capability that can identify reliability outliers. To do this we must test many devices to ensure outliers are in the sample, and we must develop characterization capability to measure many different parameters. For FY12 we increased capability for reliability characterization and sample size. We increased sample size this year by moving from loose devices to dual inline memory modules (DIMMs) with an approximate reduction of 20 to 50 times in terms of per device under test (DUT) cost. By increasing sample size we have improved our ability to characterize devices that may be considered reliability outliers. This report provides an update on the effort to improve DDR2 testing capability. Although focused on DDR2, the methods being used can be extended to DDR and DDR3 with relative ease.

Table-Top Robotics for Engineering Design

ERIC Educational Resources Information Center

Wilczynski, Vincent; Dixon, Gregg; Ford, Eric

2005-01-01

The Mechanical Engineering Section at the U.S. Coast Guard Academy has developed a comprehensive activity based course to introduce second year students to mechanical engineering design. The culminating design activity for the course requires students to design, construct and test robotic devices that complete engineering challenges. Teams of…

Fabrication of a bioadhesive transdermal device from chitosan and hyaluronic acid for the controlled release of lidocaine.

PubMed

Anirudhan, T S; Nair, Syam S; Nair, Anoop S

2016-11-05

A novel efficient transdermal (TD) lidocaine (LD) delivery device based on chitosan (CS) and hyaluronic acid (HA) was successfully developed in the present investigation. CS was grafted with glycidyl methacrylate (GMA) and butyl methacrylate (BMA) to fabricate a versatile material with improved adhesion and mechanical properties. HA was hydrophobically modified by covalently conjugating 3-(dimethylamino)-1-propylamine (DMPA) to encapsulate poorly water soluble LD and was uniformly dispersed in modified CS matrix. The prepared materials were characterized through FTIR, NMR, XRD, SEM, TEM and tensile assay. The dispersion of amine functionalized HA (AHA) on modified CS matrix offered strong matrix - filler interaction, which improved the mechanical properties and drug retention behavior of the device. In vitro skin permeation study of LD was performed with modified Franz diffusion cell using rat skin and exhibited controlled release. The influence of storage time on release profile was investigated and demonstrated that after the initial burst, LD release profile of the device after 30 and 60days storage was identical to that of a device which was not stored. In vivo skin adhesion test and skin irritation assay in human subjects, water vapor permeability and environmental fitness test was performed to judge its application in biomedical field. All results displayed that the fabricated device is a potential candidate for TD LD administration to the systemic circulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intelligent structures technology

NASA Astrophysics Data System (ADS)

Crawley, Edward F.

1991-07-01

Viewgraphs on intelligent structures technology are presented. Topics covered include: embedding electronics; electrical and mechanical compatibility; integrated circuit chip packaged for embedding; embedding devices within composite structures; test of embedded circuit in G/E coupon; temperature/humidity/bias test; single-chip microcomputer control experiment; and structural shape determination.

Intelligent structures technology

NASA Technical Reports Server (NTRS)

Crawley, Edward F.

1991-01-01

Viewgraphs on intelligent structures technology are presented. Topics covered include: embedding electronics; electrical and mechanical compatibility; integrated circuit chip packaged for embedding; embedding devices within composite structures; test of embedded circuit in G/E coupon; temperature/humidity/bias test; single-chip microcomputer control experiment; and structural shape determination.

Mechanical Performance of Two Left Atrial Appendage Occlusion Systems: In Vitro Comparison of Tug Force, Radial Force, Sealing and Deformation.

PubMed

Menne, Matthias F; Schrickel, Jan W; Nickenig, Georg; Al-Kassou, Baravan; Nelles, Dominik; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Sedaghat, Alexander

2018-05-24

The aim of this study was to establish in vitro bench-tests of left atrial appendage occlusion (LAAo) devices regarding tug force, radial force and sealing capacity. Two LAAo devices, namely the WATCHMAN™ and the Occlutech ® , of three different sizes underwent testing in novel dedicated in vitro setups. Radial force was assessed in a commercial radial force tester. At baseline, tug force of the WATCHMAN™ was significantly higher when compared to Occlutech ® for all devices. Repeated resheathing resulted in a reduction of device-diameter in the WATCHMAN™ devices of max. 7.9%, whereas diameters of Occlutech ® occluders remained unchanged. Tug force was not significantly impacted by resheathing in both devices. At baseline, sealing capacity in a bench-test using silicone LAA-models did not differ between the devices. Resheathing lead to an in vitro loss of sealing capacity of the WATCHMAN™ devices, increasing with resheathing and resulting in a max. peridevice leak of 91.1 ± 7.9%. Radial force was higher for the Occlutech ® devices and decreased for WATCHMAN™ occluders after resheathing. The WATCHMAN™ occluder series showed progressive deformation, increased peridevice leakage and decreased radial force after resheathing, presumably as a result of diameter reduction. Tug force of the WATCHMAN™ was not impaired by resheathing and was significantly higher than that of the Occlutech ® device.

Dynamic MEMS devices for multi-axial fatigue and elastic modulus measurement

NASA Astrophysics Data System (ADS)

White, Carolyn D.; Xu, Rui; Sun, Xiaotian; Komvopoulos, Kyriakos

2003-01-01

For reliable MEMS device fabrication and operation, there is a continued demand for precise characterization of materials at the micron scale. This paper presents a novel material characterization device for fatigue lifetime testing. The fatigue specimen is subjected to multi-axial loading, which is typical of most MEMS devices. Polycrystalline silicon (polysilicon) fatigue devices were fabricated using the MUMPS process with a three layer mask process ground plane, anchor, and structural layer of polysilicon. A fatigue device consists of two or three beams, attached to a rotating ring and anchored to the substrate on each end. In order to generate a sufficiently large stress, the fatigue devices were tested in resonance to produce a von Mises equivalent stress as high as 1 GPa, which is in the fracture strength range reported for polysilicon. A further increase of the stress in the beam specimens was obtained by introducing a notch with a focused ion beam. The notch resulted into a stress concentration factor of about 3.8, thereby producing maximum von Mises equivalent stress in the range of 1 through 4 GPa. This study provides insight into multi-axial fatigue testing under typical MEMS conditions and additional information about micron-scale polysilicon mechanical behavior, which is the current basic building material for MEMS devices.

Efficacy and safety of a new coverlet device on skin microclimate management: a pilot study in critical care patients.

PubMed

Forriez, O; Masseline, J; Coadic, D; David, V; Trouiller, P; Sztrymf, B

2017-02-02

To test the effect of a new coverlet device, allowing air circulation at the body/underlying surface interface, on skin microclimate management. This prospective observational pilot study took place in a 15-bed university-affiliated intensive care unit. Overall, 34 mechanically ventilated patients were included. Skin humidity and temperature were monitored before and after the implementation of the tested device at the occiput, scapulas, buttocks and sacrum. Humidity and temperature were evaluated through surface skin impedance and an infra-red thermometer, respectively. Health professionals were asked to evaluate the device. After implementation of the coverlet device, there was a rapid, sustained and significant decrease in skin humidity at all sites ranging from 6 % to 15 %, excluding the occiput. Skin temperature also significantly decreased from 1 % at both scapulas, but not at the other studied body sites. No side effects were observed. Health professionals reported that the device was easy and quick to install. Although they did not report a subjective improvement in skin moisture or temperature, they considered the device to be efficient. Although limited by its design, this pilot study suggests a good efficacy of the studied device on skin microclimate management. Further data are warranted to test the clinical implications of our findings.

Transport Powder and Liquid Samples by Surface Acoustic Waves

NASA Technical Reports Server (NTRS)

Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Louyeh, Sahar

2009-01-01

Sample transport is an important requirement for In-situ analysis of samples in NASA planetary exploration missions. Tests have shown that powders or liquid drops on a surface can be transported by surface acoustic waves (SAW) that are generated on the surface using interdigital transducers. The phenomena were investigated experimentally and to generate SAWs interdigital electrodes were deposited on wafers of 128 deg rotated Y-cut LiNbO?. Transporting capability of the SAW device was tested using particles of various sizes and drops of various viscosities liquids. Because of different interaction mechanisms with the SAWs, the powders and the liquid drops were observed to move in opposite directions. In the preliminary tests, a speed of 180 mm/s was achieved for powder transportation. The detailed experimental setup and results are presented in this paper. The transporting mechanism can potentially be applied to miniaturize sample analysis system or " lab-on-chip" devices.

Mechanical and biomechanical analysis of a linear piston design for angular-velocity-based orthotic control.

PubMed

Lemaire, Edward D; Samadi, Reza; Goudreau, Louis; Kofman, Jonathan

2013-01-01

A linear piston hydraulic angular-velocity-based control knee joint was designed for people with knee-extensor weakness to engage knee-flexion resistance when knee-flexion angular velocity reaches a preset threshold, such as during a stumble, but to otherwise allow free knee motion. During mechanical testing at the lowest angular-velocity threshold, the device engaged within 2 degrees knee flexion and resisted moment loads of over 150 Nm. The device completed 400,000 loading cycles without mechanical failure or wear that would affect function. Gait patterns of nondisabled participants were similar to normal at walking speeds that produced below-threshold knee angular velocities. Fast walking speeds, employed purposely to attain the angular-velocity threshold and cause knee-flexion resistance, reduced maximum knee flexion by approximately 25 degrees but did not lead to unsafe gait patterns in foot ground clearance during swing. In knee collapse tests, the device successfully engaged knee-flexion resistance and stopped knee flexion with peak knee moments of up to 235.6 Nm. The outcomes from this study support the potential for the linear piston hydraulic knee joint in knee and knee-ankle-foot orthoses for people with lower-limb weakness.

A new prosthesis for the metacarpophalangeal joint. Study of materials and biomechanics.

PubMed

Petrolati, M; Abbiati, G; Delaria, G; Soffiatti, R; Robotti, P; Guerriero, C

1999-02-01

This report discusses the Daphne prosthesis for the metacarpophalangeal joint on the basis of the mechanical, chemical and biological performance of the materials employed. The Daphne prosthesis is a mobile device. The main body is made of a new generation polymethylmetacrylate, while the hinge is made of AISI 316 L stainless steel. Biocompatibility tests were performed on the materials employed. Systemic toxicity, cytotoxicity and contact tests have given favourable results. Mechanical engineering tests have been used to investigate the performances and reliability of the selected materials. The polymethylmetacrylate used in Daphne behaves in a ductile fashion. No mechanical failures were encountered in fatigue tests after 10 million cycles.

Preface to the special issue of Solid State Electronics EUROSOI/ULIS 2017

NASA Astrophysics Data System (ADS)

Nassiopoulou, Androula G.

2018-05-01

This special issue is devoted to selected papers presented at the EuroSOI-ULIS2017 international conference, held in Athens on 3-5 April 2017. EuroSOI-ULIS2017 Conference was mainly devoted to Si devices, which constitute the basic building blocks of any microelectronic circuit. It included papers on advanced Si technologies, novel nanoscale devices, advanced electronic materials and device architectures, mechanisms involved, test structures, substrate materials and technologies, modeling/simulation and characterization. Both CMOS and beyond CMOS devices were presented, covering the More Moore domain, as well as new functionalities in silicon-compatible nanostructures and innovative devices, representing the More than Moore domain (on-chip sensors, biosensors, energy harvesting devices, RF passives, etc.).

Stretchable carbon nanotube charge-trap floating-gate memory and logic devices for wearable electronics.

PubMed

Son, Donghee; Koo, Ja Hoon; Song, Jun-Kyul; Kim, Jaemin; Lee, Mincheol; Shim, Hyung Joon; Park, Minjoon; Lee, Minbaek; Kim, Ji Hoon; Kim, Dae-Hyeong

2015-05-26

Electronics for wearable applications require soft, flexible, and stretchable materials and designs to overcome the mechanical mismatch between the human body and devices. A key requirement for such wearable electronics is reliable operation with high performance and robustness during various deformations induced by motions. Here, we present materials and device design strategies for the core elements of wearable electronics, such as transistors, charge-trap floating-gate memory units, and various logic gates, with stretchable form factors. The use of semiconducting carbon nanotube networks designed for integration with charge traps and ultrathin dielectric layers meets the performance requirements as well as reliability, proven by detailed material and electrical characterizations using statistics. Serpentine interconnections and neutral mechanical plane layouts further enhance the deformability required for skin-based systems. Repetitive stretching tests and studies in mechanics corroborate the validity of the current approaches.

78 FR 27117 - General and Plastic Surgery Devices: Reclassification of Ultraviolet Lamps for Tanning...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-09

... sunlamp products are mechanically safe to prevent user injury. Mechanical safety testing, such as cyclic... off) are in proper working order. This requirement would mitigate increased skin cancer risk from... that sunlamp products are electrically safe and electromagnetically compatible in their intended use...

16 CFR 1610.5 - Test apparatus and materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... electronic circuits, in addition to miscellaneous custom made cams and rods, shock absorbing linkages, and... burn time to 0.1 second. An electronic or mechanical timer can be used to record the burn time, and electro-mechanical devices (i.e., servo-motors, solenoids, micro-switches, and electronic circuits, in...

16 CFR 1610.5 - Test apparatus and materials.

Code of Federal Regulations, 2014 CFR

2014-01-01

... electronic circuits, in addition to miscellaneous custom made cams and rods, shock absorbing linkages, and... burn time to 0.1 second. An electronic or mechanical timer can be used to record the burn time, and electro-mechanical devices (i.e., servo-motors, solenoids, micro-switches, and electronic circuits, in...

16 CFR § 1610.5 - Test apparatus and materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... electronic circuits, in addition to miscellaneous custom made cams and rods, shock absorbing linkages, and... burn time to 0.1 second. An electronic or mechanical timer can be used to record the burn time, and electro-mechanical devices (i.e., servo-motors, solenoids, micro-switches, and electronic circuits, in...

Adverse Events Involving Radiation Oncology Medical Devices: Comprehensive Analysis of US Food and Drug Administration Data, 1991 to 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Connor, Michael J.; Department of Radiation Oncology, University of California Irvine School of Medicine, Irvine, California; Marshall, Deborah C.

Purpose: Radiation oncology relies on rapidly evolving technology and highly complex processes. The US Food and Drug Administration collects reports of adverse events related to medical devices. We sought to characterize all events involving radiation oncology devices (RODs) from the US Food and Drug Administration's postmarket surveillance Manufacturer and User Facility Device Experience (MAUDE) database, comparing these with non–radiation oncology devices. Methods and Materials: MAUDE data on RODs from 1991 to 2015 were sorted into 4 product categories (external beam, brachytherapy, planning systems, and simulation systems) and 5 device problem categories (software, mechanical, electrical, user error, and dose delivery impact).more » Outcomes included whether the device was evaluated by the manufacturer, adverse event type, remedial action, problem code, device age, and time since 510(k) approval. Descriptive statistics were performed with linear regression of time-series data. Results for RODs were compared with those for other devices by the Pearson χ{sup 2} test for categorical data and 2-sample Kolmogorov-Smirnov test for distributions. Results: There were 4234 ROD and 4,985,698 other device adverse event reports. Adverse event reports increased over time, and events involving RODs peaked in 2011. Most ROD reports involved external beam therapy (50.8%), followed by brachytherapy (24.9%) and treatment planning systems (21.6%). The top problem types were software (30.4%), mechanical (20.9%), and user error (20.4%). RODs differed significantly from other devices in each outcome (P<.001). RODs were more likely to be evaluated by the manufacturer after an event (46.9% vs 33.0%) but less likely to be recalled (10.5% vs 37.9%) (P<.001). Device age and time since 510(k) approval were shorter among RODs (P<.001). Conclusions: Compared with other devices, RODs may experience adverse events sooner after manufacture and market approval. Close postmarket surveillance, improved software design, and manufacturer–user training may help mitigate these events.« less

FDA's perspectives on cardiovascular devices.

PubMed

Chen, Eric A; Patel-Raman, Sonna M; O'Callaghan, Kathryn; Hillebrenner, Matthew G

2009-06-01

The Food and Drug Administration (FDA) decision process for approving or clearing medical devices is often determined by a review of robust clinical data and extensive preclinical testing of the device. The mission statement for the Center for Devices and Radiological Health (CDRH) is to review the information provided by manufacturers so that it can promote and protect the health of the public by ensuring the safety and effectiveness of medical devices deemed appropriate for human use (Food, Drug & Cosmetic Act, Section 903(b)(1, 2(C)), December 31, 2004; accessed December 17, 2008 http://www.fda.gov/opacom/laws/fdcact/fdctoc.htm). For high-risk devices, such as ventricular assist devices (VADs), mechanical heart valves, stents, cardiac resynchronization therapy (CRT) devices, pacemakers, and defibrillators, the determination is based on FDA's review of extensive preclinical bench and animal testing followed by use of the device in a clinical trial in humans. These clinical trials allow the manufacturer to evaluate a device in the intended use population. FDA reviews the data from the clinical trial to determine if the device performed as predicted and the clinical benefits outweigh the risks. This article reviews the regulatory framework for different marketing applications related to cardiovascular devices and describes the process of obtaining approval to study a cardiovascular device in a U.S. clinical trial.

Report on Alternative Devices to Pyrotechnics on Spacecraft

NASA Technical Reports Server (NTRS)

Lucy, M. H.; Hardy, R. C.; Kist, E. H., Jr.; Watson, J. J.; Wise, S. A.

1996-01-01

Pyrotechnics accomplish many functions on today's spacecraft, possessing minimum volume/weight, providing instantaneous operation on demand, and requiring little input energy. However, functional shock, safety, and overall system cost issues, combined with emergence and availability of new technologies question their continued use on space missions. Upon request from the National Aeronautics and Space Administration's (NASA) Program Management Council (PMC), Langley Research Center (LaRC) conducted a survey to identify and evaluate state-of-the-art non-explosively actuated (NEA) alternatives to pyrotechnics, identify NEA devices planned for NASA use, and investigate potential interagency cooperative efforts. In this study, over 135 organizations were contacted, including NASA field centers, Department of Defense (DOD) and other government laboratories, universities, and American and European industrial sources resulting in further detailed discussions with over half, and 18 face-to-face briefings. Unlike their single use pyrotechnic predecessors, NEA mechanisms are typically reusable or refurbishable, allowing flight of actual tested units. NEAs surveyed include spool-based devices, thermal knife, Fast Acting Shockless Separation Nut (FASSN), paraffin actuators, and shape memory alloy (SMA) devices (e.g., Frangibolt). The electro-mechanical spool, paraffin actuator and thermal knife are mature, flight proven technologies, while SMA devices have a limited flight history. There is a relationship between shock, input energy requirements, and mechanism functioning rate. Some devices (e.g., Frangibolt and spool based mechanisms) produce significant levels of functional shock. Paraffin, thermal knife, and SMA devices can provide gentle, shock-free release but cannot perform critically timed, simultaneous functions. The FASSN flywheel-nut release device possesses significant potential for reducing functional shock while activating nearly instantaneously. Specific study recommendations include: (1) development of NEA standards, specifically in areas of material characterization, functioning rates, and test methods; (2) a systems level approach to assure successful NEA technology application; and (3) further investigations into user needs, along with industry/government system-level real spacecraft cost benefit trade studies to determine NEA application foci and performance requirements. Additional survey observations reveal an industry and government desire to establish partnerships to investigate remaining unknowns and formulate NEA standards, specifically those driven by SMAs. Finally, there is increased interest and need to investigate alternative devices for such functions as stage/shroud separation and high pressure valving. This paper summarizes results of the NASA-LaRC survey of pyrotechnic alternatives. State of-the-art devices with their associated weight and cost savings are presented. Additionally, a comparison of functional shock characteristics of several devices are shown, and potentially related technology developments are highlighted.

A Novel Disintegration Tester for Solid Dosage Forms Enabling Adjustable Hydrodynamics.

PubMed

Kindgen, Sarah; Rach, Regine; Nawroth, Thomas; Abrahamsson, Bertil; Langguth, Peter

2016-08-01

A modified in vitro disintegration test device was designed that enables the investigation of the influence of hydrodynamic conditions on disintegration of solid oral dosage forms. The device represents an improved derivative of the compendial PhEur/USP disintegration test device. By the application of a computerized numerical control, a variety of physiologically relevant moving velocities and profiles can be applied. With the help of computational fluid dynamics, the hydrodynamic and mechanical forces present in the probe chamber were characterized for a variety of device moving speeds. Furthermore, a proof of concept study aimed at the investigation of the influence of hydrodynamic conditions on disintegration times of immediate release tablets. The experiments demonstrated the relevance of hydrodynamics for tablet disintegration, especially in media simulating the fasted state. Disintegration times increased with decreasing moving velocity. A correlation between experimentally determined disintegration times and computational fluid dynamics predicted shear stress on tablet surface was established. In conclusion, the modified disintegration test device is a valuable tool for biorelevant in vitro disintegration testing of solid oral dosage forms. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Mobile communication devices causing interference in invasive and noninvasive ventilators.

PubMed

Dang, Bao P; Nel, Pierre R; Gjevre, John A

2007-06-01

The aim of this study was to assess if common mobile communication systems would cause significant interference on mechanical ventilation devices and at what distances would such interference occur. We tested all the invasive and noninvasive ventilatory devices used within our region. This consisted of 2 adult mechanical ventilators, 1 portable ventilator, 2 pediatric ventilators, and 2 noninvasive positive pressure ventilatory devices. We operated the mobile devices from the 2 cellular communication systems (digital) and 1 2-way radio system used in our province at varying distances from the ventilators and looked at any interference they created. We tested the 2-way radio system, which had a fixed operation power output of 3.0 watts, the Global Systems for Mobile Communication cellular system, which had a maximum power output of 2.0 watts and the Time Division Multiple Access cellular system, which had a maximum power output of 0.2 watts on our ventilators. The ventilators were ventilating a plastic lung at fixed settings. The mobile communication devices were tested at varying distances starting at zero meter from the ventilator and in all operation modes. The 2-way radio caused the most interference on some of the ventilators, but the maximum distance of interference was 1.0 m. The Global Systems for Mobile Communication system caused significant interference only at 0 m and minor interference at 0.5 m on only 1 ventilator. The Time Division Multiple Access system caused no interference at all. Significant interference consisted of a dramatic rise and fluctuation of the respiratory rate, pressure, and positive end-expiratory pressure of the ventilators with no normalization when the mobile device was removed. From our experiment on our ventilators with the communication systems used in our province, we conclude that mobile communication devices such as cellular phones and 2-way radios are safe and cause no interference unless operated at very close distances of less than 1 meter.

Development of a fulcrum methodology to replicate the lateral ankle sprain mechanism and measure dynamic inversion speed.

PubMed

Knight, Adam C; Weimar, Wendi H

2012-09-01

When the ankle is forced into inversion, the speed at which this movement occurs may affect the extent of injury. The purpose of this investigation was to develop a fulcrum device to mimic the mechanism of a lateral ankle sprain and to determine the reliability and validity of the temporal variables produced by this device. Additionally, this device was used to determine if a single previous lateral ankle sprain or ankle taping effected the time to maximum inversion and/or mean inversion speed. Twenty-six participants (13 with history of a single lateral ankle sprain and 13 with no history of injury) completed the testing. The participants completed testing on three separate days, performing 10 trials with the fulcrum per leg on each testing day, and tape was applied to both ankles on one testing day. No significant interactions or main effects were found for either previous injury or ankle taping, but good reliability was found for time to maximum inversion (ICC = .81) and mean inversion speed (ICC = .79). The findings suggest that although neither variable was influenced by the history of a single previous lateral ankle sprain or ankle taping, both variables demonstrated good reliability and construct validity, but not discriminative validity.

Mechanical stability of heat-treated nanoporous anodic alumina subjected to repetitive mechanical deformation

NASA Astrophysics Data System (ADS)

Bankova, A.; Videkov, V.; Tzaneva, B.; Mitov, M.

2018-03-01

We report studies on the mechanical response and deformation behavior of heat-treated nanoporous anodic alumina using a micro-balance test and experimental test equipment especially designed for this purpose. AAO samples were characterized mechanically by a three-point bending test using a micro-analytical balance. The deformation behavior was studied by repetitive mechanical bending of the AAO membranes using an electronically controlled system. The nanoporous AAO structures were prepared electrochemically from Al sheet substrates using a two-step anodizing technique in oxalic acid followed by heat treatment at 700 °C in air. The morphological study of the aluminum oxide layer after the mechanical tests and mechanical deformation was conducted using scanning electron and optical microscopy, respectively. The experimental results showed that the techniques proposed are simple and accurate; they could, therefore, be combined to constitute a method for mechanical stability assessment of nanostructured AAO films, which are important structural components in the design of MEMS devices and sensors.

Algorithmic support for graphic images rotation in avionics

NASA Astrophysics Data System (ADS)

Kniga, E. V.; Gurjanov, A. V.; Shukalov, A. V.; Zharinov, I. O.

2018-05-01

The avionics device designing has an actual problem of development and research algorithms to rotate the images which are being shown in the on-board display. The image rotation algorithms are a part of program software of avionics devices, which are parts of the on-board computers of the airplanes and helicopters. Images to be rotated have the flight location map fragments. The image rotation in the display system can be done as a part of software or mechanically. The program option is worse than the mechanic one in its rotation speed. The comparison of some test images of rotation several algorithms is shown which are being realized mechanically with the program environment Altera QuartusII.

Bench-test comparison of 26 emergency and transport ventilators.

PubMed

L'Her, Erwan; Roy, Annie; Marjanovic, Nicolas

2014-10-15

Numerous emergency and transport ventilators are commercialized and new generations arise constantly. The aim of this study was to evaluate a large panel of ventilators to allow clinicians to choose a device, taking into account their specificities of use. This experimental bench-test took into account general characteristics and technical performances. Performances were assessed under different levels of FIO2 (100%, 50% or Air-Mix), respiratory mechanics (compliance 30,70,120 mL/cmH2O; resistance 5,10,20 cmH2O/mL/s), and levels of leaks (3.5 to 12.5 L/min), using a test lung. In total 26 emergency and transport ventilators were analyzed and classified into four categories (ICU-like, n = 5; Sophisticated, n = 10; Simple, n = 9; Mass-casualty and military, n = 2). Oxygen consumption (7.1 to 15.8 L/min at FIO2 100%) and the Air-Mix mode (FIO2 45 to 86%) differed from one device to the other. Triggering performance was heterogeneous, but several sophisticated ventilators depicted triggering capabilities as efficient as ICU-like ventilators. Pressurization was not adequate for all devices. At baseline, all the ventilators were able to synchronize, but with variations among respiratory conditions. Leak compensation in most ICU-like and 4/10 sophisticated devices was able to correct at least partially for system leaks, but with variations among ventilators. Major differences were observed between devices and categories, either in terms of general characteristics or technical reliability, across the spectrum of operation. Huge variability of tidal volume delivery with some devices in response to modifications in respiratory mechanics and FIO2 should make clinicians question their use in the clinical setting.

Electrical Bistabilities and Conduction Mechanisms of Nonvolatile Memories Based on a Polymethylsilsesquioxane Insulating Layer Containing CdSe/ZnS Quantum Dots

NASA Astrophysics Data System (ADS)

Ma, Zehao; Ooi, Poh Choon; Li, Fushan; Yun, Dong Yeol; Kim, Tae Whan

2015-10-01

Nonvolatile memory (NVM) devices based on a metal-insulator-metal structure consisting of CdSe/ZnS quantum dots embedded in polymethylsilsesquioxane dielectric layers were fabricated. The current-voltage ( I- V) curves showed a bistable current behavior and the presence of hysteresis. The current-time ( I- t) curves showed that the fabricated NVM memory devices were stable up to 1 × 104 s with a distinct ON/OFF ratio of 104 and were reprogrammable when the endurance test was performed. The extrapolation of the I- t curve to 105 s with corresponding current ON/OFF ratio 1 × 105 indicated a long performance stability of the NVM devices. Schottky emission, Poole-Frenkel emission, trapped-charge limited-current and Child-Langmuir law were proposed as the dominant conduction mechanisms for the fabricated NVM devices based on the obtained I- V characteristics.

Flexible energy harvesting from hard piezoelectric beams

NASA Astrophysics Data System (ADS)

Delnavaz, Aidin; Voix, Jérémie

2016-11-01

This paper presents design, multiphysics finite element modeling and experimental validation of a new miniaturized PZT generator that integrates a bulk piezoelectric ceramic onto a flexible platform for energy harvesting from the human body pressing force. In spite of its flexibility, the mechanical structure of the proposed device is simple to fabricate and efficient for the energy conversion. The finite element model involves both mechanical and piezoelectric parts of the device coupled with the electrical circuit model. The energy harvester prototype was fabricated and tested under the low frequency periodic pressing force during 10 seconds. The experimental results show that several nano joules of electrical energy is stored in a capacitor that is quite significant given the size of the device. The finite element model is validated by observing a good agreement between experimental and simulation results. the validated model could be used for optimizing the device for energy harvesting from earcanal deformations.

Thermodynamic Modeling and Mechanical Design of a Liquid Nitrogen Vaporization and Pressure Building Device

NASA Astrophysics Data System (ADS)

Leege, Brian J.

The design of a liquid nitrogen vaporization and pressure building device that has zero product waste while recovering some of its stored energy is of interest for the cost reduction of nitrogen for use in industrial processes. Current devices may waste up to 30% of the gaseous nitrogen product by venting it to atmosphere. Furthermore, no attempt is made to recover the thermal energy available in the coldness of the cryogen. A seven step cycle with changing volumes and ambient heat addition is proposed, eliminating all product waste and providing the means of energy recovery from the nitrogen. This thesis discusses the new thermodynamic cycle and modeling as well as the mechanical design and testing of a prototype device. The prototype was able to achieve liquid nitrogen vaporization and pressurization up to 1000 psi, while full cycle validation is ongoing with promising initial results.

Note: Motor-piezoelectricity coupling driven high temperature fatigue device

NASA Astrophysics Data System (ADS)

Ma, Z. C.; Du, X. J.; Zhao, H. W.; Ma, X. X.; Jiang, D. Y.; Liu, Y.; Ren, L. Q.

2018-01-01

The design and performance evaluation of a novel high temperature fatigue device simultaneously driven by servo motor and piezoelectric actuator is our focus. The device integrates monotonic and cyclic loading functions with a maximum tensile load of 1800 N, driving frequency of 50 Hz, alternating load of 95 N, and maximum service temperature of 1200 °C. Multimodal fatigue tests with arbitrary combinations of static and dynamic loads are achieved. At temperatures that range from RT to 1100 °C, the tensile and tensile-fatigue coupling mechanical behaviors of UM Co50 alloys are investigated to verify the feasibility of the device.

Bone suture anchor fixation in the lower extremity: a review of insertion principles and a comparative biomechanical evaluation.

PubMed

Scranton, Pierce E; Lawhon, S Michael; McDermott, John E

2005-07-01

Suture anchors have been developed for the fixation of ligaments, capsules, or tendons to bone. These devices have led to improved fixation, smaller incisions, earlier limb mobility, and improved outcomes. They were originally developed for use in shoulder reconstructions but are now used in almost all extremities. In the lower leg they are used in the tibia, the talus, the calcaneus, tarsal bones, and phalanges. Nevertheless, techniques for insertion and mechanisms of failure are not well described. Five suture anchors were studied to determine the pullout strength in four distal cadaver femurs and four proximal cadaver tibias from 55- and 62-year-old males. Eight hundred ninety Newton line was used, testing the anchors to failure with an Instron testing device (Instron, Norwood, MA). The anchor devices were inserted randomly and tested blindly (12 tests per anchor device, 60 tests in all). Two anchors in each group tested failed at low loads. Both types of plastic anchors had failures at the eyelet. Average pullout strength varied from 85.4 to 185.6 N. Insertion techniques are specific for each device, and they must be followed for optimal fixation. In this study, in all five groups of anchors tested two of the 12 anchors in each group failed with minimal force. On the basis of this finding we recommend that, if suture anchor fixation is necessary, at least two anchors should be used. Since there appears to be a percentage of failure in all devices, the second anchor can serve as a backup. It is imperative that surgeons be familiar with the insertion techniques of each device before use.

Design and testing of an electromagnetic coupling

NASA Technical Reports Server (NTRS)

Anderson, William J.

1986-01-01

Hostile environments such as the hard vacuum of space, and exposure to water or caustic fluids have fostered the development of devices which allow mechanical rotary feed throughs with positive sealing without the use of conventional dynamic seals. One such device is an electromagnetic coupling which transfers motion across a hermetic seal by means of a rotating magnetic field. Static pull-out torque and dynamic heat build-up and pull-out torque tests of a synchronous reluctance homopolar coupling are reported herein. Coupling efficiencies are estimated for a range of speeds and torques.

Inductively heated shape memory polymer for the magnetic actuation of medical devices.

PubMed

Buckley, Patrick R; McKinley, Gareth H; Wilson, Thomas S; Small, Ward; Benett, William J; Bearinger, Jane P; McElfresh, Michael W; Maitland, Duncan J

2006-10-01

Presently, there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with nickel zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.

Comparison of shear bond strength relative to two testing devices.

PubMed

Pecora, Nikole; Yaman, Peter; Dennison, Joseph; Herrero, Alberto

2002-11-01

Dentin adhesives are characterized on the basis of their bond strength to dentin; however, great variation exists within the same material depending on the testing apparatus. To realistically compare bond strengths, the testing mechanisms must be the same. The purpose of this investigation was to use 2 testing devices to evaluate the shear bond strength of 3 single-bottle adhesives with their multistep counterparts. The occlusal surfaces of 120 freshly extracted third molars were ground to expose the dentin and polished with 600-grit silicon carbide paper. Three single-bottle, (Optibond Solo Plus, 3M Single Bond, and Excite) and 3 multistep adhesives (Optibond FL, 3M MultiPurpose Plus, and Syntac) were each used to bond a composite cylinder (made from a 2.379 +/-.001-mm diameter by 4-mm-high mold) of Tetric Ceram to 20 teeth. The specimens were stored in 100% humidity for 24 hours. The shear bond strength at failure was measured in kilograms and converted to megapascals for each material, using a knife (conventional method) and an Ultradent testing device on a universal testing machine (Instron) at a loading rate of 0.5 mm/min. A 2-way analysis of variance (ANOVA) test was performed comparing the 2 testing devices and the materials at P<.05. Where significant, a 1-way ANOVA test was conducted among the materials for each test group, and a Tukey multiple comparison test was used to determine significant differences among the materials tested (P<.05). An independent Student t test at P<.05 was used to determine significance between testing devices. The results showed that Optibond Solo Plus (26.85 +/- 8.76 MPa), Optibond FL (25.40 +/- 4.44 MPa), 3M Single Bond (28.12 +/- 5.01 MPa), and 3M MultiPurpose Plus (34.40 +/- 7.90 MPa) had significantly higher bond strengths when tested with the Ultradent testing device. The mean values for Excite (19.47 +/- 6.17 MPa) and Syntac (20.20 +/- 7.07 MPa) were also higher with the Ultradent testing device, but the difference was not significant. Within the limitations of this study, all bonding agents tested resulted in higher mean shear bond strengths when tested with the Ultradent testing device compared with the unrestricted knife. The single-step bonding agents exhibited mean bond strengths comparable to their multistep counterparts.

An ex vivo porcine skin model to evaluate pressure-reducing devices of different mechanical properties used for pressure ulcer prevention.

PubMed

Yeung, Ching-Yan C; Holmes, David F; Thomason, Helen A; Stephenson, Christian; Derby, Brian; Hardman, Matthew J

2016-11-01

Pressure ulcers are complex wounds caused by pressure- and shear-induced trauma to skin and underlying tissues. Pressure-reducing devices, such as dressings, have been shown to successfully reduce pressure ulcer incidence, when used in adjunct to pressure ulcer preventative care. While pressure-reducing devices are available in a range of materials, with differing mechanical properties, understanding of how a material's mechanical properties will influence clinical efficacy remains limited. The aim of this study was to establish a standardized ex vivo model to allow comparison of the cell protection potential of two gel-like pressure-reducing devices with differing mechanical properties (elastic moduli of 77 vs. 35 kPa). The devices also displayed differing energy dissipation under compressive loading, and resisted strain differently under constant load in compressive creep tests. To evaluate biological efficacy we employed a new ex vivo porcine skin model, with a confirmed elastic moduli closely matching that of human skin (113 vs. 119 kPa, respectively). Static loads up to 20 kPa were applied to porcine skin ex vivo with subsequent evaluation of pressure-induced cell death and cytokine release. Pressure application alone increased the percentage of epidermal apoptotic cells from less than 2% to over 40%, and increased cellular secretion of the pro-inflammatory cytokine TNF-alpha. Co-application of a pressure-reducing device significantly reduced both cellular apoptosis and cytokine production, protecting against cellular damage. These data reveal new insight into the relationship between mechanical properties of pressure-reducing devices and their biological effects. After appropriate validation of these results in clinical pressure ulcer prevention with all tissue layers present between the bony prominence and external surface, this ex vivo porcine skin model could be widely employed to optimize design and evaluation of devices aimed at reducing pressure-induced skin damage. © 2016 The Authors Wound Repair and Regeneration published by Wiley Periodicals, Inc. on behalf of The Wound Healing Society.

Solid state television camera

NASA Technical Reports Server (NTRS)

1976-01-01

The design, fabrication, and tests of a solid state television camera using a new charge-coupled imaging device are reported. An RCA charge-coupled device arranged in a 512 by 320 format and directly compatible with EIA format standards was the sensor selected. This is a three-phase, sealed surface-channel array that has 163,840 sensor elements, which employs a vertical frame transfer system for image readout. Included are test results of the complete camera system, circuit description and changes to such circuits as a result of integration and test, maintenance and operation section, recommendations to improve the camera system, and a complete set of electrical and mechanical drawing sketches.

Passively aligned multichannel fiber-pigtailing of planar integrated optical waveguides

NASA Astrophysics Data System (ADS)

Kremmel, Johannes; Lamprecht, Tobias; Crameri, Nino; Michler, Markus

2017-02-01

A silicon device to simplify the coupling of multiple single-mode fibers to embedded single-mode waveguides has been developed. The silicon device features alignment structures that enable a passive alignment of fibers to integrated waveguides. For passive alignment, precisely machined V-grooves on a silicon device are used and the planar lightwave circuit board features high-precision structures acting as a mechanical stop. The approach has been tested for up to eight fiber-to-waveguide connections. The alignment approach, the design, and the fabrication of the silicon device as well as the assembly process are presented. The characterization of the fiber-to-waveguide link reveals total coupling losses of (0.45±0.20 dB) per coupling interface, which is significantly lower than the values reported in earlier works. Subsequent climate tests reveal that the coupling losses remain stable during thermal cycling but increases significantly during an 85°C/85 Rh-test. All applied fabrication and bonding steps have been performed using standard MOEMS fabrication and packaging processes.

Compression instrument for tissue experiments (cite) at the meso-scale: device validation - biomed 2011.

PubMed

Evans, Douglas W; Rajagopalan, Padma; Devita, Raffaella; Sparks, Jessica L

2011-01-01

Liver sinusoidal endothelial cells (LSECs) are the primary site of numerous transport and exchange processes essential for liver function. LSECs rest on a sparse extracellular matrix layer housed in the space of Disse, a 0.5-1LSECs from hepatocytes. To develop bioengineered liver tissue constructs, it is important to understand the mechanical interactions among LSECs, hepatocytes, and the extracellular matrix in the space of Disse. Currently the mechanical properties of space of Disse matrix are not well understood. The objective of this study was to develop and validate a device for performing mechanical tests at the meso-scale (100nm-100m), to enable novel matrix characterization within the space of Disse. The device utilizes a glass micro-spherical indentor attached to a cantilever made from a fiber optic cable. The 3-axis translation table used to bring the specimen in contact with the indentor and deform the cantilever. A position detector monitors the location of a laser passing through the cantilever and allows for the calculation of subsequent tissue deformation. The design allows micro-newton and nano-newton stress-strain tissue behavior to be quantified. To validate the device accuracy, 11 samples of silicon rubber in two formulations were tested to experimentally confirm their Young's moduli. Prior macroscopic unconfined compression tests determined the formulations of EcoFlex030 (n-6) and EcoFlex010 (n-5) to posses Young's moduli of 92.67+-6.22 and 43.10+-3.29 kPa respectively. Optical measurements taken utilizing CITE's position control and fiber optic cantilever found the moduli to be 106.4 kPa and 47.82 kPa.

A "TEST OF CONCEPT" COMPARISON OF AERODYNAMIC AND MECHANICAL RESUSPENSION MECHANISMS FOR PARTICLES DEPOSITED ON FIELD RYE GRASS (SECALS CERCELE). PART 2. THRESHOLD MECHANICAL ENERGIES FOR RESUSPENSION PARTICLE FLUXES

EPA Science Inventory

Kinetic energy from the oscillatory impacts of the grass stalk against a stationary object was measured with a kinetic energy measuring device. These energy inputs were measured as part of a resuspension experiment of uniform latex microspheres deposited on a single rye grass see...

Optimization of voltage output of energy harvesters with continuous mechanical rotation extracted from human motion (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rashid, Evan; Hamidi, Armita; Tadesse, Yonas

2017-04-01

With increasing popularity of portable devices for outdoor activities, portable energy harvesting devices are coming into spot light. The next generation energy harvester which is called hybrid energy harvester can employ more than one mechanism in a single device to optimize portion of the energy that can be harvested from any source of waste energy namely motion, vibration, heat and etc. In spite of few recent attempts for creating hybrid portable devices, the level of output energy still needs to be improved with the intention of employing them in commercial electronic systems or further applications. Moreover, implementing a practical hybrid energy harvester in different application for further investigation is still challenging. This proposal is projected to incorporate a novel approach to maximize and optimize the voltage output of hybrid energy harvesters to achieve a greater conversion efficiency normalized by the total mass of the hybrid device than the simple arithmetic sum of the individual harvesting mechanisms. The energy harvester model previously proposed by Larkin and Tadesse [1] is used as a baseline and a continuous unidirectional rotation is incorporated to maximize and optimize the output. The device harvest mechanical energy from oscillatory motion and convert it to electrical energy through electromagnetic and piezoelectric systems. The new designed mechanism upgrades the device in a way that can harvest energy from both rotational and linear motions by using magnets. Likewise, the piezoelectric section optimized to harvest at least 10% more energy. To the end, the device scaled down for tested with different sources of vibrations in the immediate environment, including machinery operation, bicycle, door motion while opening and closing and finally, human motions. Comparing the results from literature proved that current device has capability to be employed in commercial small electronic devices for enhancement of battery usage or as a backup power source. [1] Larkin, Miles, and Yonas Tadesse. "HM-EH-RT: hybrid multimodal energy harvesting from rotational and translational motions." International Journal of Smart and Nano Materials 4.4 (2013): 257-285.

Force Limit System

NASA Technical Reports Server (NTRS)

Pawlik, Ralph; Krause, David; Bremenour, Frank

2011-01-01

The Force Limit System (FLS) was developed to protect test specimens from inadvertent overload. The load limit value is fully adjustable by the operator and works independently of the test system control as a mechanical (non-electrical) device. When a test specimen is loaded via an electromechanical or hydraulic test system, a chance of an overload condition exists. An overload applied to a specimen could result in irreparable damage to the specimen and/or fixturing. The FLS restricts the maximum load that an actuator can apply to a test specimen. When testing limited-run test articles or using very expensive fixtures, the use of such a device is highly recommended. Test setups typically use electronic peak protection, which can be the source of overload due to malfunctioning components or the inability to react quickly enough to load spikes. The FLS works independently of the electronic overload protection.

Facilities. [for Skylab environment simulation

NASA Technical Reports Server (NTRS)

Battaglia, H. F.; Burgett, F. A.; Casey, L. O.; Correale, J. V.; Dunaway, J. Q.; Glover, W. G.; Hinners, A. H., Jr.; Leblanc, J. C.; Leech, T. B.; Mays, J. D.

1973-01-01

Detailed descriptions are provided for mechanical devices, life support systems, and data handling and communications instrumentation that are connected with the altitude chamber in which the Skylab medical experiments altitude tests were performed.

Experimental Comparison of Piezoelectric and Magnetostrictive Shunt Dampers

NASA Technical Reports Server (NTRS)

Asnani, Vivake M.; Deng, Zhangxian; Dapino, Marcelo J.; Scheidler, Justin J.

2016-01-01

A novel mechanism called the vibration ring is being developed to enable energy conversion elements to be incorporated into the driveline of a helicopter or other rotating machines. Unwanted vibration is transduced into electrical energy, which provides a damping effect on the driveline. The generated electrical energy may also be used to power other devices (e.g., health monitoring sensors). PZT (piezoceramic) and PMN-30PT (single crystal) stacks, as well as a Tb_0.3 Dy_0.7 Fe_1.92 (Terfenol-D) rod with a bias magnet array and a pickup coil, were tested as alternative energy conversion elements to use within the vibration ring. They were tuned for broadband damping using shunt resistors, and dynamic compression testing was conducted in a high-speed load frame. Energy conversion was experimentally optimized at 750Hz by tuning the applied bias stress and resistance values. Dynamic testing was conducted up to 1000Hz to determine the effective compressive modulus, shunt loss factor, internal loss factor, and total loss factor. Some of the trends of modulus and internal loss factor versus frequency were unexplained. The single crystal device exhibited the greatest shunt loss factor whereas the Terfenol-D device had the highest internal and total loss factors. Simulations revealed that internal losses in the Terfenol-D device were elevated by eddy current effects, and an improved magnetic circuit could enhance its shunt damping capabilities. Alternatively, the Terfenol-D device may be simplified to utilize only the eddy current dissipation mechanism (no pickup coil or shunt) to create broadband damping.

Experimental Comparison of Piezoelectric and Magnetostrictive Shunt Dampers

NASA Technical Reports Server (NTRS)

Asnani, Vivake M.; Deng, Zhangxian; Scheidler, Justin J.; Dapino, Marcelo J.

2016-01-01

A novel mechanism called the vibration ring is being developed to enable energy conversion elements to be incorporated into the driveline of a helicopter or other rotating machines. Unwanted vibration is transduced into electrical energy, which provides a damping effect on the driveline. The generated electrical energy may also be used to power other devices (e.g., health monitoring sensors). PZT (piezoceramic) and PMN-30%PT (single crystal) stacks, as well as a Tb_0.3 Dy_0.7 Fe_1.92 (Terfenol-D) rod with a bias magnet array and a pickup coil, were tested as alternative energy conversion elements to use within the vibration ring. They were tuned for broadband damping using shunt resistors, and dynamic compression testing was conducted in a high-speed load frame. Energy conversion was experimentally optimized at 750Hz by tuning the applied bias stress and resistance values. Dynamic testing was conducted up to 1000Hz to determine the effective compressive modulus, shunt loss factor, internal loss factor, and total loss factor. Some of the trends of modulus and internal loss factor versus frequency were unexplained. The single crystal device exhibited the greatest shunt loss factor whereas the Terfenol-D device had the highest internal and total loss factors. Simulations revealed that internal losses in the Terfenol-D device were elevated by eddy current effects, and an improved magnetic circuit could enhance its shunt damping capabilities. Alternatively, the Terfenol-D device may be simplified to utilize only the eddy current dissipation mechanism (no pickup coil or shunt) to create broadband damping.

Experimental comparison of piezoelectric and magnetostrictive shunt dampers

NASA Astrophysics Data System (ADS)

Asnani, Vivake M.; Deng, Zhangxian; Scheidler, Justin J.; Dapino, Marcelo J.

2016-04-01

A novel mechanism called the vibration ring is being developed to enable energy conversion elements to be incorporated into the driveline of a helicopter or other rotating machines. Unwanted vibration is transduced into electrical energy, which provides a damping effect on the driveline. The generated electrical energy may also be used to power other devices (e.g., health monitoring sensors). PZT (`piezoceramic') and PMN-30%PT (`single crystal') stacks, as well as a Tb0.3Dy0.7Fe1.92 (`Terfenol-D') rod with a bias magnet array and a pickup coil, were tested as alternative energy conversion elements to use within the vibration ring. They were tuned for broadband damping using shunt resistors, and dynamic compression testing was conducted in a high-speed load frame. Energy conversion was experimentally optimized at 750Hz by tuning the applied bias stress and resistance values. Dynamic testing was conducted up to 1000Hz to determine the effective compressive modulus, shunt loss factor, internal loss factor, and total loss factor. Some of the trends of modulus and internal loss factor versus frequency were unexplained. The single crystal device exhibited the greatest shunt loss factor whereas the Terfenol-D device had the highest internal and total loss factors. Simulations revealed that internal losses in the Terfenol-D device were elevated by eddy current effects, and an improved magnetic circuit could enhance its shunt damping capabilities. Alternatively, the Terfenol-D device may be simplified to utilize only the eddy current dissipation mechanism (no pickup coil or shunt) to create broadband damping.

Technical feasibility of personalized articulating knee joint distraction for treatment of tibiofemoral osteoarthritis.

PubMed

Struik, T; Jaspers, J E N; Besselink, N J; van Roermund, P M; Plomp, S; Rudert, M J; Lafeber, F P J G; Mastbergen, S C

2017-11-01

Knee osteoarthritis is a highly prevalent degenerative joint disorder characterized by joint tissue damage and pain. Knee joint distraction has been introduced as a joint preserving surgical procedure to postpone knee arthroplasty. An often used standard externally fixation device for distraction poses a burden to patients due to the absence of joint flexion during the 6weeks treatment. Therefore, a personalized articulating distraction device was developed. The aim of this study was to test technical feasibility of this device. Based on an often applied rigid device, using equal bone pin positions and connectors, a hinge mechanism was developed consisting of a cam-following system for reproducing the complex joint-specific knee kinematics. In support, a device was developed for capturing the joint-specific sagittal plane articulation. The obtained kinematic data were translated into joint-specific cam shapes that were installed bilaterally in the hinge mechanism of the distraction device, as such providing personalized knee motion. Distraction of 5mm was performed within a range of motion of 30deg. joint flexion. Pre-clinical evaluation of the working principle was performed on human cadaveric legs and system stiffness characteristics were biomechanically evaluated. The desired range of motion was obtained and distraction was maintained under physiologically representative loading. Moreover, the joint-specific approach demonstrated tolerance of deviations from anatomical and alignment origin during initial placement of the developed distraction device. Articulation during knee distraction is considered technically feasible and has potential to decrease burden and improve acceptance of distraction therapy. Testing of clinical feasibility is warranted. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of copper composition on mechanical properties of biodegradable material Mg-Zn-Cu for orthopedic application

NASA Astrophysics Data System (ADS)

Purniawan, A.; Maulidiah, H. M.; Purwaningsih, H.

2018-04-01

Implant is usually used as a treatment of bone fracture. At the moment, non-biodegradable implants is still widely employed in this application. Non-biodegradable implant requires re-surgery to retrieve implants that are installed in the body. It increase the cost and it is painful for the patient itself. In order to solve the problem, Mg-based biodegradable metals is developing so that the material will be compatible with body and gradually degrade in patient's body. However, magnesium has several disadvantages such as high degradation rates and low mechanical properties when compared to the mechanical properties of natural bone. Therefore, it is necessary to add elements into the magnesium alloy. In this research, copper (Cu) was alloyed in Mg alloy based biodegradable material. In addition, Cu is not only strengthening the structure but also for supporting element for the immune system, antibacterial and antifungal. The purpose of this research is to improve mechanical properties of Mg-based biodegradable material using Cu alloying. Powder metallurgy method was used to fabricate the device. The variation used in this research is the composition of Cu (0.5, 1, and 1.5% Cu). The porosity test was performed using apparent porosity test, compressive test and hardness test to know the mechanical properties of the alloy, and the weightless test to find out the material degradation rate. Based on the results can be conclude that Mg-Zn-Cu alloy material with 1% Cu composition is the most suitable specimen to be applied as a candidate for orthopedic devices material with hardness value is 393.6 MPa. Also obtained the value of the compressive test is 153 MPa.

Automatic robotic arm operations and sampling in near zero gravity environment - functional tests results from Phobos-Grunt mission

NASA Astrophysics Data System (ADS)

Kozlova, Tatiana; Karol Seweryn, D..; Grygorczuk, Jerzy; Kozlov, Oleg

The sample return missions have made a very significant progress to understanding of geology, the extra-terrestrial materials, processes occurring on surface and subsurface level, as well as of interactions between such materials and mechanisms operating there. The various sample return missions in the past (e.g. Apollo missions, Luna missions, Hayabusa mission) have provided scientists with samples of extra-terrestrial materials allowing to discover answers to critical scientific questions concerning the origin and evolution of the Solar System. Several new missions are currently planned: sample return missions, e.g Russian Luna-28, ESA Phootprint and MarcoPolo-R as well as both robotic and manned exploration missions to the Moon and Mars. One of the key challenges in such missions is the reliable sampling process which can be achieved by using many different techniques, e.g. static excavating technique (scoop), core drilling, sampling using dynamic mechanisms (penetrators), brushes and pneumatic systems. The effectiveness of any sampling strategy depends on many factors, including the required sample size, the mechanical and chemical soil properties (cohesive, hard or porous regolith, stones), the environment conditions (gravity, temperature, pressure, radiation). Many sampling mechanism have been studied, designed and built in the past, two techniques to collect regolith samples were chosen for the Phobos-Grunt mission. The proposed system consisted of a robotic arm with a 1,2m reach beyond the lander (IKI RAN); a tubular sampling device designed for collecting both regolith and small rock fragments (IKI RAN); the CHOMIK device (CBK PAN) - the low velocity penetrator with a single-sample container for collecting samples from the rocky surface. The functional tests were essential step in robotic arm, sampling device and CHOMIK device development process in the frame of Phobos-Grunt mission. Three major results were achieved: (i) operation scenario for autonomous sampling; (ii) technical characteristics of both devices, i.e. progress cycles of CHOMIK device in different materials and torque in the manipulator joints during sampling operations; (iii) confirmation of applicability of both devices to perform such type of tasks. The phases in operational scenario were prepared to meet mission and system requirements mainly connected with: (i) environment (near zero gravity, vacuum, dust), (ii) safety and (iii) to avoid common operation of both devices at the same time.

A randomized trial comparing two intraosseous access devices in intrahospital healthcare providers with a focus on retention of knowledge, skill, and self-efficacy.

PubMed

Derikx, H J G M; Gerritse, B M; Gans, R; van der Meer, N J M

2014-10-01

Intraosseous access is recommended in vitally compromised patients if an intravenous access cannot be easily obtained. Intraosseous infusion can be initiated by various healthcare providers. Currently, there are two mechanical intraosseous devices approved by the U.S. Food and Drug Administration (FDA) for use in adults and children. A comparison is made in this study of the theoretical and practical performance by anesthesiologists and registered nurses of anesthesia (RNAs) in the use of the battery-powered device (device A) versus the spring-loaded needle device (device B). This study entailed a 12-month follow-up of knowledge, skill retention, and self-efficacy measured by standardized testing. A prospective randomized trial was performed, initially comparing 15 anesthesiologists and 15 RNAs, both on using the two types of intraosseous devices. A structured lecture and skill station was given with the educational aids provided by the respective manufacturers. Individual knowledge and practical skills were tested at 0, 3, and 12 months after the initial course. There was no statistical significant difference in the retention of theoretical knowledge between RNAs and anesthesiologists on all testing occasions. However, the self-efficacy of the anesthesiologists is significantly higher (p < 0.01) than the self-efficacy of the RNAs for both devices, on any testing occasion. Insufficient skills were local disinfection (both groups, both devices) and attachment of the needle to the intravenous line (RNAs with both devices). In 33 % of all device B handlings, unsafe practice occurred. The use of device A is safer in handling in comparison to device B at 12 months follow-up. The hypothesis that doctors are more qualified in obtaining intraosseous access has been disproven, as anesthesiologists were as successful as RNAs. However, the low self-efficacy of RNAs in the use of intraosseous devices could diminish the chance of them actually using one.

Cell buffer with built-in test

NASA Technical Reports Server (NTRS)

Ott, William E. (Inventor)

2004-01-01

A cell buffer with built-in testing mechanism is provided. The cell buffer provides the ability to measure voltage provided by a power cell. The testing mechanism provides the ability to test whether the cell buffer is functioning properly and thus providing an accurate voltage measurement. The testing mechanism includes a test signal-provider to provide a test signal to the cell buffer. During normal operation, the test signal is disabled and the cell buffer operates normally. During testing, the test signal is enabled and changes the output of the cell buffer in a defined way. The change in the cell buffer output can then be monitored to determine if the cell buffer is functioning correctly. Specifically, if the voltage output of the cell buffer changes in a way that corresponds to the provided test signal, then the functioning of the cell buffer is confirmed. If the voltage output of the cell buffer does not change correctly, then the cell buffer is known not to be operating correctly. Thus, the built in testing mechanism provides the ability to quickly and accurately determine if the cell buffer is operating correctly. Furthermore, the testing mechanism provides this functionality without requiring excessive device size and complexity.

Effects of geared motor characteristics on tactile perception of tissue stiffness.

PubMed

Longnion, J; Rosen, J; Sinanan, M; Hannaford, B

2001-01-01

Endoscopic haptic surgical devices have shown promise in addressing the loss of tactile sensation associated with minimally invasive surgery. However, these devices must be capable of generating forces and torques similar to those applied on the tissue with a standard endoscopic tool. Geared motors are a possible solution for actuation; however, they possess mechanical characteristics that could potentially interfere with tactile perception of tissue qualities. The aim of the current research was to determine how the characteristics of a geared motor suitable for a haptic surgical device affect a user's perception of stiffness. The experiment involved six blindfolded subjects who were asked to discriminate the stiffness of six distinct silicone rubber samples whose mechanical properties are similar to those of soft tissue. Using a novel testing device whose dimensions approximated those of an endoscopic grasper, each subject palpated 30 permutations of sample pairs for each of three types of mechanical loads; the motor (friction and inertia), a flywheel (with the same inertia as motor), and a control (no significant mechanical interference). One factor ANOVA of the error scores and palpation time showed that no significant difference existed among error scores, but mean palpation time for the control was significantly less than for the other two methods. These results indicated that the mechanical characteristics of a geared motor chosen for application in a haptic surgical device did not interfere with the subjects' perception of the silicone samples' stiffness, but these characteristics may significantly affect the energy expenditure and time required for tissue palpation. Therefore, before geared motors can be considered for use in haptic surgical devices, consideration should be given to factors such as palpation speed and fatigue.

Novel failure mechanism and improvement for split-gate trench MOSFET with large current under unclamped inductive switch stress

NASA Astrophysics Data System (ADS)

Tian, Ye; Yang, Zhuo; Xu, Zhiyuan; Liu, Siyang; Sun, Weifeng; Shi, Longxing; Zhu, Yuanzheng; Ye, Peng; Zhou, Jincheng

2018-04-01

In this paper, a novel failure mechanism under unclamped inductive switch (UIS) for Split-Gate Trench Metal Oxide Semiconductor Field Effect Transistor (MOSFET) with large current is investigated. The device sample is tested and analyzed in detail. The simulation results demonstrate that the nonuniform potential distribution of the source poly should be responsible for the failure. Three structures are proposed and verified available to improve the device UIS ruggedness by TCAD simulation. The best one of the structures the device with source metal inserting into source poly through contacts in the field oxide is carried out and measured. The results demonstrate that the optimized structure can balance the trade-off between the UIS ruggedness and the static characteristics.

Flexible ferroelectric element based on van der Waals heteroepitaxy.

PubMed

Jiang, Jie; Bitla, Yugandhar; Huang, Chun-Wei; Do, Thi Hien; Liu, Heng-Jui; Hsieh, Ying-Hui; Ma, Chun-Hao; Jang, Chi-Yuan; Lai, Yu-Hong; Chiu, Po-Wen; Wu, Wen-Wei; Chen, Yi-Chun; Zhou, Yi-Chun; Chu, Ying-Hao

2017-06-01

We present a promising technology for nonvolatile flexible electronic devices: A direct fabrication of epitaxial lead zirconium titanate (PZT) on flexible mica substrate via van der Waals epitaxy. These single-crystalline flexible ferroelectric PZT films not only retain their performance, reliability, and thermal stability comparable to those on rigid counterparts in tests of nonvolatile memory elements but also exhibit remarkable mechanical properties with robust operation in bent states (bending radii down to 2.5 mm) and cycling tests (1000 times). This study marks the technological advancement toward realizing much-awaited flexible yet single-crystalline nonvolatile electronic devices for the design and development of flexible, lightweight, and next-generation smart devices with potential applications in electronics, robotics, automotive, health care, industrial, and military systems.

Flexible ferroelectric element based on van der Waals heteroepitaxy

PubMed Central

Jiang, Jie; Bitla, Yugandhar; Huang, Chun-Wei; Do, Thi Hien; Liu, Heng-Jui; Hsieh, Ying-Hui; Ma, Chun-Hao; Jang, Chi-Yuan; Lai, Yu-Hong; Chiu, Po-Wen; Wu, Wen-Wei; Chen, Yi-Chun; Zhou, Yi-Chun; Chu, Ying-Hao

2017-01-01

We present a promising technology for nonvolatile flexible electronic devices: A direct fabrication of epitaxial lead zirconium titanate (PZT) on flexible mica substrate via van der Waals epitaxy. These single-crystalline flexible ferroelectric PZT films not only retain their performance, reliability, and thermal stability comparable to those on rigid counterparts in tests of nonvolatile memory elements but also exhibit remarkable mechanical properties with robust operation in bent states (bending radii down to 2.5 mm) and cycling tests (1000 times). This study marks the technological advancement toward realizing much-awaited flexible yet single-crystalline nonvolatile electronic devices for the design and development of flexible, lightweight, and next-generation smart devices with potential applications in electronics, robotics, automotive, health care, industrial, and military systems. PMID:28630922

Impact of radiations on the electromechanical properties of materials and on the piezoresistive and capacitive transduction mechanisms used in microsystems

NASA Astrophysics Data System (ADS)

Francis, Laurent A.; Gkotsis, Petros; Kilchytska, Valeriya; Tang, Xiaohui; Druart, Sylvain; Raskin, Jean-Pierre; Flandre, Denis

2013-03-01

The impact of different types of radiation on the electromechanical properties of materials used in microfabrication and on the capacitive and piezoresistive transduction mechanisms of MEMS is investigated. MEMS technologies could revolutionize avionics, satellite and space applications provided that the stress conditions which can compromise the reliability of microsystems in these environments are well understood. Initial tests with MEMS revealed a vulnerability of some types of devices to radiation induced dielectric charging, a physical mechanism which also affects microelectronics, however integration of novel functional materials in microfabrication and the current trend to substitute SiO2 with high-k dielectrics in ICs pose new questions regarding reliability in radiation environments. The performance of MEMS devices with moving parts could also degrade due to radiation induced changes in the mechanical properties of the materials. It is thus necessary to investigate the effects of radiation on the properties of thin films used in microfabrication and here we report on tests with γ, high energy protons and fast neutrons radiation. Prototype SOI based MEMS magnetometers which were developed in UCL are also used as test vehicles to investigate radiation effects on the reliability of magnetically actuated and capacitively coupled MEMS.

The INCAS Project: An Innovative Contact-Less Angular Sensor

NASA Astrophysics Data System (ADS)

Ghislanzoni, L.; Di Cintio, A.; Solimando, M.; Parzianello, G.

2013-09-01

Angular Positions sensors are widely used in all spacecrafts, including re-entry vehicles and launchers, where mechanisms and pointing-scanning devices are required. The main applications are on mechanisms for TeleMeasure (TM) related to the release and deployment of devices, or on rotary mechanisms such as Solar Array Drive Mechanism (SADM) and Antenna Pointing Mechanism (APM). Longer lifetime (up to 7- 10 years) is becoming a new driver for the coming missions and contact technology sensors often incur in limitations due to the wear of the contacting parts [1].A Self-Compensating Absolute Angular Encoder was developed and tested in the frame of an ESA's ARTES 5.2 project, named INCAS (INnovative Contact-less Angular Sensor). More in particular, the INCAS sensor addresses a market need for contactless angular sensors aimed at replacing the more conventional rotary potentiometers, while featuring the same level of accuracy performances and extending the expected lifetime.

Analyses of Transistor Punchthrough Failures

NASA Technical Reports Server (NTRS)

Nicolas, David P.

1999-01-01

The failure of two transistors in the Altitude Switch Assembly for the Solid Rocket Booster followed by two additional failures a year later presented a challenge to failure analysts. These devices had successfully worked for many years on numerous missions. There was no history of failures with this type of device. Extensive checks of the test procedures gave no indication for a source of the cause. The devices were manufactured more than twenty years ago and failure information on this lot date code was not readily available. External visual exam, radiography, PEID, and leak testing were performed with nominal results Electrical testing indicated nearly identical base-emitter and base-collector characteristics (both forward and reverse) with a low resistance short emitter to collector. These characteristics are indicative of a classic failure mechanism called punchthrough. In failure analysis punchthrough refers to an condition where a relatively low voltage pulse causes the device to conduct very hard producing localized areas of thermal runaway or "hot spots". At one or more of these hot spots, the excessive currents melt the silicon. Heavily doped emitter material diffuses through the base region to the collector forming a diffusion pipe shorting the emitter to base to collector. Upon cooling, an alloy junction forms between the pipe and the base region. Generally, the hot spot (punch-through site) is under the bond and no surface artifact is visible. The devices were delidded and the internal structures were examined microscopically. The gold emitter lead was melted on one device, but others had anomalies in the metallization around the in-tact emitter bonds. The SEM examination confirmed some anomalies to be cosmetic defects while other anomalies were artifacts of the punchthrough site. Subsequent to these analyses, the contractor determined that some irregular testing procedures occurred at the time of the failures heretofore unreported. These testing irregularities involved the use of a breakout box and were the likely cause of the failures. There was no evidence to suggest a generic failure mechanism was responsible for the failure of these transistors.

The Validity and Reliability of an iPhone App for Measuring Running Mechanics.

PubMed

Balsalobre-Fernández, Carlos; Agopyan, Hovannes; Morin, Jean-Benoit

2017-07-01

The purpose of this investigation was to analyze the validity of an iPhone application (Runmatic) for measuring running mechanics. To do this, 96 steps from 12 different runs at speeds ranging from 2.77-5.55 m·s -1 were recorded simultaneously with Runmatic, as well as with an opto-electronic device installed on a motorized treadmill to measure the contact and aerial time of each step. Additionally, several running mechanics variables were calculated using the contact and aerial times measured, and previously validated equations. Several statistics were computed to test the validity and reliability of Runmatic in comparison with the opto-electronic device for the measurement of contact time, aerial time, vertical oscillation, leg stiffness, maximum relative force, and step frequency. The running mechanics values obtained with both the app and the opto-electronic device showed a high degree of correlation (r = .94-.99, p < .001). Moreover, there was very close agreement between instruments as revealed by the ICC (2,1) (ICC = 0.965-0.991). Finally, both Runmatic and the opto-electronic device showed almost identical reliability levels when measuring each set of 8 steps for every run recorded. In conclusion, Runmatic has been proven to be a highly reliable tool for measuring the running mechanics studied in this work.

Novel device for creating continuous curvilinear capsulorhexis.

PubMed

Soylak, Mustafa

2016-01-01

The purpose of this paper is to develop a novel capsulorhexis system. Mechatronics Laboratory, University of Erciyes and Kayseri Maya Eye Hospital. A 3D model was created and simulations were conducted to develop a new device which was designed, fabricated and tested for continuous curvilinear capsulorhexis (CCC). The name of this system is the electro-mechanical capsulorhexis system (EMCS). The 3D model was created by using a commercial design software and a 3D printer was used to fabricate the EMCS Finite element analysis and geometrical relation tests of the EMCS for different sized lenses were performed. The results show that the EMCS is a perfect solution for capsulorhexis surgeries, without mechanical or geometrical problems. The EMCS can open the anterior lens capsule more easily and effectively than manual CCC applications and needs less experience.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mantero, Sara; Longo, Iginio; Fiore, Gianfranco Beniamino

Purpose: The aim of this study was to create, perfect and test a hyperthermia balloon catheter for local treatment of cholangiocarcinoma. The device should induce hyperthermia in tumor tissue by acting locally in the bile duct lumen in contact with the tumor-infiltrated duct wall. In addition, it should exert tissue compression to cause an appreciable reduction in tumor microvasculature flow, thus improving thermal performance. Methods: According to the design specifications, the working temperature range should allow the device to be used for hyperthermia therapy either in combination with radiation and/or chemotherapy(radio/chemo-sensitizing effect at 42-45 deg. C) or alone (induction ofmore » coagulation necrosis above 65 deg. C). The balloon serves as an anchoring system during treatment and as a functional element to induce tissue compression. In vitro mechanical evaluation of the pressure/volume relationship, with the balloon inside rigid walled conduits, was performed. The heating shape around the catheter tip was determined by egg-white heating tests (coagulation at about 65 deg. C). Moreover,heating tests were carried out with explanted pig liver parenchyma. The temperature profile over time at different depths from the catheter axis was traced. Results: Three prototypes were manufactured. Mechanical functional tests showed that a 14 Fr deflated diameter balloon was suitable for bile duct diameters up to 11 mm.Thermal egg-white tests produced 4 cm long, 3 cm in diameter ellipsoidal heating figures in 30 min. In the biological tissue tests a coagulated area of similar geometry and comparable volume was produced. Conclusion: The results of tests confirm the device's usefulness and versatility.« less

A comparative evaluation of polymerization stress data obtained with four different mechanical testing systems.

PubMed

Gonçalves, Flávia; Boaro, Leticia C; Ferracane, Jack L; Braga, Roberto R

2012-06-01

The null hypothesis was that mechanical testing systems used to determine polymerization stress (σ(pol)) would rank a series of composites similarly. Two series of composites were tested in the following systems: universal testing machine (UTM) using glass rods as bonding substrate, UTM/acrylic rods, "low compliance device", and single cantilever device ("Bioman"). One series had five experimental composites containing BisGMA:TEGDMA in equimolar concentrations and 60, 65, 70, 75 or 80 wt% of filler. The other series had five commercial composites: Filtek Z250 (3M ESPE), Filtek A110 (3M ESPE), Tetric Ceram (Ivoclar), Heliomolar (Ivoclar) and Point 4 (Kerr). Specimen geometry, dimensions and curing conditions were similar in all systems. σ(pol) was monitored for 10 min. Volumetric shrinkage (VS) was measured in a mercury dilatometer and elastic modulus (E) was determined by three-point bending. Shrinkage rate was used as a measure of reaction kinetics. ANOVA/Tukey test was performed for each variable, separately for each series. For the experimental composites, σ(pol) decreased with filler content in all systems, following the variation in VS. For commercial materials, σ(pol) did not vary in the UTM/acrylic system and showed very few similarities in rankings in the others tests system. Also, no clear relationships were observed between σ(pol) and VS or E. The testing systems showed a good agreement for the experimental composites, but very few similarities for the commercial composites. Therefore, comparison of polymerization stress results from different devices must be done carefully. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Using temperature-switching approach to evaluate the ELDRS of bipolar devices

NASA Astrophysics Data System (ADS)

Li, Xiaolong; Lu, Wu; Wang, Xin; Guo, Qi; Yu, Xin; He, Chengfa; Sun, Jing; Liu, Mohan; Yao, Shuai; Wei, Xinyu

2017-12-01

Enhanced low-dose rate sensitivity (ELDRS) exhibited at low-dose rates (LDRs) by most bipolar devices is considered as one of the main concerns for spacecraft reliability. In this work, a time-saving and conservative approach - temperature-switching approach (TSA) - to simulate the ELDRS of bipolar devices is presented. Good agreement is observed between the predictive curve obtained with the TSA and the LDR data, and TSA provides us with a new insight into the test technique for ELDRS. Additionally, the mechanisms of TSA are analyzed in this paper.

MEMS resonant load cells for micro-mechanical test frames: feasibility study and optimal design

NASA Astrophysics Data System (ADS)

Torrents, A.; Azgin, K.; Godfrey, S. W.; Topalli, E. S.; Akin, T.; Valdevit, L.

2010-12-01

This paper presents the design, optimization and manufacturing of a novel micro-fabricated load cell based on a double-ended tuning fork. The device geometry and operating voltages are optimized for maximum force resolution and range, subject to a number of manufacturing and electromechanical constraints. All optimizations are enabled by analytical modeling (verified by selected finite elements analyses) coupled with an efficient C++ code based on the particle swarm optimization algorithm. This assessment indicates that force resolutions of ~0.5-10 nN are feasible in vacuum (~1-50 mTorr), with force ranges as large as 1 N. Importantly, the optimal design for vacuum operation is independent of the desired range, ensuring versatility. Experimental verifications on a sub-optimal device fabricated using silicon-on-glass technology demonstrate a resolution of ~23 nN at a vacuum level of ~50 mTorr. The device demonstrated in this article will be integrated in a hybrid micro-mechanical test frame for unprecedented combinations of force resolution and range, displacement resolution and range, optical (or SEM) access to the sample, versatility and cost.

Physics-based process modeling, reliability prediction, and design guidelines for flip-chip devices

NASA Astrophysics Data System (ADS)

Michaelides, Stylianos

Flip Chip on Board (FCOB) and Chip-Scale Packages (CSPs) are relatively new technologies that are being increasingly used in the electronic packaging industry. Compared to the more widely used face-up wirebonding and TAB technologies, flip-chips and most CSPs provide the shortest possible leads, lower inductance, higher frequency, better noise control, higher density, greater input/output (I/O), smaller device footprint and lower profile. However, due to the short history and due to the introduction of several new electronic materials, designs, and processing conditions, very limited work has been done to understand the role of material, geometry, and processing parameters on the reliability of flip-chip devices. Also, with the ever-increasing complexity of semiconductor packages and with the continued reduction in time to market, it is too costly to wait until the later stages of design and testing to discover that the reliability is not satisfactory. The objective of the research is to develop integrated process-reliability models that will take into consideration the mechanics of assembly processes to be able to determine the reliability of face-down devices under thermal cycling and long-term temperature dwelling. The models incorporate the time and temperature-dependent constitutive behavior of various materials in the assembly to be able to predict failure modes such as die cracking and solder cracking. In addition, the models account for process-induced defects and macro-micro features of the assembly. Creep-fatigue and continuum-damage mechanics models for the solder interconnects and fracture-mechanics models for the die have been used to determine the reliability of the devices. The results predicted by the models have been successfully validated against experimental data. The validated models have been used to develop qualification and test procedures for implantable medical devices. In addition, the research has helped develop innovative face-down devices without the underfill, based on the thorough understanding of the failure modes. Also, practical design guidelines for material, geometry and process parameters for reliable flip-chip devices have been developed.

The phototron: A light to RF energy conversion device

NASA Technical Reports Server (NTRS)

Freeman, J. W.; Simons, S.

1982-01-01

The phototron, a photoelectric device that converts light to radio frequency energy, is described. It is a vacuum tube, free electron, device that is mechanically similar to a reflex klystron with the hot filament cathode replaced by a large area photocathode. The device can operate either with an external voltage source used to accelerate the photoelectrons or with zero bias voltage; in which case the photokinetic energy of the electrons sustains the R.F. oscillations in the tuned R.F. circuit. One basic design of the phototron was tested. Frequencies as high as about 1 GHz and an overall efficiency of about 1% in the biased mode were obtained. In the unbiased mode, the frequencies of operation and efficiences are considerably lower. Success with test model suggests that considerable improvements are possible through design refinements. One such design refinement is the reduction of the length of the electron flight path.

Quantum random number generation

DOE PAGES

Ma, Xiongfeng; Yuan, Xiao; Cao, Zhu; ...

2016-06-28

Quantum physics can be exploited to generate true random numbers, which play important roles in many applications, especially in cryptography. Genuine randomness from the measurement of a quantum system reveals the inherent nature of quantumness -- coherence, an important feature that differentiates quantum mechanics from classical physics. The generation of genuine randomness is generally considered impossible with only classical means. Based on the degree of trustworthiness on devices, quantum random number generators (QRNGs) can be grouped into three categories. The first category, practical QRNG, is built on fully trusted and calibrated devices and typically can generate randomness at a highmore » speed by properly modeling the devices. The second category is self-testing QRNG, where verifiable randomness can be generated without trusting the actual implementation. The third category, semi-self-testing QRNG, is an intermediate category which provides a tradeoff between the trustworthiness on the device and the random number generation speed.« less

Device for high spatial resolution chemical analysis of a sample and method of high spatial resolution chemical analysis

DOEpatents

Van Berkel, Gary J.

2015-10-06

A system and method for analyzing a chemical composition of a specimen are described. The system can include at least one pin; a sampling device configured to contact a liquid with a specimen on the at least one pin to form a testing solution; and a stepper mechanism configured to move the at least one pin and the sampling device relative to one another. The system can also include an analytical instrument for determining a chemical composition of the specimen from the testing solution. In particular, the systems and methods described herein enable chemical analysis of specimens, such as tissue, to be evaluated in a manner that the spatial-resolution is limited by the size of the pins used to obtain tissue samples, not the size of the sampling device used to solubilize the samples coupled to the pins.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Xiongfeng; Yuan, Xiao; Cao, Zhu

Quantum physics can be exploited to generate true random numbers, which play important roles in many applications, especially in cryptography. Genuine randomness from the measurement of a quantum system reveals the inherent nature of quantumness -- coherence, an important feature that differentiates quantum mechanics from classical physics. The generation of genuine randomness is generally considered impossible with only classical means. Based on the degree of trustworthiness on devices, quantum random number generators (QRNGs) can be grouped into three categories. The first category, practical QRNG, is built on fully trusted and calibrated devices and typically can generate randomness at a highmore » speed by properly modeling the devices. The second category is self-testing QRNG, where verifiable randomness can be generated without trusting the actual implementation. The third category, semi-self-testing QRNG, is an intermediate category which provides a tradeoff between the trustworthiness on the device and the random number generation speed.« less

Portable device for detection of petit mal epilepsy

NASA Technical Reports Server (NTRS)

Smith, R. G.; Houge, J. C.; Webster, J. G.

1979-01-01

A portable device that analyzes the electroencephalogram to determine if petit mal epilepsy waveforms are present is developed and tested. Clinicians should find it useful in diagnosing seizure activity of their patients. The micropower, battery-operated, portable device indicates a seizure has occurred if three criteria are satisfied: (1) frequencies of 2.5-7 Hz, (2) large-amplitude waves, and (3) minimum number of waves per second. Levels and counts are adjustable, thus insuring high reliability against noise artifacts and permitting each subject to be individually fitted. The device has shown promise in giving the patient a possible mechanism of seizure control or suppression.

In situ MEMS testing: correlation of high-resolution X-ray diffraction with mechanical experiments and finite element analysis

NASA Astrophysics Data System (ADS)

Schifferle, Andreas; Dommann, Alex; Neels, Antonia

2017-12-01

New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication.

Impact of the Test Device on the Behavior of the Acoustic Emission Signals: Contribution of the Numerical Modeling to Signal Processing

NASA Astrophysics Data System (ADS)

Issiaka Traore, Oumar; Cristini, Paul; Favretto-Cristini, Nathalie; Pantera, Laurent; Viguier-Pla, Sylvie

2018-01-01

In a context of nuclear safety experiment monitoring with the non destructive testing method of acoustic emission, we study the impact of the test device on the interpretation of the recorded physical signals by using spectral finite element modeling. The numerical results are validated by comparison with real acoustic emission data obtained from previous experiments. The results show that several parameters can have significant impacts on acoustic wave propagation and then on the interpretation of the physical signals. The potential position of the source mechanism, the positions of the receivers and the nature of the coolant fluid have to be taken into account in the definition a pre-processing strategy of the real acoustic emission signals. In order to show the relevance of such an approach, we use the results to propose an optimization of the positions of the acoustic emission sensors in order to reduce the estimation bias of the time-delay and then improve the localization of the source mechanisms.

New Equipment for Testing the Fatigue Strength of Riveted and Welded Joints

NASA Technical Reports Server (NTRS)

Muller, W

1940-01-01

The mechanical and electrical construction of a new experimental instrument for fatigue testing riveted and welded joints is described. This experimental device has the advantage of being able to stress, even with comparatively low magnetic exciter force, structural components in alternate bending by resonance vibrations up to incipient fatigue failure.

Mechanical characteristics of the new BONE-LOK bi-cortical internal fixation device.

PubMed

Cachia, Victor V; Shumway, Don; Culbert, Brad; Padget, Marty

2003-01-01

The purpose of this study was to evaluate the mechanical characteristics of a new and unique titanium compression anchor with BONE-LOK (Triage Medical, Inc, Irvine, CA) technology for compressive, bi-cortical internal fixation of bone. This device provides fixation through the use of a distal grasping anchor and an adjustable proximal collar that are joined by an axially movable pin and guide wire. The titanium compression anchor, in 2.0-, 2.7-, and 3.5-mm diameters, were compared with cortex screws (Synthes USA, Paoli, PA) of the same diameter and material for pullout strength in 20 lb/cu ft and 30 lb/cu ft solid rigid polyurethane foam; and for compression strength in 20 lb/cu ft foam. Retention strength of the collar was tested independently. The results showed significantly greater pullout strength of the 2.7-mm and 3.5-mm titanium compression anchor as compared with the 2.7-mm and 3.5-mm cortex screws in these test models. Pullout strength of the 2.0-mm titanium compression anchor was not statistically different in comparison with the 2.0-mm cortical screws. Compression strength of the titanium compression anchor was significantly greater than the cortical screws for all diameters tested. These differences represent a distinct advantage with the new device, which warrants further in vivo testing. Collar retention strength testing values were obtained for reference only and have no comparative significance.

What Reliability Engineers Should Know about Space Radiation Effects

NASA Technical Reports Server (NTRS)

DiBari, Rebecca

2013-01-01

Space radiation in space systems present unique failure modes and considerations for reliability engineers. Radiation effects is not a one size fits all field. Threat conditions that must be addressed for a given mission depend on the mission orbital profile, the technologies of parts used in critical functions and on application considerations, such as supply voltages, temperature, duty cycle, and redundancy. In general, the threats that must be addressed are of two types-the cumulative degradation mechanisms of total ionizing dose (TID) and displacement damage (DD). and the prompt responses of components to ionizing particles (protons and heavy ions) falling under the heading of single-event effects. Generally degradation mechanisms behave like wear-out mechanisms on any active components in a system: Total Ionizing Dose (TID) and Displacement Damage: (1) TID affects all active devices over time. Devices can fail either because of parametric shifts that prevent the device from fulfilling its application or due to device failures where the device stops functioning altogether. Since this failure mode varies from part to part and lot to lot, lot qualification testing with sufficient statistics is vital. Displacement damage failures are caused by the displacement of semiconductor atoms from their lattice positions. As with TID, failures can be either parametric or catastrophic, although parametric degradation is more common for displacement damage. Lot testing is critical not just to assure proper device fi.mctionality throughout the mission. It can also suggest remediation strategies when a device fails. This paper will look at these effects on a variety of devices in a variety of applications. This paper will look at these effects on a variety of devices in a variety of applications. (2) On the NEAR mission a functional failure was traced to a PIN diode failure caused by TID induced high leakage currents. NEAR was able to recover from the failure by reversing the current of a nearby Thermal Electric Cooler (turning the TEC into a heater). The elevated temperature caused the PIN diode to anneal and the device to recover. It was by lot qualification testing that NEAR knew the diode would recover when annealed. This paper will look at these effects on a variety of devices in a variety of applications. Single Event Effects (SEE): (1) In contrast to TID and displacement damage, Single Event Effects (SEE) resemble random failures. SEE modes can range from changes in device logic (single-event upset, or SEU). temporary disturbances (single-event transient) to catastrophic effects such as the destructive SEE modes, single-event latchup (SEL). single-event gate rupture (SEGR) and single-event burnout (SEB) (2) The consequences of nondestructive SEE modes such as SEU and SET depend critically on their application--and may range from trivial nuisance errors to catastrophic loss of mission. It is critical not just to ensure that potentially susceptible devices are well characterized for their susceptibility, but also to work with design engineers to understand the implications of each error mode. -For destructive SEE, the predominant risk mitigation strategy is to avoid susceptible parts, or if that is not possible. to avoid conditions under which the part may be susceptible. Destructive SEE mechanisms are often not well understood, and testing is slow and expensive, making rate prediction very challenging. (3) Because the consequences of radiation failure and degradation modes depend so critically on the application as well as the component technology, it is essential that radiation, component. design and system engineers work togetherpreferably starting early in the program to ensure critical applications are addressed in time to optimize the probability of mission success.

Reliability improvement of wire bonds subjected to fatigue stresses.

NASA Technical Reports Server (NTRS)

Ravi, K. V.; Philofsky, E. M.

1972-01-01

The failure of wire bonds due to repeated flexure when semiconductor devices are operated in an on-off mode has been investigated. An accelerated fatigue testing apparatus was constructed and the major fatigue variables, aluminum alloy composition, and bonding mechanism, were tested. The data showed Al-1% Mg wires to exhibit superior fatigue characteristics compared to Al-1% Cu or Al-1% Si and ultrasonic bonding to be better than thermocompression bonding for fatigue resistance. Based on these results highly reliable devices were fabricated using Al-1% Mg wire with ultrasonic bonding which withstood 120,000 power cycles with no failures.

Photovoltaic Performance and Reliability Workshop summary

NASA Astrophysics Data System (ADS)

Kroposki, Benjamin

1997-02-01

The objective of the Photovoltaic Performance and Reliability Workshop was to provide a forum where the entire photovoltaic (PV) community (manufacturers, researchers, system designers, and customers) could get together and discuss technical issues relating to PV. The workshop included presentations from twenty-five speakers and had more than one hundred attendees. This workshop also included several open sessions in which the audience and speakers could discuss technical subjects in depth. Several major topics were discussed including: PV characterization and measurements, service lifetimes for PV devices, degradation and failure mechanisms for PV devices, standardization of testing procedures, AC module performance and reliability testing, inverter performance and reliability testing, standardization of utility interconnect requirements, experience from field deployed systems, and system certification.

Interfacial characterization of flexible hybrid electronics

NASA Astrophysics Data System (ADS)

Najafian, Sara; Amirkhizi, Alireza V.; Stapleton, Scott

2018-03-01

Flexible Hybrid Electronics (FHEs) are the new generation of electronics combining flexible plastic film substrates with electronic devices. Besides the electrical features, design improvements of FHEs depend on the prediction of their mechanical and failure behavior. Debonding of electronic components from the flexible substrate is one of the most common and critical failures of these devices, therefore, the experimental determination of material and interface properties is of great importance in the prediction of failure mechanisms. Traditional interface characterization involves isolated shear and normal mode tests such as the double cantilever beam (DCB) and end notch flexure (ENF) tests. However, due to the thin, flexible nature of the materials and manufacturing restrictions, tests mirroring traditional interface characterization experiments may not always be possible. The ideal goal of this research is to design experiments such that each mode of fracture is isolated. However, due to the complex nonlinear nature of the response and small geometries of FHEs, design of the proper tests to characterize the interface properties can be significantly time and cost consuming. Hence numerical modeling has been implemented to design these novel characterization experiments. This research involves loading case and specimen geometry parametric studies using numerical modeling to design future experiments where either shear or normal fracture modes are dominant. These virtual experiments will provide a foundation for designing similar tests for many different types of flexible electronics and predicting the failure mechanism independent of the specific FHE materials.

Pelvic Support Problems

MedlinePlus

... pelvic exam, or special tests. Treatments include special pelvic muscle exercises called Kegel exercises. A mechanical support device called a pessary helps some women. Surgery and medicines are other treatments. NIH: National Institute of Child Health and Human Development

Collaborative robotic biomechanical interactions and gait adjustments in young, non-impaired individuals.

PubMed

Dionisio, Valdeci C; Brown, David A

2016-06-16

Collaborative robots are used in rehabilitation and are designed to interact with the client so as to provide the ability to assist walking therapeutically. One such device is the KineAssist which was designed to interact, either in a self-driven mode (SDM) or in an assist mode (AM), with neurologically-impaired individuals while they are walking on a treadmill surface. To understand the level of transparency (i.e., interference with movement due to the mechanical interface) between human and robot, and to estimate and account for changes in the kinetics and kinematics of the gait pattern, we tested the KineAssist under conditions of self-drive and horizontal push assistance. The aims of this study were to compare the joint kinematics, forces and moments during walking at a fixed constant treadmill belt speed and constrained walking cadence, with and without the robotic device (OUT) and to compare the biomechanics of assistive and self-drive modes in the device. Twenty non-neurologically impaired adults participated in this study. We evaluated biomechanical parameters of walking at a fixed constant treadmill belt speed (1.0 m/s), with and without the robotic device in assistive mode. We also tested the self-drive condition, which enables the user to drive the speed and direction of a treadmill belt. Hip, knee and ankle angular displacements, ground reaction forces, hip, knee and ankle moments, and center of mass displacement were compared "in" vs "out" of the device. A repeated measures ANOVA test was applied with the three level factor of condition (OUT, AM, and SDM), and each participant was used as its own comparison. When comparing "in" and "out" of the device, we did not observe any interruptions and/or reversals of direction of the basic gait pattern trajectory, but there was increased ankle and hip angular excursions, vertical ground reaction force and hip moments and reduced center of mass displacement during the "in device" condition. Comparing assistive vs self-drive mode in device, participants had greater flexed posture and accentuated hip moments and propulsive force, but reduced braking force. Although the magnitudes and/or range of certain gait pattern components were altered by the device, we did not observe any interruption from the mechanical interface upon the advancement of the trajectories nor reversals in direction of movement which suggests that the KineAssist permits relative transparency (i.e.. lack of interference of movement by the device mechanism) to the individual's gait pattern. However, there are interactive forces to take into account, which appear to be overcome by kinematic and kinetic adjustments.

Cartridge output testing - Methods to overcome closed-bomb shortcomings

NASA Technical Reports Server (NTRS)

Bement, Laurence J.; Schimmel, Morry L.

1991-01-01

Although the closed-bomb test has achieved virtually universal acceptance for measuring the output performance of pyrotechnic cartridges, there are serious shortcomings in its ability to quantify the performance of cartridges used as energy sources for pyrotechnic-activated mechanical devices. This paper presents several examples of cartridges (including the NASA Standard Initiator NSI) that successfully met closed-bomb performance requirements, but resulted in functional failures in mechanisms. To resolve these failures, test methods were developed to demonstrate a functional margin, based on comparing energy required to accomplish the function to energy deliverable by the cartridge.

Pharmacological and neurophysiological aspects of space/motion sickness

NASA Technical Reports Server (NTRS)

Lucot, James B.; Crampton, George H.

1991-01-01

A motorized motion testing device modeled after a Ferris wheel was constructed to perform motion sickness tests on cats. Details of the testing are presented, and some of the topics covered include the following: xylazine-induced emesis; analysis of the constituents of the cerebrospinal fluid (CSF) during motion sickness; evaluation of serotonin-1A (5-HT sub 1A) agonists; other 5HT receptors; antimuscarinic mechanisms; and antihistaminergic mechanisms. The ability of the following drugs to reduce motion sickness in the cats was examined: amphetamines, adenosinergic drugs, opioid antagonists, peptides, cannabinoids, cognitive enhancers (nootropics), dextromethorphan/sigma ligands, scopolamine, and diphenhydramine.

Design and Development of a Novel Upper-Limb Cycling Prosthesis

PubMed Central

Soni-Sadar, Shivam; Rowbottom, Jack; Patel, Shilen; Mathewson, Edward; Pearson, Samuel; Hutchins, David; Head, John; Hutchins, Stephen

2017-01-01

The rise in popularity of the Paralympics in recent years has created a need for effective, low-cost sports-prosthetic devices for upper-limb amputees. There are various opportunities for lower-limb amputees to participate in cycling; however, there are only few options for those with upper-limb amputations. If the individual previously participated in cycling, a cycling-specific prosthesis could allow these activities to be integrated into rehabilitation methods. This article describes the processes involved with designing, developing and manufacturing such a prosthesis. The fundamental needs of people with upper-limb amputation were assessed and realised in the prototype of a transradial terminal device with two release mechanisms, including a sliding mechanism (for falls and minor collisions) and clamping mechanism (for head-on collisions). The sliding mechanism requires the rider to exert approximately 200 N, while the clamping mechanism requires about 700 N. The force ranges can be customised to match rider requirements. Experiments were conducted in a controlled environment to demonstrate stability of the device during normal cycling. Moreover, a volunteer test-rider was able to successfully activate the release mechanism during a simulated emergency scenario. The development of this prosthesis has the potential to enable traumatic upper-limb amputees to participate in cycling for rehabilitation or recreation. PMID:29144392

Design and Development of a Novel Upper-Limb Cycling Prosthesis.

PubMed

Tiele, Akira; Soni-Sadar, Shivam; Rowbottom, Jack; Patel, Shilen; Mathewson, Edward; Pearson, Samuel; Hutchins, David; Head, John; Hutchins, Stephen

2017-11-16

The rise in popularity of the Paralympics in recent years has created a need for effective, low-cost sports-prosthetic devices for upper-limb amputees. There are various opportunities for lower-limb amputees to participate in cycling; however, there are only few options for those with upper-limb amputations. If the individual previously participated in cycling, a cycling-specific prosthesis could allow these activities to be integrated into rehabilitation methods. This article describes the processes involved with designing, developing and manufacturing such a prosthesis. The fundamental needs of people with upper-limb amputation were assessed and realised in the prototype of a transradial terminal device with two release mechanisms, including a sliding mechanism (for falls and minor collisions) and clamping mechanism (for head-on collisions). The sliding mechanism requires the rider to exert approximately 200 N, while the clamping mechanism requires about 700 N. The force ranges can be customised to match rider requirements. Experiments were conducted in a controlled environment to demonstrate stability of the device during normal cycling. Moreover, a volunteer test-rider was able to successfully activate the release mechanism during a simulated emergency scenario. The development of this prosthesis has the potential to enable traumatic upper-limb amputees to participate in cycling for rehabilitation or recreation.

Oscillatory device for use with linear tribometer, for tribological evaluation of biomaterials

NASA Astrophysics Data System (ADS)

Athayde, J. N.; Siqueira, C. J. M.; Kuromoto, N. K.; Cambraia, H. N.

2017-07-01

Orthopedic implants still have limitations regarding their durability, despite being in use for over fifty years. Particles arising from wear due to the relative motion of their surfaces remain responsible for aseptic failure. This paper presents a device to be coupled with a reciprocal linear tribometer to reproduce the ex vivo wear of biomaterials, allowing the measurement of force and coefficient of friction. The device consists of a structure connected to the tribometer that transforms its reciprocal linear motion into one that is oscillatory for the mechanical assembly that contains the samples to test the desired biomaterials. The tribological pair used for testing consisted of Ultra High Molecular Weight Polyethylene (UHMWPE) in conjunction with the austenitic stainless steel AISI 316L in dry lubrication. The results showed that the values of the coefficient of friction in the linear mode and oscillatory mode and the UHMWPE life curve in the oscillatory mode were consistent with those cited in the literature for tests in a dry lubrication environment. Moreover, the UHMWPE sample life curve showed a reduction in the wear rate that can be explained by the preponderance of a wear mechanism over the others. The volumetric wear showed an increase with the number of cycles.

Development of devices for self-injection: using tribological analysis to optimize injection force

PubMed Central

Lange, Jakob; Urbanek, Leos; Burren, Stefan

2016-01-01

This article describes the use of analytical models and physical measurements to characterize and optimize the tribological behavior of pen injectors for self-administration of biopharmaceuticals. One of the main performance attributes of this kind of device is its efficiency in transmitting the external force applied by the user on to the cartridge inside the pen in order to effectuate an injection. This injection force characteristic is heavily influenced by the frictional properties of the polymeric materials employed in the mechanism. Standard friction tests are available for characterizing candidate materials, but they use geometries and conditions far removed from the actual situation inside a pen injector and thus do not always generate relevant data. A new test procedure, allowing the direct measurement of the coefficient of friction between two key parts of a pen injector mechanism using real parts under simulated use conditions, is presented. In addition to the absolute level of friction, the test method provides information on expected evolution of friction over lifetime as well as on expected consistency between individual devices. Paired with an analytical model of the pen mechanism, the frictional data allow the expected overall injection system force efficiency to be estimated. The test method and analytical model are applied to a range of polymer combinations with different kinds of lubrication. It is found that material combinations used without lubrication generally have unsatisfactory performance, that the use of silicone-based internal lubricating additives improves performance, and that the best results can be achieved with external silicone-based lubricants. Polytetrafluoroethylene-based internal lubrication and external lubrication are also evaluated but found to provide only limited benefits unless used in combination with silicone. PMID:27274319

Development of Quasi-3DOF upper limb rehabilitation system using ER brake: PLEMO-P1

NASA Astrophysics Data System (ADS)

Kikuchi, T.; Fukushima, K.; Furusho, J.; Ozawa, T.

2009-02-01

In recent years, many researchers have studied the potential of using robotics technology to assist and quantify the motor functions for neuron-rehabilitation. Some kinds of haptic devices have been developed and evaluated its efficiency with clinical tests, for example, upper limb training for patients with spasticity after stroke. However, almost all the devices are active-type (motor-driven) haptic devices and they basically require high-cost safety system compared to passive-type (brake-based) devices. In this study, we developed a new practical haptic device 'PLEMO-P1'; this system adopted ER brakes as its force generators. In this paper, the mechanism of PLEMO-P1 and its software for a reaching rehabilitation are described.

Synthesis and Evaluation of Single Layer, Bilayer, and Multilayer Thermoelectric Thin Films

DOE R&D Accomplishments Database

Farmer, J. C.; Barbee, T. W. Jr.; Chapline, G. C. Jr.; Olsen, M. L.; Foreman, R. J.; Summers, L. J.; Dresselhaus, M. S.; Hicks, L. D.

1995-01-20

The relative efficiency of a thermoelectric material is measured in terms of a dimensionless figure of merit, ZT. Though all known thermoelectric materials are believed to have ZT{le}1, recent theoretical results predict that thermoelectric devices fabricated as two-dimensional quantum wells (2D QWs) or one-dimensional (ID) quantum wires could have ZT{ge}3. Multilayers with the dimensions of 2D QWs have been synthesized by alternately sputtering thermoelectric and barrier materials onto a moving single-crystal sapphire substrate from dual magnetrons. These materials have been used to test the thermoelectric quantum well concept and gain insight into relevant transport mechanisms. If successful, research could lead to thermoelectric devices that have efficiencies close to that of an ideal Carnot engine. Ultimately, such devices could be used to replace conventional heat engines and mechanical refrigeration systems.

Characterization and reliability of aluminum gallium nitride/gallium nitride high electron mobility transistors

NASA Astrophysics Data System (ADS)

Douglas, Erica Ann

Compound semiconductor devices, particularly those based on GaN, have found significant use in military and civilian systems for both microwave and optoelectronic applications. Future uses in ultra-high power radar systems will require the use of GaN transistors operated at very high voltages, currents and temperatures. GaN-based high electron mobility transistors (HEMTs) have proven power handling capability that overshadows all other wide band gap semiconductor devices for high frequency and high-power applications. Little conclusive research has been reported in order to determine the dominating degradation mechanisms of the devices that result in failure under standard operating conditions in the field. Therefore, it is imperative that further reliability testing be carried out to determine the failure mechanisms present in GaN HEMTs in order to improve device performance, and thus further the ability for future technologies to be developed. In order to obtain a better understanding of the true reliability of AlGaN/GaN HEMTs and determine the MTTF under standard operating conditions, it is crucial to investigate the interaction effects between thermal and electrical degradation. This research spans device characterization, device reliability, and device simulation in order to obtain an all-encompassing picture of the device physics. Initially, finite element thermal simulations were performed to investigate the effect of device design on self-heating under high power operation. This was then followed by a study of reliability of HEMTs and other tests structures during high power dc operation. Test structures without Schottky contacts showed high stability as compared to HEMTs, indicating that degradation of the gate is the reason for permanent device degradation. High reverse bias of the gate has been shown to induce the inverse piezoelectric effect, resulting in a sharp increase in gate leakage current due to crack formation. The introduction of elevated temperatures during high reverse gate bias indicated that device failure is due to the breakdown of an unintentional gate oxide. RF stress of AlGaN/GaN HEMTs showed comparable critical voltage breakdown regime as that of similar devices stressed under dc conditions. Though RF device characteristics showed stability up to a drain bias of 20 V, Schottky diode characteristics degraded substantially at all voltages investigated. Results from both dc and RF stress conditions, under several bias regimes, confirm that the primary root for stress induced degradation was due to the Schottky contact. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Practice of Regulatory Science (Development of Medical Devices).

PubMed

Niimi, Shingo

2017-01-01

Prototypes of medical devices are made in accordance with the needs of clinical practice, and for systems required during the initial process of medical device development for new surgical practices. Verification of whether these prototypes produce the intended performance specifications is conducted using basic tests such as mechanical and animal tests. The prototypes are then improved and modified until satisfactory results are obtained. After a prototype passes through a clinical trial process similar to that for new drugs, application for approval is made. In the approval application process, medical devices are divided into new, improved, and generic types. Reviewers judge the validity of intended use, indications, operation procedures, and precautions, and in addition evaluate the balance between risk and benefit in terms of efficacy and safety. Other characteristics of medical devices are the need for the user to attain proficiency in usage techniques to ensure efficacy and safety, and the existence of a variety of medical devices for which assessment strategies differ, including differences in impact on the body in cases in which a physical burden to the body or failure of a medical device develops. Regulatory science of medical devices involves prediction, judgment, and evaluation of efficacy, safety, and quality, from which data result which can become indices in the development stages from design to application for approval. A reduction in the number of animals used for testing, improvement in efficiency, reduction of the necessity for clinical trials, etc. are expected through rational setting of evaluation items.

Flexible piezoelectric energy harvesting from jaw movements

NASA Astrophysics Data System (ADS)

Delnavaz, Aidin; Voix, Jérémie

2014-10-01

Piezoelectric fiber composites (PFC) represent an interesting subset of smart materials that can function as sensor, actuator and energy converter. Despite their excellent potential for energy harvesting, very few PFC mechanisms have been developed to capture the human body power and convert it into an electric current to power wearable electronic devices. This paper provides a proof of concept for a head-mounted device with a PFC chin strap capable of harvesting energy from jaw movements. An electromechanical model based on the bond graph method is developed to predict the power output of the energy harvesting system. The optimum resistance value of the load and the best stretch ratio in the strap are also determined. A prototype was developed and tested and its performances were compared to the analytical model predictions. The proposed piezoelectric strap mechanism can be added to all types of head-mounted devices to power small-scale electronic devices such as hearing aids, electronic hearing protectors and communication earpieces.

Quantifying the mechanical and histological properties of thrombus analog made from human blood for the creation of synthetic thrombus for thrombectomy device testing.

PubMed

Merritt, William; Holter, Anne Marie; Beahm, Sharna; Gonzalez, Connor; Becker, Timothy A; Tabor, Aaron; Ducruet, Andrew F; Bonsmann, Laura S; Cotter, Trevor R; Frenklakh, Sergey

2018-04-25

Untreated ischemic stroke can lead to severe morbidity and death, and as such, there are numerous endovascular blood-clot removal (thrombectomy) devices approved for human use. Human thrombi types are highly variable and are typically classified in qualitative terms - 'soft/red,' 'hard/white,' or 'aged/calcified.' Quantifying human thrombus properties can accelerate the development of thrombus analogs for the study of thrombectomy outcomes, which are often inconsistent among treated patients. 'Soft'human thrombi were created from blood samples ex vivo (ie, human blood clotted in sample vials) and tested for mechanical properties using a hybrid rheometer material testing system. Synthetic thrombus materials were also mechanically tested and compared with the 'soft' human blood clots. Mechanical testing quantified the shear modulus and dynamic (elastic) modulus of volunteer human thrombus samples. This data was used to formulate a synthetic blood clot made from a composite polymer hydrogel of polyacrylamide and alginate (PAAM-Alg). The PAAM-Alg interpenetrating network of covalently and ionically cross-linked polymers had tunable elastic and shear moduli properties and shape memory characteristics. Due to its adjustable properties, PAAM-Alg can be modified to mimic various thrombi classifications. Future studies will include obtaining and quantitatively classifying patient thrombectomy samples and altering the PAAM-Alg to mimic the results for use with in vitro thrombectomy studies. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Mechanism Development, Testing, and Lessons Learned for the Advanced Resistive Exercise Device

NASA Technical Reports Server (NTRS)

Lamoreaux, Christopher D.; Landeck, Mark E.

2006-01-01

The Advanced Resistive Exercise Device (ARED) has been developed at NASA Johnson Space Center, for the International Space Station (ISS) program. ARED is a multi-exercise, high-load resistive exercise device, designed for long duration, human space missions. ARED will enable astronauts to effectively maintain their muscle strength and bone mass in the micro-gravity environment more effectively than any other existing devices. ARED's resistance is provided via two, 20.3 cm (8 in) diameter vacuum cylinders, which provide a nearly constant resistance source. ARED also has a means to simulate the inertia that is felt during a 1-G exercise routine via the flywheel subassembly, which is directly tied to the motion of the ARED cylinders. ARED is scheduled to fly on flight ULF 2 to the ISS and will be located in Node 1. Presently, ARED is in the middle of its qualification and acceptance test program. An extensive testing program and engineering evaluation has increased the reliability of ARED by bringing potential design issues to light before flight production. Some of those design issues, resolutions, and design details will be discussed in this paper.

Noncontacting-optical-strain device

NASA Technical Reports Server (NTRS)

Silver, R. H.

1970-01-01

Noncontacting-strain-measuring gauge and extensometer remotely measures the mechanical displacement along the entire length of a test specimen. Measurement is accomplished by continuous scanning of a reflected light from reflective bench markings or stripes previously affixed to the specimen.

A miniature mechanical ventilator for newborn mice.

PubMed

Kolandaivelu, K; Poon, C S

1998-02-01

Transgenic/knockout mice with pre-defined mutations have become increasingly popular in biomedical research as models of human diseases. In some instances, the resulting mutation may cause cardiorespiratory distress in the neonatal or adult animals and may necessitate resuscitation. Here we describe the design and testing of a miniature and versatile ventilator that can deliver varying ventilatory support modes, including conventional mechanical ventilation and high-frequency ventilation, to animals as small as the newborn mouse. With a double-piston body chamber design, the device circumvents the problem of air leakage and obviates the need for invasive procedures such as endotracheal intubation, which are particularly important in ventilating small animals. Preliminary tests on newborn mice as early as postnatal day O demonstrated satisfactory restoration of pulmonary ventilation and the prevention of respiratory failure in mutant mice that are prone to respiratory depression. This device may prove useful in the postnatal management of transgenic/knockout mice with genetically inflicted respiratory disorders.

Titanium-based, fenestrated, in-plane microneedles for passive ocular drug delivery.

PubMed

Khandan, Omid; Famili, Amin; Kahook, Malik Y; Rao, Masaru P

2012-01-01

Drug delivery to the eye remains a key challenge, due to limitations inherent to prevailing delivery techniques. For example, while topical delivery offers simplicity and safety, its efficacy is often limited by poor bioavailability, due to natural transport barriers and clearance mechanisms. Similarly, while intravitreal injections performed across the ocular tunic provide means for circumventing such limitations, non-negligible potential for retinal detachment and other complications adversely affects safety. Herein, we discuss our initial efforts to address these limitations through development of titanium-based microneedles (MNs) which seek to provide a safer, simpler, and more efficacious means of ocular drug delivery. Devices with in-plane geometry and through-thickness fenestrations that serve as drug reservoirs for passive delivery via diffusive transport from fast-dissolving coatings are demonstrated. Details regarding device design, fabrication, and mechanical testing are presented, as are results from preliminary coating characterization and insertion testing in ex vivo rabbit cornea.

The combined effect of dismantling for steam sterilization and aging on the accuracy of spring-style mechanical torque devices

PubMed Central

Mahshid, Minoo; Sadr, Seyed Jalil; Fayyaz, Ali; Kadkhodazadeh, Mahdi

2013-01-01

Purpose This study aimed to assess the combined effect of dismantling before sterilization and aging on the accuracy (±10% of the target torque) of spring-style mechanical torque devices (S-S MTDs). Methods Twenty new S-SMTDs from two different manufacturers (Nobel Biocare and Straumann: 10 of each type) were selected and divided into two groups, namely, case (group A) and control (group B). For sterilization, 100 cycles of autoclaving were performed in 100 sequences. In each sequence, 10 repetitions of peak torque values were registered for aging. To measure and assess the output of each device, a Tohnichi torque gauge was used (P<0.05). Results Before steam sterilization, all of the tested devices stayed within 10% of their target values. After 100 cycles of steam sterilization and aging with or without dismantling of the devices, the Nobel Biocare devices stayed within 10% of their target torque. In the Straumann devices, despite the significant difference between the peak torque and target torque values, the absolute error values stayed within 10% of their target torque. Conclusion Within the limitations of this study, there was no significant difference between the mean and absolute value of error between Nobel Biocare and Straumann S-S MTDs. PMID:24236244

Method for Fabricating Miniaturized NiTi Self-Expandable Thin Film Devices with Increased Radiopacity

NASA Astrophysics Data System (ADS)

Bechtold, Christoph; Lima de Miranda, Rodrigo; Chluba, Christoph; Zamponi, Christiane; Quandt, Eckhard

2016-12-01

Nitinol is the material of choice for many medical applications, in particular for minimally invasive implants due to its superelasticity and biocompatibility. However, NiTi has limited radiopacity which complicates positioning in the body. A common strategy to increase the radiopacity of NiTi devices is the addition of radiopaque markers by micro-riveting or micro-welding. The recent trend of miniaturizing medical devices, however, reduces their radiopacity further, and makes the addition of radiopaque markers to these miniaturized devices difficult. NiTi thin film technology has great potential to overcome such limitations and to fabricate new generations of miniaturized, self-expandable NiTi medical devices with additional functionalities, such as structured multilayer devices with increased radiopacity. For this purpose, we have produced superelastic thin film NiTi samples covered locally with Tantalum structures of different thickness and different shape. These multilayer devices were characterized regarding their mechanical and corrosion properties as well as their X-ray visibility. The superelastic behavior of the underlying NiTi layer is impeded by the Ta layer, and shows therefore a dependence on the Tantalum patterning geometry and thickness. No delamination was observed after mechanical and corrosion tests. The multilayers reveal excellent corrosion resistance, as well as a significant increase in radiopacity.

Evaluation of digital micromirror devices for use in space-based multiobject spectrometer application

NASA Astrophysics Data System (ADS)

Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan; Quijada, Manuel A.; Smee, Stephen A.; Pellish, Jonathan A.; Schwartz, Tim; Robberto, Massimo; Heap, Sara; Conley, Devin; Benavides, Carlos; Garcia, Nicholas; Bredl, Zach; Yllanes, Sebastian

2017-07-01

The astronomical community continues to be interested in suitable programmable slit masks for use in multiobject spectrometers (MOSs) on space missions. There have been ground-based MOS utilizing digital micromirror devices (DMDs), and they have proven to be highly accurate and reliable instruments. This paper summarizes the results of a continuing study to investigate the performance of DMDs under conditions associated with space deployment. This includes the response of DMDs to accelerated heavy-ion radiation, to the vibration and mechanical shock loads associated with launch, and the operability of DMD under cryogenic temperatures. The optical contrast ratio and a study of the long-term reflectance of a bare device have also been investigated. The results of the radiation testing demonstrate that DMDs in orbit would experience negligible heavy-ion-induced single event upset (SEU) rate burden; we predict an SEU rate of 5.6 micromirrors/24 h. Vibration and mechanical shock testing was performed according to the NASA General Environmental Verification Standard; there were no failed mirrors in the devices tested. The results of low temperature testing suggest that DMDs are not affected by the thermal load and operate smoothly at temperatures at least as low as 78 K. The reflectivity of a bare DMD did not measurably change even after being exposed to ambient conditions over a period of 13 months even. The measured contrast ratio ("on state" versus "off state" of the DMD micromirrors) was greater than 6000∶1 when illuminated with an f/4 optical beam. Overall DMDs are extremely robust and promise to provide a reliable alternative to microshutter arrays to be used in space as remotely programmable slit masks for MOS design.

Prosthetic Jamming Terminal Device: A Case Study of Untethered Soft Robotics

PubMed Central

Amend, John; Farrell, Todd; Latour, Debra; Martinez, Carlos; Johansson, Jen; McNicoll, Anthony; Wartenberg, Marek; Naseef, Samuel; Hanson, William; Culley, William

2016-01-01

Abstract This article illuminates the major and often overlooked challenge of untethering soft robotic systems through the context of recent work, in which soft robotic gripper technology enabled by jamming of granular media was applied to a prosthetic jamming terminal device (PJTD). The PJTD's technical and market feasibility was evaluated in a pilot study with two upper-limb amputees. A PJTD prototype was tested against a commercial device (Motion Control electric terminal service with a one degree-of-freedom pinching mechanism) using two existing hand function tests: the first quantified the device's speed in picking and placing small blocks and the second evaluated a person's ability to perform activities of daily living (ADLs). The PJTD prototype performed slightly slower than its commercial counterpart in the first test. While both participants successfully completed all the ADLs with both devices in the second test, the commercial device scored marginally higher. Results suggested that PJTD can have potential benefits over existing terminal devices, such as providing the capability to firmly grasp tools due to the ability of PJTD to conform to arbitrary surfaces and reducing compensatory shoulder movements due to its axisymmetric design. Some downsides were that users reported fatigue while operating the PJTD, as most operations require pushing the PJTD against target objects to adequately conform to them. The greatest drawback for the PJTD is also a major roadblock preventing a number of soft robotic research projects from making an impact in real-world applications: pneumatic technology required for operating the PJTD is currently too large and heavy to enable compact untethered operation. PMID:28078196

Design and Characterization of an Exoskeleton for Perturbing the Knee During Gait.

PubMed

Tucker, Michael R; Shirota, Camila; Lambercy, Olivier; Sulzer, James S; Gassert, Roger

2017-10-01

An improved understanding of mechanical impedance modulation in human joints would provide insights about the neuromechanics underlying functional movements. Experimental estimation of impedance requires specialized tools with highly reproducible perturbation dynamics and reliable measurement capabilities. This paper presents the design and mechanical characterization of the ETH Knee Perturbator: an actuated exoskeleton for perturbing the knee during gait. A novel wearable perturbation device was developed based on specific experimental objectives. Bench-top tests validated the device's torque limiting capability and characterized the time delays of the on-board clutch. Further tests demonstrated the device's ability to perform system identification on passive loads with static initial conditions. Finally, the ability of the device to consistently perturb human gait was evaluated through a pilot study on three unimpaired subjects. The ETH Knee Perturbator is capable of identifying mass-spring systems within 15% accuracy, accounting for over 95% of the variance in the observed torque in 10 out of 16 cases. Five-degree extension and flexion perturbations were executed on human subjects with an onset timing precision of 2.52% of swing phase duration and a rise time of 36.5 ms. The ETH Knee Perturbator can deliver safe, precisely timed, and controlled perturbations, which is a prerequisite for the estimation of knee joint impedance during gait. Tools such as this can enhance models of neuromuscular control, which may improve rehabilitative outcomes following impairments affecting gait and advance the design and control of assistive devices.

High strength fused silica flexures manufactured by femtosecond laser

NASA Astrophysics Data System (ADS)

Bellouard, Yves; Said, Ali A.; Dugan, Mark; Bado, Philippe

2009-02-01

Flexures are mechanical elements used in micro- and precision-engineering to precisely guide the motion of micro-parts. They consist of slender bodies that deform elastically upon the application of a force. Although counter-intuitive at first, fused silica is an attractive material for flexure. Pending that the machining process does not introduce surface flaws that would lead to catastrophic failure, the material has a theoretically high ultimate tensile strength of several GPa. We report on high-aspect ratio fused silica flexures manufactured by femtosecond laser combined with chemical etching. Notch-hinges with thickness as small as twenty microns and aspect ratios comparable to aspect ratios obtained by Deep- Reactive-Ion-Etching (DRIE) were fabricated and tested under different loading conditions. Multiple fracture tests were performed for various loading conditions and the cracks morphologies were analyzed using Scanning Electron Microscopy. The manufactured elements show outstanding mechanical properties with flexural strengths largely exceeding those obtained with other technologies and materials. Fused silica flexures offer a mean to combine integrated optics with micro-mechanics in a single monolithic substrate. Waveguides and mechanical elements can be combined in a monolithic devices opening new opportunities for integrated opto-mechatronics devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mundy, D; Tryggestad, E; Beltran, C

Purpose: To develop daily and monthly quality assurance (QA) programs in support of a new spot-scanning proton treatment facility using a combination of commercial and custom equipment and software. Emphasis was placed on efficiency and evaluation of key quality parameters. Methods: The daily QA program was developed to test output, spot size and position, proton beam energy, and image guidance using the Sun Nuclear Corporation rf-DQA™3 device and Atlas QA software. The program utilizes standard Atlas linear accelerator tests repurposed for proton measurements and a custom jig for indexing the device to the treatment couch. The monthly QA program wasmore » designed to test mechanical performance, image quality, radiation quality, isocenter coincidence, and safety features. Many of these tests are similar to linear accelerator QA counterparts, but many require customized test design and equipment. Coincidence of imaging, laser marker, mechanical, and radiation isocenters, for instance, is verified using a custom film-based device devised and manufactured at our facility. Proton spot size and position as a function of energy are verified using a custom spot pattern incident on film and analysis software developed in-house. More details concerning the equipment and software developed for monthly QA are included in the supporting document. Thresholds for daily and monthly tests were established via perturbation analysis, early experience, and/or proton system specifications and associated acceptance test results. Results: The periodic QA program described here has been in effect for approximately 9 months and has proven efficient and sensitive to sub-clinical variations in treatment delivery characteristics. Conclusion: Tools and professional guidelines for periodic proton system QA are not as well developed as their photon and electron counterparts. The program described here efficiently evaluates key quality parameters and, while specific to the needs of our facility, could be readily adapted to other proton centers.« less

Feasibility and repeatability of cold and mechanical quantitative sensory testing in normal dogs

PubMed Central

Briley, Jessica D.; Williams, Morika D.; Freire, Mila; Griffith, Emily H.; Lascelles, B. Duncan X.

2015-01-01

Feasibility and inter-session repeatability of cold and mechanical quantitative sensory testing (QST) were assessed in 24 normal dogs. Cold thermal latencies were evaluated using a thermal probe (0 °C) applied to three pelvic limb sites. Mechanical thresholds were measured using an electronic von Frey anesthesiometer (EVF) and a blunt-probed pressure algometer (PA) applied to the dorsal aspect of the metatarsus. All QST trials were performed with dogs in lateral recumbency. Collection of cold QST data was easy (feasible) in 19/24 (79%) dogs. However, only 18.4%, 18.9% and 13.2% of cold QST trials elicited a response at the medial tibia, third digital pad and plantar metatarsal regions, respectively. Collection of mechanical QST data was easy (feasible) in 20/24 (83%) dogs for both EVF and PA. At consecutive sampling times, approximately 2 weeks apart, the average EVF sensory thresholds were 414 ± 186 g and 379 ± 166 g, respectively, and the average PA sensory thresholds were 1089 ± 414 g and 1028 ± 331 g, respectively. There was no significant difference in inter-session or inter-limb threshold values for either mechanical QST device. The cold QST protocol in this study was achievable, but did not provide consistently quantifiable results. Both mechanical QST devices tested provided repeatable, reliable sensory threshold measurements in normal, client-owned dogs. These findings contribute to the validation of the EVF and PA as tools to obtain repeated QST data over time in dogs to assess somatosensory processing changes. PMID:24268475

Time-elapsed screw insertion with microCT imaging.

PubMed

Ryan, M K; Mohtar, A A; Cleek, T M; Reynolds, K J

2016-01-25

Time-elapsed analysis of bone is an innovative technique that uses sequential image data to analyze bone mechanics under a given loading regime. This paper presents the development of a novel device capable of performing step-wise screw insertion into excised bone specimens, within the microCT environment, whilst simultaneously recording insertion torque, compression under the screw head and rotation angle. The system is computer controlled and screw insertion is performed in incremental steps of insertion torque. A series of screw insertion tests to failure were performed (n=21) to establish a relationship between the torque at head contact and stripping torque (R(2)=0.89). The test-device was then used to perform step-wise screw insertion, stopping at intervals of 20%, 40%, 60% and 80% between screw head contact and screw stripping. Image data-sets were acquired at each of these time-points as well as at head contact and post-failure. Examination of the image data revealed the trabecular deformation as a result of increased insertion torque was restricted to within 1mm of the outer diameter of the screw thread. Minimal deformation occurred prior to the step between the 80% time-point and post-failure. The device presented has allowed, for the first time, visualization of the micro-mechanical response in the peri-implant bone with increased tightening torque. Further testing on more samples is expected to increase our understanding of the effects of increased tightening torque at the micro-structural level, and the failure mechanisms of trabeculae. Copyright © 2015 Elsevier Ltd. All rights reserved.

MOEMs devices designed and tested for future astronomical instrumentation in space

NASA Astrophysics Data System (ADS)

Zamkotsian, Frédéric; Lanzoni, Patrick; Waldis, Severin; Noell, Wilfried; Conedera, Veronique; Fabre, Norbert; Viard, Thierry; Buisset, Christophe

2017-11-01

Next generation of astronomical instrumentation for space telescopes requires Micro-Opto-Electro- Mechanical Systems (MOEMS) with remote control capability and cryogenic operation. MOEMS devices have the capability to tailor the incoming light in terms of intensity and object selection with programmable slit masks, in terms of phase and wavefront control with micro-deformable mirrors, and finally in terms of spectrum with programmable diffraction gratings. Applications are multi-object spectroscopy (MOS), wavefront correction and programmable spectrographs. We are engaged since several years in the design, realization and characterization of MOEMS devices suited for astronomical instrumentation.

Technology for noninvasive mechanical ventilation: looking into the black box

PubMed Central

Navajas, Daniel; Montserrat, Josep M.

2016-01-01

Current devices for providing noninvasive respiratory support contain sensors and built-in intelligence for automatically modifying ventilation according to the patient's needs. These devices, including automatic continuous positive airway pressure devices and noninvasive ventilators, are technologically complex and offer a considerable number of different modes of ventilation and setting options, the details of which are sometimes difficult to capture by the user. Therefore, better predicting and interpreting the actual performance of these ventilation devices in clinical application requires understanding their functioning principles and assessing their performance under well controlled bench test conditions with simulated patients. This concise review presents an updated perspective of the theoretical basis of intelligent continuous positive airway pressure and noninvasive ventilation devices, and of the tools available for assessing how these devices respond under specific ventilation phenotypes in patients requiring breathing support. PMID:27730162

Will ethylene oxide sterilization influence the application of novel Cu/LDPE nanocomposite intrauterine devices?

PubMed

Xia, Xianping; Wang, Yun; Cai, Shuizhou; Xie, Changsheng; Zhu, Changhong

2009-01-01

Copper/low-density polyethylene (Cu/LDPE) nanocomposite intrauterine device (IUD) is an implanted medicinal device that must be sterilized before use. Sterilization processes act either chemically or physically, leading to a lethal change in the structure or function of organic macromolecules in microorganisms. Given the nature of their action, sterilization might also attack the macromolecules of polymers by the same mechanisms, resulting in changes in surface functional groups and in the internal structure of the polymer. If sterilization leads to changes in surface functional groups and in the internal structure of the LDPE matrix, which will influence the mechanical property and cupric ions release rate of novel Cu/LDPE nanocomposite IUDs, potential clinical application will be limited. Therefore, it is necessary to study the influence of ethylene oxide sterilization on the potential clinical application of novel Cu/LDPE nanocomposite IUDs. The influence of ethylene oxide sterilization on the internal structure, surface functional groups, mechanical property and cupric ions release rate of novel Cu/LDPE nanocomposite IUDs was studied using differential scanning calorimetry, attenuated total reflection Fourier transform infrared spectroscopy, tensile testing and absorbance measurement. Ethylene oxide sterilization did not have any influence on the internal structure, surface functional groups, mechanical property and cupric ions release rate of novel Cu/LDPE nanocomposite intrauterine devices. Ethylene oxide sterilization will not affect the potential application of novel Cu/LDPE nanocomposite IUDs.

The high frequency light load fatigue testing machine based on giant magnetostrictive material and stroke multiplier

NASA Astrophysics Data System (ADS)

Wang, M. D.; Li, D. S.; Huang, Y.; Zhang, C.; Zhong, K. M.; Sun, L. N.

2013-08-01

In the notebook and clamshell mobile phone, data communication wire often requires repeated bending. Generally, communication wire with the actual application conditions, the test data cannot assess bending resistance performance of data communication wire is tested conventionally using wires with weights of 90 degree to test bending number, this test method and device is not fully reflect the fatigue performance in high frequency and light load application condition, at the same time it has a large difference between the test data of the long-term reliability of high frequency and low load conditions. In this paper, high frequency light load fatigue testing machine based on the giant magnetostrictive material and stroke multiplier is put forward, in which internal reflux stroke multiplier is driven by giant magnetostrictive material to realize the rapid movement of light load. This fatigue testing device has the following advantages: (1) When the load is far less than the friction, reducing friction is very effective to improve the device performance. Because the body is symmetrical, the friction loss of radial does not exist in theory, so the stress situation of mechanism is good with high transmission efficiency and long service life. (2) The installation position of the output hydraulic cylinder, can be arranged conveniently as ordinary cylinder. (3) Reciprocating frequency, displacement and speed of high frequency movement can be programmed easily to change with higher position precision. (4)Hydraulic oil in this device is closed to transmit, which does not produce any environment pollution. The device has no hydraulic pump and tank, and less energy conversion processes, so it is with the trend of green manufacturing.

SNAP Assay Technology.

PubMed

O'Connor, Thomas P

2015-12-01

The most widely used immunoassay configuration is the enzyme-linked immunosorbent assay (ELISA) because the procedure produces highly sensitive and specific results and generally is easy to use. By definition, ELISAs are immunoassays used to detect a substance (typically an antigen or antibody) in which an enzyme is attached (conjugated) to one of the reactants and an enzymatic reaction is used to amplify the signal if the substance is present. Optimized ELISAs include several steps that are performed in sequence using a defined protocol that typically includes application of sample and an enzyme-conjugated antibody or antigen to an immobilized reagent, followed by wash and enzyme reaction steps. The SNAP assay is an in-clinic device that performs each of the ELISA steps in a timed sequential fashion with little consumer interface. The components and mechanical mechanism of the assay device are described. Detailed descriptions of features of the assay, which minimize nonspecific binding and enhance the ability to read results from weak-positive samples, are given. Basic principles used in assays with fundamentally different reaction mechanisms, namely, antigen-detection, antibody-detection, and competitive assays are given. Applications of ELISA technology, which led to the development of several multianalyte SNAP tests capable of testing for up to 6 analytes using a single-sample and a single-SNAP device are described. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Development of a MEMS device for acoustic emission testing

NASA Astrophysics Data System (ADS)

Ozevin, Didem; Pessiki, Stephen P.; Jain, Akash; Greve, David W.; Oppenheim, Irving J.

2003-08-01

Acoustic emission testing is an important technology for evaluating structural materials, and especially for detecting damage in structural members. Significant new capabilities may be gained by developing MEMS transducers for acoustic emission testing, including permanent bonding or embedment for superior coupling, greater density of transducer placement, and a bundle of transducers on each device tuned to different frequencies. Additional advantages include capabilities for maintenance of signal histories and coordination between multiple transducers. We designed a MEMS device for acoustic emission testing that features two different mechanical types, a hexagonal plate design and a spring-mass design, with multiple detectors of each type at ten different frequencies in the range of 100 kHz to 1 MHz. The devices were fabricated in the multi-user polysilicon surface micromachining (MUMPs) process and we have conducted electrical characterization experiments and initial experiments on acoustic emission detection. We first report on C(V) measurements and perform a comparison between predicted (design) and measured response. We next report on admittance measurements conducted at pressures varying from vacuum to atmospheric, identifying the resonant frequencies and again providing a comparison with predicted performance. We then describe initial calibration experiments that compare the performance of the detectors to other acoustic emission transducers, and we discuss the overall performance of the device as a sensor suite, as contrasted to the single-channel performance of most commercial transducers.

Nanox: a miniature mechanical stress rig designed for near-field X-ray diffraction imaging techniques.

PubMed

Gueninchault, N; Proudhon, H; Ludwig, W

2016-11-01

Multi-modal characterization of polycrystalline materials by combined use of three-dimensional (3D) X-ray diffraction and imaging techniques may be considered as the 3D equivalent of surface studies in the electron microscope combining diffraction and other imaging modalities. Since acquisition times at synchrotron sources are nowadays compatible with four-dimensional (time lapse) studies, suitable mechanical testing devices are needed which enable switching between these different imaging modalities over the course of a mechanical test. Here a specifically designed tensile device, fulfilling severe space constraints and permitting to switch between X-ray (holo)tomography, diffraction contrast tomography and topotomography, is presented. As a proof of concept the 3D characterization of an Al-Li alloy multicrystal by means of diffraction contrast tomography is presented, followed by repeated topotomography characterization of one selected grain at increasing levels of deformation. Signatures of slip bands and sudden lattice rotations inside the grain have been shown by means of in situ topography carried out during the load ramps, and diffraction spot peak broadening has been monitored throughout the experiment.

Nanox: a miniature mechanical stress rig designed for near-field X-ray diffraction imaging techniques

PubMed Central

Gueninchault, N.; Proudhon, H.; Ludwig, W.

2016-01-01

Multi-modal characterization of polycrystalline materials by combined use of three-dimensional (3D) X-ray diffraction and imaging techniques may be considered as the 3D equivalent of surface studies in the electron microscope combining diffraction and other imaging modalities. Since acquisition times at synchrotron sources are nowadays compatible with four-dimensional (time lapse) studies, suitable mechanical testing devices are needed which enable switching between these different imaging modalities over the course of a mechanical test. Here a specifically designed tensile device, fulfilling severe space constraints and permitting to switch between X-ray (holo)tomography, diffraction contrast tomography and topotomography, is presented. As a proof of concept the 3D characterization of an Al–Li alloy multicrystal by means of diffraction contrast tomography is presented, followed by repeated topotomography characterization of one selected grain at increasing levels of deformation. Signatures of slip bands and sudden lattice rotations inside the grain have been shown by means of in situ topography carried out during the load ramps, and diffraction spot peak broadening has been monitored throughout the experiment. PMID:27787253

Accuracy of mechanical torque-limiting devices for dental implants.

PubMed

L'Homme-Langlois, Emilie; Yilmaz, Burak; Chien, Hua-Hong; McGlumphy, Edwin

2015-10-01

A common complication in implant dentistry is unintentional implant screw loosening. The critical factor in the prevention of screw loosening is the delivery of the appropriate target torque value. Mechanical torque-limiting devices (MTLDs) are the most frequently recommended devices by the implant manufacturers to deliver the target torque value to the screw. Two types of MTLDs are available: friction-style and spring-style. Limited information is available regarding the influence of device type on the accuracy of MTLDs. The purpose of this study was to determine and compare the accuracy of spring-style and friction-style MTLDs. Five MTLDs from 6 different dental implant manufacturers (Astra Tech/Dentsply, Zimmer Dental, Biohorizons, Biomet 3i, Straumann [ITI], and Nobel Biocare) (n=5 per manufacturer) were selected to determine their accuracy in delivering target torque values preset by their manufacturers. All torque-limiting devices were new and there were 3 manufacturers for the friction-style and 3 manufacturers for the spring-style. The procedure of target torque measurement was performed 10 times for each device and a digital torque gauge (Chatillon Model DFS2-R-ND; Ametek) was used to record the measurements. Statistical analysis used nonparametric tests to determine the accuracy of the MTLDs in delivering target torque values and Bonferroni post hoc tests were used to assess pairwise comparisons. Median absolute difference between delivered torque values and target torque values of friction-style and spring-style MTLDs were not significantly different (P>.05). Accuracy of Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly different than Biohorizons torque-limiting devices (P<.05). There is no difference between the accuracy of new friction-style MTLDs and new spring-style MTLDs. All MTLDs fell within ±10% of the target torque value. Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly more accurate than Biohorizons (C) torque-limiting devices (P<.05); however, all the torque-limiting devices fell within ±10% of the target torque value preset by the manufacturers. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Anti-wear Mechanism Analysis of Nano-CaCO3 Additives

NASA Astrophysics Data System (ADS)

Xu, Zhen; Sun, Junfeng

2018-06-01

In this paper, the wear test was carried on with cylinder piston by the wear test device, receiving the results of the piston ring wear and abrasive characteristics by monitoring the wear process, the thesis analysis and put forward the nano-CaCO3 lubricating oil additive anti wear mechanism by the ferrography analysis technology, and provide the technical reference for the relevant measures to reduce wear and the friction, and provide reference value for further study on the related theories of reducing wear and reducing friction.

Assembly processes comparison for a miniaturized laser used for the Exomars European Space Agency mission

NASA Astrophysics Data System (ADS)

Ribes-Pleguezuelo, Pol; Inza, Andoni Moral; Basset, Marta Gilaberte; Rodríguez, Pablo; Rodríguez, Gemma; Laudisio, Marco; Galan, Miguel; Hornaff, Marcel; Beckert, Erik; Eberhardt, Ramona; Tünnermann, Andreas

2016-11-01

A miniaturized diode-pumped solid-state laser (DPSSL) designed as part of the Raman laser spectrometer (RLS) instrument for the European Space Agency (ESA) Exomars mission 2020 is assembled and tested for the mission purpose and requirements. Two different processes were tried for the laser assembling: one based on adhesives, following traditional laser manufacturing processes; another based on a low-stress and organic-free soldering technique called solderjet bumping technology. The manufactured devices were tested for the processes validation by passing mechanical, thermal cycles, radiation, and optical functional tests. The comparison analysis showed a device improvement in terms of reliability of the optical performances from the soldered to the assembled by adhesive-based means.

Design and control of a high precision drive mechanism

NASA Astrophysics Data System (ADS)

Pan, Bo; He, Yongqiang; Wang, Haowei; Zhang, Shuyang; Zhang, Donghua; Wei, Xiaorong; Jiang, Zhihong

2017-01-01

This paper summarizes the development of a high precision drive mechanism (HPDM) for space application, such as the directional antenna, the laser communication device, the mobile camera and other pointing mechanisms. In view of the great practical significance of high precision drive system, control technology for permanent magnet synchronous motor (PMSM) servo system is also studied and a PMSM servo controller is designed in this paper. And the software alignment was applied to the controller to eliminate the steady error of the optical encoder, which helps to realize the 1 arcsec (1σ) control precision. To assess its capabilities, the qualification environment testing including the thermal vacuum cycling testing, and the sinusoidal and random vibration were carried out. The testing results show that the performance of the HPDM is almost the same between the former and the end of each testing.

In situ MEMS testing: correlation of high-resolution X-ray diffraction with mechanical experiments and finite element analysis.

PubMed

Schifferle, Andreas; Dommann, Alex; Neels, Antonia

2017-01-01

New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication. Within this study a concept for the investigation of mechanically loaded MEMS materials on an atomic level is introduced, combining high-resolution X-ray diffraction (HRXRD) measurements with finite element analysis (FEA) and mechanical testing. In situ HRXRD measurements were performed on tensile loaded single crystal silicon (SCSi) specimens by means of profile scans and reciprocal space mapping (RSM) on symmetrical (004) and (440) reflections. A comprehensive evaluation of the rather complex XRD patterns and features was enabled by the correlation of measured with simulated, 'theoretical' patterns. Latter were calculated by a specifically developed, simple and fast approach on the basis of continuum mechanical relations. Qualitative and quantitative analysis confirmed the admissibility and accuracy of the presented method. In this context [001] Poisson's ratio was determined providing an error of less than 1.5% with respect to analytical prediction. Consequently, the introduced procedure contributes to further going investigations of weak scattering being related to strain and defects in crystalline structures and therefore supports investigations on materials and devices failure mechanisms.

In situ MEMS testing: correlation of high-resolution X-ray diffraction with mechanical experiments and finite element analysis

PubMed Central

Schifferle, Andreas; Dommann, Alex; Neels, Antonia

2017-01-01

Abstract New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication. Within this study a concept for the investigation of mechanically loaded MEMS materials on an atomic level is introduced, combining high-resolution X-ray diffraction (HRXRD) measurements with finite element analysis (FEA) and mechanical testing. In situ HRXRD measurements were performed on tensile loaded single crystal silicon (SCSi) specimens by means of profile scans and reciprocal space mapping (RSM) on symmetrical (004) and (440) reflections. A comprehensive evaluation of the rather complex XRD patterns and features was enabled by the correlation of measured with simulated, ‘theoretical’ patterns. Latter were calculated by a specifically developed, simple and fast approach on the basis of continuum mechanical relations. Qualitative and quantitative analysis confirmed the admissibility and accuracy of the presented method. In this context [001] Poisson’s ratio was determined providing an error of less than 1.5% with respect to analytical prediction. Consequently, the introduced procedure contributes to further going investigations of weak scattering being related to strain and defects in crystalline structures and therefore supports investigations on materials and devices failure mechanisms. PMID:28533825

Preliminary design development of 100 KW rotary power transfer device

NASA Technical Reports Server (NTRS)

Weinberger, S. M.

1981-01-01

Contactless power transfer devices for transferring electrical power across a rotating spacecraft interface were studied. A power level of 100 KW was of primary interest and the study was limited to alternating current devices. Rotary transformers and rotary capacitors together with the required dc to ac power conditioning electronics were examined. Microwave devices were addressed. The rotary transformer with resonant circuit power conditioning was selected as the most feasible approach. The rotary capacitor would be larger while microwave devices would be less efficient. A design analysis was made of a 100 KW, 20 kHz power transfer device consisting of a rotary transformer, power conditioning electronics, drive mechanism and heat rejection system. The size, weight and efficiency of the device were determined. The characteristics of a baseline slip ring were presented. Aspects of testing the 100 KW power transfer device were examined. The power transfer device is a feasible concept which can be implemented using presently available technologies.

A mechanical system for tensile testing of supported films at the nanoscale.

PubMed

Pantano, Maria F; Speranza, G; Galiotis, Costas; Pugno, Nicola M

2018-06-27

Standard tensile tests of materials are usually performed on freestanding specimens. However, such requirement is difficult to implement when the materials of interest are of nanoscopic dimensions due to problems related to their handling and manipulation. In the present paper, a new device is presented for tensile testing of thin nanomaterials, which allows tests to be carried out on specimens initially deposited onto a macroscopic pre-notched substrate. On loading, however, no substrate effects are introduced, allowing the films to be freely stretched. The results obtained from a variety of thin metal or polymeric films are very promising for the further development of this technique as a standard method for nanomaterial mechanical testing. © 2018 IOP Publishing Ltd.

All-optical non-mechanical fiber-coupled sensor for liquid- and airborne sound detection.

NASA Astrophysics Data System (ADS)

Rohringer, Wolfgang; Preißer, Stefan; Fischer, Balthasar

2017-04-01

Most fiber-optic devices for pressure, strain or temperature measurements are based on measuring the mechanical deformation of the optical fiber by various techniques. While excellently suited for detecting strain, pressure or structure-borne sound, their sensitivity to liquid- and airborne sound is so far not comparable with conventional capacitive microphones or piezoelectric hydrophones. Here, we present an all-optical acoustic sensor which relies on the detection of pressure-induced changes of the optical refractive index inside a rigid, millimeter-sized, fiber-coupled Fabry-Pérot interferometer (FPI). No mechanically movable or deformable parts take part in the signal transduction chain. Therefore, due to the absence of mechanical resonances, this sensing principle allows for high sensitivity as well as a flat frequency response over an extraordinary measurement bandwidth. As a fiber-coupled device, it can be integrated easily into already available distributed fiber-optic networks for geophysical sensing. We present characterization measurements demonstrating the sensitivity, frequency response and directivity of the device for sound and ultrasound detection in air and water. We show that low-frequency temperature and pressure drifts can be recorded in addition to acoustic sensing. Finally, selected application tests of the laser-based hydrophone and microphone implementation are presented.

Practical Considerations for Using Constant Force Springs in Space-Based Mechanisms

NASA Technical Reports Server (NTRS)

Williams, R. Brett; Fisher, Charles D.; Gallon, John C.

2013-01-01

Mechanical springs are a common element in mechanism from all walks of life; cars, watches, appliances, and many others. These springs generally exhibit a linear relationship between force and deflection. In small mechanisms, deflections are small so the variation in spring force between one position and another are generally small and do not influence the design or functionality of the device. However, as the spacecraft industry drives towards larger, deployable satellites, the distances a spring or springs must function over can become considerable so much so that the structural integrity of the device may be impacted. As such, an increasingly common mechanism element is the constant force spring- one that provides a constant force regardless of deflection. These elements are commonly in the conceptual design phase to deal with system-level large deflections, but in the detailed design or integration test phase they can pose significant implementation issues. This article addresses some of the detailed issues in order for these constant force springs to be properly designed into space systems.

Flip-chip fabrication of integrated micromirror arrays using a novel latching off-chip hinge mechanism

NASA Astrophysics Data System (ADS)

Michalicek, M. Adrian; Bright, Victor M.

2001-10-01

This paper presents the design, fabrication, modeling, and testing of various arrays of cantilever micromirror devices integrated atop CMOS control electronics. The upper layers of the arrays are prefabricated in the MUMPs process and then flip-chip transferred to CMOS receiving modules using a novel latching off-chip hinge mechanism. This mechanism allows the micromirror arrays to be released, rotated off the edge of the host module and then bonded to the receiving module using a standard probe station. The hinge mechanism supports the arrays by tethers that are severed to free the arrays once bonded. The resulting devices are inherently planarized since the bottom of the first releasable MUMPs layer becomes the surface of the integrated mirror. The working devices are formed by mirror surfaces bonded to address electrodes fabricated above static memory cells on the CMOS module. These arrays demonstrate highly desirable features such as compatible address potentials, less than 2 nm of RMS roughness, approximately 1 micrometers of lateral position accuracy and the unique ability to metallize reflective surfaces without masking. Ultimately, the off-chip hinge mechanism enables very low-cost, simple, reliable, repeatable and accurate assembly of advanced MEMS and integrated microsystems without specialized equipment or complex procedures.

A simple device for teaching direct ophthalmoscopy to primary care practitioners.

PubMed

Chung, Kelly D; Watzke, Robert C

2004-09-01

Ophthalmoscopy, a valuable skill for primary care practitioners, can be challenging to learn. A simple and inexpensive device for teaching direct ophthalmoscopy to primary care practitioners is described. Device description. Cylindrical plastic canisters were altered to have an artificial pupil at one end and a replaceable fundus photograph at the other end to simulate the mechanics of performing direct ophthalmoscopy on a real eye. These were tested for ease of use by primary care students. The devices to aid in teaching ophthalmoscopy proved to be simple and inexpensive to construct. They allowed students to practice direct ophthalmoscopy technique and identification of funduscopic abnormalities. This simple device for teaching direct ophthalmoscopy to primary care practitioners is inexpensive to create and is a valuable aid for teaching direct ophthalmoscopy to primary care practitioners.

Enteral Feeding Tube Clogging: What Are the Causes and What Are the Answers? A Bench Top Analysis.

PubMed

Garrison, Christopher M

2018-02-01

Clogged enteral feeding tubes remain a significant barrier to the delivery of nutrition, hydration, and medications to patients who cannot tolerate oral intake. There is limited research that compares the relative efficacy of different methods used to clear a clogged feeding tube. The objectives of this study were to better understand the factors that contribute to enteral feeding tube clogging and to test the efficacy of 3 methods for clearing clogged feeding tubes. Three formulations of clogs were artificially created and tested in vitro and composed of various quantities of crushed medication (ie, aspirin) and 0.15 g coagulated protein (ie, tofu). The following 3 clog clearing strategies were tested on all clog types (n = 5 clogs/formulation/treatment): warm water flushes, an enzyme treatment, and an actuated mechanical occlusion clearing device. The variable among the clog types that appears most responsible for decreased clearing success is the state of the coagulated protein. Dried-out protein appears to makes a greater difference than increasing the medication quantity. The actuated mechanical occlusion clearing device was significantly more successful (93%) when compared with warm water flushes (20%) and the commercially available enzyme treatment (33%; P < .005) at clearing the clogs. The actuated device required significantly less total procedure time (P < .005) and total nursing time (P < .005) when compared with the other 2 clearing methods. When clogs occur, they can be quickly and effectively resolved by the actuated device, but other methodologies such as water and enzyme treatments may be of assistance. © 2018 American Society for Parenteral and Enteral Nutrition.

Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies.

PubMed

Bock, Eduardo; Antunes, Pedro; Leao, Tarcisio; Uebelhart, Beatriz; Fonseca, Jeison; Leme, Juliana; Utiyama, Bruno; da Silva, Cibele; Cavalheiro, Andre; Filho, Diolino Santos; Dinkhuysen, Jarbas; Biscegli, Jose; Andrade, Aron; Arruda, Celso

2011-05-01

An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Materials challenges for repeatable RF wireless device reconfiguration with microfluidic channels

NASA Astrophysics Data System (ADS)

Griffin, Anthony S.; Sottos, Nancy R.; White, Scott R.

2018-03-01

Recently, adaptive wireless devices have utilized displacement of EGaIn within microchannels as an electrical switching mechanism to enable reconfigurable electronics. Device reconfiguration using EGaIn in microchannels overcomes many challenges encountered by more traditional reconfiguration mechanisms such as diodes and microelectromechanical systems (MEMS). Reconfiguration using EGaIn is severely limited by undesired permanent shorting due to retention of the liquid in microchannels caused by wetting and rapid oxide skin formation. Here, we investigate the conditions which prevent repeatable electrical switching using EGaIn in microchannels. Initial contact angle tests of EGaIn on epoxy surfaces demonstrate the wettability of EGaIn on flat surfaces. SEM cross-sections of microchannels reveal adhesion of EGaIn residue to channel walls. Micro-computed tomography (microCT) scans of provide volumetric measurements of EGaIn remaining inside channels after flow cycling. Non-wetting coatings are proposed as materials based strategy to overcome these issues in future work.

Advanced Modeling of Micromirror Devices

NASA Technical Reports Server (NTRS)

Michalicek, M. Adrian; Sene, Darren E.; Bright, Victor M.

1995-01-01

The flexure-beam micromirror device (FBMD) is a phase only piston style spatial light modulator demonstrating properties which can be used for phase adaptive corrective optics. This paper presents a complete study of a square FBMD, from advanced model development through final device testing and model verification. The model relates the electrical and mechanical properties of the device by equating the electrostatic force of a parallel-plate capacitor with the counter-acting spring force of the device's support flexures. The capacitor solution is derived via the Schwartz-Christoffel transformation such that the final solution accounts for non-ideal electric fields. The complete model describes the behavior of any piston-style device, given its design geometry and material properties. It includes operational parameters such as drive frequency and temperature, as well as fringing effects, mirror surface deformations, and cross-talk from neighboring devices. The steps taken to develop this model can be applied to other micromirrors, such as the cantilever and torsion-beam designs, to produce an advanced model for any given device. The micromirror devices studied in this paper were commercially fabricated in a surface micromachining process. A microscope-based laser interferometer is used to test the device in which a beam reflected from the device modulates a fixed reference beam. The mirror displacement is determined from the relative phase which generates a continuous set of data for each selected position on the mirror surface. Plots of this data describe the localized deflection as a function of drive voltage.

On the Mechanical Properties and Microstructure of Nitinol forBiomedical Stent Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, Scott W.

2006-01-01

This dissertation was motivated by the alarming number of biomedical device failures reported in the literature, coupled with the growing trend towards the use of Nitinol for endovascular stents. The research is aimed at addressing two of the primary failure modes in Nitinol endovascular stents: fatigue-crack growth and overload fracture. The small dimensions of stents, coupled with their complex geometries and variability among manufacturers, make it virtually impossible to determine generic material constants associated with specific devices. Instead, the research utilizes a hybrid of standard test techniques (fracture mechanics and x-ray micro-diffraction) and custom-designed testing apparatus for the determination ofmore » the fracture properties of specimens that are suitable representations of self-expanding Nitinol stents. Specifically, the role of texture (crystallographic alignment of atoms) and the austenite-to-martensite phase transformation on the propagation of cracks in Nitinol was evaluated under simulated body conditions and over a multitude of stresses and strains. The results determined through this research were then used to create conservative safe operating and inspection criteria to be used by the biomedical community for the determination of specific device vulnerability to failure by fracture and/or fatigue.« less

Soft x ray window encapsulant for HgI2 detectors

NASA Technical Reports Server (NTRS)

Entine, G.; Shah, K.; Squillante, M.

1987-01-01

HgI2 is an excellent semiconductor material for a low energy, room temperature x-ray spectrometer. The high values of the atomic numbers for its constituent elements gives high x-ray and gamma ray stopping power. The band gap of HgI2 is significantly higher than other commonly used semiconductors. Owing to the large value band gap, the leakage current for HgI2 devices is smaller, thus allowing low noise performance. Devices fabricated from HgI2 crystals have demonstrated energy resolution sufficient to distinguish the x-ray emission from the neighboring elements on the periodic table. Also the power requirements of HgI2 are very low. These characteristics make a HgI2 spectrometer an ideal component in a satellite based detection system. Unfortunately, HgI2 crystals tend to deteriorate with time, even if protected by standard semiconductor encapsulants. This degradation ruins the performance of the device in terms of its energy resolution and pulse amplitude. The degrading mechanism is believed to be material loss occurring from below the electrodes, due to high vapor pressure of HgI2 at room temperature. To address this major obstacle to rapid expansion of HgI2 technology, a research program aimed at improving device stability by encapsulation with inert polymeric materials was carried out. The program focused specifically on optimizing the encapsulant materials and their deposition techniques. The principal objectives for this program were device encapsulation, device testing, and accelerated testing to ensure very long term stability of these high resolution sensors. A variety of encapsulants were investigated with the selection criteria based on their chemical diffusion barrier properties, mechanical stability, reactivity, and morphology of encapsulant films. The investigation covered different classes of encapsulants including solvent based encapsulants, vapor deposited encapsulants, and plasma polymerized encapsulants. A variety of characterization techniques were employed to examine their effectiveness in stabilizing HgI2 devices; these included permeability evaluation, vacuum and heat testing, scanning electron microscopy (SEM) as well as studying the detector performance of coated detectors. The plasma polymerized films appear to have entirely solved the HgI2 degradation problem. Another achievement of this program was the development of an accelerated testing technique which correlates extremely well with long term tesing.

In Vitro Study of Flow Regulation for Pulmonary Insufficiency

PubMed Central

Camp, T. A.; Stewart, K. C.; Figliola, R. S.; McQuinn, T.

2007-01-01

Given the tolerance of the right heart circulation to mild regurgitation and gradient, we study the potential of using motionless devices to regulate the pulmonary circulation. In addition, we document the flow performance of two mechanical valves. A motionless diode, a nozzle, a mechanical bileaflet valve, and a tilting disk valve were tested in a pulmonary mock circulatory system over the normal human range of pulmonary vascular resistance (PVR). For the mechanical valves, regurgitant fractions (RFs) and transvalvular pressure gradients were found to be weak functions of PVR. On the low end of normal PVR, the bileaflet and tilting disk valves fluttered and would not fully close. Despite this anomaly, the regurgitant fraction of either valve did not change significantly. The values for RF and transvalvular gradient measured varied from 4 to 7% and 4 to 7 mm Hg, respectively, at 5 lpm for all tests. The diode valve was able to regulate flow with mild regurgitant fraction and trivial gradient but with values higher than either mechanical valve tested. Regurgitant fraction ranged from 2 to 17% in tests extending from PVR values of 1 to 4.5 mm Hg/lpm at 5 lpm and with concomitant increases in gradient up to 17 mm Hg. The regurgitant fraction for the nozzle increased from 2 to 23% over the range of PVR with gradients increasing to 18 mm Hg. The significant findings were: (1) the mechanical valves controlled regurgitation at normal physiological cardiac output and PVR even though they failed to close at some normal values of PVR and showed leaflet flutter; and (2) it may be possible to regulate the pulmonary circulation to tolerable levels using a motionless pulmonary valve device. PMID:17408334

Low-cost, disposable microfluidics device for blood plasma extraction using continuously alternating paramagnetic and diamagnetic capture modes

PubMed Central

Kim, Pilkee; Ong, Eng Hui; Yoon, Yong-Jin; Ng, Sum Huan Gary; Puttachat, Khuntontong

2016-01-01

Blood plasma contains biomarkers and substances that indicate the physiological state of an organism, and it can be used to diagnose various diseases or body condition. To improve the accuracy of diagnostic test, it is required to obtain the high purity of blood plasma. This paper presents a low-cost, disposable microfluidics device for blood plasma extraction using magnetophoretic behaviors of blood cells. This device uses alternating magnetophoretic capture modes to trap and separate paramagnetic and diamagnetic cells away from blood plasma. The device system is composed of two parts, a disposable microfluidics chip and a non-disposable (reusable) magnetic field source. Such modularized device helps the structure of the disposable part dramatically simplified, which is beneficial for low-cost mass production. A series of numerical simulation and parametric study have been performed to describe the mechanism of blood cell separation in the microchannel, and the results are discussed. Furthermore, experimental feasibility test has been carried out in order to demonstrate the blood plasma extraction process of the proposed device. In this experiment, pure blood plasma has been successfully extracted with yield of 21.933% from 75 μl 1:10 dilution of deoxygenated blood. PMID:27042252

Design, analysis, and testing of a flexure-based vibration-assisted polishing device

NASA Astrophysics Data System (ADS)

Gu, Yan; Zhou, Yan; Lin, Jieqiong; Lu, Mingming; Zhang, Chenglong; Chen, Xiuyuan

2018-05-01

A vibration-assisted polishing device (VAPD) composed of leaf-spring and right-circular flexure hinges is proposed with the aim of realizing vibration-assisted machining along elliptical trajectories. To design the structure, energy methods and the finite-element method are used to calculate the performance of the proposed VAPD. An improved bacterial foraging optimization algorithm is used to optimize the structural parameters. In addition, the performance of the VAPD is tested experimentally. The experimental results indicate that the maximum strokes of the two directional mechanisms operating along the Z1 and Z2 directions are 29.5 μm and 29.3 μm, respectively, and the maximum motion resolutions are 10.05 nm and 10.01 nm, respectively. The maximum working bandwidth is 1,879 Hz, and the device has a good step response.

High-Speed Device-Independent Quantum Random Number Generation without a Detection Loophole

NASA Astrophysics Data System (ADS)

Liu, Yang; Yuan, Xiao; Li, Ming-Han; Zhang, Weijun; Zhao, Qi; Zhong, Jiaqiang; Cao, Yuan; Li, Yu-Huai; Chen, Luo-Kan; Li, Hao; Peng, Tianyi; Chen, Yu-Ao; Peng, Cheng-Zhi; Shi, Sheng-Cai; Wang, Zhen; You, Lixing; Ma, Xiongfeng; Fan, Jingyun; Zhang, Qiang; Pan, Jian-Wei

2018-01-01

Quantum mechanics provides the means of generating genuine randomness that is impossible with deterministic classical processes. Remarkably, the unpredictability of randomness can be certified in a manner that is independent of implementation devices. Here, we present an experimental study of device-independent quantum random number generation based on a detection-loophole-free Bell test with entangled photons. In the randomness analysis, without the independent identical distribution assumption, we consider the worst case scenario that the adversary launches the most powerful attacks against the quantum adversary. After considering statistical fluctuations and applying an 80 Gb ×45.6 Mb Toeplitz matrix hashing, we achieve a final random bit rate of 114 bits /s , with a failure probability less than 10-5. This marks a critical step towards realistic applications in cryptography and fundamental physics tests.

A device for characterising the mechanical properties of the plantar soft tissue of the foot.

PubMed

Parker, D; Cooper, G; Pearson, S; Crofts, G; Howard, D; Busby, P; Nester, C

2015-11-01

The plantar soft tissue is a highly functional viscoelastic structure involved in transferring load to the human body during walking. A Soft Tissue Response Imaging Device was developed to apply a vertical compression to the plantar soft tissue whilst measuring the mechanical response via a combined load cell and ultrasound imaging arrangement. Accuracy of motion compared to input profiles; validation of the response measured for standard materials in compression; variability of force and displacement measures for consecutive compressive cycles; and implementation in vivo with five healthy participants. Static displacement displayed average error of 0.04 mm (range of 15 mm), and static load displayed average error of 0.15 N (range of 250 N). Validation tests showed acceptable agreement compared to a Houndsfield tensometer for both displacement (CMC > 0.99 RMSE > 0.18 mm) and load (CMC > 0.95 RMSE < 4.86 N). Device motion was highly repeatable for bench-top tests (ICC = 0.99) and participant trials (CMC = 1.00). Soft tissue response was found repeatable for intra (CMC > 0.98) and inter trials (CMC > 0.70). The device has been shown to be capable of implementing complex loading patterns similar to gait, and of capturing the compressive response of the plantar soft tissue for a range of loading conditions in vivo. Copyright © 2015. Published by Elsevier Ltd.

Generation of irradiance patterns using a semi-spherical meter of two degrees of freedom

NASA Astrophysics Data System (ADS)

Tecpoyotl-Torres, M.; Vera-Dimas, J. G.; Escobedo-Alatorre, J.; Sánchez-Mondragón, J.; Torres-Cisneros, M.; Cabello-Ruiz, R.; Varona, J.

2011-09-01

The meter device presented in this work consists of a photo-detector mounted on the mechanism of a mobile rectangular arc. One stepper motor located on the lateral axis of the device displaces the sensor along a semi-circular trajectory of 170°, almost half meridians. Another motor located at the base of the device enables 360° rotation of the illumination source under test. This arrangement effectively produces a semi-spherical volume for the sensor to move within. The number of measurement points is determined by programming the two stepper motors. Also, the use of a single photo-sensor ensures uniformity in the measurements. The mechanical structure provides enough rigidity for supporting the accuracy required by the data acquisition circuitry based on a DSPIC. Measurement of illumination sources of different sizes is possible by using adjustable lengths of the mobile base and the ring for a maximum lamp length of 0.16 m. Because this work is partially supported by a private entity interested in the characterization of its products, especial attention has been given to the luminaries based on LED technology with divergent beams. The received power by the detector is useful to obtain the irradiance profile of the lighting source under test. The meter device presented herein is a low-cost prototype designed and fabricated using recyclable materials only such as "electronic waste".

Non-Contact Stiffness Measurement of a Suspended Single Walled Carbon Nanotube Device

NASA Technical Reports Server (NTRS)

Zheng, Yun; Su, Chanmin; Getty, Stephanie

2010-01-01

A new nanoscale electric field sensor was developed for studying triboelectric charging in terrestrial and Martian dust devils. This sensor is capable to measure the large electric fields for large dust devils without saturation. However, to quantify the electric charges and the field strength it is critical to calibrate the mechanical stiffness of the sensor devices. We performed a technical feasibility study of the Nano E-field Sensor stiffness by a non-contact stiffness measurement method. The measurement is based on laser Doppler vibrometer measurement of the thermal noise due to energy flunctuations in the devices. The experiment method provides a novel approach to acquire data that is essential in analyzing the quantitative performance of the E-field Nano Sensor. To carry out the non-contact stiffness measurement, we fabricated a new Single-Walled Carbon Nanotube (SWCNT) E-field sensor with different SWCNTs suspension conditions. The power spectra of the thermal induced displacement in the nano E-field sensor were measured at the accuracy of picometer. The power spectra were then used to derive the mechanical stiffness of the sensors. Effect of suspension conditions on stiffness and sensor sensitivty was discussed. After combined deformation and resistivity measurement, we can compare with our laboratory testing and field testing results. This new non-contact measurement technology can also help to explore to other nano and MEMS devices in the future.

21 CFR 876.5280 - Implanted mechanical/hydraulic urinary continence device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Implanted mechanical/hydraulic urinary continence....5280 Implanted mechanical/hydraulic urinary continence device. (a) Identification. An implanted mechanical/hydraulic urinary continence device is a device used to treat urinary incontinence by the...

21 CFR 876.5280 - Implanted mechanical/hydraulic urinary continence device.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implanted mechanical/hydraulic urinary continence....5280 Implanted mechanical/hydraulic urinary continence device. (a) Identification. An implanted mechanical/hydraulic urinary continence device is a device used to treat urinary incontinence by the...

21 CFR 876.5280 - Implanted mechanical/hydraulic urinary continence device.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Implanted mechanical/hydraulic urinary continence....5280 Implanted mechanical/hydraulic urinary continence device. (a) Identification. An implanted mechanical/hydraulic urinary continence device is a device used to treat urinary incontinence by the...

21 CFR 876.5280 - Implanted mechanical/hydraulic urinary continence device.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implanted mechanical/hydraulic urinary continence....5280 Implanted mechanical/hydraulic urinary continence device. (a) Identification. An implanted mechanical/hydraulic urinary continence device is a device used to treat urinary incontinence by the...

21 CFR 876.5280 - Implanted mechanical/hydraulic urinary continence device.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implanted mechanical/hydraulic urinary continence....5280 Implanted mechanical/hydraulic urinary continence device. (a) Identification. An implanted mechanical/hydraulic urinary continence device is a device used to treat urinary incontinence by the...

Characterizing Information Processing With a Mobile Device: Measurement of Simple and Choice Reaction Time.

PubMed

Burke, Daniel; Linder, Susan; Hirsch, Joshua; Dey, Tanujit; Kana, Daniel; Ringenbach, Shannon; Schindler, David; Alberts, Jay

2017-10-01

Information processing is typically evaluated using simple reaction time (SRT) and choice reaction time (CRT) paradigms in which a specific response is initiated following a given stimulus. The measurement of reaction time (RT) has evolved from monitoring the timing of mechanical switches to computerized paradigms. The proliferation of mobile devices with touch screens makes them a natural next technological approach to assess information processing. The aims of this study were to determine the validity and reliability of using of a mobile device (Apple iPad or iTouch) to accurately measure RT. Sixty healthy young adults completed SRT and CRT tasks using a traditional test platform and mobile platforms on two occasions. The SRT was similar across test modality: 300, 287, and 280 milliseconds (ms) for the traditional, iPad, and iTouch, respectively. The CRT was similar within mobile devices, though slightly faster on the traditional: 359, 408, and 384 ms for traditional, iPad, and iTouch, respectively. Intraclass correlation coefficients ranged from 0.79 to 0.85 for SRT and from 0.75 to 0.83 for CRT. The similarity and reliability of SRT across platforms and consistency of SRT and CRT across test conditions indicate that mobile devices provide the next generation of assessment platforms for information processing.

The use of polyurethane materials in the surgery of the spine: a review.

PubMed

St John, Kenneth R

2014-12-01

The spine contains intervertebral discs and the interspinous and longitudinal ligaments. These structures are elastomeric or viscoelastic in their mechanical properties and serve to allow and control the movement of the bony elements of the spine. The use of metallic or hard polymeric devices to replace the intervertebral discs and the creation of fusion masses to replace discs and/or vertebral bodies changes the load transfer characteristics of the spine and the range of motion of segments of the spine. The purpose of the study was to survey the literature, regulatory information available on the Web, and industry-reported device development found on the Web to ascertain the usage and outcomes of the use of polyurethane polymers in the design and clinical use of devices for spine surgery. A systematic review of the available information from all sources concerning the subject materials' usage in spinal devices was conducted. A search of the peer-reviewed literature combining spinal surgery with polyurethane or specific types and trade names of medical polyurethanes was performed. Additionally, information available on the Food and Drug Administration Web site and for corporate Web sites was reviewed in an attempt to identify pertinent information. The review captured devices that are in testing or have entered clinical practice that use elastomeric polyurethane polymers as disc replacements, dynamic stabilization of spinal movement, or motion limitation to relieve nerve root compression and pain and as complete a listing as possible of such devices that have been designed or tested but appear to no longer be pursued. This review summarizes the available information about the uses to which polyurethanes have been tested or are being used in spinal surgery. The use of polyurethanes in medicine has expanded as modifications to the stability of the polymers in the physiological environment have been improved. The potential for the use of elastomeric materials to more closely match the mechanical properties of the structures being replaced and to maintain motion between spinal segments appears to hold promise. The published results from the use of the devices that are discussed show early success with these applications of elastomeric materials. Copyright © 2014 Elsevier Inc. All rights reserved.

Steam sterilization effect on the accuracy of friction-style mechanical torque limiting devices.

PubMed

Sadr, Seyed Jalil; Fayyaz, Ali; Mahshid, Minoo; Saboury, Aboulfazl; Ansari, Ghassem

2014-01-01

This study was aimed to evaluate the effect of steam sterilization on the accuracy (within 10%) of friction-style mechanical torque limiting devices (F-S MTLDs) to achieve their target torque values. Fifteen new F-S MTLDs were selected from Astra Tech (25 Ncm, Hader SA, La Chaux-de-Fonds, Switzerland), BioHorizons (30 Ncm, Dynatorq ITL, Irvine, California, USA), Dr. Idhe (15-60 Ncm, Dr. Idhe Dental, Eching/Munich, Germany). Every peak torque measurement was tested ten times before steam sterilization using Tohnichi torque gauge (6Tohnichi-BTG (-S), Japan). Steam sterilization was performed using a 100 cycle autoclave. Preparation steps were carried out for the devices before each autoclave sterilization cycle. Peak torque measurements were repeated after every sterilization cycle. Mean difference between the measured and the targeted torque values were evaluated before and after aging. Repeated-measures of ANOVA were used to compare the differences of accuracy between subjects. Bonferroni post-hoc test was used for pairwise comparison. Autoclaving resulted in an increase in the error values (the difference between peak torque and target torque values) in all the three groups studied (P < 0.05), with only Astra Tech devices showing >10% (maximum 12%) difference from their torque values in 5% of the measurements. Steam sterilization effect differs between target torque and measured peak values with an increase trend. The peak torque values showed a significant decrease for BioHorizons, while a significant increase was noted for Astra Tech and no significant change in Dr. Idhe group after sterilization. Within the limitation of this study the torque output of each individual device deviated in varying degrees from target torque values. However, the majority of the new frictional-style devices tested in this study, delivered fairly consistent torque output within 10% of their preset target values after sterilization. Astra Tech devices were the only one showing more than 10% difference from their torque values in 5% of the measurements. Combined effects of sterilization and aging still needs to be determined.

Hand rehabilitation after stroke using a wearable, high DOF, spring powered exoskeleton.

PubMed

Tianyao Chen; Lum, Peter S

2016-08-01

Stroke patients often have inappropriate finger flexor activation and finger extensor weakness, which makes it difficult to open their affected hand for functional grasp. The goal was to develop a passive, lightweight, wearable device to enable improved hand function during performance of activities of daily living. The device, HandSOME II, assists with opening the patient's hand using 11 elastic actuators that apply extension torques to finger and thumb joints. Device design and initial testing are described. A novel mechanical design applies forces orthogonal to the finger segments despite the fact that all of the device DOFs are not aligned with human joint DOF. In initial testing with seven stroke subjects with impaired hand function, use of HandSOME II significantly increased maximum extension angles and range of motion in all of the index finger joints (P<;0.05). HandSOME II allows performance of all the grip patterns used in daily activities and can be used as part of home-based therapy programs.

Value contamination avoidance devices

NASA Technical Reports Server (NTRS)

Endicott, D. L.

1975-01-01

Mechanical redesign methods were used to minimize contamination damage of conventional fluid components and a contamination separator device was developed for long term reusable space vehicles. These were incorporated into an existing 50.8 mm poppet valve and tested for damage tolerance in a full size open loop flow system with gaseous and liquid nitrogen. Cyclic and steady flow conditions were tested with particles of 125 to 420 micrometers aluminum oxide dispersed in the test fluids. Nonflow life tests (100,000 cycles) were made with two valve configurations in gaseous hydrogen. The redesigned valve had an acceptable cycle life and improved tolerance to contamination damage when the primary sealing surfaces were coated with thin coatings of hard plastic (Teflon S and Kynar). Analytical studies and flow testing were completed of four different versions of the separator. overall separation efficiencies in the 55-90% range were measured with these non-optimum configurations.

A novel preterm respiratory mechanics active simulator to test the performances of neonatal pulmonary ventilators

NASA Astrophysics Data System (ADS)

Cappa, Paolo; Sciuto, Salvatore Andrea; Silvestri, Sergio

2002-06-01

A patient active simulator is proposed which is capable of reproducing values of the parameters of pulmonary mechanics of healthy newborns and preterm pathological infants. The implemented prototype is able to: (a) let the operator choose the respiratory pattern, times of apnea, episodes of cough, sobs, etc., (b) continuously regulate and control the parameters characterizing the pulmonary system; and, finally, (c) reproduce the attempt of breathing of a preterm infant. Taking into account both the limitation due to the chosen application field and the preliminary autocalibration phase automatically carried out by the proposed device, accuracy and reliability on the order of 1% is estimated. The previously indicated value has to be considered satisfactory in light of the field of application and the small values of the simulated parameters. Finally, the achieved metrological characteristics allow the described neonatal simulator to be adopted as a reference device to test performances of neonatal ventilators and, more specifically, to measure the time elapsed between the occurrence of a potentially dangerous condition to the patient and the activation of the corresponding alarm of the tested ventilator.

21 CFR 876.4500 - Mechanical lithotriptor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical lithotriptor. 876.4500 Section 876.4500...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4500 Mechanical lithotriptor. (a) Identification. A mechanical lithotriptor is a device with steel jaws that is inserted into the urinary bladder...

Micro-mechanical resonators for dynamically reconfigurable reduced voltage logic gates

NASA Astrophysics Data System (ADS)

Chappanda, K. N.; Ilyas, S.; Younis, M. I.

2018-05-01

Due to the limitations of transistor-based logic devices such as their poor performance at elevated temperature, alternative computing methods are being actively investigated. In this work, we present electromechanical logic gates using electrostatically coupled in-plane micro-cantilever resonators operated at modest vacuum conditions of 5 Torr. Operating in the first resonant mode, we demonstrate 2-bit XOR, 2- and 3-bit AND, 2- and 3-bit NOR, and 1-bit NOT gates; all condensed in the same device. Through the designed electrostatic coupling, the required voltage for the logic gates is reduced by 80%, along with the reduction in the number of electrical interconnects and devices per logic operation (contrary to transistors). The device is dynamically reconfigurable between any logic gates in real time without the need for any change in the electrical interconnects and the drive circuit. By operating in the first two resonant vibration modes, we demonstrate mechanical logic gates consisting of two 2-bit AND and two 2-bit XOR gates. The device is tested at elevated temperatures and is shown to be functional as a logic gate up to 150 °C. Also, the device has high reliability with demonstrated lifetime greater than 5  ×  1012 oscillations.

Enhancement of memory margins in the polymer composite of [6,6]-phenyl-C61-butyric acid methyl ester and polystyrene.

PubMed

Sun, Yanmei; Lu, Junguo; Ai, Chunpeng; Wen, Dianzhong; Bai, Xuduo

2016-11-09

Memory devices based on composites of polystyrene (PS) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) were investigated with bistable resistive switching behavior. Current-voltage (I-V) curves for indium-tin-oxide (ITO)/PS + PCBM/Al devices with 33 wt% PCBM showed non-volatile, rewritable, flash memory properties with a maximum ON/OFF current ratio of 1 × 10 4 , which was 100 times larger than the ON/OFF ratio of the device with 5 wt% PCBM. For ITO/PS + PCBM/Al devices with 33 wt% PCBM, the write-read-erase-read test cycles demonstrated the bistable devices with ON and OFF states at the same voltage. The programmable ON and OFF states endured up to 10 4 read pulses and possessed a retention time of over 10 5 s, indicative of the memory stability of the device. In the OFF state, the I-V curve at lower voltages up to 0.45 V was attributed to the thermionic emission mechanism, and the I-V characteristics in the applied voltage above 0.5 V dominantly followed the space-charge-limited-current behaviors. In the ON state, the curve in the applied voltage range was related to an Ohmic mechanism.

Fabrication of self-expandable NiTi thin film devices with micro-electrode array for bioelectric sensing, stimulation and ablation.

PubMed

Bechtold, Christoph; de Miranda, Rodrigo Lima; Chluba, Christoph; Quandt, Eckhard

2016-12-01

Self-expandable medical devices provide mechanical functionality at a specific location of the human body and are viable for minimal invasive procedures. Besides radiopaque markers and drug-eluting coatings, next generation self-expandable devices can be equipped with additional functionality, such as conductive and flexible electrodes, which enables chronic recording of bioelectrical signals, stimulating or ablating tissue. This promises new therapeutic options in various medical fields, among them in particular neuromodulation (e.g. deep brain stimulation), BioMEMS, radio frequency ablation, mapping or denervation. However, the fabrication of such multi-functional devices is challenging. For this study we have realized a 35 μm thick, superelastic NiTi thin film stent structure with six isolated electrodes on the outer circumference, each electrode connected to a contact pad at the end of the stent structure, using magnetron sputtering, UV lithography and wet chemical etching. Mechanical and electrical properties of the device during typical loading conditions, i.e. crimping, simulated pulsatile and electrochemical testing, were characterized and reveal promising results. For the fabrication of future multifunctional, minimal invasive medical devices, such as electroceuticals or other intelligent implants, NiTi thin film technology is therefore a versatile alternative to conventional fabrication routes.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

PubMed Central

Hess, Allison E.; Potter, Kelsey A.; Tyler, Dustin J.; Zorman, Christian A.; Capadona, Jeffrey R.

2013-01-01

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation. The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex. PMID:23995288

Visible Thrombolysis Acceleration of a Nanomachine Powered by Light-Driving F0F1-ATPase Motor

NASA Astrophysics Data System (ADS)

Duan, Xiaoxia; Liu, Lifeng; Jiang, Weijian; Yue, Jiachang

2015-05-01

We report on thrombolysis acceleration of a nanomachine powered by light-driving δ-subunit-free F0F1-ATPase motor. It is composed of a mechanical device, locating device, energy storage device, and propeller. The rotory δ-subunit-free F0F1-ATPase motor acts as a mechanical device, which was obtained by reconstructing an original chromatophore extracted from Rhodospirillum rubrum. We found that the bioactivity of the F0F1-ATPase motor improved greatly after reconstruction. The zeta potential of the nanomachine is about -23.4 mV. Cytotoxicity induced by the nanomachine was measured using cell counting kit (CCK)-8 assay. The A549 cells incubated with different fractional concentrations of the nanomachine within 48 h did not show obvious cytotoxicity. The locating device helps the nanomachine bind to the thrombi. Energy was easily stored by exposing the nanomachine to 600-nm-wavelength irradiation, which promoted activity of the motor. The rotation of the long propeller accelerated thrombolysis of a blood clot in vitro in the presence of urokinase (UK). This result was based on visual inspection and confirmed by a series of tests.

Mechanical systems readiness assessment and performance monitoring study

NASA Technical Reports Server (NTRS)

1972-01-01

The problem of mechanical devices which lack the real-time readiness assessment and performance monitoring capability required for future space missions is studied. The results of a test program to establish the feasibility of implementing structure borne acoustics, a nondestructive test technique, are described. The program included the monitoring of operational acoustic signatures of five separate mechanical components, each possessing distinct sound characteristics. Acoustic signatures were established for normal operation of each component. Critical failure modes were then inserted into the test components, and faulted acoustic signatures obtained. Predominant features of the sound signature were related back to operational events occurring within the components both for normal and failure mode operations. All of these steps can be automated. The structure borne acoustics technique lends itself to reducing checkout time, simplifying maintenance procedures, and reducing manual involvement in the checkout, operation, maintenance, and fault diagnosis of mechanical systems.

Application of Thermo-Mechanical Measurements of Plastic Packages for Reliability Evaluation of PEMS

NASA Technical Reports Server (NTRS)

Sharma, Ashok K.; Teverovsky, Alexander

2004-01-01

Thermo-mechanical analysis (TMA) is typically employed for measurements of the glass transition temperature (Tg) and coefficients of thermal expansion (CTE) in molding compounds used in plastic encapsulated microcircuits (PEMs). Application of TMA measurements directly to PEMs allows anomalies to be revealed in deformation of packages with temperature, and thus indicates possible reliability concerns related to thermo-mechanical integrity and stability of the devices. In this work, temperature dependencies of package deformation were measured in several types of PEMs that failed environmental stress testing including temperature cycling, highly accelerated stress testing (HAST) in humid environments, and bum-in (BI) testing. Comparison of thermo-mechanical characteristics of packages and molding compounds in the failed parts allowed for explanation of the observed failures. The results indicate that TMA of plastic packages might be used for quality evaluation of PEMs intended for high-reliability applications.

Paper-polymer composite devices with minimal fluorescence background.

PubMed

Wang, Chang-Ming; Chen, Chong-You; Liao, Wei-Ssu

2017-04-22

Polymer film incorporated paper-based devices show advantages in simplicity and rugged backing. However, their applications are restricted by the high fluorescence background interference of conventional laminating pouches. Herein, we report a straightforward approach for minimal fluorescence background device fabrication, in which filter paper was shaped and laminated in between two biaxially oriented polypropylene (OPP) and polyvinyl butyral (PVB) composite films. This composite film provides mechanical strength for enhanced device durability, protection from environmental contamination, and prevents reagent degradation. This approach was tested by the determination of copper ions with a fluorescent probe, while the detection of glucose was used to illustrate the improved device durability. Our results show that lamination by the polymer composite lengthens device lifetime, while allowing for fluorescence detection methods combination with greatly reduced fluorescent background widely present in commercially available lamination pouches. By the combination of rapid device prototyping with low cost materials, we believe that this composite design would further expand the potential of paper-based devices. Copyright © 2017 Elsevier B.V. All rights reserved.

Adoption of medical devices: perspectives of professionals in Swedish neonatal intensive care.

PubMed

Roback, Kerstin; Gäddlin, Per-Olof; Nelson, Nina; Persson, Jan

2007-01-01

Advances in biomedical engineering enable us to treat increasingly severe conditions. This implies an increased need for regulation and priority setting in healthcare, to ensure appropriate safety cautions and to avoid accelerating expenditures. This interview study investigates the mechanisms behind the adoption and use of medical devices through the subjective experiences of hospital staff working with devices for neonatal intensive care. The adoption was found to be primarily initiated by vendor activities, but professionals preferably sought information about functionality from close colleagues. Full integration of devices was sometimes not achieved, and even though the adopting units had good introduction routines, there was no systematic follow-up of how adopted devices had been integrated in the work practices. Diffusion variations were, however, mainly found for temporarily tested devices and not for permanently available technologies. Three factors were found to be the major explanatory variables of the adoption of medical devices: (1) the subjective expected value of the device, (2) information and learning, and (3) the innovativeness of the adopting unit.

Muscle powered blood pump: design and initial test results.

PubMed

Trumble, D R; Magovern, J A

1999-01-01

A pneumatic ventricular assist device (Sarns/3M) has been redesigned for low volume hydraulic actuation to accommodate muscle powered drive systems. Design modifications include adding a bellows/piston mechanism (to compress the blood sac) and a compliance chamber for volume compensation. A simple prototype device was constructed to measure the efficacy of piston pump actuation and to validate pusher plate design. Device manufacture was affected by removing the drive line housing from the pneumatic pump and replacing it with a piston/bushing mechanism. A convex piston profile was chosen to maximize ejection fraction and minimize device size. Stroke volume was found to be a linear function of piston displacement (approximately 3 ml/mm) and reached a maximum value of 45 ml. Mean compression forces of 46-56 N acting during a 12 mm stroke (2.1 L/min at 60 cycles/min) were sufficient to generate mean afterload pressures of 70-110 mm Hg in a mock circulatory loop. Peak compression forces ranged from 72 to 86 N and work input was calculated to be 552-672 mJ/stroke. These data indicate that this method for delivering muscle power to the bloodstream is both mechanically viable and compatible with the functional capacity of conditioned latissimus dorsi muscle.

Foldable and Cytocompatible Sol-gel TiO2 Photonics

NASA Astrophysics Data System (ADS)

Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B.; Geiger, Sarah J.; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

2015-09-01

Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.

Foldable and Cytocompatible Sol-gel TiO2 Photonics

PubMed Central

Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B.; Geiger, Sarah J.; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

2015-01-01

Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices. PMID:26344823

Foldable and Cytocompatible Sol-gel TiO2 Photonics.

PubMed

Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B; Geiger, Sarah J; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

2015-09-07

Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.

21 CFR 872.3530 - Mechanical denture cleaner.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical denture cleaner. 872.3530 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3530 Mechanical denture cleaner. (a) Identification. A mechanical denture cleaner is a device, usually AC-powered, that consists of a container for...

An Integrated Analysis-Test Approach

NASA Technical Reports Server (NTRS)

Kaufman, Daniel

2003-01-01

This viewgraph presentation provides an overview of a project to develop a computer program which integrates data analysis and test procedures. The software application aims to propose a new perspective to traditional mechanical analysis and test procedures and to integrate pre-test and test analysis calculation methods. The program also should also be able to be used in portable devices and allows for the 'quasi-real time' analysis of data sent by electronic means. Test methods reviewed during this presentation include: shaker swept sine and random tests, shaker shock mode tests, shaker base driven model survey tests and acoustic tests.

Design and Application of Automatic Falling Device for Different Brands of Goods

NASA Astrophysics Data System (ADS)

Yang, Xudong; Ge, Qingkuan; Zuo, Ping; Peng, Tao; Dong, Weifu

2017-12-01

The Goods-Falling device is an important device in the intelligent sorting goods sorting system, which is responsible for the temporary storage and counting of the goods, and the function of putting the goods on the conveyor belt according to certain precision requirements. According to the present situation analysis and actual demand of the domestic goods sorting equipment, a vertical type Goods - Falling Device is designed and the simulation model of the device is established. The dynamic characteristics such as the angular error of the opening and closing mechanism are carried out by ADAMS software. The simulation results show that the maximum angular error is 0.016rad. Through the test of the device, the goods falling speed is 7031/hour, the good of the falling position error within 2mm, meet the crawl accuracy requirements of the palletizing robot.

Design and Characterization of Next-Generation Micromirrors Fabricated in a Four-Level, Planarized Surface-Micromachined Polycrystalline Silicon Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michalicek, M.A.; Comtois, J.H.; Barron, C.C.

This paper describes the design and characterization of several types of micromirror devices to include process capabilities, device modeling, and test data resulting in deflection versus applied potential curves. These micromirror devices are the first to be fabricated in the state-of-the-art four-level planarized polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics which have previously been unrealizable in standard three-layer polysilicon processes. This paper describes such characteristics as elevated address electrodes, individual address wiring beneath the device, planarized mirror surfaces usingmore » Chemical Mechanical Polishing (CMP), unique post-process metallization, and the best active surface area to date. This paper presents the design, fabrication, modeling, and characterization of several variations of Flexure-Beam (FBMD) and Axial-Rotation Micromirror Devices (ARMD). The released devices are first metallized using a standard sputtering technique relying on metallization guards and masks that are fabricated next to the devices. Such guards are shown to enable the sharing of bond pads between numerous arrays of micromirrors in order to maximize the number of on-chip test arrays. The devices are modeled and then empirically characterized using a laser interferometer setup located at the Air Force Institute of Technology (AFIT) at Wright-Patterson AFB in Dayton, Ohio. Unique design considerations for these devices and the process are also discussed.« less

An Acoustic Charge Transport Imager for High Definition Television Applications: Reliability Modeling and Parametric Yield Prediction of GaAs Multiple Quantum Well Avalanche Photodiodes. Degree awarded Oct. 1997

NASA Technical Reports Server (NTRS)

Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Yun, Ilgu

1994-01-01

Reliability modeling and parametric yield prediction of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiodes (APDs), which are of interest as an ultra-low noise image capture mechanism for high definition systems, have been investigated. First, the effect of various doping methods on the reliability of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiode (APD) structures fabricated by molecular beam epitaxy is investigated. Reliability is examined by accelerated life tests by monitoring dark current and breakdown voltage. Median device lifetime and the activation energy of the degradation mechanism are computed for undoped, doped-barrier, and doped-well APD structures. Lifetimes for each device structure are examined via a statistically designed experiment. Analysis of variance shows that dark-current is affected primarily by device diameter, temperature and stressing time, and breakdown voltage depends on the diameter, stressing time and APD type. It is concluded that the undoped APD has the highest reliability, followed by the doped well and doped barrier devices, respectively. To determine the source of the degradation mechanism for each device structure, failure analysis using the electron-beam induced current method is performed. This analysis reveals some degree of device degradation caused by ionic impurities in the passivation layer, and energy-dispersive spectrometry subsequently verified the presence of ionic sodium as the primary contaminant. However, since all device structures are similarly passivated, sodium contamination alone does not account for the observed variation between the differently doped APDs. This effect is explained by the dopant migration during stressing, which is verified by free carrier concentration measurements using the capacitance-voltage technique.

Alternative approaches to ventilator-associated pneumonia prevention.

PubMed

Berra, L; Sampson, J; Fumagalli, J; Panigada, M; Kolobow, T

2011-03-01

Ventilator-associated pneumonia (VAP), which develops in patients receiving mechanical ventilation, is the most common nosocomial infection in patients with acute respiratory failure. The major mechanism of lower respiratory tract colonization is aspiration of bacteria-colonized secretions from the oropharynx into the lower airways. The hydrostatic pressure of the secretions that collect in the subglottic space, which is the area above the endotracheal tube (ETT) cuff, or aerosolization of bacteria from the secretions collected within the respiratory tubing may facilitate the leakage into the lower airways. Ideally, the elimination of the mechanisms responsible for aspiration would decrease the incidence of VAP. Several preventive measures have been tested in clinical trials with little success.Here we present the results of our efforts to develop novel approaches for the prevention of VAP. Specifically, we found that keeping ventilated patients in a lateral position, which eliminates gravitational forces, is feasible and possibly advantageous. Additionally, several novel medical devices have been recently developed to prevent bacterial biofilm formation from the ETT and breathing tubing. These devices include coated ETTs, mucus shavers and mucus slurpers. Prevention of ETT bacterial colonization showed decreased bacterial colonization of the respiratory circuit and of the lower respiratory tract in laboratory studies and clinical trials. Future large studies should be designed to test the hypothesis that VAP can be prevented with these novel strategies. While there is a current focus on the use of respiratory devices to prevent biofilm formation and microaspiration, it is important to remember that lower respiratory tract colonization is multifactorial. Prevention of VAP cannot be achieved solely by eliminating bacterial biofilm on respiratory devices, and more comprehensive care of the intubated patient needs to be implemented.

Determining Functional Reliability of Pyrotechnic Mechanical Devices

NASA Technical Reports Server (NTRS)

Bement, Laurence J.; Multhaup, Herbert A.

1997-01-01

This paper describes a new approach for evaluating mechanical performance and predicting the mechanical functional reliability of pyrotechnic devices. Not included are other possible failure modes, such as the initiation of the pyrotechnic energy source. The requirement of hundreds or thousands of consecutive, successful tests on identical components for reliability predictions, using the generally accepted go/no-go statistical approach routinely ignores physics of failure. The approach described in this paper begins with measuring, understanding and controlling mechanical performance variables. Then, the energy required to accomplish the function is compared to that delivered by the pyrotechnic energy source to determine mechanical functional margin. Finally, the data collected in establishing functional margin is analyzed to predict mechanical functional reliability, using small-sample statistics. A careful application of this approach can provide considerable cost improvements and understanding over that of go/no-go statistics. Performance and the effects of variables can be defined, and reliability predictions can be made by evaluating 20 or fewer units. The application of this approach to a pin puller used on a successful NASA mission is provided as an example.

Design of a haptic device with grasp and push-pull force feedback for a master-slave surgical robot.

PubMed

Hu, Zhenkai; Yoon, Chae-Hyun; Park, Samuel Byeongjun; Jo, Yung-Ho

2016-07-01

We propose a portable haptic device providing grasp (kinesthetic) and push-pull (cutaneous) sensations for optical-motion-capture master interfaces. Although optical-motion-capture master interfaces for surgical robot systems can overcome the stiffness, friction, and coupling problems of mechanical master interfaces, it is difficult to add haptic feedback to an optical-motion-capture master interface without constraining the free motion of the operator's hands. Therefore, we utilized a Bowden cable-driven mechanism to provide the grasp and push-pull sensation while retaining the free hand motion of the optical-motion capture master interface. To evaluate the haptic device, we construct a 2-DOF force sensing/force feedback system. We compare the sensed force and the reproduced force of the haptic device. Finally, a needle insertion test was done to evaluate the performance of the haptic interface in the master-slave system. The results demonstrate that both the grasp force feedback and the push-pull force feedback provided by the haptic interface closely matched with the sensed forces of the slave robot. We successfully apply our haptic interface in the optical-motion-capture master-slave system. The results of the needle insertion test showed that our haptic feedback can provide more safety than merely visual observation. We develop a suitable haptic device to produce both kinesthetic grasp force feedback and cutaneous push-pull force feedback. Our future research will include further objective performance evaluations of the optical-motion-capture master-slave robot system with our haptic interface in surgical scenarios.

In vitro characterization of a magnetically suspended continuous flow ventricular assist device.

PubMed

Kim, H C; Bearnson, G B; Khanwilkar, P S; Olsen, D B; Maslen, E H; Allaire, P E

1995-01-01

A magnetically suspended continuous flow ventricular assist device using magnetic bearings was developed aiming at an implantable ventricular assist device. The main advantage of this device includes no mechanical wear and minimal chance of blood trauma such, as thrombosis and hemolysis, because there is no mechanical contact between the stationary and rotating parts. The total system consists of two subsystems: the centrifugal pump and the magnetic bearing. The centrifugal pump is comprised of a 4 vane logarithmic spiral radial flow impeller and a brushless DC motor with slotless stator, driven by the back emf commutation scheme. Two radial and one thrust magnetic bearing that dynamically controls the position of the rotor in a radial and axial direction, respectively, contains magnetic coils, the rotor's position sensors, and feedback electronic control system. The magnetic bearing system was able to successfully suspend a 365.5g rotating part in space and sustain it for up to 5000 rpm of rotation. Average force-current square factor of the magnetic bearing was measured as 0.48 and 0.44 (kg-f/Amp2) for radial and thrust bearing, respectively. The integrated system demonstrated adequate performance in mock circulation tests by providing a 6 L/min flow rate against 100 mmHg differential pressure at 2300 rpm. Based on these in vitro performance test results, long-term clinical application of the magnetically suspended continuous flow ventricular assist device is very promising after system optimization with a hybrid system using both active (electromagnet) and passive (permanent magnets) magnet bearings.

Reliability Modeling of Microelectromechanical Systems Using Neural Networks

NASA Technical Reports Server (NTRS)

Perera. J. Sebastian

2000-01-01

Microelectromechanical systems (MEMS) are a broad and rapidly expanding field that is currently receiving a great deal of attention because of the potential to significantly improve the ability to sense, analyze, and control a variety of processes, such as heating and ventilation systems, automobiles, medicine, aeronautical flight, military surveillance, weather forecasting, and space exploration. MEMS are very small and are a blend of electrical and mechanical components, with electrical and mechanical systems on one chip. This research establishes reliability estimation and prediction for MEMS devices at the conceptual design phase using neural networks. At the conceptual design phase, before devices are built and tested, traditional methods of quantifying reliability are inadequate because the device is not in existence and cannot be tested to establish the reliability distributions. A novel approach using neural networks is created to predict the overall reliability of a MEMS device based on its components and each component's attributes. The methodology begins with collecting attribute data (fabrication process, physical specifications, operating environment, property characteristics, packaging, etc.) and reliability data for many types of microengines. The data are partitioned into training data (the majority) and validation data (the remainder). A neural network is applied to the training data (both attribute and reliability); the attributes become the system inputs and reliability data (cycles to failure), the system output. After the neural network is trained with sufficient data. the validation data are used to verify the neural networks provided accurate reliability estimates. Now, the reliability of a new proposed MEMS device can be estimated by using the appropriate trained neural networks developed in this work.

Patient perception of Breezhaler® and Ellipta® device feedback mechanisms in COPD: The ADVANTAGE Study.

PubMed

Altman, Pablo; Bergna, Miguel A; Garcia, Gabriel R; Guerin, Tadhg; Pino, Andrea V; Whiteford, John L

2018-05-15

The primary objective of the ADVANTAGE study was to compare device-naïve chronic obstructive pulmonary disease (COPD) patients' perception of the Breezhaler ® and Ellipta ® devices' feedback mechanisms of dose delivery confirmation. The secondary objective was to assess comfort with the inhalers' mouthpiece in terms of ease to form a tight seal around the mouthpiece. These objectives were achieved by using a novel, patient perception of inhaler questionnaire developed and tested during cognitive interviews of patients by Evidera, London, United Kingdom. Ten COPD patients were interviewed to collect feedback on the interpretation, relevance and language of the questionnaire. This questionnaire was then used in ADVANTAGE to compare patients' perception (n = 100) of both devices. Patients completed the questionnaire after a single inhalation of placebo through each inhaler. Using the final questionnaire, patients reported being more confident of the feedback mechanism of Breezhaler than that of the Ellipta device (mean score 4.3 versus 3.6 respectively, estimated difference [95% CI]: 0.75 [0.51, 0.99], p < .0001). Patients also reported better comfort (ease to form a tight seal with the lips) with the Breezhaler mouthpiece than the Ellipta mouthpiece (mean score 4.3 versus 3.9 respectively, estimated difference [95% CI]: 0.41 [0.21, 0.61], p < .0001). There were no safety concerns associated with either device. COPD patients showed greater preference for the Breezhaler over the Ellipta inhaler for confidence of dose delivery and comfort of the mouthpiece. The trial is registered at ClinicalTrials.gov (ClinicalTrials.gov number NCT02551224).

Development of a non-explosive release actuator using shape memory alloy wire.

PubMed

Yoo, Young Ik; Jeong, Ju Won; Lim, Jae Hyuk; Kim, Kyung-Won; Hwang, Do-Soon; Lee, Jung Ju

2013-01-01

We have developed a newly designed non-explosive release actuator that can replace currently used release devices. The release mechanism is based on a separation mechanism, which relies on segmented nuts and a shape memory alloy (SMA) wire trigger. A quite fast and simple trigger operation is made possible through the use of SMA wire. This actuator is designed to allow a high preload with low levels of shock for the solar arrays of medium-size satellites. After actuation, the proposed device can be easily and instantly reset. Neither replacement, nor refurbishment of any components is necessary. According to the results of a performance test, the release time, preload capacity, and maximum shock level are 50 ms, 15 kN, and 350 G, respectively. In order to increase the reliability of the actuator, more than ten sets of performance tests are conducted. In addition, the proposed release actuator is tested under thermal vacuum and extreme vibration environments. No degradation or damage was observed during the two environment tests, and the release actuator was able to operate successfully. Considering the test results as a whole, we conclude that the proposed non-explosive release actuator can be applied reliably to intermediate-size satellites to replace existing release systems.

Accelerated life testing effects on CMOS microcircuit characteristics, phase 1

NASA Technical Reports Server (NTRS)

Maximow, B.

1976-01-01

An accelerated life test of sufficient duration to generate a minimum of 50% cumulative failures in lots of CMOS devices was conducted to provide a basis for determining the consistency of activation energy at 250 C. An investigation was made to determine whether any thresholds were exceeded during the high temperature testing, which could trigger failure mechanisms unique to that temperature. The usefulness of the 250 C temperature test as a predictor of long term reliability was evaluated.

EXiO-A Brain-Controlled Lower Limb Exoskeleton for Rhesus Macaques.

PubMed

Vouga, Tristan; Zhuang, Katie Z; Olivier, Jeremy; Lebedev, Mikhail A; Nicolelis, Miguel A L; Bouri, Mohamed; Bleuler, Hannes

2017-02-01

Recent advances in the field of brain-machine interfaces (BMIs) have demonstrated enormous potential to shape the future of rehabilitation and prosthetic devices. Here, a lower-limb exoskeleton controlled by the intracortical activity of an awake behaving rhesus macaque is presented as a proof-of-concept for a locomotorBMI. A detailed description of the mechanical device, including its innovative features and first experimental results, is provided. During operation, BMI-decoded position and velocity are directly mapped onto the bipedal exoskeleton's motions, which then move the monkey's legs as the monkey remains physicallypassive. To meet the unique requirements of such an application, the exoskeleton's features include: high output torque with backdrivable actuation, size adjustability, and safe user-robot interface. In addition, a novel rope transmission is introduced and implemented. To test the performance of the exoskeleton, a mechanical assessment was conducted, which yielded quantifiable results for transparency, efficiency, stiffness, and tracking performance. Usage under both brain control and automated actuation demonstrates the device's capability to fulfill the demanding needs of this application. These results lay the groundwork for further advancement in BMI-controlled devices for primates including humans.

Investigation of advanced fault insertion and simulator methods

NASA Technical Reports Server (NTRS)

Dunn, W. R.; Cottrell, D.

1986-01-01

The cooperative agreement partly supported research leading to the open-literature publication cited. Additional efforts under the agreement included research into fault modeling of semiconductor devices. Results of this research are presented in this report which is summarized in the following paragraphs. As a result of the cited research, it appears that semiconductor failure mechanism data is abundant but of little use in developing pin-level device models. Failure mode data on the other hand does exist but is too sparse to be of any statistical use in developing fault models. What is significant in the failure mode data is that, unlike classical logic, MSI and LSI devices do exhibit more than 'stuck-at' and open/short failure modes. Specifically they are dominated by parametric failures and functional anomalies that can include intermittent faults and multiple-pin failures. The report discusses methods of developing composite pin-level models based on extrapolation of semiconductor device failure mechanisms, failure modes, results of temperature stress testing and functional modeling. Limitations of this model particularly with regard to determination of fault detection coverage and latency time measurement are discussed. Indicated research directions are presented.

A modified SILCS contraceptive diaphragm for long-term controlled release of the HIV microbicide dapivirine.

PubMed

Major, Ian; Boyd, Peter; Kilbourne-Brook, Maggie; Saxon, Gene; Cohen, Jessica; Malcolm, R Karl

2013-07-01

There is considerable interest in developing new multipurpose prevention technologies to address women's reproductive health needs. This study describes an innovative barrier contraceptive device--based on the SILCS diaphragm--that also provides long-term controlled release of the lead candidate anti-HIV microbicide dapivirine. Diaphragm devices comprising various dapivirine-loaded polymer spring cores overmolded with a nonmedicated silicone elastomer sheath were fabricated by injection molding processes. In vitro release testing, thermal analysis and mechanical characterization were performed on the devices. A diaphragm device containing a polyoxymethylene spring core loaded with 10% w/w dapivirine provided continuous and controlled release of dapivirine over a 6-month period, with a mean in vitro daily release rate of 174 mcg/day. The mechanical properties of the new diaphragm were closely matched to the SILCS diaphragm. The study demonstrates proof of concept for a dapivirine-releasing diaphragm with daily release quantities potentially capable of preventing HIV transmission. In discontinuous clinical use, release of dapivirine may be readily extended over 1 or more years. Copyright © 2013 Elsevier Inc. All rights reserved.

An Implantable Extracardiac Soft Robotic Device for the Failing Heart: Mechanical Coupling and Synchronization.

PubMed

Payne, Christopher J; Wamala, Isaac; Abah, Colette; Thalhofer, Thomas; Saeed, Mossab; Bautista-Salinas, Daniel; Horvath, Markus A; Vasilyev, Nikolay V; Roche, Ellen T; Pigula, Frank A; Walsh, Conor J

2017-09-01

Soft robotic devices have significant potential for medical device applications that warrant safe synergistic interaction with humans. This article describes the optimization of an implantable soft robotic system for heart failure whereby soft actuators wrapped around the ventricles are programmed to contract and relax in synchrony with the beating heart. Elastic elements integrated into the soft actuators provide recoiling function so as to aid refilling during the diastolic phase of the cardiac cycle. Improved synchronization with the biological system is achieved by incorporating the native ventricular pressure into the control system to trigger assistance and synchronize the device with the heart. A three-state electro-pneumatic valve configuration allows the actuators to contract at different rates to vary contraction patterns. An in vivo study was performed to test three hypotheses relating to mechanical coupling and temporal synchronization of the actuators and heart. First, that adhesion of the actuators to the ventricles improves cardiac output. Second, that there is a contraction-relaxation ratio of the actuators which generates optimal cardiac output. Third, that the rate of actuator contraction is a factor in cardiac output.

Impact of Isothermal Aging and Testing Temperature on Large Flip-Chip BGA Interconnect Mechanical Shock Performance

NASA Astrophysics Data System (ADS)

Lee, Tae-Kyu; Chen, Zhiqiang; Guirguis, Cherif; Akinade, Kola

2017-10-01

The stability of solder interconnects in a mechanical shock environment is crucial for large body size flip-chip ball grid array (FCBGA) electronic packages. Additionally, the junction temperature increases with higher electric power condition, which brings the component into an elevated temperature environment, thus introducing another consideration factor for mechanical stability of interconnection joints. Since most of the shock performance data available were produced at room temperature, the effect of elevated temperature is of interest to ensure the reliability of the device in a mechanical shock environment. To achieve a stable␣interconnect in a dynamic shock environment, the interconnections must tolerate mechanical strain, which is induced by the shock wave input and reaches the particular component interconnect joint. In this study, large body size (52.5 × 52.5 mm2) FCBGA components assembled on 2.4-mm-thick boards were tested with various isothermal pre-conditions and testing conditions. With a heating element embedded in the test board, a test temperature range from room temperature to 100°C was established. The effects of elevated temperature on mechanical shock performance were investigated. Failure and degradation mechanisms are identified and discussed based on the microstructure evolution and grain structure transformations.

Control of unsteady separated flow associated with the dynamic stall of airfoils

NASA Technical Reports Server (NTRS)

Wilder, Michael C.

1992-01-01

The two principal objectives of this research were to achieve an improved understanding of the mechanisms involved in the onset and development of dynamic stall under compressible flow conditions, and to investigate the feasibility of employing adaptive airfoil geometry as an active flow control device in the dynamic stall engine. Presented here are the results of a quantitative (PDI) study of the compressibility effects on dynamic stall over the transiently pitching airfoil, as well as a discussion of a preliminary technique developed to measure the deformation produced by the adaptive geometry control device, and bench test results obtained using an airfoil equipped with the device.

Study of Damped Set-Back Pins for S and A Mechanisms.

DTIC Science & Technology

1976-11-01

arm device for artillery munitions. This damped set-back pin assembly is one of two safety features on a S and A device used in the M739 PD/XM587 ET...The damped set-back pin study program was for the design, testing, fabrication, and delivery and damped set-back pin assemblies for use in a safe and...fuzes for a rotating projectile. A pin, porous disc, return spring, floating O-ring, and sleeve comprise the selected damped set-back pin assembly

Finite element analysis of a micromechanical deformable mirror device

NASA Technical Reports Server (NTRS)

Sheerer, T. J.; Nelson, W. E.; Hornbeck, L. J.

1989-01-01

A monolithic spatial light modulator chip was developed consisting of a large number of micrometer-scale mirror cells which can be rotated through an angle by application of an electrostatic field. The field is generated by electronics integral to the chip. The chip has application in photoreceptor based non-impact printing technologies. Chips containing over 16000 cells were fabricated, and were tested to several billions of cycles. Finite Element Analysis (FEA) of the device was used to model both the electrical and mechanical characteristics.

Reliability assessment of multiple quantum well avalanche photodiodes

NASA Technical Reports Server (NTRS)

Yun, Ilgu; Menkara, Hicham M.; Wang, Yang; Oguzman, Isamil H.; Kolnik, Jan; Brennan, Kevin F.; May, Gray S.; Wagner, Brent K.; Summers, Christopher J.

1995-01-01

The reliability of doped-barrier AlGaAs/GsAs multi-quantum well avalanche photodiodes fabricated by molecular beam epitaxy is investigated via accelerated life tests. Dark current and breakdown voltage were the parameters monitored. The activation energy of the degradation mechanism and median device lifetime were determined. Device failure probability as a function of time was computed using the lognormal model. Analysis using the electron beam induced current method revealed the degradation to be caused by ionic impurities or contamination in the passivation layer.

A novel monolithic piezoelectric actuated flexure-mechanism based wire clamp for microelectronic device packaging.

PubMed

Liang, Cunman; Wang, Fujun; Tian, Yanling; Zhao, Xingyu; Zhang, Hongjie; Cui, Liangyu; Zhang, Dawei; Ferreira, Placid

2015-04-01

A novel monolithic piezoelectric actuated wire clamp is presented in this paper to achieve fast, accurate, and robust microelectronic device packaging. The wire clamp has compact, flexure-based mechanical structure and light weight. To obtain large and robust jaw displacements and ensure parallel jaw grasping, a two-stage amplification composed of a homothetic bridge type mechanism and a parallelogram leverage mechanism was designed. Pseudo-rigid-body model and Lagrange approaches were employed to conduct the kinematic, static, and dynamic modeling of the wire clamp and optimization design was carried out. The displacement amplification ratio, maximum allowable stress, and natural frequency were calculated. Finite element analysis (FEA) was conducted to evaluate the characteristics of the wire clamp and wire electro discharge machining technique was utilized to fabricate the monolithic structure. Experimental tests were carried out to investigate the performance and the experimental results match well with the theoretical calculation and FEA. The amplification ratio of the clamp is 20.96 and the working mode frequency is 895 Hz. Step response test shows that the wire clamp has fast response and high accuracy and the motion resolution is 0.2 μm. High speed precision grasping operations of gold and copper wires were realized using the wire clamper.

A Novel Method to Assess Wear Rates of Retrieved Tibial Inserts Following in-vivo Use

NASA Astrophysics Data System (ADS)

Paniogue, Tanille J.

Ultra-high molecular weight polyethylene (UHMWPE) on cobalt chrome is the bearing couple of choice for total knee arthroplasty. The number of patients undergoing total knee arthroplasty has been steadily growing and is projected to continue increasing rapidly in the near future. Many of these patients are younger and more active and therefore need a longer lasting device. However, many of these devices fail prematurely and often the primary reason for failure and ultimately revision is due to wear related issues. Therefore, examining how wear rates of the UHMWPE tibial insert change during in-vivo use can help elucidate the mechanisms of accelerated wear and hopefully aid in finding solutions to combat wear related failures. Different crosslinking treatments have been employed by manufacturers to improve wear resistance of the polyethylene. While this has been shown to be an effective way to reduce wear, crosslinking has led to other issues such as oxidative instability and a decline in mechanical properties. The purpose of this body of work is to examine how changes in oxidation, after in-vivo use, affect wear resistance. A novel testing method was developed to test the native articular surface from retrieved tibial inserts in a laboratory Pin-on-Disk (POD) simulator. The method was validated using short-duration implant articular surfaces and non-articular control pins. In the absence of high surface oxidation or severe surface damage, the articular surface pins had comparable steady state wear rates to their bulk counterparts. Tests of devices with longer in-vivo service show chemical changes consistent with a free-radical mediated oxidation mechanism. Tribological assessment of the articular surfaces shows increasing wear rates as a function of oxidation. While this relationship has been hypothesized in the literature, these experiments represent the first physical demonstration of the phenomenon. The wear mechanism is further explored through infrared spectroscopy, assessment of the wear scar, and documentation of evolution of the contact surfaces in the articulation.

Progress and Prospects in Stretchable Electroluminescent Devices

NASA Astrophysics Data System (ADS)

Wang, Jiangxin; Lee, Pooi See

2017-03-01

Stretchable electroluminescent (EL) devices are a new form of mechanically deformable electronics that are gaining increasing interests and believed to be one of the essential technologies for next generation lighting and display applications. Apart from the simple bending capability in flexible EL devices, the stretchable EL devices are required to withstand larger mechanical deformations and accommodate stretching strain beyond 10%. The excellent mechanical conformability in these devices enables their applications in rigorous mechanical conditions such as flexing, twisting, stretching, and folding.The stretchable EL devices can be conformably wrapped onto arbitrary curvilinear surface and respond seamlessly to the external or internal forces, leading to unprecedented applications that cannot be addressed with conventional technologies. For example, they are in demand for wide applications in biomedical-related devices or sensors and soft interactive display systems, including activating devices for photosensitive drug, imaging apparatus for internal tissues, electronic skins, interactive input and output devices, robotics, and volumetric displays. With increasingly stringent demand on the mechanical requirements, the fabrication of stretchable EL device is encountering many challenges that are difficult to resolve. In this review, recent progresses in the stretchable EL devices are covered with a focus on the approaches that are adopted to tackle materials and process challenges in stretchable EL devices and delineate the strategies in stretchable electronics. We first introduce the emission mechanisms that have been successfully demonstrated on stretchable EL devices. Limitations and advantages of the different mechanisms for stretchable EL devices are also discussed. Representative reports are reviewed based on different structural and material strategies. Unprecedented applications that have been enabled by the stretchable EL devices are reviewed. Finally, we summarize with our perspectives on the approaches for the stretchable EL devices and our proposals on the future development in these devices.

Shape Memory Actuation and Release Devices.

DTIC Science & Technology

1996-10-01

shelf devices such as pyrotechnics, gas-discharge systems, paraffin wax actuators, and other electro-mechanical devices may not be able to meet...shelf devices such as pyrotechnics, gas-discharge systems, paraffin wax actuators, and other electro-mechanical devices may not be able to meet future...shard mounts. They do have wide utility as pin-pullers and single point release devices for a variety of spacecraft appendages. Parrafin based mechanisms

Power generation systems and methods

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor); Chao, Yi (Inventor)

2011-01-01

A power generation system includes a plurality of submerged mechanical devices. Each device includes a pump that can be powered, in operation, by mechanical energy to output a pressurized output liquid flow in a conduit. Main output conduits are connected with the device conduits to combine pressurized output flows output from the submerged mechanical devices into a lower number of pressurized flows. These flows are delivered to a location remote of the submerged mechanical devices for power generation.

A summary of the mechanical design, testing and performance of the IMP-H and J attitude control systems

NASA Technical Reports Server (NTRS)

Metzger, J. R.

1974-01-01

The main aspects of the attitude control system used on both the IMP-H and J spacecraft are presented. The mechanical configuration is described. Information on all the specific components comprising the flight system is provided. The acceptance and qualification testing of both individual components and the installed system are summarized. Functional information regarding the operation and performance in relation to the orbiting spacecraft and its mission is included. Related topics which are discussed are: (1) safety requirements, (2) servicing procedures, (3) anomalous behavior, and (4) pyrotechnic devices.

High-Speed Device-Independent Quantum Random Number Generation without a Detection Loophole.

PubMed

Liu, Yang; Yuan, Xiao; Li, Ming-Han; Zhang, Weijun; Zhao, Qi; Zhong, Jiaqiang; Cao, Yuan; Li, Yu-Huai; Chen, Luo-Kan; Li, Hao; Peng, Tianyi; Chen, Yu-Ao; Peng, Cheng-Zhi; Shi, Sheng-Cai; Wang, Zhen; You, Lixing; Ma, Xiongfeng; Fan, Jingyun; Zhang, Qiang; Pan, Jian-Wei

2018-01-05

Quantum mechanics provides the means of generating genuine randomness that is impossible with deterministic classical processes. Remarkably, the unpredictability of randomness can be certified in a manner that is independent of implementation devices. Here, we present an experimental study of device-independent quantum random number generation based on a detection-loophole-free Bell test with entangled photons. In the randomness analysis, without the independent identical distribution assumption, we consider the worst case scenario that the adversary launches the most powerful attacks against the quantum adversary. After considering statistical fluctuations and applying an 80  Gb×45.6  Mb Toeplitz matrix hashing, we achieve a final random bit rate of 114  bits/s, with a failure probability less than 10^{-5}. This marks a critical step towards realistic applications in cryptography and fundamental physics tests.

Energy Dissipating Devices in Falling Rock Protection Barriers

NASA Astrophysics Data System (ADS)

Castanon-Jano, L.; Blanco-Fernandez, E.; Castro-Fresno, D.; Ballester-Muñoz, F.

2017-03-01

Rockfall is a phenomenon which, when uncontrolled, may cause extensive material damage and personal injury. One of the structures used to avoid accidents caused by debris flows or rockfalls is flexible barriers. The energy dissipating devices which absorb the energy generated by rock impact and reduce the mechanical stresses in the rest of the elements of the structure are an essential part of these kinds of structures. This document proposes an overview of the performance of energy dissipating devices, as well as of the role that they fulfil in the barrier. Furthermore, a compilation and a description of the dissipating elements found in the literature are proposed. Additionally, an analysis has been performed of the aspects taken into account in the design, such as experimental (quasi-static and dynamic) tests observing the variation of the behaviour curve depending on the test speed and numerical simulations by means of several finite element software packages.

49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles.

Code of Federal Regulations, 2014 CFR

2014-10-01

... part of the tire that is made of steel wires, wrapped or reinforced by ply cords and that is shaped to... mechanical device made of rubber, chemicals, fabric and steel or other materials, that, when mounted on an....Test sample. For the tests specified in S6, use: (a) One tire for high speed; (b) Another tire for...

49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles.

Code of Federal Regulations, 2013 CFR

2013-10-01

... part of the tire that is made of steel wires, wrapped or reinforced by ply cords and that is shaped to... mechanical device made of rubber, chemicals, fabric and steel or other materials, that, when mounted on an....Test sample. For the tests specified in S6, use: (a) One tire for high speed; (b) Another tire for...

49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles.

Code of Federal Regulations, 2012 CFR

2012-10-01

... part of the tire that is made of steel wires, wrapped or reinforced by ply cords and that is shaped to... mechanical device made of rubber, chemicals, fabric and steel or other materials, that, when mounted on an....Test sample. For the tests specified in S6, use: (a) One tire for high speed; (b) Another tire for...

Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

NASA Technical Reports Server (NTRS)

Westfall, L. J.; Petrasek, D. W.

1985-01-01

Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760C (1400 F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling.

Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

NASA Technical Reports Server (NTRS)

Westfall, Leonard J.; Petrasek, Donald W.

1988-01-01

Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760F (1400F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling.

Ageing effects due to inactivity for magnetorheological seismic dampers: a 10-year experimental investigation

NASA Astrophysics Data System (ADS)

Caterino, N.; Spizzuoco, M.; Occhiuzzi, A.

2018-06-01

The proposed work gives a response, based on the experimental evidence, to the issue of long-term magnetorheological (MR) dampers’ behavior, when they are applied for structural control of earthquake induced vibrations. MR control devices, designed for infrequent dynamic loads as earthquakes, might be dormant for most of their life until a seismic event hits the hosting controlled structure. Two prototype MR devices have been tested three times, first in 2008, then in 2013 after five years of absolute inactivity, and finally in 2017 after further four years of rest. The comparison between the results of the three experimental testing activities is made in terms of force-displacement loops, dissipated energy and maximum reacting force. It is shown that only the first stroke of the damper is characterized by an unexpected mechanical response. However, after this first movement, the damper comes back to behave similarly to what was before the rest, with only a slight not reversible decrease of the damping force. This reduction results to be more significant (about 5%) for larger currents, while less significant in the case of zero feeding current. From a civil engineering perspective, this performance decay is definitely acceptable, even if it is referred to a possible cause, deeply studied in literature, that could continue endangering the mechanical response of the devices over time. The paper shows the experimental results, but the possible causes of mechanical deterioration of the dampers will be discussed also.

Insulator-protected mechanically controlled break junctions for measuring single-molecule conductance in aqueous environments

NASA Astrophysics Data System (ADS)

Muthusubramanian, N.; Galan, E.; Maity, C.; Eelkema, R.; Grozema, F. C.; van der Zant, H. S. J.

2016-07-01

We present a method to fabricate insulated gold mechanically controlled break junctions (MCBJ) by coating the metal with a thin layer of aluminum oxide using plasma enhanced atomic layer deposition. The Al2O3 thickness deposited on the MCBJ devices was varied from 2 to 15 nm to test the suppression of leakage currents in deionized water and phosphate buffered saline. Junctions coated with a 15 nm thick oxide layer yielded atomically sharp electrodes and negligible conductance counts in the range of 1 to 10-4 G0 (1 G0 = 77 μS), where single-molecule conductances are commonly observed. The insulated devices were used to measure the conductance of an amphiphilic oligophenylene ethynylene derivative in deionized water.

An overview of robotic/mechanical devices for post-stroke thumb rehabilitation.

PubMed

Suarez-Escobar, Marian; Rendon-Velez, Elizabeth

2018-01-15

This article aims to clarify the current state-of-the-art of robotic/mechanical devices for post-stroke thumb rehabilitation as well as the anatomical characteristics and motions of the thumb that are crucial for the development of any device that aims to support its motion. A systematic literature search was conducted to identify robotic/mechanical devices for post-stroke thumb rehabilitation. Specific electronic databases and well-defined search terms and inclusion/exclusion criteria were used for such purpose. A reasoning model was devised to support the structured abstraction of relevant data from the literature of interest. Following the main search and after removing duplicated and other non-relevant studies, 68 articles (corresponding to 32 devices) were left for further examination. These articles were analyzed to extract data relative to (i) the motions assisted/permitted - either actively or passively - by the device per anatomical joint of the thumb and (ii) mechanical-related aspects (i.e., architecture, connections to thumb, other fingers supported, adjustability to different hand sizes, actuators - type, quantity, location, power transmission and motion trajectory). Most articles describe preliminary design and testing of prototypes, rather than the thorough evaluation of commercially ready devices. Defining appropriate kinematic models of the thumb upon which to design such devices still remains a challenging and unresolved task. Further research is needed before these devices can actually be implemented in clinical environments to serve their intended purpose of complementing the labour of therapists by facilitating intensive treatment with precise and repeatable exercises. Implications for Rehabilitation Post-stroke functional disability of the hand, and particularly of the thumb, significantly affects the capability to perform activities of daily living, threatening the independence and quality of life of the stroke survivors. The latest studies show that a high-dose intensive therapy (in terms of frequency, duration and intensity/effort) is the key to effectively modify neural organization and recover the motor skills that were lost after a stroke. Conventional therapy based on manual interaction with physical therapists makes the procedure labour intensive and increases the costs. Robotic/mechanical devices hold promise for complementing conventional post-stroke therapy. Specifically, these devices can provide reliable and accurate therapy for long periods of time without the associated fatigue. Also, they can be used as a means to assess patients? performance and progress in an objective and consistent manner. The full potential of robot-assisted therapy is still to be unveiled. Further exploration will surely lead to devices that can be well accepted equally by therapists and patients and that can be useful both in clinical and home-based rehabilitation practice such that motor recovery of the hand becomes a common outcome in stroke survivors. This overview provides the reader, possibly a designer of such a device, with a complete overview of the state-of-the-art of robotic/mechanical devices consisting of or including features for the rehabilitation of the thumb. Also, we clarify the anatomical characteristics and motions of the thumb that are crucial for the development of any device that aims to support its motion. Hopefully, this?combined with the outlined opportunities for further research?leads to the improvement of current devices and the development of new technology and knowledge in the field.

Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding

NASA Astrophysics Data System (ADS)

Fiori, F.; Marcantoni, M.

Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (tensile-strength tests) of the welded interface.

Bovine versus Porcine Acellular Dermal Matrix: A Comparison of Mechanical Properties.

PubMed

Adelman, David M; Selber, Jesse C; Butler, Charles E

2014-05-01

Porcine and bovine acellular dermal matrices (PADM and BADM, respectively) are the most commonly used biologic meshes for ventral hernia repair. A previous study suggests a higher rate of intraoperative device failures using PADM than BADM. We hypothesize that this difference is, in part, related to intrinsic mechanical properties of the matrix substrate and source material. The following study directly compares these 2 matrices to identify any potential differences in mechanical properties that may relate to clinical outcomes. Sections of PADM (Strattice; Lifecell, Branchburg, N.J.) and BADM (SurgiMend; TEI Biosciences, Boston, Mass.) were subjected to a series of biomechanical tests, including suture retention, tear strength, and uniaxial tensile strength. Results were collected and compared statistically. In all parameters, BADM exhibited a superior mechanical strength profile compared with PADM of similar thickness. Increased BADM thickness correlated with increased mechanical strength. In suture tear-through testing with steel wire, failure of the steel wire occurred in the 4-mm-thick BADM, whereas the matrix material failed in all other thicknesses of BADM and PADM. Before implantation, BADM is inherently stronger than PADM at equivalent thicknesses and considerably stronger at increased thicknesses. These results corroborate clinical data from a previous study in which PADM was associated with a higher intraoperative device failure rate. Although numerous properties of acellular dermal matrix contribute to clinical outcomes, surgeons should consider initial mechanical strength properties when choosing acellular dermal matrices for load-bearing applications such as hernia repair.

Centrally activated pipe snubbing system

DOEpatents

Cawley, William E.

1985-01-01

An electromechanical pipe snubbing system and an electromechanical pipe snubber. In the system, each pipe snubber, in a set of pipe snubbers, has an electromechanical mechanism to lock and unlock the snubber. A sensor, such as a seismometer, measures a quantity related to making a snubber locking or unlocking decision. A control device makes an electrical connection between a power supply and each snubber's electromechanical mechanism to simultaneously lock each snubber when the sensor measurement indicates a snubber locking condition. The control device breaks the connection to simultaneously unlock each snubber when the sensor measurement indicates a snubber unlocking condition. In the snubber, one end of the shaft slides within a bore in one end of a housing. The other end of the shaft is rotatably attached to a pipe; the other end of the housing is rotatively attached to a wall. The snubber's electromechanical mechanism locks the slidable end of the shaft to the housing and unlocks that end from the housing. The electromechanical mechanism permits remote testing and lockup status indication for each snubber.

A novel mechatronic system for measuring end-point stiffness: mechanical design and preliminary tests.

PubMed

Masia, L; Sandini, G; Morasso, P G

2011-01-01

Measuring arm stiffness is of great interest for many disciplines from biomechanics to medicine especially because modulation of impedance represents one of the main mechanism underlying control of movement and interaction with external environment. Previous works have proposed different methods to identify multijoint hand stiffness by using planar or even tridimensional haptic devices, but the associated computational burden makes them not easy to implement. We present a novel mechanism conceived for measuring multijoint planar stiffness by a single measurement and in a reduced execution time. A novel mechanical rotary device applies cyclic radial perturbation to human arm of a known displacement and the force is acquired by means of a 6-axes commercial load cell. The outcomes suggest that the system is not only reliable but allows obtaining a bi-dimensional estimation of arm stiffness in reduced amount of time and the results are comparable with those reported in previous researches. © 2011 IEEE

Lab-on-a-brane: A novel physiologically relevant planar arterial model to study transendothelial transport

NASA Astrophysics Data System (ADS)

Budhwani, Karim Ismail

The tremendous quality of life impact notwithstanding, cardiovascular diseases and Cancer add up to over US$ 700bn each year in financial costs alone. Aging and population growth are expected to further expand the problem space while drug research and development remain expensive. However, preclinical costs can be substantially mitigated by substituting animal models with in vitro devices that accurately model human cardiovascular transport. Here we present a novel physiologically relevant lab-on-a-brane that simulates in vivo pressure, flow, strain, and shear waveforms associated with normal and pathological conditions in large and small blood vessels for studying molecular transport across the endothelial monolayer. The device builds upon previously demonstrated integrated microfluidic loop design by: (a) introducing nanoscale pores in the substrate membrane to enable transmembrane molecular transport, (b) transforming the substrate membrane into a nanofibrous matrix for 3D smooth muscle cell (SMC) tissue culture, (c) integrating electrospinning fabrication methods, (d) engineering an invertible sandwich cell culture device architecture, and (e) devising a healthy co-culture mechanism for human arterial endothelial cell (HAEC) monolayer and multiple layers of human smooth muscle cells (HSMC) to accurately mimic arterial anatomy. Structural and mechanical characterization was conducted using confocal microscopy, SEM, stress/strain analysis, and infrared spectroscopy. Transport was characterized using FITC-Dextran hydraulic permeability protocol. Structure and transport characterization successfully demonstrate device viability as a physiologically relevant arterial mimic for testing transendothelial transport. Thus, our lab-on-a-brane provides a highly effective and efficient, yet considerably inexpensive, physiologically relevant alternative for pharmacokinetic evaluation; possibly reducing animals used in pre-clinical testing, clinical trials cost from false starts, and time-to-market. Furthermore, this platform can be easily configured for testing targeted therapeutic delivery and in multiple simultaneous arrays for personalized and precision medicine applications.

A tricalcium phosphate/polyether ether ketone anchor bionic fixation device for anterior cruciate ligament reconstruction: Safety and efficacy in a beagle model.

PubMed

Mao, Genwen; Qin, Zili; Li, Zheng; Li, Xiang; Qiu, Yusheng; Bian, Weiguo

2018-05-02

The goal of this study was to develop a bionic fixation device based on the use of a tricalcium phosphate/polyether ether ketone anchor and harvesting of the ulnar carpal flexor muscle tendon for application as a ligament graft in a beagle anterior cruciate ligament (ACL) reconstruction model, with the goal of accelerating the ligament graft-to-bone tunnel healing and providing a robust stability through exploration of this new kind of autologous ligament graft. The safety and efficacy of this fixation device were explored 3 and 6 months after surgery in a beagle ACL reconstruction model using biomechanical tests and comprehensive histological observation. The data were compared using a two-tailed Student's t test and a paired t test. A p value <0.05 was defined as statistically significant. All the models were successfully established. This fixation device possessed the excellent mechanical properties for ACL reconstruction. A comprehensive histological observation revealed that a cartilage layer was visible in the transition zone between the tendon and bone interface at both 3 and 6 months postoperation. The trabecular of the new bone was observed six months after surgery and was found to be similar to a direct connection. This fixation technique provided not only a robust primary mechanical fixation but also a bionic fixation for long-term knee joint stability by accelerating the healing of the tendon to the bone tunnel, showing a high potential for use in clinical practice. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc.

A federated capability-based access control mechanism for internet of things (IoTs)

NASA Astrophysics Data System (ADS)

Xu, Ronghua; Chen, Yu; Blasch, Erik; Chen, Genshe

2018-05-01

The prevalence of Internet of Things (IoTs) allows heterogeneous embedded smart devices to collaboratively provide intelligent services with or without human intervention. While leveraging the large-scale IoT-based applications like Smart Gird and Smart Cities, IoT also incurs more concerns on privacy and security. Among the top security challenges that IoTs face is that access authorization is critical in resource and information protection over IoTs. Traditional access control approaches, like Access Control Lists (ACL), Role-based Access Control (RBAC) and Attribute-based Access Control (ABAC), are not able to provide a scalable, manageable and efficient mechanisms to meet requirement of IoT systems. The extraordinary large number of nodes, heterogeneity as well as dynamicity, necessitate more fine-grained, lightweight mechanisms for IoT devices. In this paper, a federated capability-based access control (FedCAC) framework is proposed to enable an effective access control processes to devices, services and information in large scale IoT systems. The federated capability delegation mechanism, based on a propagation tree, is illustrated for access permission propagation. An identity-based capability token management strategy is presented, which involves registering, propagation and revocation of the access authorization. Through delegating centralized authorization decision-making policy to local domain delegator, the access authorization process is locally conducted on the service provider that integrates situational awareness (SAW) and customized contextual conditions. Implemented and tested on both resources-constrained devices, like smart sensors and Raspberry PI, and non-resource-constrained devices, like laptops and smart phones, our experimental results demonstrate the feasibility of the proposed FedCAC approach to offer a scalable, lightweight and fine-grained access control solution to IoT systems connected to a system network.

Hybrid Integrated Silicon Microfluidic Platform for Fluorescence Based Biodetection.

PubMed

Chandrasekaran, Arvind; Acharya, Ashwin; You, Jian Liang; Soo, Kim Young; Packirisamy, Muthukumaran; Stiharu, Ion; Darveau, André

2007-09-11

The desideratum to develop a fully integrated Lab-on-a-chip device capable ofrapid specimen detection for high throughput in-situ biomedical diagnoses and Point-of-Care testing applications has called for the integration of some of the novel technologiessuch as the microfluidics, microphotonics, immunoproteomics and Micro ElectroMechanical Systems (MEMS). In the present work, a silicon based microfluidic device hasbeen developed for carrying out fluorescence based immunoassay. By hybrid attachment ofthe microfluidic device with a Spectrometer-on-chip, the feasibility of synthesizing anintegrated Lab-on-a-chip type device for fluorescence based biosensing has beendemonstrated. Biodetection using the microfluidic device has been carried out usingantigen sheep IgG and Alexafluor-647 tagged antibody particles and the experimentalresults prove that silicon is a compatible material for the present application given thevarious advantages it offers such as cost-effectiveness, ease of bulk microfabrication,superior surface affinity to biomolecules, ease of disposability of the device etc., and is thussuitable for fabricating Lab-on-a-chip type devices.

Mechanical evaluation of a ruptured Swedish adjustable gastric band.

PubMed

Reijnen, Michael M P J; Naus, J H; Janssen, Ignace M C

2004-02-01

Leakage of a laparoscopically placed Swedish adjustable gastric band (SAGB) was observed 2 1/2 years after placement. The band was evaluated for mechanical inaccuracies by a laboratory. The ruptured SAGB was investigated microscopically and wall thicknesses were measured. An unused SAGB was tested, both empty and filled, for mechanical deformity after exposure to saline solution. A permanent transformation of the silicone rubber was found, caused by bowing of the device. 2 tears were present at the end of a kink. The mean wall thickness was within acceptable limits. Exposure of the gastric band to saline solution did not cause any sign of permanent deformity of the silicone rubber. The rupture of the gastric band did not seem to be caused by a production error. Long-term deformity, in combination with a continuous dynamic load, may increase the risk of tearing. Long-term follow up is recommended for patients treated with this device.

Evolution of Deep Brain Stimulation: Human Electrometer and Smart Devices Supporting the Next Generation of Therapy

PubMed Central

Lee, Kendall H.; Blaha, Charles D.; Garris, Paul A.; Mohseni, Pedram; Horne, April E.; Bennet, Kevin E.; Agnesi, Filippo; Bledsoe, Jonathan M.; Lester, Deranda B.; Kimble, Chris; Min, Hoon-Ki; Kim, Young-Bo; Cho, Zang-Hee

2010-01-01

Deep Brain Stimulation (DBS) provides therapeutic benefit for several neuropathologies including Parkinson’s disease (PD), epilepsy, chronic pain, and depression. Despite well established clinical efficacy, the mechanism(s) of DBS remains poorly understood. In this review we begin by summarizing the current understanding of the DBS mechanism. Using this knowledge as a framework, we then explore a specific hypothesis regarding DBS of the subthalamic nucleus (STN) for the treatment of PD. This hypothesis states that therapeutic benefit is provided, at least in part, by activation of surviving nigrostriatal dopaminergic neurons, subsequent striatal dopamine release, and resumption of striatal target cell control by dopamine. While highly controversial, we present preliminary data that are consistent with specific predications testing this hypothesis. We additionally propose that developing new technologies, e.g., human electrometer and closed-loop smart devices, for monitoring dopaminergic neurotransmission during STN DBS will further advance this treatment approach. PMID:20657744

A Novel Idea to Improve Cardiac Output of Mechanical Circulatory Support Devices by Optimizing Kinetic Energy Transfer Available in Forward Moving Aortic Blood Flow.

PubMed

Qureshi, Muhammad B; Glower, Jacob; Ewert, Daniel L; Koenig, Steven C

2017-06-01

Mechanical circulatory support devices (MCSDs) have gained widespread clinical acceptance as an effective heart failure (HF) therapy. The concept of harnessing the kinetic energy (KE) available in the forward aortic flow (AOF) is proposed as a novel control strategy to further increase the cardiac output (CO) provided by MCSDs. A complete mathematical development of the proposed theory and its application to an example MCSDs (two-segment extra-aortic cuff) are presented. To achieve improved device performance and physiologic benefit, the example MCSD timing is regulated to maximize the forward AOF KE and minimize retrograde flow. The proof-of-concept was tested to provide support with and without KE control in a computational HF model over a wide range of HF test conditions. The simulation predicted increased stroke volume (SV) by 20% (9 mL), CO by 23% (0.50 L/min), left ventricle ejection fraction (LVEF) by 23%, and diastolic coronary artery flow (CAF) by 55% (3 mL) in severe HF at a heart rate (HR) of 60 beats per minute (BPM) during counterpulsation (CP) support with KE control. The proposed KE control concept may improve performance of other MCSDs to further enhance their potential clinical benefits, which warrants further investigation. The next step is to investigate various assist technologies and determine where this concept is best applied. Then bench-test the combination of kinetic energy optimization and its associated technology choice and finally test the combination in animals.

Comparing the performance of a new disposable pneumatic tocodynamometer with a standard tocodynamometer.

PubMed

Eswaran, Hari; Wilson, James D; Murphy, Pam; Siegel, Eric R; Lowery, Curtis L

2016-03-01

The goal was to test a newly developed pneumatic tocodynamometer (pTOCO) that is disposable and lightweight, and evaluate its equivalence to the standard strain gauge-based tocodynamometer (TOCO). The equivalence between the devices was determined by both mechanical testing and recording of contractile events on women. The data were recorded simultaneously from a pTOCO prototype and standard TOCO that were in place on women who were undergoing routine contraction monitoring in the Labor and Delivery unit at the University of Arkansas for Medical Sciences. In this prospective equivalence study, the output from 31 recordings on 28 pregnant women that had 171 measureable contractions simultaneously in both types of TOCO were analyzed. The traces were scored for contraction start, peak and end times, and the duration of the event was computed from these times. The response curve to loaded weights and applied pressure were similar for both devices, indicating their mechanical equivalence. The paired differences in times and duration between devices were subjected to mixed-models analysis to test the pTOCO for equivalence with standard TOCOs using the two-one-sided tests procedure. The event times and duration analyzed simultaneously from both TOCO types were all found to be significantly equivalent to within ±10 s (all p-values ≤0.0001). pTOCO is equivalent to the standard TOCO in the detection of the timing and duration of uterine contractions. pTOCO would provide a lightweight, disposable alternative to commercially available standard TOCOs. © 2015 Nordic Federation of Societies of Obstetrics and Gynecology.

In-line Microwave Warmer for Blood and Intravenous Fluids.

DTIC Science & Technology

1989-12-14

circuit was designed and tested. This circuit uses a digitally controlled optically coupled Triac , a thyristor device, which acts as a switch to allow...three sites of the circuit : Inlet Port of Heating Chamber Interior Path of Heating Chamber Outlet Port of Heating Chamber 4) Feedback Control Mechanism...accomplished through use of a closed loop test circuit depicted in Figure 1-2. This test circuit can be used to heat iv fluids or blood on a continuous

Pharmaceutical counselling about different types of tablet-splitting methods based on the results of weighing tests and mechanical development of splitting devices.

PubMed

Somogyi, O; Meskó, A; Csorba, L; Szabó, P; Zelkó, R

2017-08-30

The division of tablets and adequate methods of splitting them are a complex problem in all sectors of health care. Although tablet-splitting is often required, this procedure can be difficult for patients. Four tablets were investigated with different external features (shape, score-line, film-coat and size). The influencing effect of these features and the splitting methods was investigated according to the precision and "weight loss" of splitting techniques. All four types of tablets were halved by four methods: by hand, with a kitchen knife, with an original manufactured splitting device and with a modified tablet splitter based on a self-developed mechanical model. The mechanical parameters (harness and friability) of the products were measured during the study. The "weight loss" and precision of splitting methods were determined and compared by statistical analysis. On the basis of the results, the external features (geometry), the mechanical parameters of tablets and the mechanical structure of splitting devices can influence the "weight loss" and precision of tablet-splitting. Accordingly, a new decision-making scheme was developed for the selection of splitting methods. In addition, the skills of patients and the specialties of therapy should be considered so that pharmaceutical counselling can be more effective regarding tablet-splitting. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and mechanical properties of construction materials from lunar simulants

NASA Technical Reports Server (NTRS)

Desai, Chandra S.

1990-01-01

The development of construction materials such as concrete from lunar soils without the use of water requires a different methodology than that used for conventional terrestrial concrete. Currently, this research involves two aspects: (1) liquefaction of lunar simulants with various additives in a furnace so as to produce a construction material like an intermediate ceramic; and (2) cyclic loading of simulant with different initial vacuums and densities with respect to the theoretical maximum densities (TMD). In both cases, bending, triaxial compression, extension, and hydrostatic tests will be performed to define the stress-strain strength response of the resulting materials. In the case of the intermediate ceramic, bending and available multiaxial test devices will be used, while for the compacted case, tests will be performed directly in the new device. The tests will be performed by simulating in situ confining conditions. A preliminary review of high-purity metal is also conducted.

Method and device for tensile testing of cable bundles

DOEpatents

Robertson, Lawrence M; Ardelean, Emil V; Goodding, James C; Babuska, Vit

2012-10-16

A standard tensile test device is improved to accurately measure the mechanical properties of stranded cables, ropes, and other composite structures wherein a witness is attached to the top and bottom mounting blocks holding the cable under test. The witness is comprised of two parts: a top and a bottom rod of similar diameter with the bottom rod having a smaller diameter stem on its upper end and the top rod having a hollow opening in its lower end into which the stem fits forming a witness joint. A small gap is present between the top rod and the larger diameter portion of the bottom rod. A standard extensometer is attached to the top and bottom rods of the witness spanning this small witness gap. When a force is applied to separate the mounting blocks, the gap in the witness expands the same length that the entire test specimen is stretched.

Design of a right ventricular mock circulation loop as a test bench for right ventricular assist devices.

PubMed

Mueller, Indra; Jansen-Park, So-Hyun; Neidlin, Michael; Steinseifer, Ulrich; Abel, Dirk; Autschbach, Rüdiger; Rossaint, Rolf; Schmitz-Rode, Thomas; Sonntag, Simon Johannes

2017-04-01

Right heart failure (RHF), e.g. due to pulmonary hypertension (PH), is a serious health issue with growing occurrence and high mortality rate. Limited efficacy of medication in advanced stages of the disease constitutes the need for mechanical circulatory support of the right ventricle (RV). An essential contribution to the process of developing right ventricular assist devices (RVADs) is the in vitro test bench, which simulates the hemodynamic behavior of the native circulatory system. To model healthy and diseased arterial-pulmonary hemodynamics in adults (mild and severe PH and RHF), a right heart mock circulation loop (MCL) was developed. Incorporating an anatomically shaped silicone RV and a silicone atrium, it not only enables investigations of hemodynamic values but also suction events or the handling of minimal invasive RVADs in an anatomical test environment. Ventricular pressure-volume loops of all simulated conditions as well as pressure and volume waveforms were recorded and compared to literature data. In an exemplary test, an RVAD was connected to the apex to further test the feasibility of studying such devices with the developed MCL. In conclusion, the hemodynamic behavior of the native system was well reproduced by the developed MCL, which is a useful basis for future RVAD tests.

Reflectivity of the AL-N coating: results of mechanical and environmental tests

NASA Astrophysics Data System (ADS)

Anisimov, Vladimir P.; Anisimova, Irina A.; Kashirin, Victor A.; Moldosanov, Kamil A.; Skrynnikov, Alexander M.

2002-09-01

This paper concerns a behavior of the total hemispherical reflectance (THR) of the Al-N coating in the course of mechanical and environmental tests. The Al-N coating has been designed to reduce the stray sunlight background in the satellite-borne optical instruments and charge-particles-analyzing apparatus operating in open space under intensive solar radiation. Usually, this problem arises when a density of instruments installed on the satellite is high and it is difficult to avoid getting to instrument the light reflected by neighboring devices. Resolution of this problem is also important in connection with development of the extra-atmosphere Far UV astronomy. The THR measurement results are presented for 10 wavelengths wihtin a range from 400 to 927 nm, and also at 121.6 nm, the most intensive line of the solar UV spectrum able to result in considerable contribution to the detector noise in space devices. The samples of the Al-N coating were exposed to standard mechanical loads including the vibratory loads, linear overloads, and impacts, to which the space equipment may be subjected when shipping to the space-vehicle launching site and also when lauching. The samples were also exposed to environmental tests simulating the vacuum, humidity, and cyclic temperature conditions, which may influence the space instruments while shipping, storing, launching, in flight, and under operating conditions. The THR measurements of the samples were made following exposure to each test. The THRs of tested samples at the wavelength of 121.6 nm were as low as 1.5-2%.

Characterization of bacterial etiologic agents of biofilm formation in medical devices in critical care setup.

PubMed

Revdiwala, Sangita; Rajdev, Bhaumesh M; Mulla, Summaiya

2012-01-01

Background. Biofilms contaminate catheters, ventilators, and medical implants; they act as a source of disease for humans, animals, and plants. Aim. Critical care units of any healthcare institute follow various interventional strategies with use of medical devices for the management of critical cases. Bacteria contaminate medical devices and form biofilms. Material and Methods. The study was carried out on 100 positive bacteriological cultures of medical devices which were inserted in hospitalized patients. The bacterial isolates were processed as per microtitre plate. All the isolates were subjected to antibiotic susceptibility testing by VITEK 2 compact automated systems. Results. Out of the total 100 bacterial isolates tested, 88 of them were biofilm formers. A 16-20-hour incubation period was found to be optimum for biofilm development. 85% isolates were multidrug resistants and different mechanisms of bacterial drug resistance like ESBL, carbapenemase, and MRSA were found among isolates. Conclusion. Availability of nutrition in the form of glucose enhances the biofilm formation by bacteria. Time and availability of glucose are important factors for assessment of biofilm progress. It is an alarm for those who are associated with invasive procedures and indwelling medical devices especially in patients with low immunity.

A Resonant Pulse Detonation Actuator for High-Speed Boundary Layer Separation Control

NASA Technical Reports Server (NTRS)

Beck, B. T.; Cutler, A. D.; Drummond, J. P.; Jones, S. B.

2004-01-01

A variety of different types of actuators have been previously investigated as flow control devices. Potential applications include the control of boundary layer separation in external flows, as well as jet engine inlet and diffuser flow control. The operating principles for such devices are typically based on either mechanical deflection of control surfaces (which include MEMS flap devices), mass injection (which includes combustion driven jet actuators), or through the use of synthetic jets (diaphragm devices which produce a pulsating jet with no net mass flow). This paper introduces some of the initial flow visualization work related to the development of a relatively new type of combustion-driven jet actuator that has been proposed based on a pulse detonation principle. The device is designed to utilize localized detonation of a premixed fuel (Hydrogen)-air mixture to periodically inject a jet of gas transversely into the primary flow. Initial testing with airflow successfully demonstrated resonant conditions within the range of acoustic frequencies expected for the design. Schlieren visualization of the pulsating air jet structure revealed axially symmetric vortex flow, along with the formation of shocks. Flow visualization of the first successful sustained oscillation condition is also demonstrated for one configuration of the current test section. Future testing will explore in more detail the onset of resonant combustion and the approach to conditions of sustained resonant detonation.

Mesoscale fabrication and design

NASA Astrophysics Data System (ADS)

Hayes, Gregory R.

A strong link between mechanical engineering design and materials science and engineering fabrication can facilitate an effective and adaptable prototyping process. In this dissertation, new developments in the lost mold-rapid infiltration forming (LM-RIF) process is presented which demonstrates the relationship between these two fields of engineering in the context of two device applications. Within the LM-RIF process, changes in materials processing and mechanical design are updated iteratively, often aided by statistical design of experiments (DOE). The LM-RIF process was originally developed by Antolino and Hayes et al to fabricate mesoscale components. In this dissertation the focus is on advancements in the process and underlying science. The presented advancements to the LM-RIF process include an augmented lithography procedure, the incorporation of engineered aqueous and non-aqueous colloidal suspensions, an assessment of constrained drying forces during LM-RIF processing, mechanical property evaluation, and finally prototype testing and validation. Specifically, the molding procedure within the LM-RIF process is capable of producing molds with thickness upwards of 1mm, as well as multi-layering to create three dimensional structures. Increasing the mold thickness leads to an increase in the smallest feature resolvable; however, the increase in mold thickness and three dimensional capability has expanded the mechanical design space. Tetragonally stabilized zirconia (3Y-TZP) is an ideal material for mesoscale instruments, as it is biocompatible, exhibits high strength, and is chemically stable. In this work, aqueous colloidal suspensions were formulated with two new gel-binder systems, increasing final natural orifice translumenal endoscopic surgery (NOTES) instrument yield from 0% to upwards of 40% in the best case scenario. The effects of the gel-binder system on the rheological behavior of the suspension along with the thermal characteristics of the gel-binder system were characterized. Finally, mechanical properties of ceramic specimens were obtained via 3-point bend testing. Another candidate material for NOTES devices as well as cellular contact aided compliant mechanisms (C3M) devices is 300 series stainless steel (300 series stainless steel). 300 series stainless steel is a common biocompatible material; it is used in surgical applications, exhibits a high corrosion resistance, and has high strength to failure. New, high solids loading, non-aqueous colloidal suspensions of 300 series stainless steel were formulated and incorporated into the LM-RIF process. The rheological behavior and thermal characteristics of the non-aqueous colloidal suspensions were analyzed and engineered to operate within the LM-RIF process. Final part yield with the non-aqueous colloidal suspensions was higher than that of the aqueous ceramic suspensions. Mechanical properties of 300 series stainless steel specimens were determined via 3-point bend testing. Furthermore, new composite non-aqueous colloidal suspensions of 3Y-TZP and 300 series stainless steel were formulated and incorporated into the LM-RIF process. The composite materials showed an increase in final part yield, and an increase in yield strength compared to pure 300 series stainless steel was determined by Vickers hardness testing. The successful incorporation of composite suspensions in the LM-RIF process was facilitated through an analysis of the rheological behavior as a function of solids loading and ceramic to metal ratio. Optimized designs of NOTES instruments, as well as C3M devices were manufactured using the LM-RIF process with the non-aqueous 300 series stainless steel suspension. The performance of the prototype NOTES instruments was evaluated and compared against the theoretically predicted performance results, showing good agreement. Similarly, good agreement was seen between the stress-displacement behavior of prototype C3M devices when compared to the theoretically calculated stress-displacement results. Finally, in a comparison by endoscopic surgeons at Hershey Medical Center between an existing industry standard endoscopic device and the mesoscale instrument prototypes fabricated via the LM-RIF process, the prototype design performed favorably in almost all categories. (Abstract shortened by UMI.)

Safety syringes and anti-needlestick devices in orthopaedic surgery.

PubMed

Sibbitt, Wilmer L; Band, Philip A; Kettwich, Lawrence G; Sibbitt, Cristina R; Sibbitt, Lori J; Bankhurst, Arthur D

2011-09-07

The American Academy of Orthopaedic Surgery (AAOS), The Joint Commission, the Occupational Safety and Health Administration (OSHA), and the Needlestick Safety and Prevention Act encourage the integration of safety-engineered devices to prevent needlestick injuries to health-care workers and patients. We hypothesized that safety syringes and needles could be used in outpatient orthopaedic injection and aspiration procedures. The study investigated the orthopaedic uses and procedural idiosyncrasies of safety-engineered devices, including (1) four safety needles (Eclipse, SafetyGlide, SurGuard, and Magellan), (2) a mechanical safety syringe (RPD), (3) two automatic retractable syringes (Integra, VanishPoint), (4) three manual retractable syringes (Procedur-SF, Baksnap, Invirosnap), and (5) three shielded syringes (Safety-Lok, Monoject, and Digitally Activated Shielded [DAS] Syringe). The devices were first tested ex vivo, and then 1300 devices were used for 425 subjects undergoing outpatient arthrocentesis, intra-articular injections, local anesthesia, aspiration biopsy, and ultrasound-guided procedures. During the clinical observation, there were no accidental needlesticks (0 needlesticks per 1300 devices). Safety needles could be successfully used on a Luer syringe but were limited to ≤1.5 in (≤3.81 cm) in length and the shield could interfere with sonography. The mechanical safety syringes functioned well in all orthopaedic procedures. Automatic retractable syringes were too small for arthrocentesis of the knee, and the plunger blew out and prematurely collapsed with high-pressure injections. The manual retractable syringes and shielded syringes could be used with conventional needles for most orthopaedic procedures. The most effective and reliable safety devices for orthopaedic syringe procedures are shielded safety needles, mechanical syringes, manual retractable syringes, and shielded syringes, but not automatic retractable syringes. Even when adopting safety-engineered devices for an orthopaedic clinic, conventional syringes larger than 20 mL and conventional needles longer than 1.5 in (3.8 cm) are necessary.

46 CFR 199.45 - Tests and inspections of lifesaving equipment and arrangements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... rescue boats, including engines and release mechanisms; (3) The proper condition of flotation equipment... indicating radiobeacons (EPIRB), search and rescue transponders (SART), and pyrotechnic signaling devices; (5... repeated; (2) The proper condition and operation of lifeboats and rescue boats, including engines and...

46 CFR 199.45 - Tests and inspections of lifesaving equipment and arrangements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... rescue boats, including engines and release mechanisms; (3) The proper condition of flotation equipment... indicating radiobeacons (EPIRB), search and rescue transponders (SART), and pyrotechnic signaling devices; (5... repeated; (2) The proper condition and operation of lifeboats and rescue boats, including engines and...

46 CFR 199.45 - Tests and inspections of lifesaving equipment and arrangements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... rescue boats, including engines and release mechanisms; (3) The proper condition of flotation equipment... indicating radiobeacons (EPIRB), search and rescue transponders (SART), and pyrotechnic signaling devices; (5... repeated; (2) The proper condition and operation of lifeboats and rescue boats, including engines and...

46 CFR 199.45 - Tests and inspections of lifesaving equipment and arrangements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... rescue boats, including engines and release mechanisms; (3) The proper condition of flotation equipment... indicating radiobeacons (EPIRB), search and rescue transponders (SART), and pyrotechnic signaling devices; (5... repeated; (2) The proper condition and operation of lifeboats and rescue boats, including engines and...

46 CFR 199.45 - Tests and inspections of lifesaving equipment and arrangements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... rescue boats, including engines and release mechanisms; (3) The proper condition of flotation equipment... indicating radiobeacons (EPIRB), search and rescue transponders (SART), and pyrotechnic signaling devices; (5... repeated; (2) The proper condition and operation of lifeboats and rescue boats, including engines and...

Intraoral laser welding: ultrastructural and mechanical analysis to compare laboratory laser and dental laser.

PubMed

Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Rocca, Jean-Paul; Merigo, Elisabetta; Vescovi, Paolo; Meleti, Marco; Manfredi, Maddalena; Nammour, Samir

2011-07-01

The Nd:YAG laser has been used since 1970 in dental laboratories to weld metals on dental prostheses. Recently in several clinical cases, we have suggested that the Nd:YAG laser device commonly utilized in the dental office could be used to repair broken fixed, removable and orthodontic prostheses and to weld metals directly in the mouth. The aim of this work was to evaluate, using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and dynamic mechanical analysis (DMA), the quality of the weld and its mechanical strength, comparing a device normally used in dental laboratory and a device normally used in the dental office for oral surgery, the same as that described for intraoral welding. Metal plates of a Co-Cr-Mo dental alloy and steel orthodontic wires were subjected to four welding procedures: welding without filler metal using the laboratory laser, welding with filler metal using the laboratory laser, welding without filler metal using the office laser, and welding with filler metal using the office laser. The welded materials were then analysed by SEM, EDS and DMA. SEM analysis did not show significant differences between the samples although the plates welded using the office laser without filler metal showed a greater number of fissures than the other samples. EDS microanalysis of the welding zone showed a homogeneous composition of the metals. Mechanical tests showed similar elastic behaviours of the samples, with minimal differences between the samples welded with the two devices. No wire broke even under the maximum force applied by the analyser. This study seems to demonstrate that the welds produced using the office Nd:YAG laser device and the laboratory Nd:YAG laser device, as analysed by SEM, EDS and DMA, showed minimal and nonsignificant differences, although these findings need to be confirmed using a greater number of samples.

Intraoral Laser Welding (ILW): ultrastructural and mechanical analysis

NASA Astrophysics Data System (ADS)

Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Nammour, Samir

2010-05-01

Nd:YAG, currently used since 1970 in dental laboratories to weld metals on dental prostheses has some limits such great dimensions, high costs and fixed delivery system. Recently it was proposed the possibility to use the Nd:YAG laser device commonly utilised in dental office, to repair broken fixed, removable and orthodontic prostheses and to weld metals directly into the mouth. The aim of this work is to value, through SEM (Scanning Electron Microscope), EDS (Energy Dispersive X-Ray Spectroscopy) and DMA (Dynamic Mechanical Analysis), quality and mechanical strength of the welding process comparing a device normally used in dental lab and a device normally used in dental office for oral surgery. Sixteen CoCrMo metal plates and twenty steel orthodontic wires were divided in four groups: one was welded without metal apposition by laboratory laser, one was welded with metal apposition by laboratory laser, one was welded without metal apposition by office laser and one was welded with metal apposition by office laser. The welding process was analysed by SEM, EDS and DMA to compare the differences between the different samples. By SEM analysis it was seen that the plates welded by office laser without apposition metal showed a greater number of fissurations compared with the other samples. By EDS analysis it was seen a homogeneous composition of the metals in all the samples. The mechanical tests showed a similar elastic behaviour of the samples, with minimal differences between the two devices. No wire broke even under the maximum strength by the Analyser. This study seems to demonstrate that the welding process by office Nd:YAG laser device and the welding process by laboratory Nd:YAG laser device, analysed by SEM, EDS and DMA, showed minimal and not significant differences even if these data will be confirmed by a greater number of samples.

Measurement of Young's modulus and residual stress of thin SiC layers for MEMS high temperature applications

NASA Astrophysics Data System (ADS)

Pabst, Oliver; Schiffer, Michael; Obermeier, Ernst; Tekin, Tolga; Lang, Klaus Dieter; Ngo, Ha-Duong

2011-06-01

Silicon carbide (SiC) is a promising material for applications in harsh environments. Standard silicon (Si) microelectromechanical systems (MEMS) are limited in operating temperature to temperatures below 130 °C for electronic devices and below 600 °C for mechanical devices. Due to its large bandgap SiC enables MEMS with significantly higher operating temperatures. Furthermore, SiC exhibits high chemical stability and thermal conductivity. Young's modulus and residual stress are important mechanical properties for the design of sophisticated SiC-based MEMS devices. In particular, residual stresses are strongly dependent on the deposition conditions. Literature values for Young's modulus range from 100 to 400 GPa, and residual stresses range from 98 to 486 MPa. In this paper we present our work on investigating Young's modulus and residual stress of SiC films deposited on single crystal bulk silicon using bulge testing. This method is based on measurement of pressure-dependent membrane deflection. Polycrystalline as well as single crystal cubic silicon carbide samples are studied. For the samples tested, average Young's modulus and residual stress measured are 417 GPa and 89 MPa for polycrystalline samples. For single crystal samples, the according values are 388 GPa and 217 MPa. These results compare well with literature values.

DRAGON - 8U Nanosatellite Orbital Deployer

NASA Technical Reports Server (NTRS)

Dobrowolski, Marcin; Grygorczuk, Jerzy; Kedziora, Bartosz; Tokarz, Marta; Borys, Maciej

2014-01-01

The Space Research Centre of the Polish Academy of Sciences (SRC PAS) together with Astronika company have developed an Orbital Deployer called DRAGON for ejection of the Polish scientific nanosatellite BRITE-PL Heweliusz (Fig. 1). The device has three unique mechanisms including an adopted and scaled lock and release mechanism from the ESA Rosetta mission MUPUS instrument. This paper discusses major design restrictions of the deployer, unique design features, and lessons learned from development through testing.

Experimental evaluation of a miniature MR device for a wide range of human perceivable haptic sensations

NASA Astrophysics Data System (ADS)

Yang, Tae-Heon; Koo, Jeong-Hoi

2017-12-01

Humans can experience a realistic and vivid haptic sensations by the sense of touch. In order to have a fully immersive haptic experience, both kinaesthetic and vibrotactile information must be presented to human users. Currently, little haptic research has been performed on small haptic actuators that can covey both vibrotactile feedback based on the frequency of vibrations up to the human-perceivable limit and multiple levels of kinaesthetic feedback rapidly. Therefore, this study intends to design a miniature haptic device based on MR fluid and experimentally evaluate its ability to convey vibrotactile feedback up to 300 Hz along with kinaesthetic feedback. After constructing a prototype device, a series of testing was performed to evaluate its performance of the prototype using an experimental setup, consisting of a precision dynamic mechanical analyzer and an accelerometer. The kinaesthetic testing results show that the prototype device can provide the force rate up to 89% at 5 V (360 mA), which can be discretized into multiple levels of ‘just noticeable difference’ force rate, indicating that the device can convey a wide range of kinaesthetic sensations. To evaluate the high frequency vibrotactile feedback performance of the device, its acceleration responses were measured and processed using the FFT analysis. The results indicate that the device can convey high frequency vibrotactile sensations up to 300 Hz with the sufficiently large intensity of accelerations that human can feel.

Virtex-II Pro PowerPC SEE Characterization Test Methods and Results

NASA Technical Reports Server (NTRS)

Petrick, David; Powell, Wesley; LaBel, Ken; Howard, James

2005-01-01

The Xilinx Vix-11 Pro is a platform FPGA that embeds multiple microprocessors within the fabric of an SRAM-based reprogrammable FPGA. The variety and quantity of resources provided by this family of devices make them very attractive for spaceflight applications. However,these devices will be susceptible to single event effects (SEE), which must be mitigated. Observations from prior testing of the Xilinx Virtex-II Pro suggest that the PowerPC core has significant vulnerability to SEES. However, these initial tests were not designed to exclusively target the functionality of the PowerPC, therefore making it difficult to distinguish processor upsets from fabric upsets. The main focus of this paper involves detailed SEE testing of the embedded PowerPC core. Due to the complexity of the PowerPC, various custom test applications, both static and dynamic, will be designed to isolate each Unit of the processor. Collective analysis of the test results will provide insight into the exact upset mechanism of the PowerPC. With this information, mitigations schemes can be developed and tested that address the specific susceptibilities of these devices. The test bed will be the Xilinx SEE Consortium Virtex-II Pro test board, which allows for configuration scrubbing, design triplication, and ease of data collection. Testing will be performed at the Indiana University Cyclotron Facility using protons of varying energy levels and fluencies. This paper will present the detailed test approach along with the results.

Humidification performance of 48 passive airway humidifiers: comparison with manufacturer data.

PubMed

Lellouche, François; Taillé, Solenne; Lefrançois, Frédéric; Deye, Nicolas; Maggiore, Salvatore Maurizio; Jouvet, Philippe; Ricard, Jean-Damien; Fumagalli, Bruno; Brochard, Laurent

2009-02-01

Heat and moisture exchangers (HMEs) are increasingly used in the ICU for gas conditioning during mechanical ventilation. Independent assessments of the humidification performance of HMEs are scarce. The aim of the present study was thus to assess the humidification performance of a large number of adult HMEs. We assessed 48 devices using a bench test apparatus that simulated real-life physiologic ventilation conditions. Thirty-two devices were described by the manufacturers as HMEs, and 16 were described as antibacterial filters. The test apparatus provided expiratory gases with an absolute humidity (AH) of 35 mg H(2)O/L. The AH of inspired gases was measured after steady state using the psychrometric method. We performed three hygrometric measurements for each device, measured their resistance, and compared our results with the manufacturer data. Of the 32 HMEs tested, only 37.5% performed well (>or= 30 mg H(2)O/L), while 25% performed poorly (< 25 mg H(2)O/L). The mean difference (+/- SD) between our measurements and the manufacturer data was 3.0 +/- 2.7 mg H(2)O/L for devices described as HMEs (maximum, 8.9 mg H(2)O/L) [p = 0.0001], while the mean difference for 36% of the HMEs was > 4 mg H(2)O/L. The mean difference for the antibacterial filters was 0.2 +/- 1.4 mg H(2)O/L. The mean resistance of all the tested devices was 2.17 +/- 0.70 cm H(2)O/L/s. Several HMEs performed poorly and should not be used as HMEs. The values determined by independent assessments may be lower than the manufacturer data. Describing a device as an HME does not guarantee that it provides adequate humidification. The performance of HMEs must be verified by independent assessment.

IMAPS Device Packaging Conference 2017 - Engineered Micro Systems & Devices Track

NASA Technical Reports Server (NTRS)

Varnavas, Kosta

2017-01-01

NASA field center Marshall Space Flight Center (Huntsville, AL), has invested in advanced wireless sensor technology development. Developments for a wireless microcontroller back-end were primarily focused on the commercial Synapse Wireless family of devices. These devices have many useful features for NASA applications, good characteristics and the ability to be programmed Over-The-Air (OTA). The effort has focused on two widely used sensor types, mechanical strain gauges and thermal sensors. Mechanical strain gauges are used extensively in NASA structural testing and even on vehicle instrumentation systems. Additionally, thermal monitoring with many types of sensors is extensively used. These thermal sensors include thermocouples of all types, resistive temperature devices (RTDs), diodes and other thermal sensor types. The wireless thermal board will accommodate all of these types of sensor inputs to an analog front end. The analog front end on each of the sensors interfaces to the Synapse wireless microcontroller, based on the Atmel Atmega128 device. Once the analog sensor output data is digitized by the onboard analog to digital converter (A/D), the data is available for analysis, computation or transmission. Various hardware features allow custom embedded software to manage battery power to enhance battery life. This technology development fits nicely into using numerous additional sensor front ends, including some of the low-cost printed circuit board capacitive moisture content sensors currently being developed at Auburn University.

Environmentally Benign and Permanent Modifications to Prevent Biofouling on Marine and Hydrokinetic Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng Zhang

2012-04-19

Semprus Biosciences is developing environmentally benign and permanent modifications to prevent biofouling on Marine and Hydrokinetic (MHK) devices. Biofouling, including growth on external surfaces by bacteria, algae, barnacles, mussels, and other marine organisms, accumulate quickly on MHK devices, causing mechanical wear and changes in performance. Biofouling on crucial components of hydrokinetic devices, such as rotors, generators, and turbines, imposes substantial mass and hydrodynamic loading with associated efficiency loss and maintenance costs. Most antifouling coatings leach toxic ingredients, such as copper and tributyltin, through an eroding process, but increasingly stringent regulation of biocides has led to interest in the development ofmore » non-biocidal technologies to control fouling. Semprus Biosciences research team is developing modifications to prevent fouling from a broad spectrum of organisms on devices of all shapes, sizes, and materials for the life of the product. The research team designed and developed betaine-based polymers as novel underwater coatings to resist the attachment of marine organisms. Different betaine-based monomers and polymers were synthesized and incorporated within various coating formulations. The formulations and application methods were developed on aluminum panels with required adhesion strength and mechanical properties. The coating polymers were chemically stable under UV, hydrolytic and oxidative environments. The sulfobetaine formulations are applicable as nonleaching and stable underwater coatings. For the first time, coating formulations modified with highly packed sulfobetaine polymers were prepared and demonstrated resistance to a broad spectrum of marine organisms. Assays for comparing nonfouling performance were developed to evaluate protein adsorption and bacteria attachment. Barnacle settlement and removal were evaluated and a 60-day field test was performed. Silicone substrates including a commercial fouling release coating were used for comparison. Compared with the unmodified silicone substrates, the sulfobetaine-modified formulations were able to exhibit a 98% reduction in fibrinogen adsorption, 97.0% (E. coli), 99.6% (S. aureus), and 99.5% (C. lytica) reduction in bacteria attachment, and 100% reduction in barnacles cyprid attachment. In addition to the significant improvement in fouling resistance of various organisms, the 60-day field test also showed an evident efficacy from visual assessment, foul rating, and fouling removal test. The research confirmed that the novel antifouling mechanism of betaine polymers provides a new avenue for marine coating development. The developed coatings out-performed currently used nontoxic underwater coatings in a broad spectrum of fouling resistance. By further developing formulations and processing methods for specific devices, the technology is ready for the next stage of development with demonstration in MHK systems.« less

Evaluation of a Low-Cost Bubble CPAP System Designed for Resource-Limited Settings.

PubMed

Bennett, Desmond J; Carroll, Ryan W; Kacmarek, Robert M

2018-04-01

Respiratory compromise is a leading contributor to global neonatal death. CPAP is a method of treatment that helps maintain lung volume during expiration, promotes comfortable breathing, and improves oxygenation. Bubble CPAP is an effective alternative to standard CPAP. We sought to determine the reliability and functionality of a low-cost bubble CPAP device designed for low-resource settings. The low-cost bubble CPAP device was compared to a commercially available bubble CPAP system. The devices were connected to a lung simulator that simulated neonates of 4 different weights with compromised respiratory mechanics (∼1, ∼3, ∼5, and ∼10 kg). The devices' abilities to establish and maintain pressure and flow under normal conditions as well as under conditions of leak were compared. Multiple combinations of pressure levels (5, 8, and 10 cm H 2 O) and flow levels (3, 6, and 10 L/min) were tested. The endurance of both devices was also tested by running the systems continuously for 8 h and measuring the changes in pressure and flow. Both devices performed equivalently during the no-leak and leak trials. While our testing revealed individual differences that were statistically significant and clinically important (>10% difference) within specific CPAP and flow-level settings, no overall comparisons of CPAP or flow were both statistically significant and clinically important. Each device delivered pressures similar to the desired pressures, although the flows delivered by both machines were lower than the set flows in most trials. During the endurance trials, the low-cost device was marginally better at maintaining pressure, while the commercially available device was better at maintaining flow. The low-cost bubble CPAP device evaluated in this study is comparable to a bubble CPAP system used in developed settings. Extensive clinical trials, however, are necessary to confirm its effectiveness. Copyright © 2018 by Daedalus Enterprises.

Feasibility and limitations of anti-fuses based on bistable non-volatile switches for power electronic applications

NASA Astrophysics Data System (ADS)

Erlbacher, T.; Huerner, A.; Bauer, A. J.; Frey, L.

2012-09-01

Anti-fuse devices based on non-volatile memory cells and suitable for power electronic applications are demonstrated for the first time using silicon technology. These devices may be applied as stand alone devices or integrated using standard junction-isolation into application-specific and smart-power integrated circuits. The on-resistance of such devices can be permanently switched by nine orders of magnitude by triggering the anti-fuse with a positive voltage pulse. Extrapolation of measurement data and 2D TCAD process and device simulations indicate that 20 A anti-fuses with 10 mΩ can be reliably fabricated in 0.35 μm technology with a footprint of 2.5 mm2. Moreover, this concept offers distinguished added-values compared to existing mechanical relays, e.g. pre-test, temporary and permanent reset functions, gradual turn-on mode, non-volatility, and extendibility to high voltage capability.

Development of advanced second-generation micromirror devices fabricated in a four-level planarized surface-micromachined polycrystalline silicon process

NASA Astrophysics Data System (ADS)

Michalicek, M. Adrian; Comtois, John H.; Schriner, Heather K.

1998-04-01

This paper describes the design and characterization of several types of micromirror devices to include process capabilities, device modeling, and test data resulting in deflection versus applied potential curves and surface contour measurements. These devices are the first to be fabricated in the state-of-the-art four-level planarized polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology. This enabling process permits the development of micromirror devices with near-ideal characteristics which have previously been unrealizable in standard three-layer polysilicon processes. This paper describes such characteristics which have previously been unrealizable in standard three-layer polysilicon processes. This paper describes such characteristics as elevated address electrodes, various address wiring techniques, planarized mirror surfaces suing Chemical Mechanical Polishing, unique post-process metallization, and the best active surface area to date.

Highly efficient flexible optoelectronic devices using metal nanowire-conducting polymer composite transparent electrode

NASA Astrophysics Data System (ADS)

Jung, Eui Dae; Nam, Yun Seok; Seo, Houn; Lee, Bo Ram; Yu, Jae Choul; Lee, Sang Yun; Kim, Ju-Young; Park, Jang-Ung; Song, Myoung Hoon

2015-09-01

Here, we report a comprehensive analysis of the electrical, optical, mechanical, and surface morphological properties of composite nanostrutures based on silver nanowires (AgNW) and PEDOT:PSS conducting polymer for the use as flexible and transparent electrodes. Compared to ITO or the single material of AgNW or PEDOT:PSS, the AgNW/PEDOT:PSS composite electrode showed high electrical conductivity with a low sheet resistance of 26.8 Ω/sq at 91% transmittance (at 550 nm), improves surface smoothness, and enhances mechanical properties assisted by an amphiphilic fluoro-surfactant. The polymeric light-emitting diodes (PLEDs) and organic solar cells (OSCs) using the AgNW/PEDOT:PSS composite electrode showed higher device performances than those with AgNW and PEDOT:PSS electrodes and excellent flexibility under bending test. These results indicates that the AgNW/PEDOT:PSS composite presented is a good candidate as next-generation transparent elelctrodes for applications into flexible optoelectronic devices. [Figure not available: see fulltext.

A hysteretic model considering Stribeck effect for small-scale magnetorheological damper

NASA Astrophysics Data System (ADS)

Zhao, Yu-Liang; Xu, Zhao-Dong

2018-06-01

Magnetorheological (MR) damper is an ideal semi-active control device for vibration suppression. The mechanical properties of this type of devices show strong nonlinear characteristics, especially the performance of the small-scale dampers. Therefore, developing an ideal model that can accurately describe the nonlinearity of such device is crucial to control design. In this paper, the dynamic characteristics of a small-scale MR damper developed by our research group is tested, and the Stribeck effect is observed in the low velocity region. Then, an improved model based on sigmoid model is proposed to describe this Stribeck effect observed in the experiment. After that, the parameters of this model are identified by genetic algorithms, and the mathematical relationship between these parameters and the input current, excitation frequency and amplitude is regressed. Finally, the predicted forces of the proposed model are validated with the experimental data. The results show that this model can well predict the mechanical properties of the small-scale damper, especially the Stribeck effect in the low velocity region.

Device for preparing combinatorial libraries in powder metallurgy.

PubMed

Yang, Shoufeng; Evans, Julian R G

2004-01-01

This paper describes a powder-metering, -mixing, and -dispensing mechanism that can be used as a method for producing large numbers of samples for metallurgical evaluation or electrical or mechanical testing from multicomponent metal and cermet powder systems. It is designed to make use of the same commercial powders that are used in powder metallurgy and, therefore, to produce samples that are faithful to the microstructure of finished products. The particle assemblies produced by the device could be consolidated by die pressing, isostatic pressing, laser sintering, or direct melting. The powder metering valve provides both on/off and flow rate control of dry powders in open capillaries using acoustic vibration. The valve is simple and involves no relative movement, avoiding seizure with fine powders. An orchestra of such valves can be arranged on a building platform to prepare multicomponent combinatorial libraries. As with many combinatorial devices, identification and evaluation of sources of mixing error as a function of sample size is mandatory. Such an analysis is presented.

Study of hollow corner retroreflectors for use in a synchronous orbit

NASA Technical Reports Server (NTRS)

Yoder, P. R., Jr.

1975-01-01

The performance of a hollow corner cube retroreflector made up of three mutually perpendicular optically flat mirrors when undergoing the thermal-mechanical strains induced by a spacecraft environment was studied. Of particular interest was a device of 200 square centimeter optical aperture used on a satellite in a synchronous orbit. It was assumed that the reflector always faces the earth. The effects of direct solar irradiance, earthshine, and albedo were considered. The results included the maximum mirror surface temperature during the orbit as well as the worst-case loss of optical performance due to thermally-induced mirror distortions. It was concluded that a device made of three suitably coated flat ULE mirrors, optically contacted to each other and supported mechanically in a nonrigid mount, would be expected to concentrate over 80 percent of the theoretical maximum energy in the central of the far field diffraction pattern. Continued development of the device through a detailed design, fabrication, and test phase was recommended.

Superhydrophilic nanopillar-structured quartz surfaces for the prevention of biofilm formation in optical devices

NASA Astrophysics Data System (ADS)

Han, Soo; Ji, Seungmuk; Abdullah, Abdullah; Kim, Duckil; Lim, Hyuneui; Lee, Donghyun

2018-01-01

Bacterial biofilm formation on optical devices such as contact lenses, optical glasses, endoscopic devices, and microscopic slides and lenses are major concerns in the field of medicine and biomedical engineering. To solve these problems, here we present the first report of superhydrophilic transparent nanopillar-structured surfaces with bactericidal properties. To construct bactericidal surfaces, we imitated a topological mechanism found in nature in which nanopillar-structured surfaces cause a mechanical disruption of the outer cell membranes of bacteria, resulting in bacterial cell death. We used nanosphere lithography to fabricate nanopillars with various sharpnesses and heights on a quartz substrate. Water contact angle and light reflectance measurements revealed superhydrophilic, antifogging and antireflective properties, which are important for use in optical devices. To determine bactericidal efficiency, the fabricated surfaces were incubated and tested against two Gram-negative bacteria associated with biofilm formation and various diseases in humans, Pseudomonas aeruginosa and Escherichia coli. The highest bactericidal activity was achieved with nanopillars that measured 300 nm in height and 10 nm in apex diameter. Quartz substrates patterned with such nanopillars killed ∼38,000 P. aeruginosa and ∼27,000 E. coli cells cm-2 min-1, respectively. Thus, the newly designed nanopillar-structured bactericidal surfaces are suitable for use in the development of superhydrophilic and transparent optical devices.

Evaluating Attenuation of Vibration Response using Particle Impact Damping for a Range of Equipment Assemblies

NASA Technical Reports Server (NTRS)

Knight, Brent; Parsons, David; Smith, Andrew; Hunt, Ron; LaVerde, Bruce; Towner, Robert; Craigmyle, Ben

2013-01-01

Particle dampers provide a mechanism for diverting energy away from resonant structural vibrations. This experimental study provides data from a series of acoustically excited tests to determine the effectiveness of these dampers for equipment mounted to a curved orthogrid panel for a launch vehicle application. Vibration attenuation trends are examined for variations in particle damper fill level, component mass, and excitation energy. A significant response reduction at the component level was achieved, suggesting that comparatively small, strategically placed, particle damper devices might be advantageously used in launch vehicle design. These test results were compared to baseline acoustic response tests without particle damping devices, over a range of isolation and damping parameters. Instrumentation consisting of accelerometers, microphones, and still photography data will be collected to correlate with the analytical results.

NASA Dryden technicians (Dave Dennis, Freddy Green and Jeff Doughty) position a support cylinder und

NASA Technical Reports Server (NTRS)

2002-01-01

NASA Dryden technicians (Dave Dennis, Freddy Green and Jeff Doughty) position a support cylinder under the right wing of the Active Aeroelastic Wing F/A-18 test aircraft prior to ground vibration tests. The cylinder contains an 'air bag' that allows vibrations induced by an electro-mechanical shaker device to propagate through the airframe as they would if the aircraft were flying.

A new device to study isoload eccentric exercise.

PubMed

Guilhem, Gaël; Cornu, Christophe; Nordez, Antoine; Guével, Arnaud

2010-12-01

This study was designed to develop a new device allowing mechanical analysis of eccentric exercise against a constant load, with a view in mind to compare isoload (IL) and isokinetic (IK) eccentric exercises. A plate-loaded resistance training device was integrated to an IK dynamometer, to perform the acquisition of mechanical parameters (i.e., external torque, angular velocity). To determine the muscular torque produced by the subject, load torque was experimentally measured (TLexp) at 11 different loads from 30° to 90° angle (0° = lever arm in horizontal position). TLexp was modeled to take friction effect and torque variations into account. Validity of modeled load torque (TLmod) was tested by determining the root mean square (RMS) error, bias, and 2SD between the descending part of TLexp (from 30° to 90°) and TLmod. Validity of TLexp was tested by a linear regression and a Passing-Bablok regression. A pilot analysis on 10 subjects was performed to determine the contribution of the torque because of the moment of inertia to the amount of external work (W). Results showed the validity of TLmod (bias = 0%; RMS error = 0.51%) and TLexp SEM = 4.1 N·m; Intraclass correlation coefficient (ICC) = 1.00; slope = 0.99; y-intercept = -0.13). External work calculation showed a satisfactory reproducibility (SEM = 38.3 J; ICC = 0.98) and moment of inertia contribution to W showed a low value (3.2 ± 2.0%). Results allow us to validate the new device developed in this study. Such a device could be used in future work to study IL eccentric exercise and to compare the effect of IL and IK eccentric exercises in standardized conditions.

Development of a Mechanical Scanning Device With High-Frequency Ultrasound Transducer for Ultrasonic Capsule Endoscopy.

PubMed

Wang, Xingying; Seetohul, Vipin; Chen, Ruimin; Zhang, Zhiqiang; Qian, Ming; Shi, Zhehao; Yang, Ge; Mu, Peitian; Wang, Congzhi; Huang, Zhihong; Zhou, Qifa; Zheng, Hairong; Cochran, Sandy; Qiu, Weibao

2017-09-01

Wireless capsule endoscopy has opened a new era by enabling remote diagnostic assessment of the gastrointestinal tract in a painless procedure. Video capsule endoscopy is currently commercially available worldwide. However, it is limited to visualization of superficial tissue. Ultrasound (US) imaging is a complementary solution as it is capable of acquiring transmural information from the tissue wall. This paper presents a mechanical scanning device incorporating a high-frequency transducer specifically as a proof of concept for US capsule endoscopy (USCE), providing information that may usefully assist future research. A rotary solenoid-coil-based motor was employed to rotate the US transducer with sectional electronic control. A set of gears was used to convert the sectional rotation to circular rotation. A single-element focused US transducer with 39-MHz center frequency was used for high-resolution US imaging, connected to an imaging platform for pulse generation and image processing. Key parameters of US imaging for USCE applications were evaluated. Wire phantom imaging and tissue phantom imaging have been conducted to evaluate the performance of the proposed method. A porcine small intestine specimen was also used for imaging evaluation in vitro. Test results demonstrate that the proposed device and rotation mechanism are able to offer good image resolution ( [Formula: see text]) of the lumen wall, and they, therefore, offer a viable basis for the fabrication of a USCE device.

The strength study of the rotating device driver indexing spatial mechanism

NASA Astrophysics Data System (ADS)

Zakharenkov, N. V.; Kvasov, I. N.

2018-04-01

The indexing spatial mechanisms are widely used in automatic machines. The mechanisms maximum load-bearing capacity measurement is possible based on both the physical and numerical models tests results. The paper deals with the driven disk indexing spatial cam mechanism numerical model at the constant angular cam velocity. The presented mechanism kinematics and geometry parameters and finite element model are analyzed in the SolidWorks design environment. The calculation initial data and missing parameters having been found from the structure analysis were identified. The structure and kinematics analysis revealed the mechanism failures possible reasons. The numerical calculations results showing the structure performance at the contact and bending stresses are represented.

Design and performance of a punch mechanism based pellet injector for alternative injection in the large helical device

NASA Astrophysics Data System (ADS)

Mishra, J. S.; Sakamoto, R.; Motojima, G.; Matsuyama, A.; Yamada, H.

2011-02-01

A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100-450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii Rc = 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes.

Volatile organic compounds discrimination based on dual mode detection

NASA Astrophysics Data System (ADS)

Yu, Yuanyuan; Wu, Enxiu; Chen, Yan; Feng, Zhihong; Zheng, Shijun; Zhang, Hao; Pang, Wei; Liu, Jing; Zhang, Daihua

2018-06-01

We report on a volatile organic compound (VOC) sensor that can provide concentration-independent signals toward target gases. The device is based on a dual-mode detection mechanism that can simultaneously record the mechanical (resonant frequency, f r) and electrical (current, I) responses of the same gas adsorption event. The two independent signals form a unique I–f r trace for each target VOC as the concentration varies. The mechanical response (frequency shift, Δf r) resulting from mass load on the device is directly related to the amount of surface adsorptions, while the electrical response (current variation, ΔI) is associated with charge transfer across the sensing interface and changes in carrier mobility. The two responses resulting from independent physical processes reflect intrinsic physical properties of each target gas. The ΔI–Δf r trace combined with the concentration dependent frequency (or current) signals can therefore be used to achieve target both recognition and quantification. The dual-mode device is designed and fabricated using standard complementary metal oxide semiconductor (CMOS) compatible processes. It exhibits consistent and stable performance in our tests with six different VOCs including ethanol, methanol, acetone, formaldehyde, benzene and hexane.

Volatile organic compounds discrimination based on dual mode detection.

PubMed

Yu, Yuanyuan; Wu, Enxiu; Chen, Yan; Feng, Zhihong; Zheng, Shijun; Zhang, Hao; Pang, Wei; Liu, Jing; Zhang, Daihua

2018-06-15

We report on a volatile organic compound (VOC) sensor that can provide concentration-independent signals toward target gases. The device is based on a dual-mode detection mechanism that can simultaneously record the mechanical (resonant frequency, f r ) and electrical (current, I) responses of the same gas adsorption event. The two independent signals form a unique I-f r trace for each target VOC as the concentration varies. The mechanical response (frequency shift, Δf r ) resulting from mass load on the device is directly related to the amount of surface adsorptions, while the electrical response (current variation, ΔI) is associated with charge transfer across the sensing interface and changes in carrier mobility. The two responses resulting from independent physical processes reflect intrinsic physical properties of each target gas. The ΔI-Δf r trace combined with the concentration dependent frequency (or current) signals can therefore be used to achieve target both recognition and quantification. The dual-mode device is designed and fabricated using standard complementary metal oxide semiconductor (CMOS) compatible processes. It exhibits consistent and stable performance in our tests with six different VOCs including ethanol, methanol, acetone, formaldehyde, benzene and hexane.

Single Event Rates for Devices Sensitive to Particle Energy

NASA Technical Reports Server (NTRS)

Edmonds, L. D.; Scheick, L. Z.; Banker, M. W.

2012-01-01

Single event rates (SER) can include contributions from low-energy particles such that the linear energy transfer (LET) is not constant. Previous work found that the environmental description that is most relevant to the low-energy contribution to the rate is a "stopping rate per unit volume" even when the physical mechanisms for a single-event effect do not require an ion to stop in some device region. Stopping rate tables are presented for four heavy-ion environments that are commonly used to assess device suitability for space applications. A conservative rate estimate utilizing limited test data is derived, and the example of SEGR rate in a power MOSFET is presented.

Crashworthiness Design of the Shear Bolts for Light Collision Safety Devices

NASA Astrophysics Data System (ADS)

Kim, Jin Sung; Huh, Hoon; Kwon, Tae Soo

This paper introduces the jig set for the crash test and the crash test results of shear bolts which are designed to fail at train crash conditions. The tension and shear bolts are attached to Light Collision Safety Devices(LCSD) as a mechanical fuse when tension and shear bolts reach their failure load designed. The kinetic energy due to the crash is absorbed by the secondary energy absorbing device after LCSD are detached from the main body by the fracture of shear bolts. A single shear bolt was designed to fail at the load of 250 kN. The jig set designed to convert a compressive loading to a shear loading was installed to the high speed crash tester for dynamic shear tests. Two strain gauges were attached at the parallel section of the jig set to measure the load responses acting on the shear bolts. Crash tests were performed with a carrier whose mass was 250 kg and the initial speed of the carrier was 9 m/sec. From the quasi-static and dynamic experiments as well as the numerical analysis, the capacity of the shear bolts were accurately predicted for the crashworthiness design.

A new device for 100 per cent humidification of inspired air

PubMed Central

Larsson, Anders; Gustafsson, Ann; Svanborg, Lennart

2000-01-01

Introduction: Devices for active humidification of the inspired air in mechanically ventilated patients cause water condensation in the ventilator tubing, which may become contaminated or interfere with the function of the ventilator. The present study describes and tests the performance of a new humidifier, which is designed to eliminate water condensation. Objectives: To test the performance of the new humidifier at different ventilator settings in a lung model, and to compare this new humidifier with a conventional active humidifier in ventilator-treated critically ill patients. Materials and methods: The humidifier (Humid-Heat; Louis Gibeck AB, Upplands Väsby, Sweden) consists of a supply unit with a microprocessor and a water pump, and a humidification device, which is placed between the Y-piece and the endotracheal tube. The humidification device is based on a hygroscopic heat-moisture exchanger (HME), which absorbs the expired heat and moisture and releases it into the inspired gas. External heat and water are then added to the patient side of the HME, so the inspired gas should reach 100% humidity at 37°C (44 mg H2O/l air). The external water is delivered to the humidification device via a pump onto a wick and then evaporated into the inspired air by an electrical heater. The microprocessor controls the water pump and the heater by an algorithm using the minute ventilation (which is fed into the microprocessor) and the airway temperature measured by a sensor mounted in the flex-tube on the patient side of the humidification device. The performance characteristics were tested in a lung model ventilated with a constant flow (inspiratory:expiratory ratio 1:2, rate 12–20 breaths/min and a minute ventilation of 3–25 l/min) or with a decelerating flow (inspiratory:expiratory ratio 1:2, rate 12–15 breaths/min and a minute ventilation of 4.7–16.4 l/min). The device was also tested prospectively and in a randomized order compared with a conventional active humidifier (Fisher & Paykel MR730, Auckland, New Zealand) in eight mechanically ventilated, endotracheally intubated patients in the intensive care unit. The test period with each device was 24 h. The amount of fluid consumed and the amount of water in the water traps were measured. The number of times that the water traps were emptied, changes of machine filters, the suctions and quality of secretions, nebulizations, and the amount of saline instillations and endotracheal tube obstruction were recorded. In order to evaluate increased expiratory resistance due to the device, the airway pressure was measured at the end of a prolonged end-expiratory pause at 1 h of use and at the end of the test, and was compared with the corresponding pressure before the experiment. The body temperature of the patient was measured before and after the test of each device. Results: Both with constant flow and decelerating flow, the Humid-Heat gave an absolute humidity of 41–44 mgH2O/l at 37°C, with the lower level at the highest ventilation. In the patients, both Humid-Heat and the conventional active humidifier (MR730) maintained temperatures, indicating that they provided the intended heat and moisture to the inspired air. With both devices, the body temperature was maintained during the test period. There was no difference in the amount of secretions, the quality of the secretions and the frequency of suctions, saline instillations or nebulizations between the test periods with the two devices. There was no endotracheal tube obstruction, and after 1 h of use and at the end of the test no increased airway resistance was found with either device. When the MR730 was used, however, the water traps needed to be emptied six to 14 (mean eight) times (total amount of fluid in the traps was 100–300 ml) and the machine filters were changed two to six (mean four) times due to an excessive amount of condensed water with flow obstruction. No condensation of water was found in the tubing with the Humid-Heat. The water consumption was 23–65 ml/h (mean 30 ml/h) with the MR730 and 4–8 ml/h (mean 6 ml/h) with the Humid-Heat (P < 0.0008). The same relations were found when the water consumption was corrected for differences in minute ventilation. Discussion: The new humidifier, the Humid-Heat, gave an absolute humidity of 41–44 mg/l at 37°C in the bench tests. The tests in ventilated patients showed that the device was well tolerated and that condensation in the tubing was eliminated. There was no need to empty water traps. The test period was too short to evaluate whether the new device had any other advantages or disadvantages compared with conventional humidifiers. PMID:11056746

Medical-device risk management and public safety: using cost-benefit as a measurement of effectiveness

NASA Astrophysics Data System (ADS)

Hughes, Allen A.

1994-12-01

Public safety can be enhanced through the development of a comprehensive medical device risk management. This can be accomplished through case studies using a framework that incorporates cost-benefit analysis in the evaluation of risk management attributes. This paper presents a framework for evaluating the risk management system for regulatory Class III medical devices. The framework consists of the following sixteen attributes of a comprehensive medical device risk management system: fault/failure analysis, premarket testing/clinical trials, post-approval studies, manufacturer sponsored hospital studies, product labeling, establishment inspections, problem reporting program, mandatory hospital reporting, medical literature surveillance, device/patient registries, device performance monitoring, returned product analysis, autopsy program, emergency treatment funds/interim compensation, product liability, and alternative compensation mechanisms. Review of performance histories for several medical devices can reveal the value of information for many attributes, and also the inter-dependencies of the attributes in generating risk information flow. Such an information flow network is presented as a starting point for enhancing medical device risk management by focusing on attributes with high net benefit values and potential to spur information dissemination.

Mechanical and histological analysis of bone-pedicle screw interface in vivo: titanium versus stainless steel.

PubMed

Sun, C; Huang, G; Christensen, F B; Dalstra, M; Overgaard, S; Bünger, C

1999-05-01

To investigate the differences in bone interface between titanium and stainless steel pedicle screws in the lumbar spine. Eighteen adult mini-pigs that underwent total laminectomy, posterolateral spinal fusion (L4-L5) were randomly selected to receive stainless steel (9) or titanium pedicle screw devices (9). In both groups, the devices were CCD (Sofamore Danek) type with the same size and shape. The postoperative observation time was 3 months. Screws from L4 were harvested along their long axis of pedicle for histomorphometric study. Bone-screw interface and bone volume from thread were examined using linear intercept techniques. Mechanical testing (torsional test and pull-out test) was performed on the screws from L5. The titanium screw group had a significantly higher maximum torque (P < 0.05) and angle related stiffness (P < 0.05) measured by torsional test. In the pull-out tests, no differences were found between the two groups in relation to the maximum load, stiffness and energy to failure. Direct bone contact with the screw in percentage was 29.4% for stainless steel and 43.8% for titanium (P < 0.05). No differences in the bone purchase between the vertebral body part and pedicle part were found. Pedicle screws made of titanium have a better bone-screw interface binding than screws made of stainless steel. Torsional tests are more informative for bone-screw interface study. Pull-out tests seem less valuable when comparing bone purchase of screws made from different materials.

A late and failure of airbag deployment case study for drivers of passenger cars in rear-end collisions

NASA Astrophysics Data System (ADS)

Toganel, George-Radu; Ovidiu Soica, Adrian

2017-10-01

The presented study was directed at two types of airbag miss-deployments: late deployment and non-deployment. Late deployment can be a product of override or underride road traffic accidents. Non-deployment can be a product of technical failure or trigger algorithm’s inability to correctly assume the state of the accident to happen. In order to analyse the phenomena through physical tests, a specialized test device was used for a series of 8 non-deployment tests and a series of 4 airbag firing tests, totalling 12 tests. Acceleration based data was recorded and analysed for the movement of the device part simulating the driver head. High speed video recording was used to analyse the mechanics of airbag deployment and correlate with the acceleration based data. It has been determined, in the limitations of the laboratory testing environment, a significant variation of the time frame for the airbag deployments, despite using similar testing conditions and identical tested products. Also, the initial time frame for airbag deployment delay was overshadowed by other factors such as time to impact.

Powered off-road wheelchair for the transportation of tetraplegics along mountain trails.

PubMed

Antonelli, Michele Gabrio; Alleva, Stefano; Beomonte Zobel, Pierluigi; Durante, Francesco; Raparelli, Terenziano

2017-12-08

For off-road mobility, some manual or power assisted devices were conceived to be self-driven by paraplegics while for tetraplegics non power-assisted devices were conceived. These devices require one or more conductors who are subjected to a high physical demand thus potentially creating: precarious safety condition for the user an elevated physical demand of conductors could reduce the care and the attention to give to the user; the time of the outdoor adventure experience of the user could be limited. To address these issues, an innovative user-centered power assisted off-road wheelchair for the transportation of tetraplegics along mountain trails was developed. The device, structured like a trike, is driven by two healthy conductors; the user is placed in the middle of the frame. A movable seat provides for the transfer from the standard to the off-road wheelchair. An electrical motor, powered by a battery pack, provides for the actuation. All the design and prototype aspects, the control system and experimental tests are detailed. The prototype satisfies mechanical, safety and duration requirements. No physical demand while using the device and for the transfer of the user to the device was identified. Fun and engaging tests were carried out and all the participants were involved. Implications for Rehabilitation The device has the potential to enhance the quality of life of tetraplegics in terms of new life experiences. The device revealed the real possibility of a full recreational experience, an enhanced participation and a better social integration of tetraplegics.

Mechanical Properties and Tensile Failure Analysis of Novel Bio-absorbable Mg-Zn-Cu and Mg-Zn-Se Alloys for Endovascular Applications

PubMed Central

Persaud-Sharma, Dharam; Budiansky, Noah; McGoron, Anthony J.

2013-01-01

In this paper, the mechanical properties and tensile failure mechanism of two novel bio-absorbable as-cast Mg-Zn-Se and Mg-Zn-Cu alloys for endovascular medical applications are characterized. Alloys were manufactured using an ARC melting process and tested as-cast with compositions of Mg-Zn-Se and Mg-Zn-Cu, being 98/1/1 wt.% respectively. Nanoindentation testing conducted at room temperature was used to characterize the elastic modulus (E) and surface hardness (H) for both the bare alloys and the air formed oxide layer. As compared to currently available shape memory alloys and degradable as-cast alloys, these experimental alloys possess superior as-cast mechanical properties that can increase their biocompatibility, degradation kinetics, and the potential for medical device creation. PMID:23543822

Simulator for Testing Spacecraft Separation Devices

NASA Technical Reports Server (NTRS)

Johnston, Nick; Gaines, Joe; Bryan, Tom

2006-01-01

A report describes the main features of a system for testing pyrotechnic and mechanical devices used to separate spacecraft and modules of spacecraft during flight. The system includes a spacecraft simulator [also denoted a large mobility base (LMB)] equipped with air thrusters, sensors, and data-acquisition equipment. The spacecraft simulator floats on air bearings over an epoxy-covered concrete floor. This free-flotation arrangement enables simulation of motion in outer space in three degrees of freedom: translation along two orthogonal horizontal axes and rotation about a vertical axis. The system also includes a static stand. In one application, the system was used to test a bolt-retraction system (BRS) intended for separation of the lifting-body and deorbit-propulsion stages of the X- 38 spacecraft. The LMB was connected via the BRS to the static stand, then pyrotechnic devices that actuate the BRS were fired. The separation distance and acceleration were measured. The report cites a document, not yet published at the time of reporting the information for this article, that is said to present additional detailed information.

Microbiological effectiveness of mineral pot filters in Cambodia.

PubMed

Brown, Joe; Chai, Ratana; Wang, Alice; Sobsey, Mark D

2012-11-06

Mineral pot filters (MPFs) are household water treatment (HWT) devices that are manufactured and distributed by the private sector, with millions of users in Southeast Asia. Their effectiveness in reducing waterborne microbes has not been previously investigated. We purchased three types of MPFs available on the Cambodian market for systematic evaluation of bacteria, virus, and protozoan surrogate microbial reduction in laboratory challenge experiments following WHO recommended performance testing protocols. Results over the total 1500 L testing period per filter indicate that the devices tested were highly effective in reducing Esherichia coli (99.99%+), moderately effective in reducing bacteriophage MS2 (99%+), and somewhat effective against Bacillus atrophaeus, a spore-forming bacterium we used as a surrogate for protozoa (88%+). Treatment mechanisms for all filters included porous ceramic and activated carbon filtration. Our results suggest that these commercially available filters may be at least as effective against waterborne pathogens as other, locally available treatment options such as ceramic pot filters or boiling. More research is needed on the role these devices may play as interim solutions to the problem of unsafe drinking water in Cambodia and globally.

In Vitro Microfluidic Models for Neurodegenerative Disorders.

PubMed

Osaki, Tatsuya; Shin, Yoojin; Sivathanu, Vivek; Campisi, Marco; Kamm, Roger D

2018-01-01

Microfluidic devices enable novel means of emulating neurodegenerative disease pathophysiology in vitro. These organ-on-a-chip systems can potentially reduce animal testing and substitute (or augment) simple 2D culture systems. Reconstituting critical features of neurodegenerative diseases in a biomimetic system using microfluidics can thereby accelerate drug discovery and improve our understanding of the mechanisms of several currently incurable diseases. This review describes latest advances in modeling neurodegenerative diseases in the central nervous system and the peripheral nervous system. First, this study summarizes fundamental advantages of microfluidic devices in the creation of compartmentalized cell culture microenvironments for the co-culture of neurons, glial cells, endothelial cells, and skeletal muscle cells and in their recapitulation of spatiotemporal chemical gradients and mechanical microenvironments. Then, this reviews neurodegenerative-disease-on-a-chip models focusing on Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Finally, this study discusses about current drawbacks of these models and strategies that may overcome them. These organ-on-chip technologies can be useful to be the first line of testing line in drug development and toxicology studies, which can contribute significantly to minimize the phase of animal testing steps. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Angular-velocity control approach for stance-control orthoses.

PubMed

Lemaire, Edward D; Goudreau, Louis; Yakimovich, Terris; Kofman, Jonathan

2009-10-01

Currently, stance-control knee orthoses require external control mechanisms to control knee flexion during stance and allow free knee motion during the swing phase of gait. A new angular-velocity control approach that uses a rotary-hydraulic device to resist knee flexion when the knee angular velocity passes a preset threshold is presented. This angular-velocity approach for orthotic stance control is based on the premise that knee-flexion angular velocity during a knee-collapse event, such as a stumble or fall, is greater than that during walking. The new hydraulic knee-flexion control device does not require an external control mechanism to switch from free motion to stance control mode. Functional test results demonstrated that the hydraulic angular-velocity activated knee joint provided free knee motion during walking, engaged upon knee collapse, and supported body weight while the end-user recovered to a safe body position. The joint was tested to 51.6 Nm in single loading tests and passed 200,000 repeated loading cycles with a peak load of 88 Nm per cycle. The hydraulic, angular velocity activation approach has potential to improve safety and security for people with lower extremity weakness or when recovering from joint trauma.

Use of loading-unloading compression curves in medical device design

NASA Astrophysics Data System (ADS)

Ciornei, M. C.; Alaci, S.; Ciornei, F. C.; Romanu, I. C.

2017-08-01

The paper presents a method and experimental results regarding mechanical testing of soft materials. In order to characterize the mechanical behaviour of technological materials used in prosthesis, a large number of material constants are required, as well as the comparison to the original. The present paper proposes as methodology the comparison between compression loading-unloading curves corresponding to a soft biological tissue and to a synthetic material. To this purpose, a device was designed based on the principle of the dynamic harness test. A moving load is considered and the force upon the indenter is controlled for loading-unloading phases. The load and specimen deformation are simultaneously recorded. A significant contribution of this paper is the interpolation of experimental data by power law functions, a difficult task because of the instability of the system of equations to be optimized. Finding the interpolation function was simplified, from solving a system of transcendental equations to solving a unique equation. The characteristic parameters of the experimentally curves must be compared to the ones corresponding to actual tissue. The tests were performed for two cases: first, using a spherical punch, and second, for a flat-ended cylindrical punch.

On the need for a biomimetic breast device

NASA Astrophysics Data System (ADS)

Danos, Nicole; German, Rebecca

2016-11-01

The function of the mammary gland, a key anatomical innovation that led to the rise of mammals, is governed by solid-fluid mechanics. There is strong evidence that these mechanical interactions regulate the production of milk and the transport of milk through the lactiferous ducts and into the infant's mouth. Solid-fluid mechanics determine the rate of milk flow and therefore may affect the safe coordination of sucking, swallowing and breathing in the infant. Additionally, links between breastfeeding, the material properties of the gland and breast cancer have been shown repeatedly. However, there is to date no direct way of characterizing breast mechanics during the physiological function for which it has evolved: infant feeding. We are developing an engineered biomimetic breast in which we can experimentally manipulate both structural and material properties of the gland. The device will be tested with an animal model of infant feeding, the pig, to measure the direct effect of gland mechanics on infant feeding. Data from these studies may lead to better designed feeding bottles for infants, milk pumps for both humans and agricultural mammals, and will provide the control mechanical environmental for studies of breast cancer mechanobiology.

Classroom to Clinic: Merging Education and Research to Efficiently Prototype Medical Devices

PubMed Central

Begg, Nikolai D.; Walsh, Conor; Custer, David; Gupta, Rajiv; Osborn, Lynn R.; Slocum, Alexander H.

2013-01-01

Innovation in patient care requires both clinical and technical skills, and this paper presents the methods and outcomes of a nine-year, clinical-academic collaboration to develop and evaluate new medical device technologies, while teaching mechanical engineering. Together, over the course of a single semester, seniors, graduate students, and clinicians conceive, design, build, and test proof-of-concept prototypes. Projects initiated in the course have generated intellectual property and peer-reviewed publications, stimulated further research, furthered student and clinician careers, and resulted in technology licenses and start-up ventures. PMID:27170859

Innovative remotely-controlled bending device for thin silicon and germanium crystals

NASA Astrophysics Data System (ADS)

De Salvador, D.; Carturan, S.; Mazzolari, A.; Bagli, E.; Bandiera, L.; Durighello, C.; Germogli, G.; Guidi, V.; Klag, P.; Lauth, W.; Maggioni, G.; Romagnoni, M.; Sytov, A.

2018-04-01

Steering of negatively charged particle beams below 1 GeV has demonstrated to be possible with thin bent silicon and germanium crystals. A newly designed mechanical holder was used for bending crystals, since it allows a remotely-controlled adjustment of crystal bending and compensation of unwanted torsion. Bent crystals were installed and tested at the MAMI Mainz MIcrotron to achieve steering of 0.855-GeV electrons at different bending radii. We report the description and characterization of the innovative bending device developed at INFN Laboratori Nazionali di Legnaro (LNL).

1988 IEEE Annual Conference on Nuclear and Space Radiation Effects, 25th, Portland, OR, July 12-15, 1988, Proceedings

NASA Technical Reports Server (NTRS)

Coakley, Peter G. (Editor)

1988-01-01

The effects of nuclear and space radiation on the performance of electronic devices are discussed in reviews and reports of recent investigations. Topics addressed include the basic mechanisms of radiation effects, dosimetry and energy-dependent effects, sensors in and for radiation environments, EMP/SGEMP/IEMP phenomena, radiation effects on isolation technologies, and spacecraft charging and space radiation effects. Consideration is given to device radiation effects and hardening, hardness assurance and testing techniques, IC radiation effects and hardening, and single-event phenomena.

Classroom to Clinic: Merging Education and Research to Efficiently Prototype Medical Devices.

PubMed

Hanumara, Nevan C; Begg, Nikolai D; Walsh, Conor; Custer, David; Gupta, Rajiv; Osborn, Lynn R; Slocum, Alexander H

2013-01-01

Innovation in patient care requires both clinical and technical skills, and this paper presents the methods and outcomes of a nine-year, clinical-academic collaboration to develop and evaluate new medical device technologies, while teaching mechanical engineering. Together, over the course of a single semester, seniors, graduate students, and clinicians conceive, design, build, and test proof-of-concept prototypes. Projects initiated in the course have generated intellectual property and peer-reviewed publications, stimulated further research, furthered student and clinician careers, and resulted in technology licenses and start-up ventures.

Mechanical Properties Analysis of 4340 Steel Specimen Heat Treated in Oven and Quenching in Three Different Fluids

NASA Astrophysics Data System (ADS)

Fakir, Rachid; Barka, Noureddine; Brousseau, Jean

2018-03-01

This paper proposes a statistical approach to analyze the mechanical properties of a standard test specimen, of cylindrical geometry and in steel 4340, with a diameter of 6 mm, heat-treated and quenched in three different fluids. Samples were evaluated in standard tensile test to access their characteristic quantities: hardness, modulus of elasticity, yield strength, tensile strength and ultimate deformation. The proposed approach is gradually being built (a) by a presentation of the experimental device, (b) a presentation of the experimental plan and the results of the mechanical tests, (c) anova analysis of variance and a representation of the output responses using the RSM response surface method, and (d) an analysis of the results and discussion. The feasibility and effectiveness of the proposed approach leads to a precise and reliable model capable of predicting the variation of mechanical properties, depending on the tempering temperature, the tempering time and the cooling capacity of the quenching medium.

Force reflecting hand controller for manipulator teleoperation

NASA Technical Reports Server (NTRS)

Bryfogle, Mark D.

1991-01-01

A force reflecting hand controller based upon a six degree of freedom fully parallel mechanism, often termed a Stewart Platform, has been designed, constructed, and tested as an integrated system with a slave robot manipulator test bed. A force reflecting hand controller comprises a kinesthetic device capable of transmitting position and orientation commands to a slave robot manipulator while simultaneously representing the environmental interaction forces of the slave manipulator back to the operator through actuators driving the hand controller mechanism. The Stewart Platform was chosen as a novel approach to improve force reflecting teleoperation because of its inherently high ratio of load generation capability to system mass content and the correspondingly high dynamic bandwidth. An additional novelty of the program was to implement closed loop force and torque control about the hand controller mechanism by equipping the handgrip with a six degree of freedom force and torque measuring cell. The mechanical, electrical, computer, and control systems are discussed and system tests are presented.

NASA SBIR product catalog, 1991

NASA Technical Reports Server (NTRS)

1991-01-01

This catalog is a partial list of products of NASA SBIR (Small Business Innovation Research) projects that have advanced to some degree into Phase 3. While most of the products evolved from work conducted during SBIR Phase 1 and 2, a few advanced to commercial status solely from Phase 1 activities. The catalog presents information provided to NASA by SBIR contractors who wished to have their products exhibited at Technology 2001, a NASA-sponsored technology transfer conference held in San Jose, California, on December 4, 5, and 6, 1991. The catalog presents the product information in the following technology areas: computer and communication systems; information processing and AI; robotics and automation; signal and image processing; microelectronics; electronic devices and equipment; microwave electronic devices; optical devices and lasers; advanced materials; materials processing; materials testing and NDE; materials instrumentation; aerodynamics and aircraft; fluid mechanics and measurement; heat transfer devices; refrigeration and cryogenics; energy conversion devices; oceanographic instruments; atmosphere monitoring devices; water management; life science instruments; and spacecraft electromechanical systems.

3D-FBK Pixel Sensors: Recent Beam Tests Results with Irradiated Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Micelli, A.; /INFN, Trieste /Udine U.; Helle, K.

2012-04-30

The Pixel Detector is the innermost part of the ATLAS experiment tracking device at the Large Hadron Collider, and plays a key role in the reconstruction of the primary vertices from the collisions and secondary vertices produced by short-lived particles. To cope with the high level of radiation produced during the collider operation, it is planned to add to the present three layers of silicon pixel sensors which constitute the Pixel Detector, an additional layer (Insertable B-Layer, or IBL) of sensors. 3D silicon sensors are one of the technologies which are under study for the IBL. 3D silicon technology ismore » an innovative combination of very-large-scale integration and Micro-Electro-Mechanical-Systems where electrodes are fabricated inside the silicon bulk instead of being implanted on the wafer surfaces. 3D sensors, with electrodes fully or partially penetrating the silicon substrate, are currently fabricated at different processing facilities in Europe and USA. This paper reports on the 2010 June beam test results for irradiated 3D devices produced at FBK (Trento, Italy). The performance of these devices, all bump-bonded with the ATLAS pixel FE-I3 read-out chip, is compared to that observed before irradiation in a previous beam test.« less

OLED integrated silicon membranes for light-modulation devices

NASA Astrophysics Data System (ADS)

Cheneler, David; Vervaeke, Michael; Thienpont, Hugo; Lambertini, Vito G.; Brignone, Mauro

2014-05-01

Organic light-emitting diodes (OLEDs) are most frequently used for display purposes and while they have also been utilized in sensing applications, their innate compliance has not previously been exploited for these applications. However, in this manuscript it is shown that OLEDs are compatible with microfabrication methods used in the production of micro mechanical devices. In particular it is shown that the compliance of OLEDs can be utilized in, and not limited to, a new generation of opto-mechanical pressure sensors. A fabrication process for a light-modulating pressure sensor is described. Prototypes were fabricated and tested and the response compared to an analytical theory developed by the authors. It is shown with simple circuitry, a resolution of 11.4 Pa up to 350 kPa is attainable using this technology.

On the Initiation Mechanism in Exploding Bridgewire and Laser Detonators

NASA Astrophysics Data System (ADS)

Stewart, D. Scott; Thomas, Keith A.; Clarke, S.; Mallett, H.; Martin, E.; Martinez, M.; Munger, A.; Saenz, Juan

2006-07-01

Since its invention by Los Alamos during the Manhattan Project era the exploding bridgewire detonator (EBW) has seen tremendous use and study. Recent development of a laser-powered device with detonation properties similar to an EBW is reviving interest in the basic physics of the deflagration-to-detonation (DDT) process in both of these devices. Cutback experiments using both laser interferometry and streak camera observations are providing new insight into the initiation mechanism in EBWs. These measurements are being correlated to a DDT model of compaction to detonation and shock to detonation developed previously by Xu and Stewart. The DDT model is incorporated into a high-resolution, multi-material model code for simulating the complete process. Model formulation and the modeling issues required to describe the test data will be discussed.

A Novel Approach For Ankle Foot Orthosis Developed By Three Dimensional Technologies

NASA Astrophysics Data System (ADS)

Belokar, R. M.; Banga, H. K.; Kumar, R.

2017-12-01

This study presents a novel approach for testing mechanical properties of medical orthosis developed by three dimensional (3D) technologies. A hand-held type 3D laser scanner is used for generating 3D mesh geometry directly from patient’s limb. Subsequently 3D printable orthotic design is produced from crude input model by means of Computer Aided Design (CAD) software. Fused Deposition Modelling (FDM) method in Additive Manufacturing (AM) technologies is used to fabricate the 3D printable Ankle Foot Orthosis (AFO) prototype in order to test the mechanical properties on printout. According to test results, printed Acrylonitrile Butadiene Styrene (ABS) AFO prototype has sufficient elasticity modulus and durability for patient-specific medical device manufactured by the 3D technologies.

A feasiblity study of an ultrasonic test phantom arm

NASA Astrophysics Data System (ADS)

Schneider, Philip

This thesis is a feasibility study for the creation of a test phantom that replicates the physiological features, from an acoustic and mechanical standpoint, of that of a human arm. Physiological feature set includes; Heart, Arteries, Veins, Bone, Muscle, Fat, Skin, and Dermotographic Features (finger prints). Mechanical Aspects include, vascular compression and distention, elasticity of tissue layers, mechanics of human heart. The end goal of which to have a working understanding of each component in order to create a controllable, real time, physiologically accurate, test phantom for a wide range of ultrasonic based applications. These applications can range from devices like wearable technologies to medical training, to biometric "Liveness" detection methods. The proposed phantom would allow for a number of natural bodily functions to be measured including but not limited to vascular mapping, blood pressure, heart rate, subdermal imaging, and general ultrasonic imaging.

Thermal-Mechanical Noise Based CMUT Characterization and Sensing

PubMed Central

Gurun, Gokce; Hochman, Michael; Hasler, Paul; Degertekin, F. Levent

2012-01-01

When capacitive micromachined ultrasonic transducers (CMUTs) are monolithically integrated with custom-designed low-noise electronics, the output noise of the system can be dominated by the CMUT thermal-mechanical noise both in air and in immersion even for devices with low capacitance. Since the thermal-mechanical noise can be related to the electrical admittance of the CMUTs, this provides an effective means of device characterization. This approach yields a novel method to test the functionality and uniformity of CMUT arrays and the integrated electronics where a direct connection to CMUT array element terminals is not available. These measurements can be performed in air at the wafer level, suitable for batch manufacturing and testing. We demonstrate this method on the elements of an 800-μm diameter CMUT-on-CMOS array designed for intravascular imaging in the 10-20 MHz range. Noise measurements in air show the expected resonance behavior and spring softening effects. Noise measurements in immersion for the same array provide useful information on both the acoustic cross talk and radiation properties of the CMUT array elements. The good agreement between a CMUT model based on finite difference and boundary element method and the noise measurements validates the model and indicates that the output noise is indeed dominated by thermal-mechanical noise. The measurement method can be exploited to implement CMUT based passive sensors to measure immersion medium properties, or other parameters affecting the electro-mechanics of the CMUT structure. PMID:22718877

Thermal-mechanical-noise-based CMUT characterization and sensing.

PubMed

Gurun, Gokce; Hochman, Michael; Hasler, Paul; Degertekin, F Levent

2012-06-01

When capacitive micromachined ultrasonic transducers (CMUTs) are monolithically integrated with custom-designed low-noise electronics, the output noise of the system can be dominated by the CMUT thermal-mechanical noise both in air and in immersion even for devices with low capacitance. Because the thermal-mechanical noise can be related to the electrical admittance of the CMUTs, this provides an effective means of device characterization. This approach yields a novel method to test the functionality and uniformity of CMUT arrays and the integrated electronics when a direct connection to CMUT array element terminals is not available. Because these measurements can be performed in air at the wafer level, the approach is suitable for batch manufacturing and testing. We demonstrate this method on the elements of an 800-μm-diameter CMUT-on-CMOS array designed for intravascular imaging in the 10 to 20 MHz range. Noise measurements in air show the expected resonance behavior and spring softening effects. Noise measurements in immersion for the same array provide useful information on both the acoustic cross talk and radiation properties of the CMUT array elements. The good agreement between a CMUT model based on finite difference and boundary element methods and the noise measurements validates the model and indicates that the output noise is indeed dominated by thermal-mechanical noise. The measurement method can be exploited to implement CMUT-based passive sensors to measure immersion medium properties, or other parameters affecting the electro-mechanics of the CMUT structure.

[Mechanical thrombectomy in acute ischemic stroke. What is the position after the latest study results?].

PubMed

Hacke, W; Diener, H-C

2015-06-01

Mechanical devices for the recanalization of vessel occlusions in severe acute ischemic stroke have been developed for more than a decade. Several devices have been approved for clinical use on the basis of uncontrolled case series. Many neurologists have asked for randomized clinical trials comparing the new devices with standard treatment, e.g. thrombolytic therapy within a 4.5 h time window. The first 3 investigator initiated randomized trials published in 2013 failed to show superiority of mechanical thrombectomy over standard treatment. In the aftermath of these negative results several new trials with changes in design (e.g. shorter time window and only proximal vessel occlusions) and the use of modern devices with proven higher recanalization rates, so called stent retrievers, have been launched. In October 2014 the first of these new trials was presented and showed a clear superiority of thrombectomy. Based on this result interim analyses of five other studies were performed and most were prematurely terminated because of overwhelming efficacy. Only one trial testing another type of recanalization device failed to reach a statistically significant result. Currently five studies have already been published and two more studies have been presented at scientific conferences. This article provides an overview of the study protocols and the results of the individual studies, their common features and the characteristics of patients who benefit from this treatment. Finally, the consequences that these results may have for the treatment of patients with severe stroke caused by proximal vessel occlusion are discussed.

Design and Testing of a Minimally Invasive Blood Clot Removal Device ConstructedWith Elements of Superelastic Nitinol

NASA Astrophysics Data System (ADS)

Puffer, Andrew J.

Many vascular system problems stem from insufficient blood return flow to the heart. One of the main causes is a blockage within veins or arteries known as a blood clot, or thrombus. This can occur after trauma, surgery, or other phenomenological reasons. Each year in the U.S. more than 175,000 bypass procedures and more than 160,000 amputations resulting from peripheral vessel disease are performed. Clinical data indicates that clot removal devices and procedures can reduce the need for an amputation by 80 percent. Percutaneous thrombectomy refers to the removal of thrombus using catheter based non-surgical methods. The ultimate goal of any modality to treat these conditions of the arterial or venous system is to restore patency, quickly, safely, and cost effectively. Catheter directed thrombectomy and thrombolysis is less traumatic and avoids the morbidity and mortality associated with conventional surgical technique. As a result, there has been a push recently for the use of percutaneous mechanical thrombectomy (PMT) devices. However, all devices have their own set of drawbacks: distal embolization, vessel wall trauma, hemolysis, to name a few. Ongoing efforts have been made to create a prototype thrombectomy device that uses elements of superelastic nitinol (a type of shape memory alloy), that seeks to address some of the drawbacks of current devices. The prototype was designed and tested in a simulated human circulatory system along side a commercially available device (The DiverCE Clot Extraction Catheter). The test evaluated how well the devices minimized distal embolization of a human blood clot created in vitro.. Results of the testing showed that the prototype device created significantly less embolization when compared to the DiverCE particles greater than 102mum (p = 0.0332). Means were statistically not different for particles between 25mum and 102mum (p = 0.2454), and particles between 5mum and 25mum (p = 0.6524). In addition the prototype was shown to create insignificant embolization when compared to a control (p = 0.108). The DiverCE, on the other hand, was shown to create significant embolization when compared to a control (p = 0.027).

Servo-controlled pneumatic pressure oscillator for respiratory impedance measurements and high-frequency ventilation.

PubMed

Kaczka, David W; Lutchen, Kenneth R

2004-04-01

The ability to provide forced oscillatory excitation of the respiratory system can be useful in mechanical impedance measurements as well as high frequency ventilation (HFV). Experimental systems currently used for generating forced oscillations are limited in their ability to provide high amplitude flows or maintain the respiratory system at a constant mean pressure during excitation. This paper presents the design and implementation of a pneumatic pressure oscillator based on a proportional solenoid valve. The device is capable of providing forced oscillatory excitations to the respiratory system over a bandwidth suitable for mechanical impedance measurements and HVF. It delivers high amplitude flows (> 1.4 l/s) and utilizes a servo-control mechanism to maintain a load at a fixed mean pressure during simultaneous oscillation. Under open-loop conditions, the device exhibited a static hysteresis of approximately 7%, while its dynamic magnitude and phase responses were flat out to 10 Hz. Broad-band measurement of total harmonic distortion was approximately 19%. Under closed-loop conditions, the oscillator was able to maintain a mechanical test load at both positive and negative mean pressures during oscillatory excitations from 0.1 to 10.0 Hz. Impedance of the test load agreed closely with theoretical predictions. We conclude that this servo-controlled oscillator can be a useful tool for respiratory impedance measurements as well as HFV.

Coupling of PZT Thin Films with Bimetallic Strip Heat Engines for Thermal Energy Harvesting.

PubMed

Boughaleb, Jihane; Arnaud, Arthur; Guiffard, Benoit; Guyomar, Daniel; Seveno, Raynald; Monfray, Stéphane; Skotnicki, Thomas; Cottinet, Pierre-Jean

2018-06-06

A thermal energy harvester based on a double transduction mechanism and which converts thermal energy into electrical energy by means of piezoelectric membranes and bimetals, has previously been developed and widely presented in the literature In such a device, the thermo-mechanical conversion is ensured by a bimetal whereas the electro-mechanical conversion is generated by a piezoelectric ceramic. However, it has been shown that only 19% of the mechanical energy delivered by the bimetal during its snap is converted into electrical energy. To extract more energy from the bimetallic strip and to increase the transduction efficiency, a new way to couple piezoelectric materials with bimetals has thus been explored through direct deposition of piezoelectric layers on bimetals. This paper consequently presents an alternative way to harvest heat, based on piezoelectric bimetallic strip heat engines and presents a proof of concept of such a system. In this light, different PZT (Lead zirconate titanate) thin films were synthesized directly on aluminium foils and were attached to the bimetals using conductive epoxy. The fabrication process of each sample is presented herein as well as the experimental tests carried out on the devices. Throughout this study, different thicknesses of the piezoelectric layers and substrates were tested to determine the most powerful configuration. Finally, the study also gives some guidelines for future improvements of piezoelectric bimetals.

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

PubMed

Carlos, Evan C; Wollin, Daniel A; Winship, Brenton B; Jiang, Ruiyang; Radvak, Daniela; Chew, Ben H; Gustafson, Michael R; Simmons, W Neal; Zhong, Pei; Preminger, Glenn M; Lipkin, Michael E

2018-06-01

The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical impact energies. We compared the efficacy and tip motion of these devices in an in vitro setting. Begostones, in the ratio 15:3, were used in all trials. Test groups were Trilogy, ShockPulse, Select ultrasound (US) only, and Select ultrasound with pneumatic (USP). For clearance testing, a single investigator facile with each lithotripter fragmented 10 stones per device. For drill testing, a hands-free apparatus with a submerged balance was used to apply 1 or 2 lbs of pressure on a stone in contact with the device tip. High-speed photography was used to assess Trilogy and ShockPulse's probe tip motion. Select-USP was slowest and Trilogy fastest on clearance testing (p < 0.01). On 1 lbs drill testing, Select-US was slowest (p = 0.001). At 2 lbs, ShockPulse was faster than Select US (p = 0.027), but did not significantly outpace Trilogy nor Select-USP. At either weight, there was no significant difference between Trilogy and ShockPulse. During its US function, Trilogy's maximum downward tip displacement was 0.041 mm relative to 0.0025 mm with ShockPulse. Trilogy had 0.25 mm of maximum downward displacement during its impactor function while ShockPulse had 0.01 mm. Single probe dual-energy devices, such as Trilogy and ShockPulse, represent the next generation of lithotripters. Trilogy more efficiently cleared stone than currently available devices, which could be explained by its larger probe diameter and greater downward tip displacement during both US and impactor functions.

High pressure rotating reverse osmosis for long term space missions

NASA Astrophysics Data System (ADS)

Christensen Pederson, Cynthia Lynn

Rotating reverse osmosis, which uses reverse osmosis to purify water and rotating filtration to improve the efficacy of filtration, has great potential for wastewater recycling on a long term space mission. Previous investigations of a proof-of-concept device indicated that the most efficient method to improve rotating reverse osmosis performance is to increase the operational pressure. Thus, a second generation device and fluid circuit were designed, fabricated, and tested to permit high pressure operation for long time periods. The design overcame several obstacles including membrane attachment, rotating seal design, and fluid and pressure management. A theoretical model of rotating reverse osmosis was modified to properly account for the flow conditions in the new design. Tests lasting a week were conducted with a variety of model wastewaters. Significant fouling and a decrease in flux were observed after three days of testing regardless of the operational parameters. A semi-empirical model, the fouling potential, was added to the theoretical model to account for the fouling. This allowed the simulation of 48 hour cleaning cycles that significantly increased the flux of the device. Experimental investigation of the rotational speed and concentrate flow rate indicated that an increase in either parameter decreased the fouling slightly. A week long test of a wastewater ersatz with a biocide did not exhibit a decrease in flux around day three that otherwise occurred. Therefore, biofouling was identified as the primary mechanism of fouling. Rotating reverse osmosis was compared with conventional spiral wound reverse osmosis and displayed increased rejection under dead end filtration conditions. The rotating device exhibited similar rejection and increased flux compared to a tubular reverse osmosis device previously used in a NASA wastewater recovery system. The integration of the rotating device into a NASA water recovery management system was evaluated. Lastly, a theoretical model of rotating hemofiltration was developed that demonstrated that the device is not clinically feasible given the permeability of available hemofiltration membranes.

Direct evidence on Ta-Metal Phases Igniting Resistive Switching in TaOx Thin Film

PubMed Central

Kyu Yang, Min; Ju, Hyunsu; Hwan Kim, Gun; Lee, Jeon-Kook; Ryu, Han-Cheol

2015-01-01

A Ta/TaOx/Pt stacked capacitor-like device for resistive switching was fabricated and examined. The tested device demonstrated stable resistive switching characteristics including uniform distribution of resistive switching operational parameters, highly promising endurance, and retention properties. To reveal the resistive switching mechanism of the device, micro structure analysis using high-resolution transmission electron microscope (HR-TEM) was performed. From the observation results, two different phases of Ta-metal clusters of cubic α-Ta and tetragonal β-Ta were founded in the amorphous TaOx mother-matrix after the device was switched from high resistance state (HRS) to low resistance state (LRS) by externally applied voltage bias. The observed Ta metal clusters unveiled the origin of the electric conduction paths in the TaOx thin film at the LRS. PMID:26365532

Direct evidence on Ta-Metal Phases Igniting Resistive Switching in TaOx Thin Film

NASA Astrophysics Data System (ADS)

Kyu Yang, Min; Ju, Hyunsu; Hwan Kim, Gun; Lee, Jeon-Kook; Ryu, Han-Cheol

2015-09-01

A Ta/TaOx/Pt stacked capacitor-like device for resistive switching was fabricated and examined. The tested device demonstrated stable resistive switching characteristics including uniform distribution of resistive switching operational parameters, highly promising endurance, and retention properties. To reveal the resistive switching mechanism of the device, micro structure analysis using high-resolution transmission electron microscope (HR-TEM) was performed. From the observation results, two different phases of Ta-metal clusters of cubic α-Ta and tetragonal β-Ta were founded in the amorphous TaOx mother-matrix after the device was switched from high resistance state (HRS) to low resistance state (LRS) by externally applied voltage bias. The observed Ta metal clusters unveiled the origin of the electric conduction paths in the TaOx thin film at the LRS.

[Analysis of bactericidal material generated by electrical devices advertising bactericidal ability against bacteria on the agar gel plates].

PubMed

Nishimura, Hidekazu

2012-11-01

Several Japanese companies sell electrical devices advertised as effective in inactivating viruses and killing bacteria by releasing special materials, e.g., Plasmacluster ions, Nanoe particle and minus ions, into the air. These companies claim that their devices killed bacteria on plates in their own experiments. We tested device effectiveness using the same experiments from the Plasmacluster ioniser SHARP Co., Japan, the Nanoe generator Panasonic Co., Japan, and the Vion KING JIM Co., Japan, to test their advertising claims. Bactericidal ability on agar plate was tested, using Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, and Enterococcus faecalis as follows: the medium containing a certain amount of each bacterium was put onto an agar plate and smeared. Plates were kept in a closed chamber (inner volume 14.4 m3) or a glove box (inner volume 0.2 m), with one of the devices run for 2 hours. Plates not exposed to any device were used as controls. Each plate was retrieved and put in an incubator to count the number of bacterial colonies formed on the plate. There was no significant difference in the number of colonies on plates exposed to devices compared to control, in the number for all devices, or in all bacteria tested in experiments in the 14.4 m3 chamber. These results strongly suggest that these devices have almost no bactericidal effect, at least in space exceeding this volume. Colony formation was suppressed in the glove box in all devices and in all bacteria tested except P. aeruginosa, although the degree of suppression differed among experiments. The colony formation suppression mechanism was analyzed, and indicated that:colony formation did not change even after the removal of Plasmacluster ions, Nanoe particles, or negative ions from the air, while colony formation was decreased drastically by the removal of ozone from space, which was revealed to be generated inevitably during device operation. These results strongly suggest that the bactericidal effect seen only on the agar plate in narrow space was explained by ozone released in space as a by-product, not by special materials as advertising claimed. It is thus important to analyze the effect of special materials such as those done in this study and to suggest the involvement of ozone as the true cause, as have been done in this study, in evaluating bactericidal effect or viral inactivation as advertised by these companies.

Application of Micro-ramp Flow Control Devices to an Oblique Shock Interaction

NASA Technical Reports Server (NTRS)

Hirt, Stefanie; Anderson, Bernhard

2007-01-01

Tests are planned in the 15cm x 15cm supersonic wind tunnel at NASA Glenn to demonstrate the applicability of micro-ramp flow control to the management of shock wave boundary layer interactions. These tests will be used as a database for computational fluid dynamics (CFD) validation and Design of Experiments (DoE) design information. Micro-ramps show potential for mechanically simple and fail-safe boundary layer control.

The development of pyro shock test requirements for Viking Lander Capsule components

NASA Technical Reports Server (NTRS)

Barrett, S.

1975-01-01

The procedure used to derive component-level pyro shock specifications for the Viking Lander Capsule (VLC) is described. Effects of shock path distance and mechanical joints between the device and the point at which the environment is to be estimated are accounted for in the method. The validity of the prediction technique was verified by a series of shock tests on a full-scale structural model of the lander body.

Development and Testing of a ``Backlash-Free'' Gas-Tight High Precision Sample Handling Mechanism for Combined Science on the ExoMars 2018 Rover

NASA Astrophysics Data System (ADS)

Paul, R.; Redlich, D.; Richter, L.; Zuknik, K.-H.; Muhlbauer, Q.; Thiel, M.; Fowler, L.; Tattusch, T.; Weisz, H.; Musso, F.; Durrant, S.

2015-09-01

This paper presents the development and testing by the OHB System AG of the Powdered Sample Handling Mechanism (PSHS) that is part of the rover of the European Space Agency 2018 ExoMars Mission, a cooperative mission with Roscosmos including a scientific instrument contribution from NASA. The task of this mechanism is to flatten and position powdered Martian soil samples allowing subsequent investigation of selected grains by different optical instruments thus providing combined science in an ultra-clean environment.The exceptional sensitivity of these instruments causes extremely challenging requirements with respect to positioning performance as well as cleanliness and contamination control. The impact of these design drivers is highlighted focusing on specific mechanism features such as the pre-torque device to minimize the backlash and the dynamic feed-through, allowing a gas-tight encapsulation of an ultra-clean zone free of drive-train components.Subsequently the results of the test campaign of an elegant breadboard under Mars-like conditions, as well as first QM test results are described. Furthermore the outcomes of combined tests with an optical instrument are reported.

Testing biomaterials for application in artificial organs: impact of procedures, donor and patient properties.

PubMed

Vienken, Joerg

2008-12-01

Many factors can affect the characterisation of biomaterials during testing. These include drugs administered prior to testing and shear stress on blood cells induced by different blood flows and specific blood donor conditions. Some of the misconceptions in testing are described here and serve to indicate that a systems approach, and not only individual test parameters, is best when testing for biocompatibility. "Methodology is everything and the devil is in the details", remarked Paul Simmons, the current president of the International Society for Stemcell Research, in an article in Nature magazine [1]. The article refers to current problems related to the reproducibility of data in stem cell research. Reproducibility in in vitro testing is also mandatory when selecting polymers for medical device applications. Many mechanical and physical engineers are surprised when they realise the enormous standard deviations (sometimes between 50 and 100%) of data found in biological or physiological investigations of biomaterials. The reasons for this are the complexity of physiological parameters such as the nature of blood originating from a variety of donors and hour-to-hour and day-to-day physiological differences. As a consequence, standardisation is a condition sine qua non in biomaterial testing, and knowledge of possible pitfalls is absolutely necessary. Therefore ISO 10993-4, Biological Evaluation of Medical Devices, Selection of Tests for Interaction With Blood, [2] provides a practical tool, including a decision tree for use in the selection of appropriate polymers for biomaterial applications. However, the interested reader finds in Section 3.1 of ISO 10993-4 the definition of blood-device interaction: "Any interaction between blood or any component of blood and a device, resulting in effects on blood, or on any organ or tissue, or on the device". A note added to this definition further clarifies: "Such effects may or may not have clinically significant or undesirable consequences." This prompts one to ask if effects leading to undesirable consequences that are not clinically significant would be helpful to the polymer chemist. This article provides some observations and examples of the misconceptions and pitfalls that exist in testing biomaterials for biocompatibility.

Paper-based analytical devices for clinical diagnosis: recent advances in the fabrication techniques and sensing mechanisms

PubMed Central

Sher, Mazhar; Zhuang, Rachel; Demirci, Utkan; Asghar, Waseem

2017-01-01

Introduction There is a significant interest in developing inexpensive portable biosensing platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings. Current diagnostic assays available in the developed world require sophisticated laboratory infrastructure and expensive reagents. Hence, they are not suitable for resource-constrained settings with limited financial resources, basic health infrastructure, and few trained technicians. Cellulose and flexible transparency paper-based analytical devices have demonstrated enormous potential for developing robust, inexpensive and portable devices for disease diagnostics. These devices offer promising solutions to disease management in resource-constrained settings where the vast majority of the population cannot afford expensive and highly sophisticated treatment options. Areas covered In this review, the authors describe currently developed cellulose and flexible transparency paper-based microfluidic devices, device fabrication techniques, and sensing technologies that are integrated with these devices. The authors also discuss the limitations and challenges associated with these devices and their potential in clinical settings. Expert commentary In recent years, cellulose and flexible transparency paper-based microfluidic devices have demonstrated the potential to become future healthcare options despite a few limitations such as low sensitivity and reproducibility. PMID:28103450

Paper-based analytical devices for clinical diagnosis: recent advances in the fabrication techniques and sensing mechanisms.

PubMed

Sher, Mazhar; Zhuang, Rachel; Demirci, Utkan; Asghar, Waseem

2017-04-01

There is a significant interest in developing inexpensive portable biosensing platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings. Current diagnostic assays available in the developed world require sophisticated laboratory infrastructure and expensive reagents. Hence, they are not suitable for resource-constrained settings with limited financial resources, basic health infrastructure, and few trained technicians. Cellulose and flexible transparency paper-based analytical devices have demonstrated enormous potential for developing robust, inexpensive and portable devices for disease diagnostics. These devices offer promising solutions to disease management in resource-constrained settings where the vast majority of the population cannot afford expensive and highly sophisticated treatment options. Areas covered: In this review, the authors describe currently developed cellulose and flexible transparency paper-based microfluidic devices, device fabrication techniques, and sensing technologies that are integrated with these devices. The authors also discuss the limitations and challenges associated with these devices and their potential in clinical settings. Expert commentary: In recent years, cellulose and flexible transparency paper-based microfluidic devices have demonstrated the potential to become future healthcare options despite a few limitations such as low sensitivity and reproducibility.

Micromachined devices for interfacing neurons

NASA Astrophysics Data System (ADS)

Stieglitz, Thomas; Beutel, Hansjoerg; Blau, Cornelia; Meyer, Joerg-Uwe

1998-07-01

Micromachining technologies were established to fabricate microelectrode arrays and devices for interfacing parts of the central or peripheral nervous system. The devices were part of a neural prosthesis that allows simultaneous multichannel recording and multisite stimulation of neurons. Overcoming the brittle mechanics of silicon devices and challenging housing demands close to the nerve we established a process technology to fabricate light-weighted and highly flexible polyimide based devices. Platinum and iridium thin-film electrodes were embedded in the polyimide. With reactive ion etching we got the possibility to simply integrate interconnections and to form nearly arbitrary outer shapes of the devices. We designed multichannel devices with up to 24 electrodes in the shape of plates, hooks and cuffs for different applications. In vitro tests exhibited stable electrode properties and no cytotoxicity of the materials and the devices. Sieve electrodes were chronically implanted in rats to interface the regenerating sciatic nerve. After six months, recordings and stimulation of the nerve via electrodes on the micro-device proved functional reinnervation of the limb. Concentric circular structures were designed for a retina implant for the blind. In preliminary studies in rabbits, evoked potentials in the visual cortex corresponded to stimulation sites of the implant.

DipTest: A litmus test for E. coli detection in water.

PubMed

Gunda, Naga Siva Kumar; Dasgupta, Saumyadeb; Mitra, Sushanta K

2017-01-01

We have developed a new litmus paper test (DipTest) for detecting Escherichia coli (E. coli) in water samples by performing enzymatic reactions directly on the porous paper substrate. The paper strip consists of a long narrow piece of cellulose blotting paper coated with chemoattractant (at bottom edge), wax hydrophobic barrier (at the top edge), and custom formulated chemical reagents (at reaction zone immediately below the wax hydrophobic barrier). When the paper strip is dipped in water, E. coli in the water sample is attracted toward the paper strip due to a chemotaxic mechanism followed by the ascent along the paper strip toward the reaction zone due to a capillary wicking mechanism, and finally the capillary motion is arrested at the top edge of the paper strip by the hydrophobic barrier. The E. coli concentrated at the reaction zone of the paper strip will react with custom formulated chemical reagents to produce a pinkish-red color. Such a color change on the paper strip when dipped into water samples indicates the presence of E. coli contamination in potable water. The performance of the DipTest device has been checked with different known concentrations of E. coli contaminated water samples using different dip and wait times. The DipTest device has also been tested with different interfering bacteria and chemical contaminants. It has been observed that the different interfering contaminants do not have any impact on the DipTest, and it can become a potential solution for screening water samples for E. coli contamination at the point of source.

DipTest: A litmus test for E. coli detection in water

PubMed Central

Gunda, Naga Siva Kumar; Dasgupta, Saumyadeb

2017-01-01

We have developed a new litmus paper test (DipTest) for detecting Escherichia coli (E. coli) in water samples by performing enzymatic reactions directly on the porous paper substrate. The paper strip consists of a long narrow piece of cellulose blotting paper coated with chemoattractant (at bottom edge), wax hydrophobic barrier (at the top edge), and custom formulated chemical reagents (at reaction zone immediately below the wax hydrophobic barrier). When the paper strip is dipped in water, E. coli in the water sample is attracted toward the paper strip due to a chemotaxic mechanism followed by the ascent along the paper strip toward the reaction zone due to a capillary wicking mechanism, and finally the capillary motion is arrested at the top edge of the paper strip by the hydrophobic barrier. The E. coli concentrated at the reaction zone of the paper strip will react with custom formulated chemical reagents to produce a pinkish-red color. Such a color change on the paper strip when dipped into water samples indicates the presence of E. coli contamination in potable water. The performance of the DipTest device has been checked with different known concentrations of E. coli contaminated water samples using different dip and wait times. The DipTest device has also been tested with different interfering bacteria and chemical contaminants. It has been observed that the different interfering contaminants do not have any impact on the DipTest, and it can become a potential solution for screening water samples for E. coli contamination at the point of source. PMID:28877199

Study on the mechanical analysis and the testing technology of the optical fiber cables released from the bobbin

NASA Astrophysics Data System (ADS)

Wang, Rong; Li, Zhen-hua; Bian, Bao-min; Liu, Cheng-lin; Ji, Yun-jing

2014-12-01

Accurate measurements of forces applied to the optical cable reels with high spinning speeds, will render information on the breakdown of optical fibers, and thus improve the odds of success and un-winding efficiency. In this paper we analyze and deduce the cable wire stress at high pay-off speeds. A high-sensitive opti-mechanical testing sensory device is designed to measure both the axial tension of the cables and the radial pressure of the cable reels at varying stress points simultaneously. The time resolution of this new device is less than 0.015ms, the response time is up to 15μs, and its sensitivity is about 500pc/N, which satisfies the mechanical testing requirements at high spinning speeds. In addition, the spinning speed of 260m/s led to the break-down of the optical fibers, and the spinning speed of 250m/s tested finally led to a deceleration near the end of the broken fibers. It is obvious that this kit can meet the requirement to obtain the periodic signals of the varying forces for each layer and each turn of optical fiber cables. Moreover, we found that the pay-off fiber cable is safe with the unwinding speed of 250m/s and the break-down of optical cables happens during the deceleration process. However, it is under the unwinding speed of 260m/s that pay-off fiber cables broke during the experiment. The abnormal breakdown signals are captured at these unwinding speeds, respectively.

Liquid acquisition devices for superfluid helium transfer

NASA Technical Reports Server (NTRS)

Dipirro, M. J.

1990-01-01

To transfer superfluid helium (He II) in the milli-g or micro-g environment in orbit, it is necessary to provide a reasonably steady supply of liquid to the inlet of the pump in the supply dewar. To accomplish this without providing an artificial gravity through acceleration requires a liquid acquisition device. Fluid swirl and electrostatic devices have been proposed to orientate the fluid. However, the simplest mechanisms appear to be the use of surface tension or the thermomechanical effect. This paper examines four concepts for providing He II to the inlet of a thermomechanical pump. The devices are a distributed thermomechanical pump, a distributed pump with a main thermomechanical pump, a screened channel system and a vane/sponge combination. Calculations on the efficiency of these types of liquid acquisition devices are made using laboratory data from tests involving small scale devices where applicable. These calculations show that the latter two types of liquid acquisition devices are the most efficient. Questions as to the probability of cavitation and the effect of the residual shuttle acceleration on their operation remain to be answered, however.

Characterizing the Material Properties of Polymer-Based Microelectrode Arrays for Retinal Prosthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Christina Soyeun

2003-06-01

The Retinal Prosthesis project is a three year project conducted in part at the Lawrence Livermore National Laboratory and funded by the Department of Energy to create an epiretinal microelectrode array for stimulating retinal cells. The implant must be flexible to conform to the retina, robust to sustain handling during fabrication and implantation, and biocompatible to withstand physiological conditions within the eye. Using poly(dimethyl siloxane) (PDMS), LLNL aims to use microfabrication techniques to increase the number of electrodes and integrate electronics. After the initial designs were fabricated and tested in acute implantation, it became obvious that there was a needmore » to characterize and understand the mechanical and electrical properties of these new structures. This knowledge would be imperative in gaining credibility for polymer microfabrication and optimizing the designs. Thin composite microfabricated devices are challenging to characterize because they are difficult to handle, and exhibit non-linear, viscoelastic, and anisotropic properties. The objective of this research is to device experiments and protocols, develop an analytical model to represent the composite behavior, design and fabricate test structures, and conduct experimental testing to determine the mechanical and electrical properties of PDMS-metal composites. Previous uniaxial stretch tests show an average of 7% strain before failure on resistive heaters of similar dimensions deposited on PDMS. Lack of background information and questionable human accuracy demands a more sophisticated and thorough testing method. An Instron tensile testing machine was set up to interface with a digital multiplexor and computer interface to simultaneously record and graph position, load, and resistance across devices. With a compliant load cell for testing polymers and electrical interconnect grips designed and fabricated to interface the sample to the electronics, real-time resistance measurements were taken. Wafers of test structures were fabricated with variables such as lead width, pad to lead interface shape, PDMS thickness, metal (Ti and Au) thickness, and lead shape. Results showed that the serpentine shaped leads were 70% more effective, and that thicker adhesion layers of Ti were too brittle for testing. The other variables did not produce significant results.« less

Usability test of a hand exoskeleton for activities of daily living: an example of user-centered design.

PubMed

Almenara, Maria; Cempini, Marco; Gómez, Cristina; Cortese, Mario; Martín, Cristina; Medina, Josep; Vitiello, Nicola; Opisso, Eloy

2017-01-01

(1) To assess a robotic device (Handexos) during the design process with regard to usability, end user satisfaction and safety, (2) to determine whether Handexos can improve the activities of daily living (ADLs) of spinal cord injury (SCI) patients and stroke patients with upper-limb dysfunction. During a 2-year development stage of the device, a total of 37 participants (aged 22-68), 28 clinicians (experts) and nine patients with SCI or stroke (end users) were included in a user-centered design process featuring usability tests. They performed five grasps wearing the device. The assessments were obtained at the end of the session by filling out a questionnaire and making suggestions. The experts' opinion was that the modified device was an improvement over the preliminary version, although this was not reflected in the scores. Whereas end user scores for comfort, grasp, performance and safety were above the sufficiency threshold, the scores for year 2 were lower than those for year 1. The findings demonstrate that although Handexos meets the initial functional requirements and underlines the potential for assisting SCI and post-stroke subjects in ADLs, several aspects such as mechanical complexity and low adaptability to different hand sizes need to be further addressed. Implications for Rehabilitation Wearable robotics devices could improve the activities of daily living in patients with spinal cord injury or stroke. They could be a tool for rehabilitation of the upper limb. Further usability tests to improve this type of tools are recommended.

Assessment of a new silicone tri-leaflet valve seamlessly assembled with blood chamber for a low-cost ventricular assist device.

PubMed

Hirai, S; Fukunaga, S; Sueshiro, M; Watari, M; Sueda, T; Matsuura, Y

1998-06-01

We have developed a practical, low-cost ventricular assist device (VAD) comprising a newly designed blood chamber with a silicone lenticular sac and two silicone tri-leaflet valves (STV), made en bloc. This new VAD is seamless, can be made cost-effectively and assembled with the blood chamber and valve as one body. This novel design should reduce the incident of thrombus formation because of the absence of a junction at the connecting ring and because of the use of flexible silicone materials which have both antithrombogenecity and biocompatibility. In in vitro hemodynamics testing, a batch of 3 consecutively manufactured VADs with STVs underwent hydrodynamic functional testing. These showed less regurgitation, a lower value of water hammer phenomenon, and a slightly greater pressure gradient across the valves than a mechanical valve (MV) [Björk-Shiley monostrut valve]. The flow and pulsatile efficiency were adequate and similar to that of a VAD with MVs. In in vitro durability and hemolysis tests, a VAD with STV functioned well for 54 days and showed similar hemolytic profiles to a VAD with MVs. In an in vivo acute experiment using an adult sheep, our device was problem-free providing sufficient output as a left ventricular assist device (LVAD). Although it will be necessary to decrease the pressure gradient across this STV in the future, our device showed efficient performance as a practical land cost-effective VAD for short term use.

Piezoelectric energy harvesting computer controlled test bench

NASA Astrophysics Data System (ADS)

Vázquez-Rodriguez, M.; Jiménez, F. J.; de Frutos, J.; Alonso, D.

2016-09-01

In this paper a new computer controlled (C.C.) laboratory test bench is presented. The patented test bench is made up of a C.C. road traffic simulator, C.C. electronic hardware involved in automating measurements, and test bench control software interface programmed in LabVIEW™. Our research is focused on characterizing electronic energy harvesting piezoelectric-based elements in road traffic environments to extract (or "harvest") maximum power. In mechanical to electrical energy conversion, mechanical impacts or vibrational behavior are commonly used, and several major problems need to be solved to perform optimal harvesting systems including, but no limited to, primary energy source modeling, energy conversion, and energy storage. It is described a novel C.C. test bench that obtains, in an accurate and automatized process, a generalized linear equivalent electrical model of piezoelectric elements and piezoelectric based energy store harvesting circuits in order to scale energy generation with multiple devices integrated in different topologies.

Piezoelectric energy harvesting computer controlled test bench.

PubMed

Vázquez-Rodriguez, M; Jiménez, F J; de Frutos, J; Alonso, D

2016-09-01

In this paper a new computer controlled (C.C.) laboratory test bench is presented. The patented test bench is made up of a C.C. road traffic simulator, C.C. electronic hardware involved in automating measurements, and test bench control software interface programmed in LabVIEW™. Our research is focused on characterizing electronic energy harvesting piezoelectric-based elements in road traffic environments to extract (or "harvest") maximum power. In mechanical to electrical energy conversion, mechanical impacts or vibrational behavior are commonly used, and several major problems need to be solved to perform optimal harvesting systems including, but no limited to, primary energy source modeling, energy conversion, and energy storage. It is described a novel C.C. test bench that obtains, in an accurate and automatized process, a generalized linear equivalent electrical model of piezoelectric elements and piezoelectric based energy store harvesting circuits in order to scale energy generation with multiple devices integrated in different topologies.

Study on intelligent processing system of man-machine interactive garment frame model

NASA Astrophysics Data System (ADS)

Chen, Shuwang; Yin, Xiaowei; Chang, Ruijiang; Pan, Peiyun; Wang, Xuedi; Shi, Shuze; Wei, Zhongqian

2018-05-01

A man-machine interactive garment frame model intelligent processing system is studied in this paper. The system consists of several sensor device, voice processing module, mechanical parts and data centralized acquisition devices. The sensor device is used to collect information on the environment changes brought by the body near the clothes frame model, the data collection device is used to collect the information of the environment change induced by the sensor device, voice processing module is used for speech recognition of nonspecific person to achieve human-machine interaction, mechanical moving parts are used to make corresponding mechanical responses to the information processed by data collection device.it is connected with data acquisition device by a means of one-way connection. There is a one-way connection between sensor device and data collection device, two-way connection between data acquisition device and voice processing module. The data collection device is one-way connection with mechanical movement parts. The intelligent processing system can judge whether it needs to interact with the customer, realize the man-machine interaction instead of the current rigid frame model.

[Design of an external prosthetic system with a polycentric mechanism].

PubMed

Valentino Orozco, Gerardo Alejandro; Guerrero Beltrán, Leobardo; Obregón Velasco, Dinora; Avalos Fernández, Oscar

2008-01-01

This medical and engineering work explains the process carried out to build a four-barred polycentric knee mechanism using a mechanical actuator for modular prosthetics. Imitation of the knee performance was the main goal, as well as to cover the basic needs of amputated patients with a low production cost. The polycentric knee mechanism was developed in three stages. The first one was the design and building of the four-barred mechanism using materials as stainless steel 304 and aluminum 6,061 which both have high reliability, corrosion resistance and a relatively easy modeling capability. The total mass was of 700 g. Autocad was used for design and effort analysis was done by using ANSYS. At the end of the first stage, it was observed that its density did not allow mass optimization and no assistant actuator was available for the walking movement. In the second stage, mechanism mass estimation was done by using Alumold 400; this material brings lower density than stainless steel keeping strength and fatigue resistance higher than aluminum 6061. The better ergonomic device was built; a mechanical actuator based on a spring was implemented and tested on two female patients, one geriatric and one 16 years old. The third stage will be described in a future publication, the device mass was optimized by using poly-tetra-fluor-ethylene enhanced with carbon and carbon fiber. Also, the mechanical actuator was complemented with reo-magnetic liquid addition and an electronic control. At the end of this research, an external polycentric knee mechanism was developed, by observing movement stages, velocities, ergonomics, shapes, sizes and significant weights of Mexican patients. Effort analysis by finite element was done and it was determined that the mechanism was capable of modifying its center of rotation according to the knee flexion angle making it a polycentric mechanisms. Also, it was tested on two patients, both females, one 16 and one 75 years old.

Ethylene-Vinyl Acetate Potential Problems for Photovoltaic Packaging: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempe, M. D.; Jorgensen, G. J.; Terwilliger, K. M.

2006-05-01

Photovoltaic (PV) devices are typically encapsulated using ethylene-vinyl acetate (EVA) to provide mechanical support, optical coupling, electrical isolation, and protection against environmental exposure. Under exposure to atmospheric water and/or ultraviolet radiation, EVA will decompose to produce acetic acid, lowering the pH and increasing the surface corrosion rates of embedded devices. Even though acetic acid is produced at a very slow rate, it may not take much to catalyze reactions that lead to rapid module deterioration. Another consideration is that the glass transition of EVA, as measured using dynamic mechanical analysis, begins at temperatures of about ?15 C. Temperatures lower thanmore » this can be reached for extended periods of time in some climates. Because of increased moduli below the glass transition temperature, a module may be more vulnerable to damage if a mechanical load is applied by snow or wind at low temperatures. Modules using EVA should not be rated for use at such low temperatures without additional low-temperature mechanical testing beyond the scope of UL 1703.« less

Ethylene-Vinyl Acetate Potential Problems for Photovoltaic Packaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempe, M. D.; Jorgensen, G. J.; Terwilliger, K. M.

2006-01-01

Photovoltaic (PV) devices are typically encapsulated using ethylene-vinyl acetate (EVA) to provide mechanical support, optical coupling, electrical isolation, and protection against environmental exposure. Under exposure to atmospheric water and/or ultraviolet radiation, EVA will decompose to produce acetic acid, lowering the pH and increasing the surface corrosion rates of embedded devices. Even though acetic acid is produced at a very slow rate, it may not take much to catalyze reactions that lead to rapid module deterioration. Another consideration is that the glass transition of EVA, as measured using dynamic mechanical analysis, begins at temperatures of about -15 degC. Temperatures lower thanmore » this can be reached for extended periods of time in some climates. Because of increased moduli below the glass transition temperature, a module may be more vulnerable to damage if a mechanical load is applied by snow or wind at low temperatures. Modules using EVA should not be rated for use at such low temperatures without additional low-temperature mechanical testing beyond the scope of UL1703.« less

Potential Problems with Ethylene-Vinyl Acetate for Photovoltaic Packaging (Poster)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempe, M. D.; Jorgensen, G. J.; Terwilliger, K, M.

2006-05-01

Photovoltaic (PV) devices are typically encapsulated using ethylene-vinyl acetate (EVA) to provide mechanical support electrical isolation, optical coupling, and protection against environmental exposure. Under exposure to atmospheric water and/or ultraviolet radiation, EVA will decompose to produce acetic acid, lowering the pH and increasing the surface corrosion rates of embedded devices. Even though acetic acid is produced at a very slow rate it may not take much to catalyze reactions that lead to rapid module deterioration. Another consideration is that the glass transition of EVA, as measured using dynamic mechanical analysis, begins at temperatures of about -15 C. Temperatures lower thanmore » this can be reached for extended periods of time in some climates. Due to increased moduli below the glass transition temperature, a module may be more vulnerable to damage if a mechanical load is applied by snow or wind at low temperatures. Modules using EVA should not be rated for use at such low temperatures without additional low-temperature mechanical testing beyond the scope of UL 1703.« less

A new UV-curing elastomeric substrate for rapid prototyping of microfluidic devices

NASA Astrophysics Data System (ADS)

Alvankarian, Jafar; Yeop Majlis, Burhanuddin

2012-03-01

Rapid prototyping in the design cycle of new microfluidic devices is very important for shortening time-to-market. Researchers are facing the challenge to explore new and suitable substrates with simple and efficient microfabrication techniques. In this paper, we introduce and characterize a UV-curing elastomeric polyurethane methacrylate (PUMA) for rapid prototyping of microfluidic devices. The swelling and solubility of PUMA in different chemicals is determined. Time-dependent measurements of water contact angle show that the native PUMA is hydrophilic without surface treatment. The current monitoring method is used for measurement of the electroosmotic flow mobility in the microchannels made from PUMA. The optical, physical, thermal and mechanical properties of PUMA are evaluated. The UV-lithography and molding process is used for making micropillars and deep channel microfluidic structures integrated to the supporting base layer. Spin coating is characterized for producing different layer thicknesses of PUMA resin. A device is fabricated and tested for examining the strength of different bonding techniques such as conformal, corona treating and semi-curing of two PUMA layers in microfluidic application and the results show that the bonding strengths are comparable to that of PDMS. We also report fabrication and testing of a three-layer multi inlet/outlet microfluidic device including a very effective fluidic interconnect for application demonstration of PUMA as a promising new substrate. A simple micro-device is developed and employed for observing the pressure deflection of membrane made from PUMA as a very effective elastomeric valve in microfluidic devices.

Design and preliminary testing of a handheld antagonistic SMA actuator for cancellation of human tremor

NASA Astrophysics Data System (ADS)

Pathak, Anupam; Brei, Diann; Luntz, Jonathan

2009-03-01

Essential Tremor is a debilitating disorder that in the US alone is estimated to affect up to ten million people. Unfortunately current treatments (i.e. drug therapy and surgical procedures), are limited in effectiveness and often pose a risk of adverse side-effects. In response to this problem, this paper describes an active cancellation device based on a hand-held Shape Memory Alloy (SMA) actuated stabilization platform. The assistive device is designed to hold and stabilize various objects (e.g. eating utensils, tools, pointing implements, etc.) by sensing the user's tremor and moving the object in an opposite direction using SMA actuators configured in biologically inspired antagonistic pairs. To aid in the design, performance prediction and control of the device, a device model is described that accounts for the device kinematics, SMA thermo-mechanics, and the heat transfer resulting from electrical heating and convective cooling. The system of differential equations in this device model coupled with the controller gain can be utilized to design the operation given a frequency range and power requirement. To demonstrate this, a prototype was built and experimentally tested under external disturbances in the range of 1-5 Hz, resulting in amplitude reduction of up to 80%. The extent of cancellation measured for both single-frequencies and actual human tremor disturbances demonstrate the promise of this approach as a broadly used assistive device for the multitudes afflicted by tremor.

Goals, History and Current Programs of Workshop

NASA Technical Reports Server (NTRS)

2001-01-01

Mr. Robert Fusaro, coordinator for the Glenn Research Center Space Mechanisms program, presented the goals of the workshop, history of previous workshops and gave an overview of current space mechanisms work performed by Glenn Research Center. Highlights of his presentation are shown. Following the presentation, Mr. Fusaro demonstrated the new NASA Space Mechanisms Handbook and Reference Guide CD ROM, which was featured as a highlight of the workshop. The handbook is an authoritative guide for design and testing of space mechanisms and related components. Over 600 pages of guidelines written by 25 experts in the field provide in-depth information on how to design space mechanisms and components, including: deployables, release devices, latches, rotating and pointing mechanisms, dampers, motors, gears, fasteners, valves, etc. The handbook provides details on appropriate environmental and tribological testing methods and practices required to evaluate new mechanisms and components. Distribution of the Handbook and Reference Guide is limited by ITAR (International Traffic in Arms Regulations). It is available only to US companies and citizens. A request form for the CD ROM can be found on the Space Mechanisms Project website at http://www.grc.nasa.gov/WWW/spacemech/.

Design and development of a low-cost biphasic charge-balanced functional electric stimulator and its clinical validation.

PubMed

Shendkar, Chandrashekhar; Lenka, Prasanna K; Biswas, Abhishek; Kumar, Ratnesh; Mahadevappa, Manjunatha

2015-10-01

Functional electric stimulators that produce near-ideal, charge-balanced biphasic stimulation waveforms with interphase delay are considered safer and more efficacious than conventional stimulators. An indigenously designed, low-cost, portable FES device named InStim is developed. It features a charge-balanced biphasic single channel. The authors present the complete design, mathematical analysis of the circuit and the clinical evaluation of the device. The developed circuit was tested on stroke patients affected by foot drop problems. It was tested both under laboratory conditions and in clinical settings. The key building blocks of this circuit are low dropout regulators, a DC-DC voltage booster and a single high-power current source OP-Amp with current-limiting capabilities. This allows the device to deliver high-voltage, constant current, biphasic pulses without the use of a bulky step-up transformer. The advantages of the proposed design over the currently existing devices include improved safety features (zero DC current, current-limiting mechanism and safe pulses), waveform morphology that causes less muscle fatigue, cost-effectiveness and compact power-efficient circuit design with minimal components. The device is also capable of producing appropriate ankle dorsiflexion in patients having foot drop problems of various Medical Research Council scale grades.

Immunologic and tissue biocompatibility of flexible/stretchable electronics and optoelectronics.

PubMed

Park, Gayoung; Chung, Hyun-Joong; Kim, Kwanghee; Lim, Seon Ah; Kim, Jiyoung; Kim, Yun-Soung; Liu, Yuhao; Yeo, Woon-Hong; Kim, Rak-Hwan; Kim, Stanley S; Kim, Jong-Seon; Jung, Yei Hwan; Kim, Tae-Il; Yee, Cassian; Rogers, John A; Lee, Kyung-Mi

2014-04-01

Recent development of flexible/stretchable integrated electronic sensors and stimulation systems has the potential to establish an important paradigm for implantable electronic devices, where shapes and mechanical properties are matched to those of biological tissues and organs. Demonstrations of tissue and immune biocompatibility are fundamental requirements for application of such kinds of electronics for long-term use in the body. Here, a comprehensive set of experiments studies biocompatibility on four representative flexible/stretchable device platforms, selected on the basis of their versatility and relevance in clinical usage. The devices include flexible silicon field effect transistors (FETs) on polyimide and stretchable silicon FETs, InGaN light-emitting diodes (LEDs), and AlInGaPAs LEDs, each on low modulus silicone substrates. Direct cytotoxicity measured by exposure of a surrogate fibroblast line and leachable toxicity by minimum essential medium extraction testing reveal that all of these devices are non-cytotoxic. In vivo immunologic and tissue biocompatibility testing in mice indicate no local inflammation or systemic immunologic responses after four weeks of subcutaneous implantation. The results show that these new classes of flexible implantable devices are suitable for introduction into clinical studies as long-term implantable electronics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

AN APPLICATION OF REINFORCEMENT PRINCIPLES TO CLASSROOM TEACHING.

ERIC Educational Resources Information Center

PORTER, DOUGLAS

THIS RESEARCH CONSIDERED THE TEACHING OF SPELLING AS A PHENOMENON MORE OR LESS ISOLATED FROM THE OTHER AREAS OF LANGUAGE ARTS INSTRUCTION THAT PROBABLY CONTRIBUTE TO SPELLING PERFORMANCE. THE MAJOR OBJECTIVES WERE--(1) TO DESIGN, CONSTRUCT, AND TEST MECHANICAL DEVICES FOR THE TEACHING OF SPELLING, AND (2) TO CARRY OUT AN EXPLORATORY INVESTIGATION…

Degradable phosphate glass fiber reinforced polymer matrices: mechanical properties and cell response.

PubMed

Brauer, Delia S; Rüssel, Christian; Vogt, Sebastian; Weisser, Jürgen; Schnabelrauch, Matthias

2008-01-01

The development of biodegradable materials for internal fracture fixation is of great interest, as they would both eliminate the problem of stress shielding and obviate the need for a second operation to remove fixation devices. Preliminary investigations for the production of degradable fiber reinforced polymer composite materials are detailed. Composites were produced of phosphate invert glass fibers of the glass system P(2)O(5)-CaO-MgO-Na(2)O-TiO(2), which showed a low solubility in previous work. The fibers were embedded into a matrix of a degradable organic polymer network based on methacrylate-modified oligolactide. Fracture behavior, bending strength and elastic modulus were evaluated during 3-point bending tests and the fracture surface of the composites was investigated using a scanning electron microscope. Short-term biocompatibility was tested in an FDA/EtBr viability assay using MC3T3-E1 murine pre-osteoblast cells and showed a good cell compatibility of the composite materials. Results suggested that these composite materials are biocompatible and show mechanical properties which are of interest for the production of degradable bone fixation devices.

Microassembly of Heterogeneous Materials using Transfer Printing and Thermal Processing

PubMed Central

Keum, Hohyun; Yang, Zining; Han, Kewen; Handler, Drew E.; Nguyen, Thong Nhu; Schutt-Aine, Jose; Bahl, Gaurav; Kim, Seok

2016-01-01

Enabling unique architectures and functionalities of microsystems for numerous applications in electronics, photonics and other areas often requires microassembly of separately prepared heterogeneous materials instead of monolithic microfabrication. However, microassembly of dissimilar materials while ensuring high structural integrity has been challenging in the context of deterministic transferring and joining of materials at the microscale where surface adhesion is far more dominant than body weight. Here we present an approach to assembling microsystems with microscale building blocks of four disparate classes of device-grade materials including semiconductors, metals, dielectrics, and polymers. This approach uniquely utilizes reversible adhesion-based transfer printing for material transferring and thermal processing for material joining at the microscale. The interfacial joining characteristics between materials assembled by this approach are systematically investigated upon different joining mechanisms using blister tests. The device level capabilities of this approach are further demonstrated through assembling and testing of a microtoroid resonator and a radio frequency (RF) microelectromechanical systems (MEMS) switch that involve optical and electrical functionalities with mechanical motion. This work opens up a unique route towards 3D heterogeneous material integration to fabricate microsystems. PMID:27427243

Multiscale strain analysis of tissue equivalents using a custom-designed biaxial testing device.

PubMed

Bell, B J; Nauman, E; Voytik-Harbin, S L

2012-03-21

Mechanical signals transferred between a cell and its extracellular matrix play an important role in regulating fundamental cell behavior. To further define the complex mechanical interactions between cells and matrix from a multiscale perspective, a biaxial testing device was designed and built. Finite element analysis was used to optimize the cruciform specimen geometry so that stresses within the central region were concentrated and homogenous while minimizing shear and grip effects. This system was used to apply an equibiaxial loading and unloading regimen to fibroblast-seeded tissue equivalents. Digital image correlation and spot tracking were used to calculate three-dimensional strains and associated strain transfer ratios at macro (construct), meso, matrix (collagen fibril), cell (mitochondria), and nuclear levels. At meso and matrix levels, strains in the 1- and 2-direction were statistically similar throughout the loading-unloading cycle. Interestingly, a significant amplification of cellular and nuclear strains was observed in the direction perpendicular to the cell axis. Findings indicate that strain transfer is dependent upon local anisotropies generated by the cell-matrix force balance. Such multiscale approaches to tissue mechanics will assist in advancement of modern biomechanical theories as well as development and optimization of preconditioning regimens for functional engineered tissue constructs. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Micromachined structures for vertical microelectrooptical devices on InP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seassal, C.; Leclercq, J.L.; Letartre, X.

1996-12-31

The authors presented a microstructuring method in order to fabricate tunable vertical resonant cavity optical devices. PL characterizations were performed on a test structure in order to evaluate the effect of the cavity thickness on the peak characteristics. Modeling of the mechanical, electrostatic, and optical behavior of the device, PL simulation were performed, and showed a good agreement with the experiments. This is a first preliminary validation of InP-based MOEMS for further realization of tunable wavelength-selective passive filters, or photodiodes and lasers by incorporating active region within the cavity. Micro-reflectivity measurements with a spatial resolution of 20 {micro}m are underwaymore » in their group, in order to measure directly the resonance shift and spectral linewidth.« less

The hammer QSD-quick stop device for high speed machining and rubbing

NASA Technical Reports Server (NTRS)

Black, J. T.; James, C. R.

1980-01-01

A quick stop device (QSD) was designed for use in orthogonal machining and rubbing experiments. QSD's are used to obtain chip root samples that are representative of the deformation taking place during dynamic (actual) cutting conditions. These 'frozen' specimens are helpful in examining the plastic deformation that occurs in the regions of compression and shear which form the chip; the secondary shear at the tool-chip interface; and the nose ploughing/flank rubbing action which operates on the newly machined surface. The Hammer QSD employs a shear pin mechanism, broken by a flying hammer, which is traveling at the same velocity as the workpiece. The device has been successfully tested up to 6000 sfpm (30.48 m/sec).

Fabrication of a helical coil shape memory alloy actuator

NASA Astrophysics Data System (ADS)

Odonnell, R. E.

1992-02-01

A fabrication process was developed to form, heat treat, and join NiTi shape memory alloy helical coils for use as mechanical actuators. Tooling and procedures were developed to wind both extension and compression-type coils on a manual lathe. Heat treating fixtures and techniques were used to set the 'memory' of the NiTi alloy to the desired configuration. A swaging process was devised to fasten shape memory alloy extension coils to end fittings for use in actuator testing and for potential attachment to mechanical devices. The strength of this mechanical joint was evaluated.

A stab in the dark: Design and construction of a novel device for conducting incised knife trauma investigations and its initial test.

PubMed

Humphrey, Caitlin; Kumaratilake, Jaliya; Henneberg, Maciej

2016-05-01

Knife attacks are commonly seen in Australia and other countries. During forensic investigations the force with which a wound was inflicted is often questioned. The ability to examine resultant trauma and particular weapons at different forces with an experimental device may lead to better interpretations of knife wounds. The objective of this study is to design, construct and test a device to analyse the characteristics and forces involved in knife attacks, particularly incised wounds. The mechanical variables (e.g. force, angle, knife geometry) involved in knife attacks have been considered to design and construct a suitable device which allows these variables to be systematically controlled and varied. A device was designed and constructed from mild steel. This included a pivoting arm and instrumented knife holder. The arm has adjustable angle and weight so that knives can be operated at different calculated forces. A device was successfully constructed and the repeatability of incised knife trauma and its characteristics in skeletal tissues were investigated. A device which allows reproducible and controlled experiments with knife wounds will be advantageous to forensic investigations. In particular, in determining forces and types of weapons associated with particular wounds, identifying or eliminating suspected weapons and more accurately answering the common question: How much force would be required to cause that particular wound. This could help to characterise the perpetrator. The device can be altered to be used in the future to investigate trauma caused by other weapons. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

An overview of thin film nitinol endovascular devices.

PubMed

Shayan, Mahdis; Chun, Youngjae

2015-07-01

Thin film nitinol has unique mechanical properties (e.g., superelasticity), excellent biocompatibility, and ultra-smooth surface, as well as shape memory behavior. All these features along with its low-profile physical dimension (i.e., a few micrometers thick) make this material an ideal candidate in developing low-profile medical devices (e.g., endovascular devices). Thin film nitinol-based devices can be collapsed and inserted in remarkably smaller diameter catheters for a wide range of catheter-based procedures; therefore, it can be easily delivered through highly tortuous or narrow vascular system. A high-quality thin film nitinol can be fabricated by vacuum sputter deposition technique. Micromachining techniques were used to create micro patterns on the thin film nitinol to provide fenestrations for nutrition and oxygen transport and to increase the device's flexibility for the devices used as thin film nitinol covered stent. In addition, a new surface treatment method has been developed for improving the hemocompatibility of thin film nitinol when it is used as a graft material in endovascular devices. Both in vitro and in vivo test data demonstrated a superior hemocompatibility of the thin film nitinol when compared with commercially available endovascular graft materials such as ePTFE or Dacron polyester. Promising features like these have motivated the development of thin film nitinol as a novel biomaterial for creating endovascular devices such as stent grafts, neurovascular flow diverters, and heart valves. This review focuses on thin film nitinol fabrication processes, mechanical and biological properties of the material, as well as current and potential thin film nitinol medical applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

°Enhancing High Temperature Anode Performance with 2° Anchoring Phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Robert A.; Sofie, Stephen W.; Amendola, Roberta

2015-10-01

Project accomplishments included developing and optimizing strength testing of aluminum titanate (ALT)-doped Ni-YSZ materials and identified the dopant levels that optimized mechanical strength and enhanced electrochemical performance. We also optimized our ability to fabricate electrolyte supported button cells with anodes consisting of powders provided by Fuel Cell Energy. In several instances, those anodes were infiltrated with ALT and tested with hydrogen for 30 hours at 800°C at an applied potential of 0.4 V. Our research activities were focused in three areas: 1) mechanical strength testing on as prepared and reducced nickel-YSZ structures that were either free of a dopant ormore » prepared by mechanically mixing in ALT at various weight percents (up to 10 wt%); 2) 24-hour electrochemical testing of electroylte supported cells having anodes made from Ni/YSZ and Ni/YSZ/ALT anodes with specific attention focused on modeling degradation rates; and 3) operando EIS and optical testing of both in-house fabricated devices as well as membrane electrode assemblies that were acquired from commercial vendors.« less

Topical review: spins and mechanics in diamond

NASA Astrophysics Data System (ADS)

Lee, Donghun; Lee, Kenneth W.; Cady, Jeffrey V.; Ovartchaiyapong, Preeti; Bleszynski Jayich, Ania C.

2017-03-01

There has been rapidly growing interest in hybrid quantum devices involving a solid-state spin and a macroscopic mechanical oscillator. Such hybrid devices create exciting opportunities to mediate interactions between disparate quantum bits (qubits) and to explore the quantum regime of macroscopic mechanical objects. In particular, a system consisting of the nitrogen-vacancy defect center (NV center) in diamond coupled to a high-quality-factor mechanical oscillator is an appealing candidate for such a hybrid quantum device, as it utilizes the highly coherent and versatile spin properties of the defect center. In this paper, we will review recent experimental progress on diamond-based hybrid quantum devices in which the spin and orbital dynamics of single defects are driven by the motion of a mechanical oscillator. In addition, we discuss prospective applications for this device, including long-range, phonon-mediated spin-spin interactions, and phonon cooling in the quantum regime. We conclude the review by evaluating the experimental limitations of current devices and identifying alternative device architectures that may reach the strong coupling regime.

A mechanical energy harvested magnetorheological damper with linear-rotary motion converter

NASA Astrophysics Data System (ADS)

Chu, Ki Sum; Zou, Li; Liao, Wei-Hsin

2016-04-01

Magnetorheological (MR) dampers are promising to substitute traditional oil dampers because of adaptive properties of MR fluids. During vibration, significant energy is wasted due to the energy dissipation in the damper. Meanwhile, for conventional MR damping systems, extra power supply is needed. In this paper, a new energy harvester is designed in an MR damper that integrates controllable damping and energy harvesting functions into one device. The energy harvesting part of this MR damper has a unique mechanism converting linear motion to rotary motion that would be more stable and cost effective when compared to other mechanical transmissions. A Maxon motor is used as a power generator to convert the mechanical energy into electrical energy to supply power for the MR damping system. Compared to conventional approaches, there are several advantages in such an integrated device, including weight reduction, ease in installation with less maintenance. A mechanical energy harvested MR damper with linear-rotary motion converter and motion rectifier is designed, fabricated, and tested. Experimental studies on controllable damping force and harvested energy are performed with different transmissions. This energy harvesting MR damper would be suitable to vehicle suspensions, civil structures, and smart prostheses.

A Reliable Handoff Mechanism for Mobile Industrial Wireless Sensor Networks.

PubMed

Ma, Jian; Yang, Dong; Zhang, Hongke; Gidlund, Mikael

2017-08-04

With the prevalence of low-power wireless devices in industrial applications, concerns about timeliness and reliability are bound to continue despite the best efforts of researchers to design Industrial Wireless Sensor Networks (IWSNs) to improve the performance of monitoring and control systems. As mobile devices have a major role to play in industrial production, IWSNs should support mobility. However, research on mobile IWSNs and practical tests have been limited due to the complicated resource scheduling and rescheduling compared with traditional wireless sensor networks. This paper proposes an effective mechanism to guarantee the performance of handoff, including a mobility-aware scheme, temporary connection and quick registration. The main contribution of this paper is that the proposed mechanism is implemented not only in our testbed but in a real industrial environment. The results indicate that our mechanism not only improves the accuracy of handoff triggering, but also solves the problem of ping-pong effect during handoff. Compared with the WirelessHART standard and the RSSI-based approach, our mechanism facilitates real-time communication while being more reliable, which can help end-to-end packet delivery remain an average of 98.5% in the scenario of mobile IWSNs.

Bending strength measurements at different materials used for IR-cut filters in mobile camera devices

NASA Astrophysics Data System (ADS)

Dietrich, Volker; Hartmann, Peter; Kerz, Franca

2015-03-01

Digital cameras are present everywhere in our daily life. Science, business or private life cannot be imagined without digital images. The quality of an image is often rated by its color rendering. In order to obtain a correct color recognition, a near infrared cut (IRC-) filter must be used to alter the sensitivity of imaging sensor. Increasing requirements related to color balance and larger angle of incidence (AOI) enforced the use of new materials as the e.g. BG6X series which substitutes interference coated filters on D263 thin glass. Although the optical properties are the major design criteria, devices have to withstand numerous environmental conditions during use and manufacturing - as e.g. temperature change, humidity, and mechanical shock, as wells as mechanical stress. The new materials show different behavior with respect to all these aspects. They are usually more sensitive against these requirements to a larger or smaller extent. Mechanical strength is especially different. Reliable strength data are of major interest for mobile phone camera applications. As bending strength of a glass component depends not only upon the material itself, but mainly on the surface treatment and test conditions, a single number for the strength might be misleading if the conditions of the test and the samples are not described precisely,. Therefore, Schott started investigations upon the bending strength data of various IRC-filter materials. Different test methods were used to obtain statistical relevant data.

21 CFR 890.3850 - Mechanical wheelchair.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mechanical wheelchair. 890.3850 Section 890.3850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3850 Mechanical...

21 CFR 890.3850 - Mechanical wheelchair.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mechanical wheelchair. 890.3850 Section 890.3850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3850 Mechanical...

21 CFR 890.3850 - Mechanical wheelchair.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mechanical wheelchair. 890.3850 Section 890.3850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3850 Mechanical...

21 CFR 890.3850 - Mechanical wheelchair.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical wheelchair. 890.3850 Section 890.3850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3850 Mechanical...

21 CFR 890.3850 - Mechanical wheelchair.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mechanical wheelchair. 890.3850 Section 890.3850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3850 Mechanical...

MECHANICAL STRENGTH RESPONSES OF POLED LEAD ZIRCONATE TITANATE UNDER EXTREME ELECTRIC FIELD AND VARIOUS TEMPERATURE CONDITIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hong; Matsunaga, Tadashi; Zhang, Kewei

PZT (lead zirconate titanate), particularly PZT-5A, is used in a variety of critical actuation and sensing systems because of its high Curie temperature and large piezoelectric coefficients. However, PZT is susceptible to mechanical failure. The evaluation of the mechanical strength of the material under the target working conditions is very important. This study presents part of the recent experimental developments in mechanical testing and evaluation of PZT materials at Oak Ridge National Laboratory. Ball-on-ring and four-point bending testing setups were used, with modifications made to account for testing requirements from high-level electric field and elevated temperature. The poled PZT-5A ormore » equivalent material was tested under various specimen and testing conditions. The parameters of the distribution of strengths (characteristic strength and Weibull modulus) are discussed in relation to the testing conditions. Fractographic results based on scanning electron microscopy are also presented and discussed. The related data can serve as input for the design of piezoceramic devices, not only those used in energy systems like fuel injectors in heavy-duty diesel engines, but also those used in structural health monitoring, energy harvesting, and other critical systems in aerospace and civil engineering.« less

Hydraulic Apparatus for Mechanical Testing of Nuts

NASA Technical Reports Server (NTRS)

Hinkel, Todd J.; Dean, Richard J.; Hacker, Scott C.; Harrington, Douglas W.; Salazar, Frank

2004-01-01

The figure depicts an apparatus for mechanical testing of nuts. In the original application for which the apparatus was developed, the nuts are of a frangible type designed for use with pyrotechnic devices in spacecraft applications in which there are requirements for rapid, one-time separations of structures that are bolted together. The apparatus can also be used to test nonfrangible nuts engaged without pyrotechnic devices. This apparatus was developed to replace prior testing systems that were extremely heavy and immobile and characterized by long setup times (of the order of an hour for each nut to be tested). This apparatus is mobile, and the setup for each test can now be completed in about five minutes. The apparatus can load a nut under test with a static axial force of as much as 6.8 x 10(exp 5) lb (3.0 MN) and a static moment of as much as 8.5 x 10(exp 4) lb in. (9.6 x 10(exp 3) N(raised dot)m) for a predetermined amount of time. In the case of a test of a frangible nut, the pyrotechnic devices can be exploded to break the nut while the load is applied, in which case the breakage of the nut relieves the load. The apparatus can be operated remotely for safety during an explosive test. The load-generating portion of the apparatus is driven by low-pressure compressed air; the remainder of the apparatus is driven by 110-Vac electricity. From its source, the compressed air is fed to the apparatus through a regulator and a manually operated valve. The regulated compressed air is fed to a pneumatically driven hydraulic pump, which pressurizes oil in a hydraulic cylinder, thereby causing a load to be applied via a hydraulic nut (not to be confused with the nut under test). During operation, the hydraulic pressure is correlated with the applied axial load, which is verified by use of a load cell. Prior to operation, one end of a test stud (which could be an ordinary threaded rod or bolt) is installed in the hydraulic nut. The other end of the test stud passes through a bearing plate; a load cell is slid onto that end, and then the nut to be tested is threaded onto that end and tightened until the nut and load cell press gently against the bearing plate.

The Effect of Aging on the Accuracy of New Friction-Style Mechanical Torque Limiting Devices for Dental Implants

PubMed Central

Saboury, Aboulfazl; Sadr, Seyed Jalil; Fayaz, Ali; Mahshid, Minoo

2013-01-01

Objective: High variability in delivering the target torque is reported for friction-style mechanical torque limiting devices (F-S MTLDs). The effect of aging (number of use) on the accuracy of these devices is not clear. The purpose of this study was to assess the effect of aging on the accuracy (±10% of the target torque) of F-S MTLDs. Materials and Methods: Fifteen new F-S MTLDs and their appropriate drivers from three different implant manufacturers (Astra Tech, Biohorizon and Dr Idhe), five for each type, were selected. The procedure of peak torque measurement was performed in ten sequences before and after aging. In each sequence, ten repetitions of peak torque values were registered for the aging procedure. To measure the output of each device, a Tohnichi torque gauge was used. Results: Before aging, peak torque measurements of all the devices tested in this study falled within 10% of their preset target values. After aging, a significant difference was seen between raw error values of three groups of MTLDs (P<0.05). More than 50% of all peak torque measurements demonstrated more than 10% difference from their torque values after aging. Conclusion: Within the limitation of this study, aging as an independent factor affects the accuracy of F-S MTLDs. Astra Tech MTLDs presented the most consistent torque output for 25 Ncm target torque. PMID:23724202

Insulator-protected mechanically controlled break junctions for measuring single-molecule conductance in aqueous environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muthusubramanian, N.; Zant, H. S. J. van der; Galan, E.

We present a method to fabricate insulated gold mechanically controlled break junctions (MCBJ) by coating the metal with a thin layer of aluminum oxide using plasma enhanced atomic layer deposition. The Al{sub 2}O{sub 3} thickness deposited on the MCBJ devices was varied from 2 to 15 nm to test the suppression of leakage currents in deionized water and phosphate buffered saline. Junctions coated with a 15 nm thick oxide layer yielded atomically sharp electrodes and negligible conductance counts in the range of 1 to 10{sup −4} G{sub 0} (1 G{sub 0} = 77 μS), where single-molecule conductances are commonly observed. The insulated devices were usedmore » to measure the conductance of an amphiphilic oligophenylene ethynylene derivative in deionized water.« less

New Challenges in Tribology: Wear Assessment Using 3D Optical Scanners

PubMed Central

Valigi, Maria Cristina; Logozzo, Silvia; Affatato, Saverio

2017-01-01

Wear is a significant mechanical and clinical problem. To acquire further knowledge on the tribological phenomena that involve freeform mechanical components or medical prostheses, wear tests are performed on biomedical and industrial materials in order to solve or reduce failures or malfunctions due to material loss. Scientific and technological advances in the field of optical scanning allow the application of innovative devices for wear measurements, leading to improvements that were unimaginable until a few years ago. It is therefore important to develop techniques, based on new instrumentations, for more accurate and reproducible measurements of wear. The aim of this work is to discuss the use of innovative 3D optical scanners and an experimental procedure to detect and evaluate wear, comparing this technique with other wear evaluation methods for industrial components and biomedical devices. PMID:28772905

New Challenges in Tribology: Wear Assessment Using 3D Optical Scanners.

PubMed

Valigi, Maria Cristina; Logozzo, Silvia; Affatato, Saverio

2017-05-18

Wear is a significant mechanical and clinical problem. To acquire further knowledge on the tribological phenomena that involve freeform mechanical components or medical prostheses, wear tests are performed on biomedical and industrial materials in order to solve or reduce failures or malfunctions due to material loss. Scientific and technological advances in the field of optical scanning allow the application of innovative devices for wear measurements, leading to improvements that were unimaginable until a few years ago. It is therefore important to develop techniques, based on new instrumentations, for more accurate and reproducible measurements of wear. The aim of this work is to discuss the use of innovative 3D optical scanners and an experimental procedure to detect and evaluate wear, comparing this technique with other wear evaluation methods for industrial components and biomedical devices.

Mechanical Stability Study for Integrable Optics Test Accelerator at Fermilab

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGee, Mike; Andrews, Richard; Carlson, Kermit

2016-07-01

The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. A heavy low frequency steel floor girder is proposed as the primary tier for IOTA device component support. Two design lengths; (8) 4 m and (2) 2.8 m long girders with identical cross section completely encompass the ring. This study focuses on the 4 m length girder and the development ofmore » a working prototype. Hydrostatic Level Sensor (HLS), temperature, metrology and fast motion measurements characterize the anticipated mechanical stability of the IOTA ring.« less

Experimental Durability Testing of 4H SiC JFET Integrated Circuit Technology at 727 C

NASA Technical Reports Server (NTRS)

Spry, David; Neudeck, Phil; Chen, Liangyu; Chang, Carl; Lukco, Dorothy; Beheim, Glenn M

2016-01-01

We have reported SiC integrated circuits (IC's) with two levels of metal interconnect that have demonstrated prolonged operation for thousands of hours at their intended peak ambient operational temperature of 500 C [1, 2]. However, it is recognized that testing of semiconductor microelectronics at temperatures above their designed operating envelope is vital to qualification. Towards this end, we previously reported operation of a 4H-SiC JFET IC ring oscillator on an initial fast thermal ramp test through 727 C [3]. However, this thermal ramp was not ended until a peak temperature of 880 C (well beyond failure) was attained. Further experiments are necessary to better understand failure mechanisms and upper temperature limit of this extreme-temperature capable 4H-SiC IC technology. Here we report on additional experimental testing of custom-packaged 4H-SiC JFET IC devices at temperatures above 500 C. In one test, the temperature was ramped and then held at 727 C, and the devices were periodically measured until electrical failure was observed. A 4H-SiC JFET on this chip electrically functioned with little change for around 25 hours at 727 C before rapid increases in device resistance caused failure. In a second test, devices from our next generation 4H-SiC JFET ICs were ramped up and then held at 700 C (which is below the maximum deposition temperature of the dielectrics). Three ring oscillators functioned for 8 hours at this temperature before degradation. In a third experiment, an alternative die attach of gold paste and package lid was used, and logic circuit operation was demonstrated for 143.5 hours at 700 C.

Experimental Durability Testing of 4H SiC JFET Integrated Circuit Technology at 727 Degrees Centigrade

NASA Technical Reports Server (NTRS)

Spry, David J.; Neudeck, Philip G.; Chen, Liangyu; Chang, Carl W.; Lukco, Dorothy; Beheim, Glenn M.

2016-01-01

We have reported SiC integrated circuits (ICs) with two levels of metal interconnect that have demonstrated prolonged operation for thousands of hours at their intended peak ambient operational temperature of 500 degrees Centigrade. However, it is recognized that testing of semiconductor microelectronics at temperatures above their designed operating envelope is vital to qualification. Towards this end, we previously reported operation of a 4H-SiC JFET IC ring oscillator on an initial fast thermal ramp test through 727 degrees Centigrade. However, this thermal ramp was not ended until a peak temperature of 880 degrees Centigrade (well beyond failure) was attained. Further experiments are necessary to better understand failure mechanisms and upper temperature limit of this extreme-temperature capable 4H-SiC IC technology.Here we report on additional experimental testing of custom-packaged 4H-SiC JFET IC devices at temperatures above 500 degrees Centigrade. In one test, the temperature was ramped and then held at 727 degrees Centigrade, and the devices were periodically measured until electrical failure was observed. A 4H-SiC JFET on this chip electrically functioned with little change for around 25 hours at 727 degrees Centigrade before rapid increases in device resistance caused failure. In a second test, devices from our next generation 4H-SiC JFET ICs were ramped up and then held at 700 degrees Centigrade (which is below the maximum deposition temperature of the dielectrics). Three ring oscillators functioned for 8 hours at this temperature before degradation. In a third experiment, an alternative die attach of gold paste and package lid was used, and logic circuit operation was demonstrated for 143.5 hours at 700 degrees Centigrade.

Hybrid water immersion simulation of manual IVA performance in weightlessness

NASA Technical Reports Server (NTRS)

Loats, H. L., Jr.; Mattingly, G. S.

1971-01-01

A description is given of the development, tests, and analysis of a manual simulator. The simulator was developed to test mass handling and translation under weightlessness conditions by a test subject. The system is composed of a hybrid simulator with a combination of water immersion and mechanical, Peter Pan, simulation. The concept operates on the equivalence principle, with the subject and the cargo remaining quasi-stationary. Movement is effected through a moving device controlled through force by the subject. Motion response is determined through computations of the inertial movement under such conditions.

Hermetic Seal Leak Detection Apparatus with Variable Size Test Chamber

NASA Technical Reports Server (NTRS)

Kelley, Anthony R. (Inventor)

2015-01-01

The present invention is a versatile hermetic seal leak detection apparatus for testing hermetically sealed containers and devices for leaks without the need to create a custom or specially manufactured testing chamber conforming to the dimensions of the specific object under test. The size of the testing chamber may be mechanically adjusted by the novel use of bellows to reduce and optimize the amount of gas space in a test chamber which surrounds the hermetically sealed object under test. The present invention allows the size of the test chamber to be selectively adjusted during testing to provide an optimum test chamber gas space. The present invention may be further adapted to isolate and test specific portions of the hermetically sealed object under test for leaks.

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3750 - Mechanical table.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical table. 890.3750 Section 890.3750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3750 Mechanical table. (a...

21 CFR 890.3750 - Mechanical table.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mechanical table. 890.3750 Section 890.3750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3750 Mechanical table. (a...

21 CFR 890.3100 - Mechanical chair.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mechanical chair. 890.3100 Section 890.3100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3100 Mechanical chair. (a...

21 CFR 890.3750 - Mechanical table.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mechanical table. 890.3750 Section 890.3750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3750 Mechanical table. (a...

21 CFR 890.3750 - Mechanical table.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mechanical table. 890.3750 Section 890.3750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3750 Mechanical table. (a...

21 CFR 890.3100 - Mechanical chair.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mechanical chair. 890.3100 Section 890.3100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3100 Mechanical chair. (a...

21 CFR 890.3100 - Mechanical chair.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mechanical chair. 890.3100 Section 890.3100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3100 Mechanical chair. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3100 - Mechanical chair.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mechanical chair. 890.3100 Section 890.3100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3100 Mechanical chair. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3750 - Mechanical table.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mechanical table. 890.3750 Section 890.3750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3750 Mechanical table. (a...

21 CFR 890.3100 - Mechanical chair.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical chair. 890.3100 Section 890.3100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3100 Mechanical chair. (a...

Mechanical code comparator

DOEpatents

Peter, Frank J.; Dalton, Larry J.; Plummer, David W.

2002-01-01

A new class of mechanical code comparators is described which have broad potential for application in safety, surety, and security applications. These devices can be implemented as micro-scale electromechanical systems that isolate a secure or otherwise controlled device until an access code is entered. This access code is converted into a series of mechanical inputs to the mechanical code comparator, which compares the access code to a pre-input combination, entered previously into the mechanical code comparator by an operator at the system security control point. These devices provide extremely high levels of robust security. Being totally mechanical in operation, an access control system properly based on such devices cannot be circumvented by software attack alone.

Characterization and Compensation of Network-Level Anomalies in Mixed-Signal Neuromorphic Modeling Platforms

PubMed Central

Petrovici, Mihai A.; Vogginger, Bernhard; Müller, Paul; Breitwieser, Oliver; Lundqvist, Mikael; Muller, Lyle; Ehrlich, Matthias; Destexhe, Alain; Lansner, Anders; Schüffny, René; Schemmel, Johannes; Meier, Karlheinz

2014-01-01

Advancing the size and complexity of neural network models leads to an ever increasing demand for computational resources for their simulation. Neuromorphic devices offer a number of advantages over conventional computing architectures, such as high emulation speed or low power consumption, but this usually comes at the price of reduced configurability and precision. In this article, we investigate the consequences of several such factors that are common to neuromorphic devices, more specifically limited hardware resources, limited parameter configurability and parameter variations due to fixed-pattern noise and trial-to-trial variability. Our final aim is to provide an array of methods for coping with such inevitable distortion mechanisms. As a platform for testing our proposed strategies, we use an executable system specification (ESS) of the BrainScaleS neuromorphic system, which has been designed as a universal emulation back-end for neuroscientific modeling. We address the most essential limitations of this device in detail and study their effects on three prototypical benchmark network models within a well-defined, systematic workflow. For each network model, we start by defining quantifiable functionality measures by which we then assess the effects of typical hardware-specific distortion mechanisms, both in idealized software simulations and on the ESS. For those effects that cause unacceptable deviations from the original network dynamics, we suggest generic compensation mechanisms and demonstrate their effectiveness. Both the suggested workflow and the investigated compensation mechanisms are largely back-end independent and do not require additional hardware configurability beyond the one required to emulate the benchmark networks in the first place. We hereby provide a generic methodological environment for configurable neuromorphic devices that are targeted at emulating large-scale, functional neural networks. PMID:25303102

Characterization and compensation of network-level anomalies in mixed-signal neuromorphic modeling platforms.

PubMed

Petrovici, Mihai A; Vogginger, Bernhard; Müller, Paul; Breitwieser, Oliver; Lundqvist, Mikael; Muller, Lyle; Ehrlich, Matthias; Destexhe, Alain; Lansner, Anders; Schüffny, René; Schemmel, Johannes; Meier, Karlheinz

2014-01-01

Advancing the size and complexity of neural network models leads to an ever increasing demand for computational resources for their simulation. Neuromorphic devices offer a number of advantages over conventional computing architectures, such as high emulation speed or low power consumption, but this usually comes at the price of reduced configurability and precision. In this article, we investigate the consequences of several such factors that are common to neuromorphic devices, more specifically limited hardware resources, limited parameter configurability and parameter variations due to fixed-pattern noise and trial-to-trial variability. Our final aim is to provide an array of methods for coping with such inevitable distortion mechanisms. As a platform for testing our proposed strategies, we use an executable system specification (ESS) of the BrainScaleS neuromorphic system, which has been designed as a universal emulation back-end for neuroscientific modeling. We address the most essential limitations of this device in detail and study their effects on three prototypical benchmark network models within a well-defined, systematic workflow. For each network model, we start by defining quantifiable functionality measures by which we then assess the effects of typical hardware-specific distortion mechanisms, both in idealized software simulations and on the ESS. For those effects that cause unacceptable deviations from the original network dynamics, we suggest generic compensation mechanisms and demonstrate their effectiveness. Both the suggested workflow and the investigated compensation mechanisms are largely back-end independent and do not require additional hardware configurability beyond the one required to emulate the benchmark networks in the first place. We hereby provide a generic methodological environment for configurable neuromorphic devices that are targeted at emulating large-scale, functional neural networks.

Analysis of Glenoid Fixation with Anatomic Total Shoulder Arthroplasty in an Extreme Cyclic Loading Scenario.

PubMed

Roche, Christopher P; Staunch, Cameron; Hahn, William; Grey, Sean G; Flurin, Pierre-Henri; Wright, Thomas W; Zuckerman, Joseph D

2015-12-01

ASTM F2028-14 was adopted to recom mend a cyclic eccentric glenoid edge loading test that simulates the rocking horse loading mechanism beleived to cause aTSA glenoid loosening. While this method accurately simulates that failure mechanism, the recommended 750 N load may not be sufficient to simulate worst-case loading magnitudes, and the recommended 100,000 cycles may not be sufficient to simulate device fatigue-related failure modes. Finally, if greater loading magnitude or a larger number of cycles is performed, the recommended substrate density may not be sufficiently strong to support the elevated loads and cycles. To this end, a new test method is proposed to supplement ASTM F2028-14. A series of cyclic tests were performed to evaluate the long-term fixation strength of two different hybrid glenoid designs in both low (15 pcf) and high (30 pcf) density polyurethane blocks at elevated loads relative to ASTM F2028-14. To simulate a worst case clinical condition in which the humeral head is superiorly migrated, a cyclic load was applied to the superior glenoid rim to induce a maximum torque on the fixation pegs for three different cyclic loading tests: 1. 1,250 N load for 0.75 M cycles in a 15 pcf block, 2. 1,250 N load for 1.5 M cycles in a 30 pcf block, and 3. 2,000 N load for 0.65 M cycles in a 30 pcf block. All devices completed cyclic loading without failure, fracture, or loss of fixation regardless of glenoid design, polyurethane density, loading magnitude, or cycle length. No significant difference in post-cyclic displacement was noted between designs in any of the three tests. Post-cyclic radiographs demonstrated that each device maintained fixa - tion with the metal pegs within the bone-substitute blocks with no fatigue related failures. These results demonstrate that both cemented hybrid glenoids maintained fixation when tested according to each cyclic loading scenario, with no difference in post-cyclic displacement observed between designs. The lack of fatigue-related failures in these elevated load and high cycle test scenarios are promising, as are the relatively low displacements given the extreme nature of each test. This cyclic loading method is intended to supplement the ASTM F2028-14 standard that adequately simulates the rocking horse loading mechanism but may not adequately simulate the fatigue-related failure modes.

Development of the sonic pump levitator

NASA Technical Reports Server (NTRS)

Dunn, S. A.

1985-01-01

The process and mechanism involved in producing glass microballoons (GMBs) of acceptable quality for laser triggered inertial fusion through use of glass jet levitation and manipulation are considered. The gas jet levitation device, called sonic pumps, provides positioning by timely and appropriate application of gas mementum from one or more of six sonic pumps which are arranged orthogonally in opposed pairs about the levitation region and are activated by an electrooptical, computer controlled, feedback system. The levitation device was fabricated and its associated control systems were assembled into a package and tested in reduced gravity flight regime of the NASA KC-135 aircraft.

Experimental determination of micromachined discrete and continuous device spring constants using nanoindentation method

NASA Astrophysics Data System (ADS)

Chan, M. L.; Tay, Francis E.; Logeeswaran, V. J.; Zeng, Kaiyang; Shen, Lu; Chau, Fook S.

2002-04-01

A rapid and accurate static and quasi-static method for determining the out-of-plane spring constraints of cantilevers and a micromachined vibratory sensor is presented. In the past, much of the effort in nanoindentation application was to investigate the thin-film mechanical properties. In this paper, we have utilized the nanoindentation method to measure directly some micromachined device (e.g. microgyroscope) spring constants. The cantilevers and devices tested were fabricated using the MUMPS process and an SOI process (patent pending). Spring constants are determined using a commercial nanoindentation apparatus UMIS-2000 configured with both Berkovich and spherical indenter tip that can be placed onto the device with high accuracy. Typical load resolution is 20micrometers N to 0.5N and a displacement resolution of 0.05nm. Information was deduced from the penetration depth versus load curves during both loading and unloading.

An easy way to measure accurately the direct magnetoelectric voltage coefficient of thin film devices

NASA Astrophysics Data System (ADS)

Poullain, Gilles; More-Chevalier, Joris; Cibert, Christophe; Bouregba, Rachid

2017-01-01

TbxDy1-xFe2/Pt/Pb(Zrx, Ti1-x)O3 thin films were grown on Pt/TiO2/SiO2/Si substrate by multi-target sputtering. The magnetoelectric voltage coefficient αΗΜΕ was determined at room temperature using a lock-in amplifier. By adding, in series in the circuit, a capacitor of the same value as that of the device under test, we were able to demonstrate that the magnetoelectric device behaves as a voltage source. Furthermore, a simple way to subtract the stray voltage arising from the flow of eddy currents in the measurement set-up, is proposed. This allows the easy and accurate determination of the true magnetoelectric voltage coefficient. A large αΗΜΕ of 8.3 V/cm. Oe was thus obtained for a Terfenol-D/Pt/PZT thin film device, without DC magnetic field nor mechanical resonance.

Separation control by vortex generator devices in a transonic channel flow

NASA Astrophysics Data System (ADS)

Bur, Reynald; Coponet, Didier; Carpels, Yves

2009-12-01

An experimental study was conducted in a transonic channel to control by mechanical vortex generator devices the strong interaction between a shock wave and a separated turbulent boundary layer. Control devices—co-rotating and counter-rotating vane-type vortex generators—were implemented upstream of the shock foot region and tested both on a steady shock wave and on a forced shock oscillation configurations. The spanwise spacing of vortex generator devices along the channel appeared to be an important parameter to control the flow separation region. When the distance between each device is decreased, the vortices merging is more efficient to reduce the separation. Their placement upstream of the shock wave is determinant to ensure that vortices have mixed momentum all spanwise long before they reach the separation line, so as to avoid separation cells. Then, vortex generators slightly reduced the amplitude of the forced shock wave oscillation by delaying the upstream displacement of the leading shock.

Annual Conference on Nuclear and Space Radiation Effects, 19th, Las Vegas, NV, July 20-22, 1982, Proceedings

NASA Technical Reports Server (NTRS)

Long, D. M.

1982-01-01

The results of research concerning the effects of nuclear and space radiation are presented. Topics discussed include the basic mechanisms of nuclear and space radiation effects, radiation effects in devices, and radiation effects in microcircuits, including studies of radiation-induced paramagnetic defects in MOS structures, silicon solar cell damage from electrical overstress, radiation-induced charge dynamics in dielectrics, and the enhanced radiation effects on submicron narrow-channel NMOS. Also examined are topics in SGEMP/IEMP phenomena, hardness assurance and testing, energy deposition, desometry, and radiation transport, and single event phenomena. Among others, studies are presented concerning the limits to hardening electronic boxes to IEMP coupling, transient radiation screening of silicon devices using backside laser irradiation, the damage equivalence of electrons, protons, and gamma rays in MOS devices, and the single event upset sensitivity of low power Schottky devices.

Ultra low-cost, portable smartphone optosensors for mobile point-of-care diagnostics

NASA Astrophysics Data System (ADS)

Wang, Li-Ju; Chang, Yu-Chung; Sun, Rongrong; Li, Lei

2018-02-01

Smartphone optosensors with integrated optical components make mobile point-of-care (MPoC) diagnostics be done near patients' side. It'll especially have a significant impact on healthcare delivery in rural or remote areas. Current FDA-approved PoC devices achieving clinical level are still at high cost and not affordable in rural hospitals. We present a series of ultra low-cost smartphone optical sensing devices for mobile point-of-care diagnosis. Aiming different targeting analytes and sensing mechanisms, we developed custom required optical components for each smartphone optosensros. These optical devices include spectrum readers, colorimetric readers for microplate, lateral flow device readers, and chemiluminescence readers. By integrating our unique designed optical components into smartphone optosening platform, the anlaytes can be precisely detected. Clinical testing results show the clinical usability of our smartphone optosensors. Ultra low-cost portable smartphone optosensors are affordable for rural/remote doctors.

[Design of warm-acupuncture technique training evaluation device].

PubMed

Gao, Ming; Xu, Gang; Yang, Huayuan; Liu, Tangyi; Tang, Wenchao

2017-01-12

To design a warm-acupuncture teaching instrument to train and evaluate its manipulation. We refer to the principle and technical operation characteristics of traditional warm-acupuncture, as well as the mechanical design and single-chip microcomputer technology. The device is consisted of device noumenon, universal acupoints simulator, vibration reset system and circuit control system, including frame, platform framework, the swing framework, universal acupoints simulator, vibration reset outfit, operation time circuit, acupuncture sensation display, and vibration control circuit, etc. It can be used to train needle inserting with different angles and moxa rubbing and loading. It displays whether a needle point meets the location required. We determine whether the moxa group on a needle handle is easy to fall off through vibration test, and operation time is showed. The device can objectively help warm-acupuncture training and evaluation so as to promote its clinical standardization manipulation.

Optical to optical interface device

NASA Technical Reports Server (NTRS)

Oliver, D. S.; Vohl, P.; Nisenson, P.

1972-01-01

The development, fabrication, and testing of a preliminary model of an optical-to-optical (noncoherent-to-coherent) interface device for use in coherent optical parallel processing systems are described. The developed device demonstrates a capability for accepting as an input a scene illuminated by a noncoherent radiation source and providing as an output a coherent light beam spatially modulated to represent the original noncoherent scene. The converter device developed under this contract employs a Pockels readout optical modulator (PROM). This is a photosensitive electro-optic element which can sense and electrostatically store optical images. The stored images can be simultaneously or subsequently readout optically by utilizing the electrostatic storage pattern to control an electro-optic light modulating property of the PROM. The readout process is parallel as no scanning mechanism is required. The PROM provides the functions of optical image sensing, modulation, and storage in a single active material.

[Study on an Exoskeleton Hand Function Training Device].

PubMed

Hu, Xin; Zhang, Ying; Li, Jicai; Yi, Jinhua; Yu, Hongliu; He, Rongrong

2016-02-01

Based on the structure and motion bionic principle of the normal adult fingers, biological characteristics of human hands were analyzed, and a wearable exoskeleton hand function training device for the rehabilitation of stroke patients or patients with hand trauma was designed. This device includes the exoskeleton mechanical structure and the electromyography (EMG) control system. With adjustable mechanism, the device was capable to fit different finger lengths, and by capturing the EMG of the users' contralateral limb, the motion state of the exoskeleton hand was controlled. Then driven by the device, the user's fingers conducting adduction/abduction rehabilitation training was carried out. Finally, the mechanical properties and training effect of the exoskeleton hand were verified through mechanism simulation and the experiments on the experimental prototype of the wearable exoskeleton hand function training device.

An Authentication and Key Management Mechanism for Resource Constrained Devices in IEEE 802.11-based IoT Access Networks.

PubMed

Kim, Ki-Wook; Han, Youn-Hee; Min, Sung-Gi

2017-09-21

Many Internet of Things (IoT) services utilize an IoT access network to connect small devices with remote servers. They can share an access network with standard communication technology, such as IEEE 802.11ah. However, an authentication and key management (AKM) mechanism for resource constrained IoT devices using IEEE 802.11ah has not been proposed as yet. We therefore propose a new AKM mechanism for an IoT access network, which is based on IEEE 802.11 key management with the IEEE 802.1X authentication mechanism. The proposed AKM mechanism does not require any pre-configured security information between the access network domain and the IoT service domain. It considers the resource constraints of IoT devices, allowing IoT devices to delegate the burden of AKM processes to a powerful agent. The agent has sufficient power to support various authentication methods for the access point, and it performs cryptographic functions for the IoT devices. Performance analysis shows that the proposed mechanism greatly reduces computation costs, network costs, and memory usage of the resource-constrained IoT device as compared to the existing IEEE 802.11 Key Management with the IEEE 802.1X authentication mechanism.

An Authentication and Key Management Mechanism for Resource Constrained Devices in IEEE 802.11-based IoT Access Networks

PubMed Central

Han, Youn-Hee; Min, Sung-Gi

2017-01-01

Many Internet of Things (IoT) services utilize an IoT access network to connect small devices with remote servers. They can share an access network with standard communication technology, such as IEEE 802.11ah. However, an authentication and key management (AKM) mechanism for resource constrained IoT devices using IEEE 802.11ah has not been proposed as yet. We therefore propose a new AKM mechanism for an IoT access network, which is based on IEEE 802.11 key management with the IEEE 802.1X authentication mechanism. The proposed AKM mechanism does not require any pre-configured security information between the access network domain and the IoT service domain. It considers the resource constraints of IoT devices, allowing IoT devices to delegate the burden of AKM processes to a powerful agent. The agent has sufficient power to support various authentication methods for the access point, and it performs cryptographic functions for the IoT devices. Performance analysis shows that the proposed mechanism greatly reduces computation costs, network costs, and memory usage of the resource-constrained IoT device as compared to the existing IEEE 802.11 Key Management with the IEEE 802.1X authentication mechanism. PMID:28934152

Frequency Rectification Applied to Piezoelectric Energy Harvesting and Improving Available Power of Piezoelectric Motors

NASA Astrophysics Data System (ADS)

Kuroda, Kazuaki; LCGT Collaboration

Piezoelectric materials are just now, within the last decade, coming into their own as a commercial material. Capable of converting energy from the mechanical domain to the electrical domain; piezos are ideal sensors, vibration dampers, energy harvesters, and actuators. Frequency rectification, or the conversion of small, high frequency piezoelectric vibrations into useful low frequency actuation, is required to obtain widespread industrial use of piezoelectric devices. This work examines three manifestations of piezoelectric frequency rectification: energy harvesting, a hydraulic motor, and friction based commercial-off-the-shelf motors. An energy harvesting device is developed, manufactured, and tested in this work, resulting in the development of a high Energy Density (J/m 3), high Power Density (W/m3) energy harvester. The device is shown to have an Energy Density nearly twice that of a similar conventional energy harvesting device. The result of this work is the development of an energy harvesting system that generates more energy in a given volume of piezoelectric material, opening the possibility of miniaturization of energy harvesting devices. Also presented is an effort to integrate a high frequency, high flow rate micromachined valve array into a PiezoHydraulic Pump (PHP), enabling resonant operation of the PHP. Currently, the device is limited by the resonant frequency of the proprietary passive check valves. The PHP is fully characterized, and the microvalve array is tested to determine its resonant frequency in a fluid medium. The valve testing resulted in a resonant frequency of 6.9 kHz, slightly lower than the target operating frequency of 10 kHz. Finally, the results of an examination of frequency rectification as applied to COTS piezoelectric motors are presented. Currently, motors are almost universally characterized based upon their available mechanical power. A better comparison is one based upon the actual Energy Density of the piezoelectric material utilized in the motor compared to the theoretical maximum Energy Density under the motor operating conditions (i.e., frequency, applied electric field). The result of this work is a more descriptive metric to evaluate piezoelectric motors that provides information on the effectiveness of the motor drive train; that is, how effectively the motion of the piezoelectric is transferred to the outside world.

Dynamic Loading Assembly for Testing Actuators of Segmented Mirror Telescope

NASA Astrophysics Data System (ADS)

Deshmukh, Prasanna Gajanan; Parihar, Padmakar; Balasubramaniam, Karthik A.; Mishra, Deepta Sundar; Mahesh, P. K.

Upcoming large telescopes are based on Segmented Mirror Telescope (SMT) technology which uses small hexagonal mirror segments placed side by side to form the large monolithic surface. The segments alignment needs to be maintained against external disturbances like wind, gravity, temperature and structural vibration. This is achieved by using three position actuators per segment working at few-nanometer scale range along with a local closed loop controller. The actuator along with a controller is required to meet very stringent performance requirements, such as track rates up to 300nm/s (90mN/s) with tracking errors less than 5nm, dynamical forces of up to ±40N, ability to reject disturbances introduced by the wind as well as by mechanical vibration generated in the mirror cell, etc. To conduct these performance tests in more realistic manner, we have designed and developed a Dynamic Loading Assembly (DLA) at Indian Institute of Astrophysics (IIA), Bangalore. DLA is a computer controlled force-inducing device, designed in a modular fashion to generate different types of user-defined disturbances in extremely precise and controlled manner. Before realizing the device, using a simple spring-mass-damper-based mathematical model, we ensured that the concept would indeed work. Subsequently, simple concept was converted into a detailed mechanical design and parts were manufactured and assembled. DLA has static and dynamic loading capabilities up to 250N and 18N respectively, with a bandwidth sufficient to generate wind disturbances. In this paper, we present various performance requirements of SMT actuators as well as our effort to develop a dynamic loading device which can be used to test these actuators. Well before using DLA for meaningful testing of the actuator, the DLA itself have gone through various tests and improvements phases. We have successfully demonstrated that DLA can be used to check the extreme performance of two different SMT actuators, which are expected to track the position/force with a few nanometer accuracy.