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Sample records for cantilever cross-arch fixed

  1. The cantilever fixed partial denture--a literature review.

    PubMed

    Himmel, R; Pilo, R; Assif, D; Aviv, I

    1992-04-01

    The cantilever fixed partial denture (FPD) is a restoration with one or more abutments at one end and unsupported at the other end. Forces transmitted through the cantilevered pontics can cause tilting and rotational movements of the abutments. In a cross-arch unilateral cantilever FPD, the distal cantilevered unit is subjected to comparatively less force than the contralateral posterior abutment. The unilateral lack of terminal abutments causes lateral bending forces activate peripheral inhibitory feedback reactions from the periodontal and/or temporomandibular mechanoreceptors. The greatest strain in distal cantilevered FPDs is recorded mesial to the most distal retainer because most fractures occur in this location. To improve the prognosis of the FPD cantilever, the number of abutments should be increased and the number of pontics decreased. The abutment teeth need long roots and acceptable alveolar support. Prepared abutments require adequate length and parallel axial walls. An equilibrated and harmonious occlusion is necessary, as well as exemplary oral hygiene. A cantilevered FPD with adequate periodontal support can replace any tooth in the dental arch, but is especially useful as an alternative to a removable partial denture. The cantilevered FPD requires at least two abutment teeth. The only documented exception permitting a single abutment is the replacement of a maxillary lateral incisor with the canine as an abutment. An alternative to the cantilevered FPD is the osseointegrated implant. As osseointegrated implants become more popular, the need for the tooth-supported cantilevered FPD may decline, but it will remain an alternative treatment modality. PMID:1507130

  2. 41. Fixed Span, Floor Beam 1, showing the cantilever; looking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Fixed Span, Floor Beam 1, showing the cantilever; looking N. (The splice between the original beam and the 1960 extension (widening) is between the two stringers to the left of the bottom chord tension members). - Pacific Shortline Bridge, U.S. Route 20,spanning Missouri River, Sioux City, Woodbury County, IA

  3. Assessment of Various Factors for Feasibility of Fixed Cantilever Bridge: A Review Study

    PubMed Central

    Sharma, Ashu; Rahul, G. R.; Poduval, Soorya T.; Shetty, Karunakar

    2012-01-01

    Cantilever fixed partial dentures are defined as having one or more abutments at one end of the prosthesis while the other end is unsupported. Much controversy without documentary evidence has surrounded this prosthesis. Despite negative arguments, the cantilever prosthesis has been used extensively by the clinicians. If used nonjudiciously without following proper guidelines these might lead to some complications. Although complications may be an indication that clinical failure has occurred, this is not typically the case. It is also possible that complications may reflect substandard care. Apart from the substandard care, the unique arrangement of the abutments and pontic also accounts for the prime disadvantage: the creation of a class I lever system. When the cantilevered pontic is placed under occlusal function, forces are placed on the abutments. There are various criteria and factors necessary for a successful cantilever fixed partial denture (FPD). The purpose of this paper is to discuss briefly various factors involved in the planning of a cantilever fixed partial denture. PMID:22461987

  4. Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures.

    PubMed

    Suedam, Valdey; Moretti Neto, Rafael Tobias; Sousa, Edson Antonio Capello; Rubo, José Henrique

    2016-04-01

    Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm) was used. Six groups were formed according to the alloy's framework (CoCr or PdAg) and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm). A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05) between the groups. Pearson correlation test (p<0.05) was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm. PMID:27119758

  5. Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures

    PubMed Central

    SUEDAM, Valdey; MORETTI, Rafael Tobias; SOUSA, Edson Antonio Capello; RUBO, José Henrique

    2016-01-01

    ABSTRACT Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm) was used. Six groups were formed according to the alloy’s framework (CoCr or PdAg) and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm). A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05) between the groups. Pearson correlation test (p<0.05) was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm. PMID:27119758

  6. Three-dimensional finite element analysis of anterior two-unit cantilever resin-bonded fixed dental prostheses.

    PubMed

    Keulemans, Filip; Shinya, Akikazu; Lassila, Lippo V J; Vallittu, Pekka K; Kleverlaan, Cornelis J; Feilzer, Albert J; De Moor, Roeland J G

    2015-01-01

    The aim of this study was to evaluate the influence of different framework materials on biomechanical behaviour of anterior two-unit cantilever resin-bonded fixed dental prostheses (RBFDPs). A three-dimensional finite element model of a two-unit cantilever RBFDP replacing a maxillary lateral incisor was created. Five framework materials were evaluated: direct fibre-reinforced composite (FRC-Z250), indirect fibre-reinforced composite (FRC-ES), gold alloy (M), glass ceramic (GC), and zirconia (ZI). Finite element analysis was performed and stress distribution was evaluated. A similar stress pattern, with stress concentrations in the connector area, was observed in RBFDPs for all materials. Maximal principal stress showed a decreasing order: ZI>M>GC>FRC-ES>FRC-Z250. The maximum displacement of RBFDPs was higher for FRC-Z250 and FRC-ES than for M, GC, and ZI. FE analysis depicted differences in location of the maximum stress at the luting cement interface between materials. For FRC-Z250 and FRC-ES, the maximum stress was located in the upper part of the proximal area of the retainer, whereas, for M, GC, and ZI, the maximum stress was located at the cervical outline of the retainer. The present study revealed differences in biomechanical behaviour between all RBFDPs. The general observation was that a RBFDP made of FRC provided a more favourable stress distribution. PMID:25879077

  7. Three-Dimensional Finite Element Analysis of Anterior Two-Unit Cantilever Resin-Bonded Fixed Dental Prostheses

    PubMed Central

    Shinya, Akikazu; Lassila, Lippo V. J.; Vallittu, Pekka K.; Kleverlaan, Cornelis J.; Feilzer, Albert J.; De Moor, Roeland J. G.

    2015-01-01

    The aim of this study was to evaluate the influence of different framework materials on biomechanical behaviour of anterior two-unit cantilever resin-bonded fixed dental prostheses (RBFDPs). A three-dimensional finite element model of a two-unit cantilever RBFDP replacing a maxillary lateral incisor was created. Five framework materials were evaluated: direct fibre-reinforced composite (FRC-Z250), indirect fibre-reinforced composite (FRC-ES), gold alloy (M), glass ceramic (GC), and zirconia (ZI). Finite element analysis was performed and stress distribution was evaluated. A similar stress pattern, with stress concentrations in the connector area, was observed in RBFDPs for all materials. Maximal principal stress showed a decreasing order: ZI > M > GC > FRC-ES > FRC-Z250. The maximum displacement of RBFDPs was higher for FRC-Z250 and FRC-ES than for M, GC, and ZI. FE analysis depicted differences in location of the maximum stress at the luting cement interface between materials. For FRC-Z250 and FRC-ES, the maximum stress was located in the upper part of the proximal area of the retainer, whereas, for M, GC, and ZI, the maximum stress was located at the cervical outline of the retainer. The present study revealed differences in biomechanical behaviour between all RBFDPs. The general observation was that a RBFDP made of FRC provided a more favourable stress distribution. PMID:25879077

  8. Inlay-retained cantilever fixed dental prostheses to substitute a single premolar: impact of zirconia framework design after dynamic loading.

    PubMed

    Shahin, Ramez; Tannous, Fahed; Kern, Matthias

    2014-08-01

    The purpose of this in-vitro study was to evaluate the influence of the framework design on the durability of inlay-retained cantilever fixed dental prostheses (IR-FDPs), made from zirconia ceramic, after artificial ageing. Forty-eight caries-free human premolars were prepared as abutments for all-ceramic cantilevered IR-FDPs using six framework designs: occlusal-distal (OD) inlay, OD inlay with an oral retainer wing, OD inlay with two retainer wings, mesial-occlusal-distal (MOD) inlay, MOD inlay with an oral retainer ring, and veneer partial coping with a distal box (VB). Zirconia IR-FDPs were fabricated via computer-aided design/computer-aided manufacturing (CAD/CAM) technology. The bonding surfaces were air-abraded (50 μm alumina/0.1 MPa), and the frameworks were bonded with adhesive resin cement. Specimens were stored for 150 d in a 37°C water bath during which they were thermocycled between 5 and 55°C for 37,500 cycles; thereafter, they were exposed to 600,000 cycles of dynamic loading with a 5-kg load in a chewing simulator. All surviving specimens were loaded onto the pontic and tested until failure using a universal testing machine. The mean failure load of the groups ranged from 260.8 to 746.7 N. Statistical analysis showed that both MOD groups exhibited significantly higher failure loads compared with the other groups (i.e. the three OD groups and the VB group) and that there was no significant difference in the failure load among the OD groups and the VB group. In conclusion, zirconia IR-FDPs with a modified design exhibited promising failure modes. PMID:24910293

  9. [Influence of retainer design on fixation strength of resin-bonded glass fiber reinforced composite fixed cantilever dentures].

    PubMed

    Petrikas, O A; Voroshilin, Iu G; Petrikas, I V

    2013-01-01

    Fiber-reinforced composite (FRC) fixed partial dentures (FPD) have become an accepted part of the restorative dentist's armamentarium. The aim of this study was to evaluate in vitro the influence of retainer design on the strength of two-unit cantilever resin-bonded glass FRC-FPDs. Four retainer designs were tested: a dual wing, a dual wing + horizontal groove, a dual wing + occlusal rest and a step-box. Of each design on 7 human mandibular molars, FRC-FPDs of a premolar size were produced. The FRC framework was made of resin Revolution (Kerr) impregnated glass fibers (GlasSpan, GlasSpan) and veneered with hybrid resin composite (Charisma, Kulzer). Revolution (Kerr) was used as resin luting cement. FRC-FPDs were loaded to failure in a universal testing machine. T (Student's)-test was used to evaluate the data. The four designs were analyzed with finite element analysis (FEA) to reveal the stress distribution within the tooth/restoration complex. Significantly lower fracture strengths were observed with inlay-retained FPDs (step-box: 172±11 N) compared to wing-retained FPDs (p<0.05) (a dual wing + horizontal groove 222±9 N). The highest fracture strengths were observed with dual wing + occlusal rest FPDs: 250±10 N compared to inlay-retained FPDs (p<0.001) and wing-retained FPDs (p<0.001). FEA showed more favorable stress distributions within the tooth/restoration complex for dual wing retainers+ occlusal rest FPDs. There was stress concentration around connectors and retainers near connectors. A dual-wing retainer with occlusal rest is the optimal design for replacement of a single premolar by means of a two-unit cantilever FRC-FPDs. PMID:23715455

  10. INFLUENCE OF DIFFERENT CANTILEVER EXTENSIONS AND GLASS OR POLYARAMID REINFORCEMENT FIBERS ON FRACTURE STRENGTH OF IMPLANT-SUPPORTED TEMPORARY FIXED PROSTHESIS

    PubMed Central

    Colán Guzmán, Paola; de Freitas, Fernando Furtado Antunes; Ferreira, Paulo Martins; de Freitas, César Antunes; Reis, Kátia Rodrigues

    2008-01-01

    In long-term oral rehabilitation treatments, resistance of provisional crowns is a very important factor, especially in cases of an extensive edentulous distal space. The aim of this laboratorial study was to evaluate an acrylic resin cantilever-type prosthesis regarding the flexural strength of its in-balance portion as a function of its extension variation and reinforcement by two types of fibers (glass and polyaramid), considering that literature is not conclusive on this subject. Each specimen was composed by 3 total crowns at its mesial portion, each one attached to an implant component (abutment), while the distal portion (cantilever) had two crowns. Each specimen was constructed by injecting acrylic resin into a two-part silicone matrix placed on a metallic base. In each specimen, the crowns were fabricated with either acrylic resin (control group) or acrylic resin reinforced by glass (Fibrante, Angelus) or polyaramide (Kevlar 49, Du Pont) fibers. Compression load was applied on the cantilever, in a point located 7, 14 or 21 mm from the distal surface of the nearest crown with abutment, to simulate different extensions. The specimen was fixed on the metallic base and the force was applied until fracture in a universal test machine. Each one of the 9 sub-groups was composed by 10 specimens. Flexural strength means (in kgf) for the distances of 7, 14 and 21 mm were, respectively, 28.07, 8.27 and 6.39 for control group, 31.89, 9.18 and 5.16 for Kevlar 49 and 30.90, 9.31 and 6.86 for Fibrante. Data analysis ANOVA showed statistically significant difference (p<0.05) only regarding cantilever extension. Tukey's test detected significantly higher flexural strength for the 7 mm-distance, followed by 14 and 21 mm. Fracture was complete only on specimens of non-reinforced groups. PMID:19089201

  11. Biomechanical load analysis of cantilevered implant systems.

    PubMed

    Osier, J F

    1991-01-01

    Historically, dental implants have been placed in areas where quality bone exists. The maxillary sinus areas and mandibular canal proximities have been avoided. From these placements, various cantilevered prosthetic applications have emerged. This analysis uses static engineering principles to define the loads (i.e., forces) placed upon the implants. These principles make use of Newton's first and third laws of mechanics by summing the forces and moments to zero. These summations then generate mathematical equations and their algebraic solutions. Three implant systems are analyzed. The first is a two-implant system. The second is a three-implant cross-arch stabilized system usually found in mandibular replacements of lower full dentures. The third is a five-implant system which is identical to the three-implant cantilevered system but which uses implants in the first molar area, thereby negating the cantilevered load magnification of the three-implant design. These analyses demonstrate that, in a cantilevered application, the implant closest to the point of load application (usually the most posterior implant) takes the largest compressive load. Implants opposite the load application (generally the anterior implant) are in tension. These loads on the implants are normally magnified over the biting force and can easily reach 2 1/2 to five times the biting load. PMID:1942131

  12. [Physiological behavior of Cantilever].

    PubMed

    Feeldman, I; Frugone, R; Vládilo, N T

    1990-11-01

    The prosthetic rehabilitation is common of the integral treatment of patients that integral treatment of patients that have lost one or several dental pieces as a consequence of periodontal diseases. It has been demonstrated that plural fixed prothesis to extention, plovide a distribution pattern and magnitude of favourable forces to the periodontal during the different functions of the stomathologic apparatus, that justify rehabilitation based to it patients periodontically affected. The physiological behaviour of cantilever was basically analized on report on different investigation studies performed on patients periodontically diminis hed treated with plural fixed prothesis of crossed are with two unit or bilateral vear cantilever units, dento supported or fixed in place on implants. It is important to emphasize that favourable results previously analized in base to this type of rehabilitation in its different varieties have been obtained through record done on patients in which considerations of indications, design and occlusion stability have been optimized. PMID:2075270

  13. Compliant cantilevered micromold

    DOEpatents

    Morales, Alfredo Martin; Domeier, Linda A.; Gonzales, Marcela G.; Keifer, Patrick N.; Garino, Terry Joseph

    2006-08-15

    A compliant cantilevered three-dimensional micromold is provided. The compliant cantilevered micromold is suitable for use in the replication of cantilevered microparts and greatly simplifies the replication of such cantilevered parts. The compliant cantilevered micromold may be used to fabricate microparts using casting or electroforming techniques. When the compliant micromold is used to fabricate electroformed cantilevered parts, the micromold will also comprise an electrically conducting base formed by a porous metal substrate that is embedded within the compliant cantilevered micromold. Methods for fabricating the compliant cantilevered micromold as well as methods of replicating cantilevered microparts using the compliant cantilevered micromold are also provided.

  14. Piezoelectric cantilever sensors

    NASA Technical Reports Server (NTRS)

    Shih, Wan Y. (Inventor); Shih, Wei-Heng (Inventor); Shen, Zuyan (Inventor)

    2008-01-01

    A piezoelectric cantilever with a non-piezoelectric, or piezoelectric tip useful as mass and viscosity sensors. The change in the cantilever mass can be accurately quantified by monitoring a resonance frequency shift of the cantilever. For bio-detection, antibodies or other specific receptors of target antigens may be immobilized on the cantilever surface, preferably on the non-piezoelectric tip. For chemical detection, high surface-area selective absorbent materials are coated on the cantilever tip. Binding of the target antigens or analytes to the cantilever surface increases the cantilever mass. Detection of target antigens or analytes is achieved by monitoring the cantilever's resonance frequency and determining the resonance frequency shift that is due to the mass of the adsorbed target antigens on the cantilever surface. The use of a piezoelectric unimorph cantilever allows both electrical actuation and electrical sensing. Incorporating a non-piezoelectric tip (14) enhances the sensitivity of the sensor. In addition, the piezoelectric cantilever can withstand damping in highly viscous liquids and can be used as a viscosity sensor in wide viscosity range.

  15. Use of Cantilever Mechanics for Impacted Teeth: Case Series

    PubMed Central

    Paduano, Sergio; Spagnuolo, Gianrico; Franzese, Gerardo; Pellegrino, Gioacchino; Valletta, Rosa; Cioffi, Iacopo

    2013-01-01

    This paper describes the orthodontic treatment, and the biomechanics of cantilevers for the impaction of permanent teeth in youngs, adolescents, and adults. In these case series, multibracket straightwire fixed appliances, together with cantilever mechanics, were used to treat the impaired occlusion. PMID:24511332

  16. Cantilevered carbon nanotube hygrometer

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Toshinori; Terada, Yuki; Takei, Kuniharu; Akita, Seiji; Arie, Takayuki

    2014-05-01

    We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT.

  17. A Weed Cantilever

    ERIC Educational Resources Information Center

    Keller, Elhannan L.; Padalino, John

    1977-01-01

    Describes the Environmental Action Task activity, which may be used as a recreational game or an environmental perception experience, may be conducted indoors or out-of-doors, using weed stems (or spaghetti) and masking tape to construct a cantilever. Small groups of children work together to make the cantilever with the longest arm. Further…

  18. VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER SECTION, LOOKING WEST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER SECTION, LOOKING WEST. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  19. VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER PORTAL ON WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER PORTAL ON WEST BANK SIDE LOOKING NORTHWEST. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  20. Measuring the cantilever-position-sensitive detector distance and cantilever curvature for cantilever sensor applications.

    PubMed

    Xu, Meng; Tian, Ye; Coates, M L; Beaulieu, L Y

    2009-09-01

    Measuring cantilever sensor deflections using an optical beam deflection system is more complicated than often assumed. The direction of the reflected beam is dependent on the surface normal of the cantilever, which in turn is dependent on the state of the cantilever. It is often assumed that the cantilever is both straight and perfectly level before the onset of sensing experiments although this assumption, especially the former, is rarely true. Failure to characterize the initial state of the cantilever can lead to irreproducibility in cantilever sensor measurements. We have developed three new methods for characterizing the initial state of the cantilever. In the first case we show how to define the initial angle of inclination beta of the chip on which the cantilever is attached. This method was tested using an aluminum block with a known angle of inclination. A new method for determining the initial distance L(o) between the cantilever and the position-sensitive detector (PSD) is also presented. This parameter which behaves as an amplification factor of the PSD signal is critical for obtaining precise cantilever sensor data. Lastly, we present a method for determining the initial curvature of the cantilever which often results from depositing the sensing platform on the lever. Experiments conducted using deflected cantilevers showed the model to be accurate. The characterization methods presented in this work are simple to use, easy to implement, and can be incorporated into most cantilever sensor setups. PMID:19791971

  1. Cantilever and implant biomechanics: a review of the literature. Part 1.

    PubMed

    Rodriguez, A M; Aquilino, S A; Lund, P S

    1994-03-01

    In Part 1 of this two-part literature review, the biomechanics of cantilever fixed partial dentures are reviewed. Theoretical constructs of implant biomechanics with special emphasis on implant-supported cantilevers are also discussed. Finally, an overview of the literature regarding occlusal forces generated by patients with implant-supported prostheses is presented. PMID:8061790

  2. 77 FR 826 - Cantilever Capital, LLC and Cantilever Group, LLC; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-06

    ... COMMISSION Cantilever Capital, LLC and Cantilever Group, LLC; Notice of Application December 29, 2011. AGENCY...)(3) of the Act. Applicants: Cantilever Capital, LLC (``Cantilever'' or the ``Company'') and Cantilever Group, LLC (the ``Adviser''). Summary of Application: Cantilever, or any successor to...

  3. Gland With Cantilever Seal

    NASA Technical Reports Server (NTRS)

    Melton, Patrick B.

    1989-01-01

    Single-piece gland forms tight seal on probe or tube containing liquid or gas at high pressure. Gland and probe align as assembled by simple torquing procedure. Disconnected easily and reused at same site. Made from any of wide variety of materials so compatible with application. Cantilever ring at top of gland bites into wall of tube or probe, sealing it. Wall of tube or probe must be thick enough to accommodate deformation without rupturing. Maximum deformation designed in coordination with seating and deformation of boss or conical seal.

  4. Cantilever clamp fitting

    NASA Technical Reports Server (NTRS)

    Melton, Patrick B. (Inventor)

    1989-01-01

    A device is disclosed for sealing and clamping a cylindrical element which is to be attached to an object such as a wall, a pressurized vessel or another cylindrical element. The device includes a gland having an inner cylindrical wall, which is threaded at one end and is attached at a bendable end to a deformable portion, which in turn is attached to one end of a conical cantilever structure. The other end of the cantilever structure connects at a bendable area to one end of an outer cylindrical wall. The opposite end of cylindrical wall terminates in a thickened portion, the radially outer surface of which is adapted to accommodate a tool for rotating the gland. The terminal end of cylindrical wall also includes an abutment surface, which is adapted to engage a seal, which in turn engages a surface of a receiver. The receiver further includes a threaded portion for engagement with the threaded portion of gland whereby a tightening rotation of gland relative to receiver will cause relative movement between cylindrical walls and of gland. This movement causes a rotation of the conical structure and thus a bending action at bending area and at the bending end of the upper end of inner cylindrical wall. These rotational and bending actions result in a forcing of the deformable portion radially inwardly so as to contact and deform a pipe. This forcible contact creates a seal between gland and pipe, and simultaneously clamps the pipe in position.

  5. Cantilever epitaxial process

    DOEpatents

    Ashby, Carol I.; Follstaedt, David M.; Mitchell, Christine C.; Han, Jung

    2003-07-29

    A process of growing a material on a substrate, particularly growing a Group II-VI or Group III-V material, by a vapor-phase growth technique where the growth process eliminates the need for utilization of a mask or removal of the substrate from the reactor at any time during the processing. A nucleation layer is first grown upon which a middle layer is grown to provide surfaces for subsequent lateral cantilever growth. The lateral growth rate is controlled by altering the reactor temperature, pressure, reactant concentrations or reactant flow rates. Semiconductor materials, such as GaN, can be produced with dislocation densities less than 10.sup.7 /cm.sup.2.

  6. Vertical electrostatic force in MEMS cantilever IR sensor

    NASA Astrophysics Data System (ADS)

    Rezadad, Imen; Boroumand Azad, Javaneh; Smith, Evan M.; Alhasan, Ammar; Peale, Robert E.

    2014-06-01

    A MEMS cantilever IR detector that repetitively lifts from the surface under the influence of a saw-tooth electrostatic force, where the contact duty cycle is a measure of the absorbed IR radiation, is analyzed. The design is comprised of three parallel conducting plates. Fixed buried and surface plates are held at opposite potential. A moveable cantilever is biased the same as the surface plate. Calculations based on energy methods with position-dependent capacity and electrostatic induction coefficients demonstrate the upward sign of the force on the cantilever and determine the force magnitude. 2D finite element method calculations of the local fields confirm the sign of the force and determine its distribution across the cantilever. The upward force is maximized when the surface plate is slightly larger than the other two. The electrostatic repulsion is compared with Casimir sticking force to determine the maximum useful contact area. MEMS devices were fabricated and the vertical displacement of the cantilever was observed in a number of experiments. The approach may be applied also to MEMS actuators and micromirrors.

  7. Chemical sensor with oscillating cantilevered probe

    DOEpatents

    Adams, Jesse D

    2013-02-05

    The invention provides a method of detecting a chemical species with an oscillating cantilevered probe. A cantilevered beam is driven into oscillation with a drive mechanism coupled to the cantilevered beam. A free end of the oscillating cantilevered beam is tapped against a mechanical stop coupled to a base end of the cantilevered beam. An amplitude of the oscillating cantilevered beam is measured with a sense mechanism coupled to the cantilevered beam. A treated portion of the cantilevered beam is exposed to the chemical species, wherein the cantilevered beam bends when exposed to the chemical species. A second amplitude of the oscillating cantilevered beam is measured, and the chemical species is determined based on the measured amplitudes.

  8. Viscous drag measurements utilizing microfabricated cantilevers

    SciTech Connect

    Oden, P.I.; Chen, G.Y.; Steele, R.A.; Warmack, R.J.; Thundat, T.

    1996-06-01

    The influence of viscous drag forces on cantilevers is investigated using standard atomic force microscope (AFM) cantilevers. Viscosity effects on several geometrically different cantilevers manifest themselves as variations in resonance frequencies, quality factors, and cantilever response amplitudes. With this novel measurement, a single cantilever can be used to measure viscosities ranging from {eta}=10{sup {minus}2} to 10{sup 2} g/cms. {copyright} {ital 1996 American Institute of Physics.}

  9. Mechanical behavior simulation of MEMS-based cantilever beam using COMSOL multiphysics

    SciTech Connect

    Acheli, A. Serhane, R.

    2015-03-30

    This paper presents the studies of mechanical behavior of MEMS cantilever beam made of poly-silicon material, using the coupling of three application modes (plane strain, electrostatics and the moving mesh) of COMSOL Multi-physics software. The cantilevers playing a key role in Micro Electro-Mechanical Systems (MEMS) devices (switches, resonators, etc) working under potential shock. This is why they require actuation under predetermined conditions, such as electrostatic force or inertial force. In this paper, we present mechanical behavior of a cantilever actuated by an electrostatic force. In addition to the simplification of calculations, the weight of the cantilever was not taken into account. Different parameters like beam displacement, electrostatics force and stress over the beam have been calculated by finite element method after having defining the geometry, the material of the cantilever model (fixed at one of ends but is free to move otherwise) and his operational space.

  10. High throughout reproducible cantilever functionalization

    DOEpatents

    Evans, Barbara R; Lee, Ida

    2014-11-25

    A method for functionalizing cantilevers is provided that includes providing a holder having a plurality of channels each having a width for accepting a cantilever probe and a plurality of probes. A plurality of cantilever probes are fastened to the plurality of channels of the holder by the spring clips. The wells of a well plate are filled with a functionalization solution, wherein adjacent wells in the well plate are separated by a dimension that is substantially equal to a dimension separating adjacent channels of the plurality of channels. Each cantilever probe that is fastened within the plurality of channels of the holder is applied to the functionalization solution that is contained in the wells of the well plate.

  11. High throughput reproducible cantilever functionalization

    SciTech Connect

    Evans, Barbara R; Lee, Ida

    2014-01-21

    A method for functionalizing cantilevers is provided that includes providing a holder having a plurality of channels each having a width for accepting a cantilever probe and a plurality of probes. A plurality of cantilever probes are fastened to the plurality of channels of the holder by the spring clips. The wells of a well plate are filled with a functionalization solution, wherein adjacent wells in the well plate are separated by a dimension that is substantially equal to a dimension separating adjacent channels of the plurality of channels. Each cantilever probe that is fastened within the plurality of channels of the holder is applied to the functionalization solution that is contained in the wells of the well plate.

  12. Micromachined Silicon Cantilever Magnetometry.

    NASA Astrophysics Data System (ADS)

    Chaparala, M. V.

    1998-03-01

    Magnetic torque measurements give us a simple and attractive method for characterizing the anisotropic properties of magnetic materials. Silicon torque and force magnetometers have many advantages over traditional torsion fiber torque magnetometers. We have fabricated micromachined silicon torque and force magnetometers employing both capacitive(``Capacitance platform magnetometer for thin film and small crystal superconductor studies'', M. Chaparala et al.), AIP Conf. Proc. (USA), AIP Conference Proceedings, no.273, p. 407 1993. and strain dependent FET detection(``Strain Dependent Characterstics of Silicon MOSFETs and their Applications'', M. Chaparala et al.), ISDRS Conf. Proc. 1997. schemes which realize some of these gains. We will present the pros and cons of each of the different detection schemes and the associated design constraints. We have developed a feedback scheme which enables null detection thus preserving the integrity of the sample orientation. We will present a method of separating out the torque and force terms in the measured signals and will discuss the errors associated with each of the designs. Finally, we present the static magnetic torque measurements on various materials with these devices, including equilibrium properties on sub microgram specimens of superconductors, and dHvA measurements near H_c2. We will also discuss their usefulness in pulsed magnetic fields(``Cantilever magnetometry in pulsed magnetic fields", M. J. Naughton et al.), Rev. of Sci. Instrum., vol.68, p. 4061 1997..

  13. Multidomain piezo-ceramic cantilever

    NASA Astrophysics Data System (ADS)

    Sedorook, David P.

    PZT-5H is a ferroelectric and piezoelectric material that has many applications that are the subjects of current research. As a ferroelectric, PZT-5H has a permanent electrical polarization that arises from ferroelectric domains. In this thesis, numerical simulations were conducted via the well know Finite Element Method of several types of piezoelectric cantilevers that were made of PIC-181, a high quality PZT-5H made in Germany. Single crystal cantilever models with multiple polarization vectors were investigated with Q factors ranging from Q = 50 to Q = 1200, where the acoustical displacements were calculated. Further, the displacements were calculated for a multidomain cantilever model with inversely poled domains and uniform electrode configuration as well as a single crystal cantilever model with uniformly poled crystal and bipolar electrode configuration. It was shown that cantilevers that are less oblong in shape could benefit from the bipolar electrode configuration in applications where size may be an important parameter, for instance in small flying robotic insects. From the experimental measurements of the resonance and anti-resonance frequencies in various PIC-181 samples, the radial and longitudinal components of speed of sound in material were calculated. Experimental results of longitudinal speed of sound differed from the accepted value of 4.6 km/s by 1.6 % error.

  14. Compact cantilever force probe for plasma pressure measurements

    SciTech Connect

    Nedzelskiy, I. S.; Silva, C.; Fernandes, H.; Duarte, P.; Varandas, C. A. F.

    2007-12-15

    A simple, compact cantilever force probe (CFP) has been developed for plasma pressure measurements. It is based on the pull-in phenomenon well known in microelectromechanical-system electrostatic actuators. The probe consists of a thin (25 {mu}m) titanium foil cantilever (38 mm of length and 14 mm of width) and a fixed electrode separated by a 0.75 mm gap. The probe is shielded by brass box and enclosed into boron nitride housing with a 9 mm diameter window for exposing part of cantilever surface to the plasma. When the voltage is applied between the cantilever and the electrode, an attractive electrostatic force is counterbalanced by cantilever restoring spring force. At some threshold (pull-in) voltage the system becomes unstable and the cantilever abruptly pulls toward the fixed electrode until breakdown occurs between them. The threshold voltage is sensitive to an additional externally applied force, while a simple detection of breakdown occurrence can be used to measure that threshold voltage value. The sensitivity to externally applied forces obtained during calibration is 0.28 V/{mu}N (17.8 V/Pa for pressure). However, the resolution of the measurements is {+-}0.014 mN ({+-}0.22 Pa) due to the statistical scattering in measured pull-in voltages. The diagnostic temporal resolution is {approx}10 ms, being determined by the dynamics of pull-in process. The probe has been tested in the tokamak ISTTOK edge plasma, and a plasma force of {approx}0.07 mN (plasma pressure {approx}1.1 Pa) has been obtained near the leading edge of the limiter. This value is in a reasonable agreement with the estimations using local plasma parameters measured by electrical probes. The use of the described CFP is limited by a heat flux of Q{approx}10{sup 6} W/m{sup 2} due to uncontrollable rise of the cantilever temperature ({delta}T{approx}20 deg. C) during CFP response time.

  15. Precise atomic force microscope cantilever spring constant calibration using a reference cantilever array

    SciTech Connect

    Gates, Richard S.; Reitsma, Mark G.

    2007-08-15

    A method for calibrating the stiffness of atomic force microscope (AFM) cantilevers is demonstrated using an array of uniform microfabricated reference cantilevers. A series of force-displacement curves was obtained using a commercial AFM test cantilever on the reference cantilever array, and the data were analyzed using an implied Euler-Bernoulli model to extract the test cantilever spring constant from linear regression fitting. The method offers a factor of 5 improvement over the precision of the usual reference cantilever calibration method and, when combined with the Systeme International traceability potential of the cantilever array, can provide very accurate spring constant calibrations.

  16. 16. PIER CAP DETAIL, SHOWING EXPANSION AND FIXED BEARING SHOES, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. PIER CAP DETAIL, SHOWING EXPANSION AND FIXED BEARING SHOES, BOTTOM CHORD / END POST CONNECTION AND CANTILEVERED SIDEWALK. VIEW TO WEST. - Holbrook Bridge, Spanning Little Colorado River at AZ 77, Holbrook, Navajo County, AZ

  17. 22. VIEW OF FIXED SPAN SUBSTRUCTURE, EAST SPAN, SHOWING CANTILEVEREDBEAM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. VIEW OF FIXED SPAN SUBSTRUCTURE, EAST SPAN, SHOWING CANTILEVERED-BEAM SIDEWALK SUPPORTS, LONGITUDINAL GIRDER AND TRANSVERSE ROADBED BEAMS, LOOKING SOUTHEAST - Congress Street Bascule Bridge, Spanning Fort Point Channel at Congress Street, Boston, Suffolk County, MA

  18. Dual-Cantilever-Beam Accelerometer

    NASA Technical Reports Server (NTRS)

    Reynolds, Emmitt A.; Speckhart, Frank H.

    1988-01-01

    Sensitivity to velocity changes along beam axis reduced. Weighted-end cantilever beams of accelerometer deflected equally by acceleration in y direction. When acceleration to right as well as up or down, right beam deflected more, while left beam deflected less. Bridge circuit averages outputs of strain gauges measuring deflections, so cross-axis sensitivity of accelerometer reduced. New device simple and inexpensive.

  19. Cantilevered probe detector with piezoelectric element

    SciTech Connect

    Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

    2014-04-29

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  20. Cantilevered probe detector with piezoelectric element

    DOEpatents

    Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

    2013-04-30

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  1. Cantilevered probe detector with piezoelectric element

    DOEpatents

    Adams, Jesse D.; Sulchek, Todd A.; Feigin, Stuart C.

    2012-07-10

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  2. Cantilevered probe detector with piezoelectric element

    DOEpatents

    Adams, Jesse D.; Sulchek, Todd A.; Feigin, Stuart C.

    2010-04-06

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  3. Design for minimizing fracture risk of all-ceramic cantilever dental bridge.

    PubMed

    Zhang, Zhongpu; Zhou, Shiwei; Li, Eric; Li, Wei; Swain, Michael V; Li, Qing

    2015-01-01

    Minimization of the peak stresses and fracture incidence induced by mastication function is considered critical in design of all-ceramic dental restorations, especially for cantilever fixed partial dentures (FPDs). The focus of this study is on developing a mechanically-sound optimal design for all-ceramic cantilever dental bridge in a posterior region. The topology optimization procedure in association with Extended Finite Element Method (XFEM) is implemented here to search for the best possible distribution of porcelain and zirconia materials in the bridge structure. The designs with different volume fractions of zirconia are considered. The results show that this new methodology is capable of improving FPD design by minimizing incidence of crack in comparison with the initial design. Potentially, it provides dental technicians with a new design tool to develop mechanically sound cantilever fixed partial dentures for more complicated clinical situation. PMID:26405963

  4. Nanomechanical humidity detection through porous alumina cantilevers

    PubMed Central

    Klimenko, Alexey; Lebedev, Vasiliy; Lukashin, Alexey; Eliseev, Andrey

    2015-01-01

    Summary We present here the behavior of the resonance frequency of porous anodic alumina cantilever arrays during water vapor adsorption and emphasize their possible use in the micromechanical sensing of humidity levels at least in the range of 10–22%. The sensitivity of porous anodic aluminium oxide cantilevers (Δf/Δm) and the humidity sensitivity equal about 56 Hz/pg and about 100 Hz/%, respectively. The approach presented here for the design of anodic alumina cantilever arrays by the combination of anodic oxidation and photolithography enables easy control over porosity, surface area, geometric and mechanical characteristics of the cantilever arrays for micromechanical sensing. PMID:26199836

  5. Dynamic response of cantilever retaining walls

    SciTech Connect

    Veletsos, A.S.; Younan, A.H.; Bandyopadhyay, K.

    1996-10-01

    A critical evaluation is made of the response to horizontal ground shaking of flexible cantilever retaining walls that are elastically constrained against rotation at their base. The retained medium is idealized as a uniform, linear, viscoelastic stratum of constant thickness and semi-infinite extent in the horizontal direction. The parameters varied include the flexibilities of the wall and its base, the properties of the retained medium, and the characteristics of the ground motion. In addition to long-period, effectively static excitations, both harmonic base motions and an actual earthquake record are considered. The response quantities examined include the displacements of the wall relative to the moving base, the wall pressures, and the associated shears and bending moments. The method of analysis employed is described only briefly, emphasis being placed on the presentation and interpretation of the comprehensive numerical solutions. It is shown that, for realistic wall flexibilities, the maximum wall forces are significantly lower than those obtained for fixed-based rigid walls and potentially of the same order of magnitude as those computed by the Mononobe-Okabe method.

  6. Prototype cantilevers for quantitative lateral force microscopy

    SciTech Connect

    Reitsma, Mark G.; Gates, Richard S.; Friedman, Lawrence H.; Cook, Robert F.

    2011-09-15

    Prototype cantilevers are presented that enable quantitative surface force measurements using contact-mode atomic force microscopy (AFM). The ''hammerhead'' cantilevers facilitate precise optical lever system calibrations for cantilever flexure and torsion, enabling quantifiable adhesion measurements and friction measurements by lateral force microscopy (LFM). Critically, a single hammerhead cantilever of known flexural stiffness and probe length dimension can be used to perform both a system calibration as well as surface force measurements in situ, which greatly increases force measurement precision and accuracy. During LFM calibration mode, a hammerhead cantilever allows an optical lever ''torque sensitivity'' to be generated for the quantification of LFM friction forces. Precise calibrations were performed on two different AFM instruments, in which torque sensitivity values were specified with sub-percent relative uncertainty. To examine the potential for accurate lateral force measurements using the prototype cantilevers, finite element analysis predicted measurement errors of a few percent or less, which could be reduced via refinement of calibration methodology or cantilever design. The cantilevers are compatible with commercial AFM instrumentation and can be used for other AFM techniques such as contact imaging and dynamic mode measurements.

  7. Cantilevers orthodontics forces measured by fiber sensors

    NASA Astrophysics Data System (ADS)

    Schneider, Neblyssa; Milczewski, Maura S.; de Oliveira, Valmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

    2015-09-01

    Fibers Bragg Gratings were used to evaluate the transmission of the forces generates by orthodontic mechanic based one and two cantilevers used to move molars to the upright position. The results showed levels forces of approximately 0,14N near to the root of the molar with one and two cantilevers.

  8. Resonance response of scanning force microscopy cantilevers

    SciTech Connect

    Chen, G.Y.; Warmack, R.J.; Thundat, T.; Allison, D.P. ); Huang, A. )

    1994-08-01

    A variational method is used to calculate the deflection and the fundamental and harmonic resonance frequencies of commercial V-shaped and rectangular atomic force microscopy cantilevers. The effective mass of V-shaped cantilevers is roughly half that calculated for the equivalent rectangular cantilevers. Damping by environmental gases, including air, nitrogen, argon, and helium, affects the frequency of maximum response and to a much greater degree the quality factor [ital Q]. Helium has the lowest viscosity, resulting in the highest [ital Q], and thus provides the best sensitivity in noncontact force microscopy. Damping in liquids is dominated by an increase in effective mass of the cantilever due to an added mass of the liquid being dragged with that cantilever.

  9. A cantilever array-based artificial nose

    PubMed

    Baller; Lang; Fritz; Gerber; Gimzewsk; Drechsler; Rothuizen; Despont; Vettiger; Battiston; Ramseyer; Fornaro; Meyer; Guntherodt

    2000-02-01

    We present quantitative and qualitative detection of analyte vapors using a microfabricated silicon cantilever array. To observe transduction of physical and chemical processes into nanomechanical motion of the cantilever, swelling of a polymer layer on the cantilever is monitored during exposure to the analyte. This motion is tracked by a beam-deflection technique using a time multiplexing scheme. The response pattern of eight cantilevers is analyzed via principal component analysis (PCA) and artificial neural network (ANN) techniques, which facilitates the application of the device as an artificial chemical nose. Analytes tested comprise chemical solvents, a homologous series of primary alcohols, and natural flavors. First differential measurements of surface stress change due to protein adsorption on a cantilever array are shown using a liquid cell. PMID:10741645

  10. Oscillations of end loaded cantilever beams

    NASA Astrophysics Data System (ADS)

    Macho-Stadler, E.; Elejalde-García, M. J.; Llanos-Vázquez, R.

    2015-09-01

    This article presents several simple experiments based on changing transverse vibration frequencies in a cantilever beam, when acted on by an external attached mass load at the free end. By using a mechanical wave driver, available in introductory undergraduate laboratories, we provide various experimental results for end loaded cantilever beams that fit reasonably well into a linear equation. The behaviour of the cantilever beam’s weak-damping resonance response is studied for the case of metal resonance strips. As the mass load increases, a more pronounced decrease occurs in the fundamental frequency of beam vibration. It is important to note that cantilever construction is often used in architectural design and engineering construction projects but current analysis also predicts the influence of mass load on the sound generated by musical free reeds with boundary conditions similar to a cantilever beam.

  11. Combined intrusion and retraction generated by cantilevers with helical coils.

    PubMed

    Melsen, B; Konstantellos, V; Lagoudakis, M; Planert, J

    1997-01-01

    Combined retraction and intrusion of the anterior teeth is often needed as part of orthodontic treatment. The use of a statically determinate force system has many advantages over statically indeterminate systems. In the case of the cantilevers the orthodontist can evaluate the line of action of the delivered force directly in the clinical situation. In the present paper the force system delivered by stainless steel and beta titanium cantilevers with an eccentrically placed helix was evaluated. The cantilever consisted of a straight piece of wire bent to form a helix with an external diameter of 3 mm. The wire was fixed into a bracket of sensor 1, touching sensor 2 of a test bench with a 1-point contact to. Activation was induced by rotating sensor 1 into which the wire was tightly fixed. This was done in 2 different modes, one in the direction in which the helix was bent and one in the opposite direction. With an interval of 5 degrees the force system generated with respect to sensor 1 and the direction of the force delivered to sensor 2 (the other bracket) were registered. The results were expressed graphically and the influence of material and activation mode were evaluated statistically by comparing the coefficient of regression. As expected, the influence of the material reflected the relative stiffness of the 2 alloys. As TMA is monocrystalline (i.e. consists of homogeneous crystals) the mode of activation did not reflect any significant Bauschinger effect as seen in the case of stainless steel. Analysis of the force direction confirmed that the suggested wire configuration is useful for delivery of a predetermined combination of horizontal and vertical force. This was confirmed by a finite element analysis. PMID:9282550

  12. Atomic Force Microscopy in Dynamic Mode with Displacement Current Detection in Double Cantilever Devices

    NASA Astrophysics Data System (ADS)

    Müller, Falk; Müller, Anne‑Dorothea; Hietschold, Michael; Gessner, Thomas

    2006-03-01

    A cantilever array for dynamic mode atomic force microscopy (AFM) is presented, the vertical displacement of which is analyzed by the detection of displacement currents in the electrodes. Each cantilever in the array consists of an actuation part that allows an independent vertical movement, and a sensor part. The lateral distance between the tips of the different cantilevers is fixed to 10 μm. When operated as an actuator, a voltage is applied between the silicon membrane and the underlaying electrode. Due to the resulting coulomb forces, the vertical position of the tip is controllable. The reaction time in this mode is shorter than the response time of a piezostack. The sensor part, on the other hand, allows the device to work in dynamic mode without a laser deflection system. The vertical resolution achieved is below 1 nm. The dependence of force distance curves on the excitation amplitude is shown.

  13. Self-reciprocating radioisotope-powered cantilever

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lal, Amit; Blanchard, James; Henderson, Douglass

    2002-07-01

    A reciprocating cantilever utilizing emitted charges from a millicurie radioisotope thin film is presented. The actuator realizes a direct collected-charge-to-motion conversion. The reciprocation is obtained by self-timed contact between the cantilever and the radioisotope source. A static model balancing the electrostatic and mechanical forces from an equivalent circuit leads to an analytical solution useful for device characterization. Measured reciprocating periods agree with predicted values from the analytical model. A scaling analysis shows that microscale arrays of such cantilevers provide an integrated sensor and actuator platform.

  14. Cantilevers and tips for atomic force microscopy.

    PubMed

    Tortonese, M

    1997-01-01

    The cantilever and the tip are at the centerpiece of the AFM. Properties such as the cantilever stiffness and resonant frequency, tip shape and sharpness, and material characteristics determine the mode of operation of the AFM and the type of experiments and measurements that can be performed. The possibility of batch fabricating cantilevers has permitted the fabrication and characterization of specialized tips for a variety of experiments. We believe that the use of new materials and tip shapes will allow new applications for the AFM in the future. PMID:9086369

  15. Development of double-cantilever infrared detectors

    NASA Astrophysics Data System (ADS)

    Huang, Shusen

    Detection and imaging of infrared (IR) radiation are of great importance to a variety of military and civilian applications. Recent advances in microelectromechanical systems (MEMS) have led to the development of uncooled cantilever IR focal plane arrays (FPAs), which function based on the bending of bimaterial cantilevers upon the absorption of IR energy. In this dissertation, capacitive-based double-cantilever IR FPAs, which have a potential of reaching a noise-equivalent temperature difference (NETD) approaching the theoretical limit, i.e., <10 mK, are developed. Each pixel in the proposed double-cantilever IR FPAs consists of two facing bimaterial cantilevers: one bends upward and the other downward upon IR radiation, resulting in an extremely high sensitivity of the device. It is predicted that the NETD of the double-cantilever IR FPAs is about 60% of the current single-cantilever IR FPAs, which is a significant improvement of device performance. A surface micromachining module with polyimide as a sacrificial material is developed for the fabrication of both simplified single- and double-cantilever FPAs. It is found the as-fabricated FPAs are curved because of the imbalanced residual stresses (strains) in thin films developed in the fabrication processes. In this dissertation, therefore, the general relationship between the residual strain and the resultant elastic bending deformation is modeled. A thorough investigation of residual stresses in cantilever IR materials and structures is then conducted using the theory developed in this dissertation. Furthermore, thermal-cycling experiments reveal that the residual stresses in IR materials, i.e., plasma-enhanced chemical vapor deposited (PECVD) SiNx and electron beam (Ebeam) AI, can be significantly modified by thermal annealing. Therefore, an engineering approach to flattening IR FPAs is developed by using rapid thermal annealing (RTA). Finally, this dissertation demonstrates the thermal detection of cantilever

  16. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer.

    PubMed

    Inada, Natsumi; Asakawa, Hitoshi; Kobayashi, Taiki; Fukuma, Takeshi

    2016-01-01

    Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC) layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid. PMID:27335733

  17. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer

    PubMed Central

    Inada, Natsumi; Kobayashi, Taiki; Fukuma, Takeshi

    2016-01-01

    Summary Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC) layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid. PMID:27335733

  18. Double sided surface stress cantilever sensor

    NASA Astrophysics Data System (ADS)

    Rasmussen, P. A.; Grigorov, A. V.; Boisen, A.

    2005-05-01

    Micromachined cantilevers, originally developed for use in atomic force microscopy, are gaining more and more interest as biochemical sensors, where the way in which the binding of chemical species changes the mechanical properties of the cantilever is utilized. Mass and stiffness changes are measured on resonating structures (Cherian and Thundat 2002 Appl. Phys. Lett. 80 2219-21 Gupta et al 2004 Appl. Phys. Lett. 84 1976-8), whereas changes in surface energy from the binding event are measured as static deflections of cantilevers (Savran et al 2004 Anal. Chem. 76 3194-8). The latter measurement type is referred to as a surface stress sensor and it is the description of a new and more sensitive cantilever surface stress measurement technique that is the topic of this paper.

  19. Generation of squeezing: magnetic dipoles on cantilevers

    NASA Astrophysics Data System (ADS)

    Seok, Hyojun; Singh, Swati; Steinke, Steven; Meystre, Pierre

    2011-05-01

    We investigate the generation of motional squeezed states in a nano-mechanical cantilever. Our model system consists of a nanoscale cantilever - whose center-of-mass motion is initially cooled to its quantum mechanical ground state - magnetically coupled a classically driven mechanical tuning fork. We show that the magnetic dipole-dipole interaction can produce significant phonon squeezing of the center-of-mass motion of the cantilever, and evaluate the effect of various dissipation channels, including the coupling of the cantilever to a heat bath and phase and amplitude fluctuations in the oscillating field driving the tuning fork. US National Science Foundation, the US Army Research Office, DARPA ORCHID program through a grant from AFOSR.

  20. Demonstration of an electrostatic-shielded cantilever

    SciTech Connect

    Pingue, P.; Piazza, V.; Baschieri, P.; Ascoli, C.; Menozzi, C.; Alessandrini, A.; Facci, P.

    2006-01-23

    The fabrication and performances of cantilevered probes with reduced parasitic capacitance starting from a commercial Si{sub 3}N{sub 4} cantilever chip is presented. Nanomachining and metal deposition induced by focused ion beam techniques were employed in order to modify the original insulating pyramidal tip and insert a conducting metallic tip. Two parallel metallic electrodes deposited on the original cantilever arms are employed for tip biasing and as ground plane in order to minimize the electrostatic force due to the capacitive interaction between cantilever and sample surface. Excitation spectra and force-to-distance characterization are shown with different electrode configurations. Applications of this scheme in electrostatic force microscopy, Kelvin probe microscopy and local anodic oxidation is discussed.

  1. Piezoresistive Cantilever Performance—Part II: Optimization

    PubMed Central

    Park, Sung-Jin; Doll, Joseph C.; Rastegar, Ali J.; Pruitt, Beth L.

    2010-01-01

    Piezoresistive silicon cantilevers fabricated by ion implantation are frequently used for force, displacement, and chemical sensors due to their low cost and electronic readout. However, the design of piezoresistive cantilevers is not a straightforward problem due to coupling between the design parameters, constraints, process conditions, and performance. We systematically analyzed the effect of design and process parameters on force resolution and then developed an optimization approach to improve force resolution while satisfying various design constraints using simulation results. The combined simulation and optimization approach is extensible to other doping methods beyond ion implantation in principle. The optimization results were validated by fabricating cantilevers with the optimized conditions and characterizing their performance. The measurement results demonstrate that the analytical model accurately predicts force and displacement resolution, and sensitivity and noise tradeoff in optimal cantilever performance. We also performed a comparison between our optimization technique and existing models and demonstrated eight times improvement in force resolution over simplified models. PMID:20333323

  2. Cantilever based optical interfacial force microscope

    NASA Astrophysics Data System (ADS)

    Bonander, Jeremy R.; Kim, Byung I.

    2008-03-01

    We developed a cantilever based optical interfacial force microscopy (COIFM) that employs a microactuated silicon cantilever and optical detection method to establish the measurement of the single molecular interactions using the force feedback technique. Through the direct measurement of the COIFM force-distance curves, we have demonstrated that the COIFM is capable of unveiling structural and mechanical information on interfacial water at the single molecular level over all distances between two hydrophilic surfaces.

  3. Torsion and transverse bending of cantilever plates

    NASA Technical Reports Server (NTRS)

    Reissner, Eric; Stein, Manuel

    1951-01-01

    The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included. The application of this method to specific problems involving static deflection, vibration, and buckling of cantilever plates is presented. In the static-deflection problems, taper and sweep are considered.

  4. 2. DETAIL OF STRUCTURAL SYSTEM FOR CANTILEVERED HOG RUN; BUILDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. DETAIL OF STRUCTURAL SYSTEM FOR CANTILEVERED HOG RUN; BUILDING 168 (1960 HOG KILL) IS BENEATH HOG RUN - Rath Packing Company, Cantilevered Hog Run, Sycamore Street between Elm & Eighteenth Streets, Waterloo, Black Hawk County, IA

  5. Cantilever and capacitor technique for measuring dilatation

    SciTech Connect

    Primak, W.; Monahan, E.

    1983-05-01

    The relationship of EerNisse's technique for measuring small dilatations caused by irradiation with short-range particles, which utilizes a metallized thin plate mounted as a cantilever below whose free end an electrode is placed (forming a capacitor), to a photoelastic technique and to an interferometric technique are derived. The effects of stray capacitance, the fringing field of the capacitor, the clamping stress on the cantilever plate, the electrical resistance of the metallic coating, the charging of the tank circuit of which the capacitor is an element, the flange bolting stress, and the beam heating are assessed, and examples of the manner in which they contaminate the data are given.

  6. Self-heating in piezoresistive cantilevers

    PubMed Central

    Doll, Joseph C.; Corbin, Elise A.; King, William P.; Pruitt, Beth L.

    2011-01-01

    We report experiments and models of self-heating in piezoresistive microcantilevers that show how cantilever measurement resolution depends on the thermal properties of the surrounding fluid. The predicted cantilever temperature rise from a finite difference model is compared with detailed temperature measurements on fabricated devices. Increasing the fluid thermal conductivity allows for lower temperature operation for a given power dissipation, leading to lower force and displacement noise. The force noise in air is 76% greater than in water for the same increase in piezoresistor temperature. PMID:21731884

  7. Physics-based signal processing algorithms for micromachined cantilever arrays

    DOEpatents

    Candy, James V; Clague, David S; Lee, Christopher L; Rudd, Robert E; Burnham, Alan K; Tringe, Joseph W

    2013-11-19

    A method of using physics-based signal processing algorithms for micromachined cantilever arrays. The methods utilize deflection of a micromachined cantilever that represents the chemical, biological, or physical element being detected. One embodiment of the method comprises the steps of modeling the deflection of the micromachined cantilever producing a deflection model, sensing the deflection of the micromachined cantilever and producing a signal representing the deflection, and comparing the signal representing the deflection with the deflection model.

  8. Note: Improved calibration of atomic force microscope cantilevers using multiple reference cantilevers

    SciTech Connect

    Sader, John E.; Friend, James R.

    2015-05-15

    Overall precision of the simplified calibration method in J. E. Sader et al., Rev. Sci. Instrum. 83, 103705 (2012), Sec. III D, is dominated by the spring constant of the reference cantilever. The question arises: How does one take measurements from multiple reference cantilevers, and combine these results, to improve uncertainty of the reference cantilever’s spring constant and hence the overall precision of the method? This question is addressed in this note. Its answer enables manufacturers to specify of a single set of data for the spring constant, resonant frequency, and quality factor, from measurements on multiple reference cantilevers. With this data set, users can trivially calibrate cantilevers of the same type.

  9. Forced Vibrations of a Cantilever Beam

    ERIC Educational Resources Information Center

    Repetto, C. E.; Roatta, A.; Welti, R. J.

    2012-01-01

    The theoretical and experimental solutions for vibrations of a vertical-oriented, prismatic, thin cantilever beam are studied. The beam orientation is "downwards", i.e. the clamped end is above the free end, and it is subjected to a transverse movement at a selected frequency. Both the behaviour of the device driver and the beam's weak-damping…

  10. Calibration of higher eigenmodes of cantilevers

    NASA Astrophysics Data System (ADS)

    Labuda, Aleksander; Kocun, Marta; Lysy, Martin; Walsh, Tim; Meinhold, Jieh; Proksch, Tania; Meinhold, Waiman; Anderson, Caleb; Proksch, Roger

    2016-07-01

    A method is presented for calibrating the higher eigenmodes (resonant modes) of atomic force microscopy cantilevers that can be performed prior to any tip-sample interaction. The method leverages recent efforts in accurately calibrating the first eigenmode by providing the higher-mode stiffness as a ratio to the first mode stiffness. A one-time calibration routine must be performed for every cantilever type to determine a power-law relationship between stiffness and frequency, which is then stored for future use on similar cantilevers. Then, future calibrations only require a measurement of the ratio of resonant frequencies and the stiffness of the first mode. This method is verified through stiffness measurements using three independent approaches: interferometric measurement, AC approach-curve calibration, and finite element analysis simulation. Power-law values for calibrating higher-mode stiffnesses are reported for several cantilever models. Once the higher-mode stiffnesses are known, the amplitude of each mode can also be calibrated from the thermal spectrum by application of the equipartition theorem.

  11. Calibration of higher eigenmodes of cantilevers.

    PubMed

    Labuda, Aleksander; Kocun, Marta; Lysy, Martin; Walsh, Tim; Meinhold, Jieh; Proksch, Tania; Meinhold, Waiman; Anderson, Caleb; Proksch, Roger

    2016-07-01

    A method is presented for calibrating the higher eigenmodes (resonant modes) of atomic force microscopy cantilevers that can be performed prior to any tip-sample interaction. The method leverages recent efforts in accurately calibrating the first eigenmode by providing the higher-mode stiffness as a ratio to the first mode stiffness. A one-time calibration routine must be performed for every cantilever type to determine a power-law relationship between stiffness and frequency, which is then stored for future use on similar cantilevers. Then, future calibrations only require a measurement of the ratio of resonant frequencies and the stiffness of the first mode. This method is verified through stiffness measurements using three independent approaches: interferometric measurement, AC approach-curve calibration, and finite element analysis simulation. Power-law values for calibrating higher-mode stiffnesses are reported for several cantilever models. Once the higher-mode stiffnesses are known, the amplitude of each mode can also be calibrated from the thermal spectrum by application of the equipartition theorem. PMID:27475563

  12. Direct and alignment-insensitive measurement of cantilever curvature

    SciTech Connect

    Hermans, Rodolfo I.; Aeppli, Gabriel; Bailey, Joe M.

    2013-07-15

    We analytically derive and experimentally demonstrate a method for the simultaneous measurement of deflection for large arrays of cantilevers. The Fresnel diffraction patterns of a cantilever independently reveal tilt, curvature, cubic, and higher order bending of the cantilever. It provides a calibrated absolute measurement of the polynomial coefficients describing the cantilever shape, without careful alignment and could be applied to several cantilevers simultaneously with no added complexity. We show that the method is easily implemented, works in both liquid media and in air, for a broad range of displacements and is especially suited to the requirements for multi-marker biosensors.

  13. Improved atomic force microscopy cantilever performance by partial reflective coating.

    PubMed

    Schumacher, Zeno; Miyahara, Yoichi; Aeschimann, Laure; Grütter, Peter

    2015-01-01

    Optical beam deflection systems are widely used in cantilever based atomic force microscopy (AFM). Most commercial cantilevers have a reflective metal coating on the detector side to increase the reflectivity in order to achieve a high signal on the photodiode. Although the reflective coating is usually much thinner than the cantilever, it can still significantly contribute to the damping of the cantilever, leading to a lower mechanical quality factor (Q-factor). In dynamic mode operation in high vacuum, a cantilever with a high Q-factor is desired in order to achieve a lower minimal detectable force. The reflective coating can also increase the low-frequency force noise. In contact mode and force spectroscopy, a cantilever with minimal low-frequency force noise is desirable. We present a study on cantilevers with a partial reflective coating on the detector side. For this study, soft (≈0.01 N/m) and stiff (≈28 N/m) rectangular cantilevers were used with a custom partial coating at the tip end of the cantilever. The Q-factor, the detection and the force noise of fully coated, partially coated and uncoated cantilevers are compared and force distance curves are shown. Our results show an improvement in low-frequency force noise and increased Q-factor for the partially coated cantilevers compared to fully coated ones while maintaining the same reflectivity, therefore making it possible to combine the best of both worlds. PMID:26199849

  14. Optical actuation of silicon cantilevers: modelling and experimental investigation

    NASA Astrophysics Data System (ADS)

    Jiang, Fei; Keating, Adrian; Martyuink, Mariusz; Silva, Dilusha; Faraone, Lorenzo; Dell, John M.

    2013-05-01

    This paper reports on the modeling and experimental investigation of optical excitation of silicon cantilevers. In this work, the silicon cantilevers fabricated have dimensions with width of 15 μm, thickness of 0.26 μm, and variable length from 50 to 120 μm. In order to investigate the effect of the laser modulation frequency and position on the temperature at the anchor edge and displacements at the tip of cantilevers, a transient thermal ANSYS simulation and a steady-state static thermal mechanical ANSYS simulation were undertaken using a structure consisting of silicon device layer, SiO2 sacrificial layer and silicon substrate. The dynamic properties of silicon cantilevers were undertaken by a series of experiments. The period optical driving signal with controlled modulation amplitude was provided by a 405 nm diode laser with a 2.9 μW/μm2 laser power and variable frequencies. The laser spot was located through the longitude direction of silicon cantilevers. In factor, simulation results well matched with experimental observation, including: 1) for untreated silicon cantilevers, the maximum of displacement is observed when the laser beam was located half a diameter way from the anchor on the silicon suspended cantilever side; 2) for the both cantilevers, maximum displacement occurs when the optical actuation frequency is equal to the resonant frequency of cantilevers. Understanding the optical excitation on silicon cantilevers, as waveguides, can potentially increase sensing detection sensitivity (ratio of transmission to cantilever deflection).

  15. Closed-form solution for a cantilevered sectorial plate subjected to a tip concentrated force.

    PubMed

    Christy, Carl W; Weggel, David C; Smelser, R E

    2016-01-01

    A closed-form solution is presented for a cantilevered sectorial plate subjected to a tip concentrated force. Since the particular solution for this problem was not found in the literature, it is derived here. Deflections from the total solution (particular plus homogeneous solutions) are compared to those from a finite element analysis and are found to be in excellent agreement, producing an error within approximately 0.08 %. Normalized closed-form deflections and slopes at the fixed support, resulting from an approximate enforcement of the boundary conditions there, deviate from zero by <0.08 %. Finally, the total closed-form solutions for a cantilevered sectorial plate subjected to independent applications of a tip concentrated force, a tip bending moment, and a tip twisting moment, are compiled. PMID:27390653

  16. Correction of Multiple Canine Impactions by Mixed Straightwire and Cantilever Mechanics: A Case Report

    PubMed Central

    Iodice, Giorgio; d'Antò, Vincenzo; Riccitiello, Francesco; Pellegrino, Gioacchino; Valletta, Rosa

    2014-01-01

    Background. This case report describes the orthodontic treatment of a woman, aged 17 years, with a permanent dentition, brachyfacial typology, Angle Class I, with full impaction of two canines (13,33), and a severe ectopy of the maxillary left canine. Her main compliant was the position of the ectopic teeth. Methods. Straightwire fixed appliances, together with cantilever mechanics, were used to correct the impaired occlusion and to obtain an ideal torque control. Results and Conclusion. The treatment objectives were achieved in 26 months of treatment. The impactions were fully corrected with an optimal torque. The cantilever mechanics succeeded in obtaining tooth repositioning in a short lapse of time. After treatment, the dental alignment was stable. PMID:25140261

  17. Intrinsic dissipation in atomic force microscopy cantilevers.

    PubMed

    Zypman, Fredy

    2011-07-01

    In this paper we build a practical modification to the standard Euler-Bernoulli equation for flexural modes of cantilever vibrations most relevant for operation of AFM in high vacuum conditions. This is done by the study of a new internal dissipation term into the Euler-Bernoulli equation. This term remains valid in ultra-high vacuum, and becomes particularly relevant when viscous dissipation with the fluid environment becomes negligible. We derive a compact explicit equation for the quality factor versus pressure for all the flexural modes. This expression is used to compare with corresponding extant high vacuum experiments. We demonstrate that a single internal dissipation parameter and a single viscosity parameter provide enough information to reproduce the first three experimental flexural resonances at all pressures. The new term introduced here has a mesoscopic origin in the relative motion between adjacent layers in the cantilever. PMID:21741914

  18. Linear and Nonlinear Photoinduced Deformations of Cantilevers

    NASA Astrophysics Data System (ADS)

    Corbett, D.; Warner, M.

    2007-10-01

    Glassy and elastomeric nematic networks with dye molecules present can be very responsive to illumination, huge reversible strains being possible. If absorption is appreciable, strain decreases with depth into a cantilever, leading to bend that is the basis of micro-opto-mechanical systems (MOMS). Bend actually occurs even when Beer’s law suggests a tiny penetration of light into a heavily dye-doped system. We model the nonlinear opto-elastic processes behind this effect. In the regime of cantilever thickness giving optimal bending for a given incident light intensity, there are three neutral surfaces. In practice such nonlinear absorptive effects are very important since heavily doped systems are commonly used.

  19. Cantilever mounted resilient pad gas bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I. (Inventor)

    1978-01-01

    A gas-lubricated bearing is described, employing at least one pad mounted on a rectangular cantilever beam to produce a lubricating wedge between the face of the pad and a moving surface. The load-carrying and stiffness characteristics of the pad are related to the dimensions and modulus of elasticity of the beam. The bearing is applicable to a wide variety of types of hydrodynamic bearings.

  20. Understanding interferometry for micro-cantilever displacement detection.

    PubMed

    von Schmidsfeld, Alexander; Nörenberg, Tobias; Temmen, Matthias; Reichling, Michael

    2016-01-01

    Interferometric displacement detection in a cantilever-based non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum is demonstrated for the Michelson and Fabry-Pérot modes of operation. Each mode is addressed by appropriately adjusting the distance between the fiber end delivering and collecting light and a highly reflective micro-cantilever, both together forming the interferometric cavity. For a precise measurement of the cantilever displacement, the relative positioning of fiber and cantilever is of critical importance. We describe a systematic approach for accurate alignment as well as the implications of deficient fiber-cantilever configurations. In the Fabry-Pérot regime, the displacement noise spectral density strongly decreases with decreasing distance between the fiber-end and the cantilever, yielding a noise floor of 24 fm/Hz(0.5) under optimum conditions. PMID:27547601

  1. Exploiting cantilever curvature for noise reduction in atomic force microscopy.

    PubMed

    Labuda, Aleksander; Grütter, Peter H

    2011-01-01

    Optical beam deflection is a widely used method for detecting the deflection of atomic force microscope (AFM) cantilevers. This paper presents a first order derivation for the angular detection noise density which determines the lower limit for deflection sensing. Surprisingly, the cantilever radius of curvature, commonly not considered, plays a crucial role and can be exploited to decrease angular detection noise. We demonstrate a reduction in angular detection shot noise of more than an order of magnitude on a home-built AFM with a commercial 450 μm long cantilever by exploiting the optical properties of the cantilever curvature caused by the reflective gold coating. Lastly, we demonstrate how cantilever curvature can be responsible for up to 45% of the variability in the measured sensitivity of cantilevers on commercially available AFMs. PMID:21280834

  2. Understanding interferometry for micro-cantilever displacement detection

    PubMed Central

    Nörenberg, Tobias; Temmen, Matthias; Reichling, Michael

    2016-01-01

    Summary Interferometric displacement detection in a cantilever-based non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum is demonstrated for the Michelson and Fabry–Pérot modes of operation. Each mode is addressed by appropriately adjusting the distance between the fiber end delivering and collecting light and a highly reflective micro-cantilever, both together forming the interferometric cavity. For a precise measurement of the cantilever displacement, the relative positioning of fiber and cantilever is of critical importance. We describe a systematic approach for accurate alignment as well as the implications of deficient fiber–cantilever configurations. In the Fabry–Pérot regime, the displacement noise spectral density strongly decreases with decreasing distance between the fiber-end and the cantilever, yielding a noise floor of 24 fm/Hz0.5 under optimum conditions. PMID:27547601

  3. Internal resonance in forced vibration of coupled cantilevers subjected to magnetic interaction

    NASA Astrophysics Data System (ADS)

    Chen, Li-Qun; Zhang, Guo-Ce; Ding, Hu

    2015-10-01

    Forced vibration is investigated for two elastically connected cantilevers, under harmonic base excitation. One of the cantilevers is with a tip magnet repelled by a magnet fixed on the base. The cantilevers are uniform viscoelastic beams constituted by the Kelvin model. The system is formulated as a set of two linear partial differential equations with nonlinear boundary conditions. The method of multiple scales is developed to analyze the effects of internal resonances on the steady-state responses to external excitations in the nonlinear boundary problem of the partial differential equations. In the presence of 2:1 internal resonance, both the first and the second primary resonances are examined in detail. The analytical frequency-amplitude response relationships are derived from the solvability conditions. It is found that the frequency-amplitude response curves reveal typical nonlinear phenomena such as jumping and hysteresis in both primary resonances as well as saturation in the second primary resonance. The frequency-amplitude response curves may be converted from hardening-type single-jumping to double-jumpings, and further to softening-type single-jumping by adjusting the distance between two magnets. It is also found that the unstable parts of the frequency-amplitude response curves correspond to quasi-periodic motions. The finite difference scheme is proposed to discretize both the temporal and the spatial variables, and thus the numerical solutions can be calculated. The analytical results are supported by the numerical solutions.

  4. Micromachined silicon cantilever beam accelerometer incorporating an integrated optical waveguide

    NASA Technical Reports Server (NTRS)

    Burcham, Kevin E.; De Brabander, Gregory N.; Boyd, Joseph T.

    1993-01-01

    A micromachined cantilever beam accelerometer is described in which beam deflection is determined optically. A diving board structure is anisotropically etched into a silicon wafer. This diving board structure is patterned from the wafer backside so as to leave a small gap between the tip of the diving board and the opposite fixed edge on the front side of the wafer. In order to sense a realistic range of accelerations, a foot mass incorporated onto the end of the beam is found to provide design flexibility. A silicon nitride optical waveguide is then deposited by low pressure chemical vapor deposition (LPCVD) onto the sample. Beam deflection is measured by the decrease of light coupled across the gap between the waveguide sections. In order to investigate sensor response and simulate deflection of the beam, we utilized a separate beam and waveguide section which could be displaced from one another in a precisely controlled manner. Measurements were performed on samples with gaps of 4.0, 6.0, and 8.0 micron and the variation of the fraction of light coupled across the gap as a function of displacement and gap spacing was found to agree with overlap integral calculations.

  5. 11. VIEW, LOOKING SOUTHEAST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWARD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. VIEW, LOOKING SOUTHEAST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWARD TOWARD NORTH PORTAL. Note vertical displacement in deck caused by partial collapse at point of connection between south cantilever arm and suspended span. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  6. CLOSEUP VIEW OF BOTTOM OF MAIN BRIDGE CANTILEVER THROUGH TRUSS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CLOSE-UP VIEW OF BOTTOM OF MAIN BRIDGE CANTILEVER THROUGH TRUSS SPAN SHOWING CANTILEVERED HIGHWAY FLOOR BRACKET LOOKING NORTHWEST AT PIER “II”. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  7. Fiber-optic, cantilever-type acoustic motion velocity hydrophone.

    PubMed

    Cranch, G A; Miller, G A; Kirkendall, C K

    2012-07-01

    The interaction between fluid loaded fiber-optic cantilevers and a low frequency acoustic wave is investigated as the basis for an acoustic vector sensor. The displacements of the prototype cantilevers are measured with an integrated fiber laser strain sensor. A theoretical model predicting the frequency dependent shape of acoustically driven planar and cylindrical fiber-optic cantilevers incorporating effects of fluid viscosity is presented. The model demonstrates good agreement with the measured response of two prototype cantilevers, characterized with a vibrating water column, in the regime of Re ≥ 1. The performance of each cantilever geometry is also analyzed. Factors affecting the sensor performance such as fluid viscosity, laser mode profile, and support motion are considered. The planar cantilever is shown to experience the largest acoustically induced force and hence the highest acoustic responsivity. However, the cylindrical cantilever exhibits the smoothest response in water, due to the influence of viscous fluid damping, and is capable of two axis particle velocity measurement. These cantilevers are shown to be capable of achieving acoustic resolutions approaching the lowest sea-state ocean noise. PMID:22779459

  8. Hysteresis of the resonance frequency of magnetostrictive bending cantilevers

    NASA Astrophysics Data System (ADS)

    Löffler, Michael; Kremer, Ramona; Sutor, Alexander; Lerch, Reinhard

    2015-05-01

    Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the ΔE-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible.

  9. Improved assembly processes for the Quartz Digital Accelerometer cantilever

    SciTech Connect

    Romero, A.M.; Gebert, C.T.

    1990-07-01

    This report covers the development of improved assembly processes for the Quartz Digital Accelerometer cantilever. In this report we discuss improved single-assembly tooling, the development of tooling and processes for precision application of polyimide adhesive, the development of the wafer scale assembly procedure, and the application of eutectic bonding to cantilever assembly. 2 refs., 17 figs.

  10. Resonating cantilever mass sensor with mechanical on-plane excitation

    NASA Astrophysics Data System (ADS)

    Teva, Jordi; Abadal, Gabriel; Jordà, Xavier; Borrise, Xavier; Davis, Zachary; Barniol, Nuria

    2003-04-01

    The aim of this paper is to report the experimental setup designed, developed and tested in order to achieve the first vibrating mode of a lateral cantilever with mechanical excitation. The on-plane oscillating cantilever is the basis of a proposed mass sensor with an expected resolution in the atto-gram scale. In a first system design, the cantilever is driven electrostatically by an electrode, which is placed parallel to the cantilever. The cantilever is driven to its first resonant mode applying an AC voltage between the cantilever and a driver. Also, a DC voltage is applied to increase the system response. The signal read-out of the transducer is the capacitive current of the cantilever-driver system. The mass sensor proposed, based on this cantilever-driver structure (CDS), is integrated with a CMOS circuitry in order to minimize the parasitic capacitances, that in this case take special relevance because of the low level output current coming from the transducer. Moreover, the electrostatic excitation introduces a parasitic current that overlaps the current due to the resonance. The mechanical excitation is an alternative excitation method which aim is to eliminate the excitation current. Here we describe the experimental facilities developed to achieve mechanical excitation and report preliminary results obtained by this excitation technique. The results are complemented with dynamic simulations of an equivalent system model that are in accordance with the experimental values.

  11. Cantilever transducers as a platform for chemical and biological sensors

    NASA Astrophysics Data System (ADS)

    Lavrik, Nickolay V.; Sepaniak, Michael J.; Datskos, Panos G.

    2004-07-01

    Since the late 1980s there have been spectacular developments in micromechanical or microelectro-mechanical (MEMS) systems which have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged. In this article, we discuss sensors with transducers in a form of cantilevers. While MEMS represents a diverse family of designs, devices with simple cantilever configurations are especially attractive as transducers for chemical and biological sensors. The review deals with four important aspects of cantilever transducers: (i) operation principles and models; (ii) microfabrication; (iii) figures of merit; and (iv) applications of cantilever sensors. We also provide a brief analysis of historical predecessors of the modern cantilever sensors.

  12. Fabricating optical fibre-top cantilevers for temperature sensing

    NASA Astrophysics Data System (ADS)

    Li, J.; Albri, F.; Sun, J. N.; Miliar, M. M.; Maier, R. R. J.; Hand, D. P.; MacPherson, W. N.

    2014-03-01

    In this paper, we propose techniques to fabricate micro-cantilevers onto the end of standard single mode optical fibres using a combination of picosecond laser machining and focused ion beam milling techniques and demonstrate their use as temperature sensors. Using this approach the cantilever can be pre-aligned with the core of the fibre during fabrication, therefore offering a stable and straightforward means of optically addressing the cantilever. The cantilever is designed to measure deflection over a range of 10 µm using a simple readout technique. A phase recovery algorithm is employed to reduce the interrogation error to around 2-3 nm. Finally, a temperature cycling experiment demonstrates that the cantilever could be used as a temperature sensor from room temperature to 500 °C with an average rms temperature error from 20 °C to 500 °C of ˜±1.4 °C.

  13. Serial weighting of micro-objects with resonant microchanneled cantilevers.

    PubMed

    Ossola, Dario; Dörig, Pablo; Vörös, János; Zambelli, Tomaso; Vassalli, Massimo

    2016-10-14

    Atomic force microscopy (AFM) cantilevers have proven to be very effective mass sensors. The attachment of a small mass to a vibrating cantilever produces a resonance frequency shift that can be monitored, providing the ability to measure mass changes down to a few molecules resolution. Nevertheless, the lack of a practical method to handle the catch and release process required for dynamic weighting of microobjects strongly hindered the application of the technology beyond proof of concept measurements. Here, a method is proposed in which FluidFM hollow cantilevers are exploited to overcome the standard limitations of AFM-based mass sensors, providing high throughput single object weighting with picogram accuracy. The extension of the dynamic models of AFM cantilevers to hollow cantilevers was discussed and the effectiveness of mass weighting in air was validated on test samples. PMID:27608651

  14. Microfabricated cantilever-based detector for molecular beam experiments

    NASA Astrophysics Data System (ADS)

    Bachels, T.; Schäfer, R.

    1998-11-01

    A low cost detector for particles in molecular beam experiments is presented which can easily be mounted in a molecular beam apparatus. The detector is based on microfabricated cantilevers, which can be employed either as single sensors or as sensor arrays. The single cantilever technique has been used to measure the absolute number of atoms coming out of a pulsed laser vaporization cluster source. The particles are detected by the shift of the thermally excited resonance frequency of the cantilever due to the cluster deposition. We have determined with the single cantilever the ratio of neutral to ionized clusters and we have investigated the cluster generation at different source conditions. In addition to this, a microfabricated cantilever array has been used to measure molecular beam profiles, which opens new possibilities for molecular beam deflection experiments.

  15. Pulling on super paramagnetic beads with micro cantilevers: single molecule mechanical assay application.

    PubMed

    Muñoz, Romina; Aguilar Sandoval, Felipe; Wilson, Christian A M; Melo, Francisco

    2015-07-01

    This paper demonstrates that it is possible to trap and release a super paramagnetic micro bead by fixing three super paramagnetic micro beads in a triangular array at the sensitive end of a micro cantilever, and by simply switching on/off an external magnetic field. To provide evidence of this principle we trap a micro bead that is attached to the free end of single DNA molecule and that has been previously fixed at the other end to a glass surface, using the standard sample preparation protocol of magnetic tweezers assays. The switching process is reversible which preserves the integrity of the tethered molecule, and a local force applied over the tethered bead excludes the neighbouring beads from the magnetic trap. We have developed a quadrature phase interferometer which is able to perform under fluid environments to accurately measure small deflections, which permits the exploration of DNA elasticity. Our results agree with measurements from magnetic tweezer assays performed under similar conditions. Furthermore, compared to the magnetic tweezer methodology, the combination of the magnetic trap with a suitable measurement system for cantilever deflection, allows for the exploration of a wide range of forces using a local method that has an improved temporal resolution. PMID:26200136

  16. Effect of cantilever nonlinearity in nanoscale tensile testing

    NASA Astrophysics Data System (ADS)

    Ding, Weiqiang; Guo, Zaoyang; Ruoff, Rodney S.

    2007-02-01

    Microcantilevers are widely used in micro-/nanoscale mechanics studies. The nonlinear response of a cantilever at large deflection is sometimes overlooked. A general study of cantilever beam nonlinearity under a variety of loading conditions was performed with analytical and finite element analyses. Analytical equations for the applied load and the cantilever deflection were obtained. The cantilever nonlinearity was found to increase with increasing cantilever deflection and/or angle of loading. Tensile tests were performed on templated carbon nanotubes (TCNTs) with a custom-made nanomanipulator inside a scanning electron microscope. Atomic force microscope (AFM) cantilevers were used to load the TCNTs and sense the force. During the tests the AFM cantilevers were loaded to relatively large deflections with nonvertical loads applied at the AFM tip. Based on the slope and the loading angle measurements, the breaking forces of the TCNTs were obtained through numerical integration of the analytical equations. A comparison was made between the load results obtained from linear and nonlinear analyses. The linear analysis was found to underestimate the applied load by up to 15%.

  17. In-situ piezoresponse force microscopy cantilever mode shape profiling

    SciTech Connect

    Proksch, R.

    2015-08-21

    The frequency-dependent amplitude and phase in piezoresponse force microscopy (PFM) measurements are shown to be a consequence of the Euler-Bernoulli (EB) dynamics of atomic force microscope (AFM) cantilever beams used to make the measurements. Changes in the cantilever mode shape as a function of changes in the boundary conditions determine the sensitivity of cantilevers to forces between the tip and the sample. Conventional PFM and AFM measurements are made with the motion of the cantilever measured at one optical beam detector (OBD) spot location. A single OBD spot location provides a limited picture of the total cantilever motion, and in fact, experimentally observed cantilever amplitude and phase are shown to be strongly dependent on the OBD spot position for many measurements. In this work, the commonly observed frequency dependence of PFM response is explained through experimental measurements and analytic theoretical EB modeling of the PFM response as a function of both frequency and OBD spot location on a periodically poled lithium niobate sample. One notable conclusion is that a common choice of OBD spot location—at or near the tip of the cantilever—is particularly vulnerable to frequency dependent amplitude and phase variations stemming from dynamics of the cantilever sensor rather than from the piezoresponse of the sample.

  18. Deflection of a flexural cantilever beam

    NASA Astrophysics Data System (ADS)

    Sherbourne, A. N.; Lu, F.

    The behavior of a flexural elastoplastic cantilever beam is investigated in which geometric nonlinearities are considered. The result of an elastica analysis by Frisch-Fay (1962) is extended to include postyield behavior. Although a closed-form solution is not possible, as in the elastic case, simple algebraic equations are derived involving only one unknown variable, which can also be expressed in the standard form of elliptic integrals if so desired. The results, in comparison with those of the small deflection analyses, indicate that large deflection analyses are necessary when the relative depth of the beam is very small over the length. The present exact solution can be used as a reference by those who resort to a finite element method for more complicated problems. It can also serve as a building block to other beam problems such as a simply supported beam or a beam with multiple loads.

  19. Cantilevered multilevel LIGA devices and methods

    DOEpatents

    Morales, Alfredo Martin; Domeier, Linda A.

    2002-01-01

    In the formation of multilevel LIGA microstructures, a preformed sheet of photoresist material, such as polymethylmethacrylate (PMMA) is patterned by exposure through a mask to radiation, such as X-rays, and developed using a developer to remove the exposed photoresist material. A first microstructure is then formed by electroplating metal into the areas from which the photoresist has been removed. Additional levels of microstructure are added to the initial microstructure by covering the first microstructure with a conductive polymer, machining the conductive polymer layer to reveal the surface of the first microstructure, sealing the conductive polymer and surface of the first microstructure with a metal layer, and then forming the second level of structure on top of the first level structure. In such a manner, multiple layers of microstructure can be built up to allow complex cantilevered microstructures to be formed.

  20. Voltage generation of piezoelectric cantilevers by laser heating

    PubMed Central

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y.; Gao, Xiaotong; Shih, Wei-Heng

    2012-01-01

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity. PMID:23258941

  1. Piezoresistive cantilever array sensor for consolidated bioprocess monitoring

    SciTech Connect

    Kim, Seonghwan Sam; Rahman, Touhidur; Senesac, Larry R; Davison, Brian H; Thundat, Thomas George

    2009-01-01

    Cellulolytic microbes occur in diverse natural niches and are being screened for industrial modification and utility. A microbe for Consolidated bioprocessing (CBP) development can rapidly degrade pure cellulose and then ferment the resulting sugars into fuels. To identify and screen for novel microbes for CBP, we have developed a piezoresistive cantilever array sensor which is capable of simultaneous monitoring of glucose and ethanol concentration changes in a phosphate buffer solution. 4-mercaptophenylboronic acid (4-MPBA) and polyethyleneglycol (PEG)-thiol are employed to functionalize each piezoresistive cantilever for glucose and ethanol sensing, respectively. Successful concentration measurements of glucose and ethanol with minimal interferences are obtained with our cantilever array sensor.

  2. Magnetic cantilever actuator with sharpened magnetic thin film ellipses

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Yu; Ger, Tzong-Rong; Lai, Mei-Feng; Chen, We-Yun; Huang, Hao-Ting; Chen, Jiann-Yeu; Wang, Pei-Jen; Wei, Zung-Hang

    2015-05-01

    A SiO2 cantilever covered by elliptical magnetic thin films was designed as an actuator. Under magnetic field, the elliptical magnetic film with sharp ends would exhibit single-domain structures and generate torque to push or pull the two arms of the cantilever. The cantilever could then stretch or compress and the displacement could be controlled by adjusting the magnitude and direction of the external magnetic field. The combination between micromagnetism of patterned films and actuator was successfully demonstrated. The magnetic actuator can be applied for future application in the biological field and would be valuable for microelectromechanical systems (MEMS).

  3. An approach towards 3D sensitive AFM cantilevers

    NASA Astrophysics Data System (ADS)

    Koops, Richard; Fokkema, Vincent

    2014-04-01

    The atomic force microscope (AFM) tapping mode is a highly sensitive local probing technique that is very useful to study and measure surface properties down to the atomic scale. The tapping mode is mostly implemented using the resonance of the first bending mode of the cantilever and therefore provides sensitivity mainly along the direction of this oscillation. Driven by the semiconductor industry, there is an increasing need for accurate measurements of nanoscale structures for side wall characterization by AFM that requires additional sensitivity in the lateral direction. The conventional tapping mode has been augmented by various authors, for example by tilting the cantilever system (Cho et al 2011 Rev. Sci. Instrum. 82 023707) to access the sidewall or using a torsion mode (Dai et al 2011 Meas. Sci. Technol. 22 094009) of the cantilever to provide additional lateral sensitivity. These approaches however trade lateral sensitivity for vertical sensitivity or still lack sensitivity in the remaining lateral direction. We present an approach towards true 3D sensitivity for AFM cantilevers based on simultaneous excitation and optical detection of multiple cantilever resonance modes along three axes. Tuning the excitation of the cantilever to specific frequencies provides a mechanism to select only those cantilever modes that have the desired characteristics. Additionally, cantilever engineering has been used to design and create a substructure within the cantilever that has been optimized for specific resonance behavior around 4 MHz. In contrast to the conventional approach of using a piezo to actuate the cantilever modulation, we present results on photo-thermal excitation using an intensity modulated low-power laser source. By tightly focusing the excitation spot on the cantilever we were able to attain a deflection efficiency of 0.7 nm µW-1 for the first bending mode. The presented approach results in an efficient all optical excitation and deflection detection

  4. Cantilever arrays for multiplexed mechanical analysis of biomolecular reactions.

    PubMed

    Yue, Min; Stachowiak, Jeanne C; Majumdar, Arunava

    2004-09-01

    Microchips containing arrays of cantilever beams have been used to mechanically detect and quantitatively analyze multiple reactions of DNA hybridization and antigen-antibody binding simultaneously. The reaction-induced deflection of a cantilever beam reflects the interplay between strain energy increase of the beam and the free energy reduction of a reaction, providing an ideal tool for investigating the connection between mechanics and chemistry of biomolecular reactions. Since free energy reduction is common for all reactions, the cantilever array forms a universal platform for label-free detection of various specific biomolecular reactions. A few such reactions and their implications in biology and biotechnology are discussed. PMID:16783934

  5. Voltage generation of piezoelectric cantilevers by laser heating.

    PubMed

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y; Gao, Xiaotong; Shih, Wei-Heng

    2012-11-15

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity. PMID:23258941

  6. Energy harvesting from radio frequency propagation using piezoelectric cantilevers

    NASA Astrophysics Data System (ADS)

    Ahmad, Mahmoud Al; Alshareef, H. N.

    2012-02-01

    This work reports an induced strain in a piezoelectric cantilever due to radio frequency signal propagation. The piezoelectric actuator is coupled to radio frequency (RF) line through a gap of 0.25 mm. When a voltage signal of 10 Vpp propagates in the line it sets an alternating current in the actuator electrodes. This flowing current drives the piezoelectric cantilever to mechanical movement, especially when the frequency of the RF signal matches the mechanical resonant frequency of the cantilever. Output voltage signals versus frequency for both mechanical vibrational and RF signal excitations have been measured using different loads.

  7. Voltage generation of piezoelectric cantilevers by laser heating

    NASA Astrophysics Data System (ADS)

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y.; Gao, Xiaotong; Shih, Wei-Heng

    2012-11-01

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity.

  8. Self-sensing piezoresistive cantilever and its magnetic force microscopy applications.

    PubMed

    Takahashi, Hiroshi; Ando, Kazunori; Shirakawabe, Yoshiharu

    2002-05-01

    A newly developed Si self-sensing piezoresistive cantilever is presented. Si piezoresistive cantilevers for scanning microscopy are fabricated by Si micro-machining technique. The sensitivity of the piezoresistive cantilever is comparable to the current laser detecting system. Topographic images are successfully obtained with the piezoresistive cantilever and some comparisons are made with the laser detecting system. Furthermore, the magnetic film (Co-Cr-Pt) is coated on the tip of the piezoresistive cantilever for magnetic force microscopy (MFM) application. The magnetic images are successfully obtained with the self-sensing MFM piezoresistive cantilever. The self-sensing piezoresistive cantilevers have been successfully applied in scanning probe microscopy and MFM. PMID:12211485

  9. 278. Frank Deras Jr., Photographer April 1999 VIEW OF CANTILEVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    278. Frank Deras Jr., Photographer April 1999 VIEW OF CANTILEVER TRUSS, THROUGH TRUSS, AND DECK TRUSS SPANS, SOUTH SIDE, FACING NORTHEAST. - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  10. 258. Dennis Hill, Photographer April 1998 VIEW OF CANTILEVER TRUSS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    258. Dennis Hill, Photographer April 1998 VIEW OF CANTILEVER TRUSS ANCHOR ARM AT PIERS E- AND E-2, SOUTH SIDE, FACING NORTH. - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  11. Cantilever Arrays as a platform for chemical and biological sensors

    NASA Astrophysics Data System (ADS)

    Datskos, Panos

    2005-03-01

    Since the late 1980's there have been spectacular developments in micro-mechanical or micro-electro-mechanical (MEMS) systems which have enabled exploration of new transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result, an innovative family of chemical and biological sensors has emerged. While MEMS represents a diverse family of designs, devices with simple cantilever configurations are especially attractive as transducers for chemical and biological sensors. In our presentation we deal with four important aspects of cantilever transducers: (i) operation principles and models, (ii) micro-fabrication, (iii) figures of merit, and (iv) applications of cantilever sensors. We also provide a brief analysis of historical predecessors of the modern cantilever sensors. Finally we have demonstrated that using large well designed arrays of differentially coated microcantilevers coupled artificial neural network techniques can provide information on the identity and amount of target chemicals. We will present our results and discuss future directions.

  12. 57. VIEW WEST, DETAIL OF CANTILEVER SPAN SHOWING OVERHANG FRAMING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    57. VIEW WEST, DETAIL OF CANTILEVER SPAN SHOWING OVERHANG FRAMING AND UNDERSIDE FRAMING - Route 1 Extension, Southbound Viaduct, Spanning Conrail Yards, Wilson Avenue, Delancy Street, & South Street on Routes 1 & 9 Southbound, Newark, Essex County, NJ

  13. 21. DETAIL OF WEST (AMERICAN) CANTILEVER AND ANCHOR ARMS OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. DETAIL OF WEST (AMERICAN) CANTILEVER AND ANCHOR ARMS OF MAIN SPAN, SHOWING PIER M. VIEW TO NORTH. - Blue Water Bridge, Spanning St. Clair River at I-69, I-94, & Canadian Route 402, Port Huron, St. Clair County, MI

  14. 12. VIEW EAST ALONG DECK CENTERLINE, PRIOR TO CANTILEVERING SIDEWALK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW EAST ALONG DECK CENTERLINE, PRIOR TO CANTILEVERING SIDEWALK ON DOWNSTREAM SIDE File photo, Caltrans Office of Strutures Maintenance, March 1938. Photographer unknown. Photocopy of photograph - San Roque Canyon Bridge, State Highway 192, Santa Barbara, Santa Barbara County, CA

  15. 19. Cantilevered barn in Cades Cove looking SSW. Great ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Cantilevered barn in Cades Cove looking SSW. - Great Smoky Mountains National Park Roads & Bridges, Cades Cove Road & Laurel Creek Road, From Townsend Wye to Cades Cove, Gatlinburg, Sevier County, TN

  16. 13. VIEW OF CANTILEVERED NORTHERN TRUSS SECTION (LOWER CENTER OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW OF CANTILEVERED NORTHERN TRUSS SECTION (LOWER CENTER OF PHOTOGRAPH), SHOWING LINKAGES TO THE CENTRAL BRIDGE SUPERSTRUCTURE. FACING NORTHEAST. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

  17. 22. DETAIL OF EAST (CANADIAN) CANTILEVER AND ANCHOR ARMS OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. DETAIL OF EAST (CANADIAN) CANTILEVER AND ANCHOR ARMS OF MAIN SPAN, SHOWING PIER C. VIEW TO NORTH. - Blue Water Bridge, Spanning St. Clair River at I-69, I-94, & Canadian Route 402, Port Huron, St. Clair County, MI

  18. 14. VIEW OF CANTILEVERED SOUTHERN TRUSS SECTION AND WOOD DECK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. VIEW OF CANTILEVERED SOUTHERN TRUSS SECTION AND WOOD DECK FROM THE CENTRAL BRIDGE SUPERSTRUCTURE SHOWN IN PA-474-13. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

  19. 10. REPRESENTATIVE DETAIL VIEW OF CANTILEVERED DECK AND CONSTRUCTION OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. REPRESENTATIVE DETAIL VIEW OF CANTILEVERED DECK AND CONSTRUCTION OF BRIDGE SUBSTRUCTURE - Central of Georgia Railway, Bay Street Viaduct, U.S. 17 & Bay Street, spanning Central of Georgia Railroad, Savannah, Chatham County, GA

  20. 4. SIDE VIEW OF BRIDGE, LOOKING SOUTHWEST, SHOWING ARCHES, CANTILEVERED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SIDE VIEW OF BRIDGE, LOOKING SOUTHWEST, SHOWING ARCHES, CANTILEVERED WALKWAY, DECK BEAMS AND STREAMBED - Benson Street Concrete Bowstring Bridge, Spanning Mill Creek at Benson Street, Lockland, Hamilton County, OH

  1. UNDERSIDE. NOTE DOUBLE BEAMS CANTILEVERED FOR PEDESTRIAN WALKWAY. DATE ADDED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    UNDERSIDE. NOTE DOUBLE BEAMS CANTILEVERED FOR PEDESTRIAN WALKWAY. DATE ADDED TO BRIDGE UNKNOWN, BUT PROBABLY 1921-22 OR AFTER 1927. - Bath-Haverhill Bridge, Spanning Ammonoosuc River, bypassed section of Ammanoosuc Street (SR 135), Woodsville, Grafton County, NH

  2. 14. UNDERSIDE, SHOWING PIERS, CROSS BEAMS, AND CANTILEVERED EXTENSION OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. UNDERSIDE, SHOWING PIERS, CROSS BEAMS, AND CANTILEVERED EXTENSION OF BRIDGE FOR ACCESS TO WAREHOUSE, LOOKING NORTH - Appomattox Bridge, U.S. Route 1 over Appomattox River, Petersburg, Petersburg, VA

  3. Parallel optical readout of cantilever arrays in dynamic mode.

    PubMed

    Koelmans, W W; van Honschoten, J; de Vries, J; Vettiger, P; Abelmann, L; Elwenspoek, M C

    2010-10-01

    Parallel frequency readout of an array of cantilevers is demonstrated using optical beam deflection with a single laser-diode pair. Multi-frequency addressing makes the individual nanomechanical response of each cantilever distinguishable within the received signal. Addressing is accomplished by exciting the array with the sum of all cantilever resonant frequencies. This technique requires considerably less hardware compared to other parallel optical readout techniques. Readout is demonstrated in beam deflection mode and interference mode. Many cantilevers can be readout in parallel, limited by the oscillators' quality factor and available bandwidth. The proposed technique facilitates parallelism in applications at the nano-scale, including probe-based data storage and biological sensing. PMID:20820095

  4. 20. DETAIL OF WEST ANCHOR SPAN, CANTILEVER ARMS AND WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. DETAIL OF WEST ANCHOR SPAN, CANTILEVER ARMS AND WEST HALF OF SUSPENDED SPAN OF THROUGH TRUSS. VIEW TO NORTHEAST. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

  5. 29. DECK / WEB / LATERAL BRACING DETAIL OF CANTILEVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. DECK / WEB / LATERAL BRACING DETAIL OF CANTILEVER ARM OF THROUGH TRUSS. VIEW TO WEST. - MacArthur Bridge, Spanning Mississippi River on Highway 34 between IA & IL, Burlington, Des Moines County, IA

  6. Wedged AFM-cantilevers for parallel plate cell mechanics.

    PubMed

    Stewart, Martin P; Hodel, Adrian W; Spielhofer, Andreas; Cattin, Cedric J; Müller, Daniel J; Helenius, Jonne

    2013-04-01

    The combination of atomic force microscopy (AFM) and optical microscopy has gained popularity for mechanical analysis of living cells. In particular, recent AFM-based assays featuring tipless cantilevers and whole-cell deformation have yielded insights into cellular function, structure, and dynamics. However, in these assays the standard ≈10° tilt of the cantilever prevents uniaxial loading, which complicates assessment of cellular geometry and can cause cell sliding or loss of loosely adherent cells. Here, we describe an approach to modify tipless cantilevers with wedges and, thereby, achieve proper parallel plate mechanics. We provide guidance on material selection, the wedge production process, property and geometry assessment, and the calibration of wedged cantilevers. Furthermore, we demonstrate their ability to simplify the assessment of cell shape, prevent lateral displacement of round cells during compression, and improve the assessment of cell mechanical properties. PMID:23473778

  7. OBLIQUE VIEW OF THE NORTHEAST SIDE. NOTE THE CANTILEVERED CANOPY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OBLIQUE VIEW OF THE NORTHEAST SIDE. NOTE THE CANTILEVERED CANOPY OVER THE FRONT DOOR AND BELT COURSE OF THREE FLARED BANDS. VIEW FACING SOUTHEAST. - Hickam Field, Officers' Housing Type M, 113 Beard Avenue, Honolulu, Honolulu County, HI

  8. 12. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM NORTH CANTILEVER TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM NORTH CANTILEVER TOWER TOWARD SOUTH PORTAL. As with previous photo, note vertical displacement in deck. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  9. Low temperature scanning force microscopy using piezoresistive cantilevers

    NASA Astrophysics Data System (ADS)

    Meiser, P.; Koblischka, M. R.; Hartmann, U.

    2015-08-01

    A low temperature dynamic scanning force microscope has been constructed using commercially available piezoresistive cantilevers that can be coated with a ferromagnetic material for MFM application. The setup is able to work in a temperature range from room temperature down to 1.5 K. The performance of the piezoresistive cantilevers has been investigated under different working conditions. Topographic as well as magnetic images of a magnetite thin film sample have been taken at 50 and 4.2 K confirming the proper operation of the microscope at cryogenic temperatures. Furthermore, force-distance-curves taken on thin lead films at 4.2 K demonstrate the levitation forces between the magnetized cantilever tip and the superconducting films. Flux lines were generated by the magnetized cantilever tip itself when approaching the sample. It has also been shown that the microscope is sensitive to the detection of single magnetic flux lines penetrating the lead films.

  10. A new cantilever system for gas and liquid sensing.

    PubMed

    Vidic, A; Then, D; Ziegler, Ch

    2003-01-01

    A novel setup for gas and liquid sensing was developed and tested. It is based on both detection of frequency shift and of bending of micro-cantilevers to measure mass changes as well as viscosity changes. To drive the cantilevers new electrostatic and magnetic actuations were invented with a closed feed-back loop which forces the cantilever to oscillate always at its resonance frequency. The oscillation is detected via the beam-deflection technique. By measuring the DC signal of the photodiode the static bending of the cantilever can be monitored simultaneously. The closed feed-back loop propagates a very stable oscillation at the resonance frequency and gives a strong increase in the quality factor compared to a system without such feed-back loop. Furthermore, it is possible to operate this cantilever transducer system in liquids. These cantilever sensors hence, show the potential for use in easy-to-use and highly sensitive sensor systems for gas and liquid phase chemical and biochemical sensing. PMID:12801696

  11. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy.

    PubMed

    Coutu, Ronald A; Medvedev, Ivan R; Petkie, Douglas T

    2016-01-01

    In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever's anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA) coefficients of approximately 4.28 × 10(-10) cm(-1)·WHz(-1/2). This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy. PMID:26907280

  12. Active control of cantilever-beam vibration

    NASA Astrophysics Data System (ADS)

    Serbyn, M. Roman

    2002-11-01

    A bang-bang control system previously developed for the stabilization of a rigid platform [ISA Trans. 21, 55-59 (1982)] has been adapted to the problem of reducing flexural vibrations of a beam. The electromechanical system develops an appropriate control signal for the actuator from samples of the disturbance by analog and digital signal processing using integrated circuits. The effectiveness of this approach is predicated upon the sampling rate being much higher than the maximum vibration frequency to be silenced. It is also robust with respect to the waveform of the disturbance. Noise reductions of 10-20 dB have been achieved, depending on the bandwidth of the noise. The cantilever, chosen because of its mechanical and theoretical simplicity, provides a good foundation for the study of more complex structures, like airfoils and nonrigid platforms. In both experimental and analytical investigations the emphasis has been on the optimization of control parameters, particularly with regard to the application of the cancellation signal. Reduction in size and cost of the control unit is possible by incorporating the latest technological advances in electronic and electromechanical devices, such as FPGA boards and MEMS components.

  13. Piezoresistive cantilever force-clamp system

    SciTech Connect

    Park, Sung-Jin; Petzold, Bryan C.; Pruitt, Beth L.; Goodman, Miriam B.

    2011-04-15

    We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or ''clamps'' the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of {mu}N force and nm up to tens of {mu}m displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

  14. Piezoresistive cantilever force-clamp system

    PubMed Central

    Park, Sung-Jin; Petzold, Bryan C.; Goodman, Miriam B.; Pruitt, Beth L.

    2011-01-01

    We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or “clamps” the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of μN force and nm up to tens of μm displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode. PMID:21529009

  15. Measurement of Mechanical Properties of Cantilever Shaped Materials

    PubMed Central

    Finot, Eric; Passian, Ali; Thundat, Thomas

    2008-01-01

    Microcantilevers were first introduced as imaging probes in Atomic Force Microscopy (AFM) due to their extremely high sensitivity in measuring surface forces. The versatility of these probes, however, allows the sensing and measurement of a host of mechanical properties of various materials. Sensor parameters such as resonance frequency, quality factor, amplitude of vibration and bending due to a differential stress can all be simultaneously determined for a cantilever. When measuring the mechanical properties of materials, identifying and discerning the most influential parameters responsible for the observed changes in the cantilever response are important. We will, therefore, discuss the effects of various force fields such as those induced by mass loading, residual stress, internal friction of the material, and other changes in the mechanical properties of the microcantilevers. Methods to measure variations in temperature, pressure, or molecular adsorption of water molecules are also discussed. Often these effects occur simultaneously, increasing the number of parameters that need to be concurrently measured to ensure the reliability of the sensors. We therefore systematically investigate the geometric and environmental effects on cantilever measurements including the chemical nature of the underlying interactions. To address the geometric effects we have considered cantilevers with a rectangular or circular cross section. The chemical nature is addressed by using cantilevers fabricated with metals and/or dielectrics. Selective chemical etching, swelling or changes in Young's modulus of the surface were investigated by means of polymeric and inorganic coatings. Finally to address the effect of the environment in which the cantilever operates, the Knudsen number was determined to characterize the molecule-cantilever collisions. Also bimaterial cantilevers with high thermal sensitivity were used to discern the effect of temperature variations. When appropriate

  16. Improved single molecule force spectroscopy using micromachined cantilevers.

    PubMed

    Bull, Matthew S; Sullan, Ruby May A; Li, Hongbin; Perkins, Thomas T

    2014-05-27

    Enhancing the short-term force precision of atomic force microscopy (AFM) while maintaining excellent long-term force stability would result in improved performance across multiple AFM modalities, including single molecule force spectroscopy (SMFS). SMFS is a powerful method to probe the nanometer-scale dynamics and energetics of biomolecules (DNA, RNA, and proteins). The folding and unfolding rates of such macromolecules are sensitive to sub-pN changes in force. Recently, we demonstrated sub-pN stability over a broad bandwidth (Δf = 0.01-16 Hz) by removing the gold coating from a 100 μm long cantilever. However, this stability came at the cost of increased short-term force noise, decreased temporal response, and poor sensitivity. Here, we avoided these compromises while retaining excellent force stability by modifying a short (L = 40 μm) cantilever with a focused ion beam. Our process led to a ∼10-fold reduction in both a cantilever's stiffness and its hydrodynamic drag near a surface. We also preserved the benefits of a highly reflective cantilever while mitigating gold-coating induced long-term drift. As a result, we extended AFM's sub-pN bandwidth by a factor of ∼50 to span five decades of bandwidth (Δf ≈ 0.01-1000 Hz). Measurements of mechanically stretching individual proteins showed improved force precision coupled with state-of-the-art force stability and no significant loss in temporal resolution compared to the stiffer, unmodified cantilever. Finally, these cantilevers were robust and were reused for SFMS over multiple days. Hence, we expect these responsive, yet stable, cantilevers to broadly benefit diverse AFM-based studies. PMID:24670198

  17. SiC-Based Miniature High-Temperature Cantilever Anemometer

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.; Fralick, Gustave; Saad, George J.

    2004-01-01

    The figure depicts a miniature cantilever-type anemometer that has been developed as a prototype of compact, relatively nonintrusive anemometers that can function at temperatures up to 600 C and that can be expected to be commercially mass-producible at low cost. The design of this anemometer, and especially the packaging aspect of the design, is intended to enable measurement of turbulence in the high-temperature, high-vibration environment of a turbine engine or in any similar environment. The main structural components of the anemometer include a single-crystal SiC cantilever and two polycrystalline SiC clamping plates, all made from chemical-vapor-deposited silicon carbide. Fabrication of these components from the same basic material eliminates thermal-expansion mismatch, which has introduced spurious thermomechanical stresses in cantilever-type anemometers of prior design. The clamping plates are heavily oxidized to improve electrical insulation at high temperature. A cavity that serves as a receptacle for the clamped end of the cantilever is etched into one end of one clamping plate. Trenches that collectively constitute a socket for a multipin electrical plug (for connection to external electronic circuitry) are etched into the opposite end of this clamping plate. Metal strips for electrical contact are deposited on one face of the other clamping plate. Piezoresistive single-crystal SiC thin-film strain gauges are etched in the n-type SiC epilayer in a Wheatstone-bridge configuration. Metal contact pads on the cantilever that extend into the clamping-receptacle area, are obtained by deposition and patterning using standard semiconductor photolithography and etching methods. The cantilever and the two clamping plates are assembled into a sandwich structure that is then clamped in a stainless-steel housing. The Wheatstone- bridge carrying SiC cantilever with the metal contact pads on the piezoresistors is slid into the receptacle in the bottom clamping plate

  18. Palpationlike soft-material elastic modulus measurement using piezoelectric cantilevers

    NASA Astrophysics Data System (ADS)

    Szewczyk, Steven T.; Shih, Wan Y.; Shih, Wei-Heng

    2006-04-01

    We have developed an all-electrical piezoelectric cantilever sensor that can self-excite and self-detect for tissue elastic modulus measurement. An all-electrical piezoelectric cantilever is consisted of a sandwich of piezoelectric layer, e.g., lead zirconate titanate (PZT), a nonpiezoelectric layer, e.g., stainless steel, and a second piezoelectric layer. The top piezoelectric layer serves as the driving layer (self-exciting) and the second piezoelectric layer as the sensing layer (self-sensing). The driving and sensing piezoelectric layers may be of different lengths. Applying a dc voltage across the driving PZT layer causes the piezoelectric cantilever to bend. The resultant bending stress in the sensing PZT layer generates a piezoelectric voltage across the sensing PZT layer that rises rapidly to a maximum before it decays with time. The maximum induced voltage was used to measure the axial displacement of the piezoelectric cantilever. With its force generation and displacement sensing capability, we show that an all-electrical piezoelectric cantilever can measure the elastic modulus of tissues both under the regular compression geometry and the flat-punch indentation geometry. In addition, the sensor can map the local elastic modulus variations of tissues much like palpation.

  19. Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester

    PubMed Central

    Kubba, Ali E.; Jiang, Kyle

    2014-01-01

    Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (Vave), and average normal strain in the piezoelectric transducer (εave) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle). PMID:24366177

  20. Efficiency enhancement of a cantilever-based vibration energy harvester.

    PubMed

    Kubba, Ali E; Jiang, Kyle

    2013-01-01

    Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (V(ave)), and average normal strain in the piezoelectric transducer (ε(ave)) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle). PMID:24366177

  1. Cantilever with immobilized antibody for liver cancer biomarker detection

    NASA Astrophysics Data System (ADS)

    Shuaipeng, Wang; Jingjing, Wang; Yinfang, Zhu; Jinling, Yang; Fuhua, Yang

    2014-10-01

    A novel cantilever array-based bio-sensor was batch-fabricated with IC compatible MEMS technology for precise liver cancer bio-marker detection. A micro-cavity was designed in the free end of the cantilever for local antibody-immobilization, thus the adsorption of the cancer biomarker takes place only in the local region of the cantilever instead of the whole lever, and the effect of adsorption-induced k variation can be dramatically reduced. These structural features offer several advantages: high sensitivity, high throughput, high mass detection accuracy, and a portable system. In addition, an analytical model has been established to eliminate the effect of the adsorption-induced lever stiffness change and has been applied to the precise mass detection of the cancer biomarker AFP; the experimentally detected AFP antigen mass by the sensor (7.6 pg/mL) is quite close to the calculated one (5.5 pg/mL), two orders of magnitude better than those of the fully antibody-immobilized cantilever sensor. These approaches can promote real applications of the cantilever sensors in cancer diagnosis.

  2. Defect reduction in gallium nitride using cantilever epitaxy.

    SciTech Connect

    Mitchell, Christine Charlotte

    2003-08-01

    Cantilever epitaxy (CE) has been developed to produce GaN on sapphire with low dislocation densities as needed for improved devices. The basic mechanism of seeding growth on sapphire mesas and lateral growth of cantilevers until they coalesce has been modified with an initial growth step at 950 C. This step produces a gable with (11{bar 2}2) facets over the mesas, which turns threading dislocations from vertical to horizontal in order to reduce the local density above mesas. This technique has produced material with densities as low as 2-3x10{sup 7}/cm{sup 2} averaged across extended areas of GaN on sapphire, as determined with AFM, TEM and cathodoluminescence (CL). This density is about two orders of magnitude below that of conventional planar growths; these improvements suggest that locating wide-area devices across both cantilever and mesa regions is possible. However, the first implementation of this technique also produced a new defect: cracks at cantilever coalescences with associated arrays of lateral dislocations. These defects have been labeled 'dark-block defects' because they are non-radiative and appear as dark rectangles in CL images. Material has been grown that does not have dark-block defects. Examination of the evolution of the cantilever films for many growths, both partial and complete, indicates that producing a film without these defects requires careful control of growth conditions and crystal morphology at multiple steps. Their elimination enhances optical emission and uniformity over large (mm) size areas.

  3. Energy harvesting of two cantilever beams structure: interfacing circuit discussion

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Yin; Vasic, Dejan

    2015-03-01

    Today research on supplying of low power consumption device is highly focused on piezoelectric energy harvesting from ambient vibration. The most popular structure is a cantilever beam with piezoelectric patch to convert mechanical energy into electric energy. In the past researches, the theoretical analysis and interfacing circuit design of single cantilever beam structure is highly developed. In this study, the electrical interfacing circuit of two (or more) piezoelectric generators connected to only one load is proposed and discussed. The nonlinear synchronized switching technique SSHI (Synchronized Switching Harvesting in Inductor) is examined to increase the power efficiency effectively of each piezoelectric generator. In the multiple cantilever beam or flag structure application, the structure may be composed of many piezoelectric patches and the interfacing circuit becomes more complicated and important. From the theoretical analysis and the governing equation, the equivalent circuit of two cantilever beam will be proposed and simulated with the optimized synchronous electric charge extraction (OSECE) nonlinear technique to optimize the interfacing circuit and increase the power efficiency by using the Matlab and PSIM software. The experiments will also show the good agreement with the theoretical analysis. The interfacing circuit design concept in the two cantilever beams structure can be further used in the multi-piezoelectric patches energy harvesting system such as piezoelectric flag to optimize the circuit and increase the power efficiency.

  4. Cantilever Type Lead Zirconate Titanate Microactuator Utilizing Ruthenium Oxide

    NASA Astrophysics Data System (ADS)

    Lee, Sun-Ho; Jeon, Min-Seok; Hong, Kyung-Il; Lee, Jin-Won; Kim, Chang-Kyung; Choi, Duck-Kyun

    2000-05-01

    A new and simple cantilever type Pb(Zr, Ti)O3 [PZT] microactuator was fabricated by adopting RuO2. The RuO2 has reasonably good conductivity and stiffness and it can replace the double layer of electrode and supporting layer to a single layer in a cantilever beam. The RuO2, PZT and Al thin films were deposited on the Si substrate. The patterning of the Al was carried out by a lithography process and etched with a chemical wet etchant. The etching of PZT and RuO2 were performed by a reactive ion etching system. The Si was etched isotropically to form a cantilever beam. The fabricated cantilever beam consists of Al, PZT and RuO2, and the thicknesses of the films are 0.40, 0.25 and 0.70 μm, respectively. The beams were from 140 μm to 275 μm in length and all of them were 60 μm wide. Driving tilt angles of the cantilever beams were almost proportional to the applied voltages.

  5. Tuning the Spring Constant of Cantilever-free Probe Arrays

    NASA Astrophysics Data System (ADS)

    Eichelsdoerfer, Daniel J.; Brown, Keith A.; Boya, Radha; Shim, Wooyoung; Mirkin, Chad A.

    2013-03-01

    The versatility of atomic force microscope (AFM) based techniques such as scanning probe lithography is due in part to the utilization of a cantilever that can be fabricated to match a desired application. In contrast, cantilever-free scanning probe lithography utilizes a low cost array of probes on a compliant backing layer that allows for high throughput nanofabrication but lacks the tailorability afforded by the cantilever in traditional AFM. Here, we present a method to measure and tune the spring constant of probes in a cantilever-free array by adjusting the mechanical properties of the underlying elastomeric layer. Using this technique, we are able to fabricate large-area silicon probe arrays with spring constants that can be tuned in the range from 7 to 150 N/m. This technique offers an advantage in that the spring constant depends linearly on the geometry of the probe, which is in contrast to traditional cantilever-based lithography where the spring constant varies as the cube of the beam width and thickness. To illustrate the benefit of utilizing a probe array with a lower spring constant, we pattern a block copolymer on a delicate 50 nm thick silicon nitride window.

  6. Experimental investigation of fatigue in a cantilever energy harvesting beam

    NASA Astrophysics Data System (ADS)

    Avvari, Panduranga Vittal; Yang, Yaowen; Liu, Peiwen; Soh, Chee Kiong

    2015-03-01

    Over the last decade, cantilever energy harvesters gained immense popularity owing to the simplicity of the design and piezoelectric energy harvesting (PEH) using the cantilever design has undergone considerable evolution. The major drawback of a vibrating cantilever beam is its vulnerability to fatigue over a period of time. This article brings forth an experimental investigation into the phenomenon of fatigue of a PEH cantilever beam. As there has been very little literature reported in this area, an effort has been made to scrutinize the damage due to fatigue in a linear vibrating cantilever PEH beam consisting of an aluminum substrate with a piezoelectric macro-fiber composite (MFC) patch attached near the root of the beam and a tip mass attached to the beam. The beam was subjected to transverse vibrations and the behavior of the open circuit voltage was recorded with passing time. Moreover, electro-mechanical admittance readings were obtained periodically using the same MFC patch as a Structural health monitoring (SHM) sensor to assess the health of the PEH beam. The results show that with passing time the PEH beam underwent fatigue in both the substrate and MFC, which is observed in a complimentary trend in the voltage and admittance readings. The claim is further supported using the variation of root mean square deviation (RMSD) of the real part of admittance (conductance) readings. Thus, this study concludes that the fatigue issue should be addressed in the design of PEH for long term vibration energy harvesting.

  7. SU-8 hollow cantilevers for AFM cell adhesion studies

    NASA Astrophysics Data System (ADS)

    Martinez, Vincent; Behr, Pascal; Drechsler, Ute; Polesel-Maris, Jérôme; Potthoff, Eva; Vörös, Janos; Zambelli, Tomaso

    2016-05-01

    A novel fabrication method was established to produce flexible, transparent, and robust tipless hollow atomic force microscopy (AFM) cantilevers made entirely from SU-8. Channels of 3 μm thickness and several millimeters length were integrated into 12 μm thick and 40 μm wide cantilevers. Connected to a pressure controller, the devices showed high sealing performance with no leakage up to 6 bars. Changing the cantilever lengths from 100 μm to 500 μm among the same wafer allowed the targeting of various spring constants ranging from 0.5 to 80 N m‑1 within a single fabrication run. These hollow polymeric AFM cantilevers were operated in the optical beam deflection configuration. To demonstrate the performance of the device, single-cell force spectroscopy experiments were performed with a single probe detaching in a serial protocol more than 100 Saccharomyces cerevisiae yeast cells from plain glass and glass coated with polydopamine while measuring adhesion forces in the sub-nanoNewton range. SU-8 now offers a new alternative to conventional silicon-based hollow cantilevers with more flexibility in terms of complex geometric design and surface chemistry modification.

  8. Nonlinear resonances of a single-wall carbon nanotube cantilever

    NASA Astrophysics Data System (ADS)

    Kim, I. K.; Lee, S. I.

    2015-03-01

    The dynamics of an electrostatically actuated carbon nanotube (CNT) cantilever are discussed by theoretical and numerical approaches. Electrostatic and intermolecular forces between the single-walled CNT and a graphene electrode are considered. The CNT cantilever is analyzed by the Euler-Bernoulli beam theory, including its geometric and inertial nonlinearities, and a one-mode projection based on the Galerkin approximation and numerical integration. Static pull-in and pull-out behaviors are adequately represented by an asymmetric two-well potential with the total potential energy consisting of the CNT elastic energy, electrostatic energy, and the Lennard-Jones potential energy. Nonlinear dynamics of the cantilever are simulated under DC and AC voltage excitations and examined in the frequency and time domains. Under AC-only excitation, a superharmonic resonance of order 2 occurs near half of the primary frequency. Under both DC and AC loads, the cantilever exhibits linear and nonlinear primary and secondary resonances depending on the strength of the excitation voltages. In addition, the cantilever has dynamic instabilities such as periodic or chaotic tapping motions, with a variation of excitation frequency at the resonance branches. High electrostatic excitation leads to complex nonlinear responses such as softening, multiple stability changes at saddle nodes, or period-doubling bifurcation points in the primary and secondary resonance branches.

  9. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy

    PubMed Central

    Coutu, Ronald A.; Medvedev, Ivan R.; Petkie, Douglas T.

    2016-01-01

    In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA) coefficients of approximately 4.28 × 10−10 cm−1·WHz−1/2. This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy. PMID:26907280

  10. Piezoresistive cantilever based nanoflow and viscosity sensor for microchannels.

    PubMed

    Quist, Arjan; Chand, Ami; Ramachandran, Srinivasan; Cohen, Dan; Lal, Ratnesh

    2006-11-01

    Microfluidic channels are microreactors with a wide range of applications, including molecular separations based upon micro/nanoscale physicochemical properties, targeting and delivery of small amount of fluids and molecules, and patterned/directed growth. Their successful applications would require a detailed understanding of phenomena associated with the microscale flow of liquids through these channels, including velocity, viscosity and miscibility. Here we demonstrate a highly sensitive piezoresistive cantilever to measure flow properties in microfluidic channels. By milling down the legs of the piezoresistive cantilevers, we have achieved significantly higher mechanical sensitivity and a smaller spring constant, as determined by AFM. These cantilevers were used in microchannels to measure the viscosity and flow rate of ethylene glycol mixtures in water over a range of concentrations, as well as of low viscosity biologically relevant buffers with different serum levels. The sensor can be used alone or can be integrated in AFM systems for multidimensional study in micro and nanochannels. PMID:17066169

  11. Shear force microscopy using piezoresistive cantilevers in surface metrology

    NASA Astrophysics Data System (ADS)

    Gotszalk, Teodor; Kopiec, Daniel; Sierakowski, Andrzej; Janus, Paweł; Grabiec, Piotr; Rangelow, Ivo W.

    2014-09-01

    In this article we describe application of piezoresistive cantilevers in surface investigations carried out with the use of shear force microscopy (ShFM). The novel piezoresistive cantilevers integrate a Wheatstone piezoresistive bridge was used to detect the cantilever deflection, thermal deflection detector and planar tip protruding out of the spring beam. Because the planar tip deflection can be detected and controlled electronically the described technology is very flexible and can be applied in many surface investigations. In this article we will present operation theory of the described solution, experimental setup, methods for calibration of the tip deflection detection and actuation The analysis will be illustrated with example results of topography measurements performed using the described technology.

  12. Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

    SciTech Connect

    Grutzik, Scott J.; Zehnder, Alan T.; Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F.

    2013-11-15

    There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included.

  13. Liquid-phase chemical sensing using lateral mode resonant cantilevers.

    PubMed

    Beardslee, L A; Demirci, K S; Luzinova, Y; Mizaikoff, B; Heinrich, S M; Josse, F; Brand, O

    2010-09-15

    Liquid-phase operation of resonant cantilevers vibrating in an out-of-plane flexural mode has to date been limited by the considerable fluid damping and the resulting low quality factors (Q factors). To reduce fluid damping in liquids and to improve the detection limit for liquid-phase sensing applications, resonant cantilever transducers vibrating in their in-plane rather than their out-of-plane flexural resonant mode have been fabricated and shown to have Q factors up to 67 in water (up to 4300 in air). In the present work, resonant cantilevers, thermally excited in an in-plane flexural mode, are investigated and applied as sensors for volatile organic compounds in water. The cantilevers are fabricated using a complementary metal oxide semiconductor (CMOS) compatible fabrication process based on bulk micromachining. The devices were coated with chemically sensitive polymers allowing for analyte sorption into the polymer. Poly(isobutylene) (PIB) and poly(ethylene-co-propylene) (EPCO) were investigated as sensitive layers with seven different analytes screened with PIB and 12 analytes tested with EPCO. Analyte concentrations in the range of 1-100 ppm have been measured in the present experiments, and detection limits in the parts per billion concentration range have been estimated for the polymer-coated cantilevers exposed to volatile organics in water. These results demonstrate significantly improved sensing properties in liquids and indicate the potential of cantilever-type mass-sensitive chemical sensors operating in their in-plane rather than out-of-plane flexural modes. PMID:20715842

  14. A surface-acoustic-wave-based cantilever bio-sensor.

    PubMed

    De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

    2015-06-15

    A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices. PMID:25643594

  15. Lead zirconate titanate cantilever for noncontact atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Miyahara, Y.; Fujii, T.; Watanabe, S.; Tonoli, A.; Carabelli, S.; Yamada, H.; Bleuler, H.

    1999-02-01

    Noncontact atomic force microscopy with frequency modulation detection is a promising technique for surface observation with true atomic resolution. The piezoelectric material itself can be an actuator and sensor of the oscillating probe simultaneously, without the need for additional electro-mechanical transducers or other measurement systems. A vertical resolution of 0.01 nm rms has been achieved using a microfabricated cantilever with lead zirconate titanate thin film in noncontact mode frequency modulation detection. The cantilever also has a sharpened pyramidal stylus with a radius of about 10 nm for noncontact atomic force microscopy.

  16. 254. Frank Deras Jr., Photographer July 1998 VIEW OF CANTILEVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    254. Frank Deras Jr., Photographer July 1998 VIEW OF CANTILEVER TRUSS, THROUGH TRUSS, AND DECK TRUSS SPANS FROM YERBA BUENA ISLAND TO OAKLAND, SOUTH SIDE (2 OF 3 PANORAMA), FACING NORTH. - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  17. Strategy Guideline: Quality Management in Existing Homes - Cantilever Floor Example

    SciTech Connect

    Taggart, J.; Sikora, J.; Wiehagen, J.; Wood, A.

    2011-12-01

    This guideline is designed to highlight the QA process that can be applied to any residential building retrofit activity. The cantilevered floor retrofit detailed in this guideline is included only to provide an actual retrofit example to better illustrate the QA activities being presented.

  18. Cantilever springs maintain tension in thermally expanded wires

    NASA Technical Reports Server (NTRS)

    Terselic, R. A.

    1965-01-01

    Two deflected cantilever springs strung with wire provide force displacement compensation to maintain tension in the wires as they undergo thermal expansion. This method of maintaining tension in thermally expanded wires is used in electric space heaters and residential heat exchangers.

  19. 4. WIDEANGLE VIEW OF THE EASTERN BRIDGE ELEVATION, SHOWING CANTILEVERED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. WIDE-ANGLE VIEW OF THE EASTERN BRIDGE ELEVATION, SHOWING CANTILEVERED SOUTHERN (LEFT) AND NORTHERN (RIGHT) TRUSS SECTIONS. THE CENTRAL TRUSS SECTION IS OBSCURED BY TREES AT CENTER OF PHOTOGRAPH. FACING WEST. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

  20. 56. VIEW SOUTH, WEST SIDE AT CANTILEVER SPAN (SPAN 70) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. VIEW SOUTH, WEST SIDE AT CANTILEVER SPAN (SPAN 70) SHOWING FACADE, DOUBLE CROSS BRACING AT COLUMNS, AND CONCRETE BASE - Route 1 Extension, Southbound Viaduct, Spanning Conrail Yards, Wilson Avenue, Delancy Street, & South Street on Routes 1 & 9 Southbound, Newark, Essex County, NJ

  1. CLOSEUP VIEW OF BOTTOM OF MAIN BRIDGE CANTILEVER THROUGH TRUSS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CLOSE-UP VIEW OF BOTTOM OF MAIN BRIDGE CANTILEVER THROUGH TRUSS SPAN SHOWING RAILROAD PORTION OF FLOOR BEAMS AND OTHER STRUCTURAL COMPONENTS AND LOOKING NORTHWEST. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  2. Bridge Types: Suspension Bridge Spans, Section AA; Cantilever Truss Spans, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Bridge Types: Suspension Bridge Spans, Section A-A; Cantilever Truss Spans, Section B-B; Through Truss Spans, Section C-C; Deck Truss Spans, Section D-D - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  3. Electro-opto-mechanical cantilever-based logic gates

    NASA Astrophysics Data System (ADS)

    Rehder, G.; Alayo, M. I.; Medina, H. B.; Carreño, M. N. P.

    2007-01-01

    In this work we describe the fabrication and characterization of micro-opto-electro-mechanical AND, OR and XOR logic gates based in a combination of optical and micro-electro-mechanical devices. These structures consist of silicon oxynitride-based optical waveguides, through which a light beam of 633-nm can be conducted, and mobile thermo-electro actuated cantilevers, which form part of the waveguide and can work as ON-OFF switches for the laser. These switches are combined to form AND, OR and XOR gates, allowing the laser light to pass or blocking the laser light when activated electrically. The cantilevers are fabricated by freeing regions of the waveguide, which is done by front side micromachining the silicon wafer used as substrate. Also, they are actuated electrically through the heating of a metallic resistance positioned in the device, where the applied current heats the cantilevers and, due to the difference in thermal expansion coefficients of the constituent materials, it is possible to produce a controlled motion proportional to the heating current. Therefore, the switches can be electrically polarized in on/off cycles allowing or blocking the light through the waveguide, similar to logic "1's" and "0's". These switches are adequately arranged to produce an output that is similar to the conventional digital logic gates through electric control (input) of cantilever-based ON-OFF switches.

  4. 13. DETAIL OF SOUTH PIER TOP (WEST SIDE) AND CANTILEVERED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. DETAIL OF SOUTH PIER TOP (WEST SIDE) AND CANTILEVERED SIDEWALK. LOOKING NORTH. - Route 31 Bridge, New Jersey Route 31, crossing disused main line of Central Railroad of New Jersey (C.R.R.N.J.) (New Jersey Transit's Raritan Valley Line), Hampton, Hunterdon County, NJ

  5. VIEW OF CANTILEVER THROUGH TRUSS BRIDGE PORTALS AT JUNCTION BETWEEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF CANTILEVER THROUGH TRUSS BRIDGE PORTALS AT JUNCTION BETWEEN SIMPLE THROUGH TRUSS SPAN LOOKING SOUTHEAST TOWARD WEST BANK. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  6. 69. COMPLETED 'A' FRAME STRUCTURE LOOKING NORTHWEST SHOWING CANTILEVERED WALKWAYS, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. COMPLETED 'A' FRAME STRUCTURE LOOKING NORTHWEST SHOWING CANTILEVERED WALKWAYS, 'CROWS NEST', CAMERA TOWER, COUNTERWEIGHT CAR AND ROADWAY ARCH, April 30, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  7. A micro-SPM head array with exchangeable cantilevers

    NASA Astrophysics Data System (ADS)

    Gao, S.; Wolff, H.; Herrmann, K.; Brand, U.; Hiller, K.; Hahn, S.; Sorger, A.; Mehner, J.

    2012-04-01

    In this paper a MEMS based micro-SPM head array is proposed to enhance the performance of the currently available nano-measuring machines and effectively reduce the measurement time for large specimen. It consists of 1 × N ( N = 7 in our case) micro-SPM heads/units, realized in one chip by MEMS technique. And it can be easily extended to a micro- SPM head matrix. The main part of the micro-SPM head is the MEMS-positioning stage, which is realized on the basis of an electrostatic lateral comb-drive actuator. In order to take the advantage of the high lateral resolution of conventional cantilevers, a flexible cantilever gripper was designed to be integrated into the MEMS-positioning stage within the SPM head. Conventional cantilevers can be mechanically mounted onto the MEMS-positioning stage or dismantled from the MEMS-positioning stage after the tip is worn out. In this way, the well-designed and calibrated MEMS-positioning stage can be repeatedly and efficiently utilized. The structure design and simulation of mechanical and electrical performances of the mico-SPM head will be detailed in this paper. First experimental results proved the feasibility of the cantilever gripper design.

  8. Piezoresistive Cantilever Performance-Part I: Analytical Model for Sensitivity.

    PubMed

    Park, Sung-Jin; Doll, Joseph C; Pruitt, Beth L

    2010-02-01

    An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors. PMID:20336183

  9. Piezoresistive Cantilever Performance—Part I: Analytical Model for Sensitivity

    PubMed Central

    Park, Sung-Jin; Doll, Joseph C.; Pruitt, Beth L.

    2010-01-01

    An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors. PMID:20336183

  10. CLOSEUP VIEW OF PORTION OF MAIN BRIDGE CANTILEVER THROUGH TRUSS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CLOSE-UP VIEW OF PORTION OF MAIN BRIDGE CANTILEVER THROUGH TRUSS SPAN LOOKING UP AND NORTHEAST. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  11. Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays

    SciTech Connect

    Sathishkumar, P.; Punyabrahma, P.; Sri Muthu Mrinalini, R.; Jayanth, G. R.

    2015-09-15

    A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array.

  12. Calibrating laser beam deflection systems for use in atomic force microscopes and cantilever sensors

    SciTech Connect

    Beaulieu, L.Y.; Godin, Michel; Laroche, Olivier; Tabard-Cossa, Vincent; Gruetter, Peter

    2006-02-20

    Most atomic force microscopes and cantilever-based sensors use an optical laser beam detection system to monitor cantilever deflections. We have developed a working model that accurately describes the way in which a position sensitive photodetector interprets the deflection of a cantilever in these instruments. This model exactly predicts the numerical relationship between the measured photodetector signal and the actual cantilever deflection. In addition, the model is used to optimize the geometry of such laser deflection systems, which greatly simplifies the use of any cantilever-based instrument that uses a laser beam detection system.

  13. Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays.

    PubMed

    Sathishkumar, P; Punyabrahma, P; Mrinalini, R Sri Muthu; Jayanth, G R

    2015-09-01

    A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array. PMID:26429493

  14. Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays

    NASA Astrophysics Data System (ADS)

    Sathishkumar, P.; Punyabrahma, P.; Sri Muthu Mrinalini, R.; Jayanth, G. R.

    2015-09-01

    A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array.

  15. Vortex-Induced Vibration of a Flexible Cantilever

    NASA Astrophysics Data System (ADS)

    Fujarra, A. L. C.; Pesce, C. P.; Flemming, F.; Williamson, C. H. K.

    2001-04-01

    This study is concerned with the vortex-induced vibrations of a flexible cantilever in a fluid flow. Our cantilever comprises a leaf spring encased within a rubber flexible cylinder, restricting the vibrations of the body in a water channel flow to principally transverse motion. It is found that the transverse amplitude response of the cantilever has a marked similarity with transverse vibrations of an elastically mounted rigid cylinder, in that there is a clear initial branch extending to high amplitudes, with a jump to a lower branch response, as normalized velocity is increased. The continuous initial branch suggests that a distinct upper branch does not exist for the cantilever, as is found for a rigid cylinder under similar conditions of low mass and damping. Good agreement is found between the response amplitude and frequency for two identical cantilevers, one set up by Pesce and Fujarra, where strain is measured to infer the body dynamics, and the other arrangement by Flemming and Williamson, where the tip motion is measured using optical techniques. An interesting large-amplitude response mode is found at higher normalized velocities (U*>12) outside the principal synchronization regime (typically U*=4-8), which is observed for an increasing velocity, or may be triggered by manual streamwise disturbances of the body. This vibration mode is due to a coupled streamwise-transverse motion, where the streamwise amplitude becomes non-negligible, and may be related to a further vibration mode at high normalized speed, found for a vibrating pivoted rod, by Kitagawa et al. (1999).

  16. Sobol method application in dimensional sensitivity analyses of different AFM cantilevers for biological particles

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Taheri, M.; Ghahnaviyeh, S. D.

    2015-08-01

    Due to the more delicate nature of biological micro/nanoparticles, it is necessary to compute the critical force of manipulation. The modeling and simulation of reactions and nanomanipulator dynamics in a precise manipulation process require an exact modeling of cantilevers stiffness, especially the stiffness of dagger cantilevers because the previous model is not useful for this investigation. The stiffness values for V-shaped cantilevers can be obtained through several methods. One of them is the PBA method. In another approach, the cantilever is divided into two sections: a triangular head section and two slanted rectangular beams. Then, deformations along different directions are computed and used to obtain the stiffness values in different directions. The stiffness formulations of dagger cantilever are needed for this sensitivity analyses so the formulations have been driven first and then sensitivity analyses has been started. In examining the stiffness of the dagger-shaped cantilever, the micro-beam has been divided into two triangular and rectangular sections and by computing the displacements along different directions and using the existing relations, the stiffness values for dagger cantilever have been obtained. In this paper, after investigating the stiffness of common types of cantilevers, Sobol sensitivity analyses of the effects of various geometric parameters on the stiffness of these types of cantilevers have been carried out. Also, the effects of different cantilevers on the dynamic behavior of nanoparticles have been studied and the dagger-shaped cantilever has been deemed more suitable for the manipulation of biological particles.

  17. Measurements of the solidification process of resins from cantilever beams resonances

    NASA Astrophysics Data System (ADS)

    Arenas, Gustavo F.; Duchowicz, Ricardo

    2013-01-01

    In this work, we introduce a technique to infer elastic and mechanical properties of light-curing resins by using cantilever beams. The methodology includes vibration resonance measurements performed with a fiber optic Fizeau interferometer. As is known, the natural resonance frequency of cantilever beams depends strongly on any variation in its physical properties and geometry. Following this idea, square shaped solid aluminum beams with a short transverse deep crack drilled near its fixed end were studied. The slot was filled with photo-curing resins and resonance frequency was monitored as polymerization proceeded. In order to track resonance peaks, we adopted a simple electromagnetic actuator to force the beam into oscillations of variable frequencies. Beams were scanned periodically around its natural resonance as photo-curing was carried out. Due to the small vibrations amplitude present at the free end of beams (tens of microns typically), we used a Fizeau interferometric fiber optic sensor placed near the free end. Its extremely high sensitivity and resolution are its outstanding features, yielding a non-invasive sensor that ensures natural evolution and distortionless amplitude and frequency measurements. Results show that liquid resin in the slot did not produce changes on beam resonance prior to curing. On the other hand, photo-polymerization partially recovered original properties of the beam in a few tens of seconds, suggesting that vitrification of resins is completely achieved while photoreaction is still occurring. Moreover, additional information of volumetric shrinkage of polymers can be extracted from these measurements. In summary, this powerful and simple technique enables to evaluate the static resonance of beams as well as polymer shrinkage and solidification time evolution in one single measurement.

  18. Topography imaging with a heated atomic force microscope cantilever in tapping mode

    SciTech Connect

    Park, Keunhan; Lee, Jungchul; Zhang, Zhuomin M.; King, William P.

    2007-04-15

    This article describes tapping mode atomic force microscopy (AFM) using a heated AFM cantilever. The electrical and thermal responses of the cantilever were investigated while the cantilever oscillated in free space or was in intermittent contact with a surface. The cantilever oscillates at its mechanical resonant frequency, 70.36 kHz, which is much faster than its thermal time constant of 300 {mu}s, and so the cantilever operates in thermal steady state. The thermal impedance between the cantilever heater and the sample was measured through the cantilever temperature signal. Topographical imaging was performed on silicon calibration gratings of height 20 and 100 nm. The obtained topography sensitivity is as high as 200 {mu}V/nm and the resolution is as good as 0.5 nm/Hz{sup 1/2}, depending on the cantilever power. The cantilever heating power ranges 0-7 mW, which corresponds to a temperature range of 25-700 deg. C. The imaging was performed entirely using the cantilever thermal signal and no laser or other optics was required. As in conventional AFM, the tapping mode operation demonstrated here can suppress imaging artifacts and enable imaging of soft samples.

  19. Modular apparatus for electrostatic actuation of common atomic force microscope cantilevers

    SciTech Connect

    Long, Christian J.; Cannara, Rachel J.

    2015-07-15

    Piezoelectric actuation of atomic force microscope (AFM) cantilevers often suffers from spurious mechanical resonances in the loop between the signal driving the cantilever and the actual tip motion. These spurious resonances can reduce the accuracy of AFM measurements and in some cases completely obscure the cantilever response. To address these limitations, we developed a specialized AFM cantilever holder for electrostatic actuation of AFM cantilevers. The holder contains electrical contacts for the AFM cantilever chip, as well as an electrode (or electrodes) that may be precisely positioned with respect to the back of the cantilever. By controlling the voltages on the AFM cantilever and the actuation electrode(s), an electrostatic force is applied directly to the cantilever, providing a near-ideal transfer function from drive signal to tip motion. We demonstrate both static and dynamic actuations, achieved through the application of direct current and alternating current voltage schemes, respectively. As an example application, we explore contact resonance atomic force microscopy, which is a technique for measuring the mechanical properties of surfaces on the sub-micron length scale. Using multiple electrodes, we also show that the torsional resonances of the AFM cantilever may be excited electrostatically, opening the door for advanced dynamic lateral force measurements with improved accuracy and precision.

  20. Selective enhancement of individual cantilever high resonance modes

    NASA Astrophysics Data System (ADS)

    Penedo, Marcos; Hormeño, Silvia; Prieto, Patricia; Alvaro, Raquel; Anguita, José; Briones, Fernando; Luna, Mónica

    2015-12-01

    Multifrequency atomic force microscopy (AFM) in liquid media where several eigenmodes or harmonics are simultaneously excited is improving the performance of the scanning probe techniques in biological studies. As a consequence, an important effort is being made to search for a reliable, efficient and strong cantilever high mode excitation method that operates in liquids. In this work we present (theoretical and experimentally) a technique for improving the efficiency of the most common excitation methods currently used in AFM operated in liquids: photothermal, torque (MAC Mode™) and magnetostriction. By etching specific areas of the cantilever coating, the oscillation amplitude (both flexural and torsional) of each specific eigenmode increases, leading to an improvement in signal to noise ratio of the multifrequency techniques. As an alternative, increment in high mode oscillation amplitude is also obtained by Ga+ ion implantation in the specific areas of the magnetic material.

  1. Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

    SciTech Connect

    Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

    2015-04-21

    A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

  2. Limit cycle oscillation of a fluttering cantilever plate

    NASA Technical Reports Server (NTRS)

    Dowell, Earl; Ye, Weiliang

    1991-01-01

    A response of a cantilever plate in high supersonic flow to a disturbance is considered. The Rayleigh-Ritz method is used to solve the nonlinear oscillation of a fluttering plate. It is found that the length-to-width ratio for a cantilever plate has a great effect on flutter amplitude of the limit cycle. For small length-to-width ratio, the dominant chordwise modes are translation and rotation. It is suggested that higher bending modes must be included to obtain an accurate prediction of the flutter onset and limit cycle oscillation. For large length-to-width ratio, significant chordwise bending is apparent in the flutter motion, with the trailing edge area having the largest motion.

  3. Laser Actuation of Cantilevers for Picometre Amplitude Dynamic Force Microscopy

    PubMed Central

    Evans, Drew R.; Tayati, Ponlawat; An, Hongjie; Lam, Ping Koy; Craig, Vincent S. J.; Senden, Tim J.

    2014-01-01

    As nanoscale and molecular devices become reality, the ability to probe materials on these scales is increasing in importance. To address this, we have developed a dynamic force microscopy technique where the flexure of the microcantilever is excited using an intensity modulated laser beam to achieve modulation on the picoscale. The flexure arises from thermally induced bending through differential expansion and the conservation of momentum when the photons are reflected and absorbed by the cantilever. In this study, we investigated the photothermal and photon pressure responses of monolithic and layered cantilevers using a modulated laser in air and immersed in water. The developed photon actuation technique is applied to the stretching of single polymer chains. PMID:24993548

  4. Laser actuation of cantilevers for picometre amplitude dynamic force microscopy.

    PubMed

    Evans, Drew R; Tayati, Ponlawat; An, Hongjie; Lam, Ping Koy; Craig, Vincent S J; Senden, Tim J

    2014-01-01

    As nanoscale and molecular devices become reality, the ability to probe materials on these scales is increasing in importance. To address this, we have developed a dynamic force microscopy technique where the flexure of the microcantilever is excited using an intensity modulated laser beam to achieve modulation on the picoscale. The flexure arises from thermally induced bending through differential expansion and the conservation of momentum when the photons are reflected and absorbed by the cantilever. In this study, we investigated the photothermal and photon pressure responses of monolithic and layered cantilevers using a modulated laser in air and immersed in water. The developed photon actuation technique is applied to the stretching of single polymer chains. PMID:24993548

  5. Selective enhancement of individual cantilever high resonance modes.

    PubMed

    Penedo, Marcos; Hormeño, Silvia; Prieto, Patricia; Alvaro, Raquel; Anguita, José; Briones, Fernando; Luna, Mónica

    2015-12-01

    Multifrequency atomic force microscopy (AFM) in liquid media where several eigenmodes or harmonics are simultaneously excited is improving the performance of the scanning probe techniques in biological studies. As a consequence, an important effort is being made to search for a reliable, efficient and strong cantilever high mode excitation method that operates in liquids. In this work we present (theoretical and experimentally) a technique for improving the efficiency of the most common excitation methods currently used in AFM operated in liquids: photothermal, torque (MAC Mode™) and magnetostriction. By etching specific areas of the cantilever coating, the oscillation amplitude (both flexural and torsional) of each specific eigenmode increases, leading to an improvement in signal to noise ratio of the multifrequency techniques. As an alternative, increment in high mode oscillation amplitude is also obtained by Ga(+) ion implantation in the specific areas of the magnetic material. PMID:26559931

  6. Large and small deflections of a cantilever beam

    NASA Astrophysics Data System (ADS)

    Beléndez, Tarsicio; Neipp, Cristian; Beléndez, Augusto

    2002-05-01

    The classical problem of the deflection of a cantilever beam of linear elastic material, under the action of an external vertical concentrated load at the free end, is analysed. We present the differential equation governing the behaviour of this physical system and show that this equation, although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. In this sense, this system is similar to another well known physical system: the simple pendulum. An approximation of the behaviour of a cantilever beam for small deflections was obtained from the equation for large deflections, and we present various numerical results for both cases. Finally, we compare the theoretical results with the experimental results obtained in the laboratory.

  7. Cantilever spring constant calibration using laser Doppler vibrometry

    SciTech Connect

    Ohler, Benjamin

    2007-06-15

    Uncertainty in cantilever spring constants is a critical issue in atomic force microscopy (AFM) force measurements. Though numerous methods exist for calibrating cantilever spring constants, the accuracy of these methods can be limited by both the physical models themselves as well as uncertainties in their experimental implementation. Here we report the results from two of the most common calibration methods, the thermal tune method and the Sader method. These were implemented on a standard AFM system as well as using laser Doppler vibrometry (LDV). Using LDV eliminates some uncertainties associated with optical lever detection on an AFM. It also offers considerably higher signal to noise deflection measurements. We find that AFM and LDV result in similar uncertainty in the calibrated spring constants, about 5%, using either the thermal tune or Sader methods provided that certain limitations of the methods and instrumentation are observed.

  8. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-01-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  9. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    NASA Astrophysics Data System (ADS)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-10-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  10. Vibration of skewed cantilever plates and helicoidal shells

    NASA Technical Reports Server (NTRS)

    Beres, D. P.; Bailey, C. D.

    1975-01-01

    Theoretical vibration frequencies and mode shapes are obtained for skewed plates and helicoidal shells with a cantilever boundary. Using Hamilton's law of varying action, a power series solution is developed to obtain converged numerical results for the five lowest frequencies. Effects of geometrical variables such as aspect ratio, sweep angle and shell radius to thickness ratio are investigated. Accuracy of the solution method is substantiated by comparison with existing skewed plate spherical cap, and conical shell results.

  11. A counterfort versus a cantilever retaining wall - a seismic equivalence

    NASA Astrophysics Data System (ADS)

    Chugh, Ashok K.

    2005-08-01

    A procedure is presented to develop geometric dimensions and material property values for a model cantilever wall from those of a prototype counterfort wall such that the model wall will simulate the response of the prototype wall for seismic loads. The equivalency criteria are given. A sample problem is included to illustrate the use of the proposed procedure. Accuracy of results is discussed. Published in 2005 by John Wiley & Sons, Ltd.

  12. Accurate method for determining adhesion of cantilever beams

    SciTech Connect

    de Boer, M.P.; Michalske, T.A.

    1999-07-01

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying. {copyright} {ital 1999 American Institute of Physics.}

  13. Accurate Method for Determining Adhesion of Cantilever Beams

    SciTech Connect

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  14. Analysis of AFM cantilever dynamics close to sample surface

    NASA Astrophysics Data System (ADS)

    Habibnejad Korayem, A.; Habibnejad Korayem, Moharam; Ghaderi, Reza

    2013-07-01

    For imaging and manipulation of biological specimens application of atomic force microscopy (AFM) in liquid is necessary. In this paper, tapping-mode AFM cantilever dynamics in liquid close to sample surface is modeled and simulated by well defining the contact forces. The effect of cantilever tilting angle has been accounted carefully. Contact forces have some differences in liquid in comparison to air or vacuum in magnitude or formulation. Hydrodynamic forces are also applied on the cantilever due to the motion in liquid. A continuous beam model is used with its first mode and forward-time simulation method for simulation of its hybrid dynamics and the frequency response and amplitude versus separation diagrams are extracted. The simulation results show a good agreement with experimental results. The resonance frequency in liquid is so small in comparison to air due to additional mass and also additional damping due to the viscosity of the liquid around. The results show that the effect of separation on free vibration amplitude is great. Its effect on resonance frequency is considerable too.

  15. Contractile cell forces deform macroscopic cantilevers and quantify biomaterial performance.

    PubMed

    Allenstein, U; Mayr, S G; Zink, M

    2015-07-01

    Cells require adhesion to survive, proliferate and migrate, as well as for wound healing and many other functions. The strength of contractile cell forces on an underlying surface is a highly relevant quantity to measure the affinity of cells to a rigid surface with and without coating. Here we show with experimental and theoretical studies that these forces create surface stresses that are sufficient to induce measurable bending of macroscopic cantilevers. Since contractile forces are linked to the formation of focal contacts, results give information on adhesion promoting qualities and allow a comparison of very diverse materials. In exemplary studies, in vitro fibroblast adhesion on the magnetic shape memory alloy Fe-Pd and on the l-lysine derived plasma-functionalized polymer PPLL was determined. We show that cells on Fe-Pd are able to induce surface stresses three times as high as on pure titanium cantilevers. A further increase was observed for PPLL, where the contractile forces are four times higher than on the titanium reference. In addition, we performed finite element simulations on the beam bending to back up the calculation of contractile forces from cantilever bending under non-homogenous surface stress. Our findings consolidate the role of contractile forces as a meaningful measure of biomaterial performance. PMID:26027952

  16. A cantilever-free approach to dot-matrix nanoprinting

    PubMed Central

    Brown, Keith A.; Eichelsdoerfer, Daniel J.; Shim, Wooyoung; Rasin, Boris; Radha, Boya; Liao, Xing; Schmucker, Abrin L.; Liu, Guoliang; Mirkin, Chad A.

    2013-01-01

    Scanning probe lithography (SPL) is a promising candidate approach for desktop nanofabrication, but trade-offs in throughput, cost, and resolution have limited its application. The recent development of cantilever-free scanning probe arrays has allowed researchers to define nanoscale patterns in a low-cost and high-resolution format, but with the limitation that these are duplication tools where each probe in the array creates a copy of a single pattern. Here, we report a cantilever-free SPL architecture that can generate 100 nanometer-scale molecular features using a 2D array of independently actuated probes. To physically actuate a probe, local heating is used to thermally expand the elastomeric film beneath a single probe, bringing it into contact with the patterning surface. Not only is this architecture simple and scalable, but it addresses fundamental limitations of 2D SPL by allowing one to compensate for unavoidable imperfections in the system. This cantilever-free dot-matrix nanoprinting will enable the construction of surfaces with chemical functionality that is tuned across the nano- and macroscales. PMID:23861495

  17. SU8 diaphragm micropump with monolithically integrated cantilever check valves.

    PubMed

    Ezkerra, Aitor; Fernández, Luis José; Mayora, Kepa; Ruano-López, Jesús Miguel

    2011-10-01

    This paper presents a SU8 unidirectional diaphragm micropump with embedded out-of-plane cantilever check valves. The device represents a reliable and low-cost solution for integration of microfluidic control in lab-on-a-chip devices. Its planar architecture allows monolithic definition of its components in a single step and potential integration with previously reported PCR, electrophoresis and flow-sensing SU8 microdevices. Pneumatic actuation is applied on a PDMS diaphragm, which is bonded to the SU8 body at wafer level, further enhancing its integration and mass production capabilities. The cantilever check valves move synchronously with the diaphragm, feature fast response (10ms), low dead volume (86nl) and a 94% flow blockage up to 300kPa. The micropump achieves a maximum flow rate of 177 μl min(-1) at 6 Hz and 200 kPa with an effective area of 10 mm(2). The device is reliable, self-priming and tolerant to particles and big bubbles. To the knowledge of the authors, this is the first micropump in SU8 with monolithically integrated cantilever check valves. PMID:21853192

  18. Ultrasensitive magnetometry and magnetic resonance imaging using cantilever detection

    NASA Astrophysics Data System (ADS)

    Rugar, Daniel

    2009-03-01

    Micromachined cantilevers make remarkable magnetometers for nanoscale measurements of magnetic materials and for magnetic resonance imaging (MRI). We present various applications of cantilever magnetometry at low temperature using cantilevers capable of attonewton force sensitivity. Small, unexpected magnetic effects can be seen, such as anomalous damping in magnetic field. A key application is magnetic resonance force microscopy (MRFM) of both electron and nuclear spins. In recent experiments with MRFM-based NMR imaging, 3D spatial resolution better than 10 nm was achieved for protons in individual virus particles. The achieved volumetric resolution represents an improvement of 100 million compared to the best conventional MRI. The microscope is sensitive enough to detect NMR signals from adsorbed layers of hydrocarbon contamination, hydrogen in multiwall carbon nanotubes and the phosphorus in DNA. Operating with a force noise on the order of 6 aN per root hertz with a magnetic tip that produces a field gradient in excess of 30 gauss per nanometer, the magnetic moment sensitivity is ˜0.2 Bohr magnetons. The corresponding field sensitivity is ˜3 nT per root hertz. To our knowledge, this combination of high field sensitivity and nanometer spatial resolution is unsurpassed by any other form of nanometer-scale magnetometry.

  19. MEMS cantilever sensor for THz photoacoustic chemical sensing and pectroscopy

    NASA Astrophysics Data System (ADS)

    Glauvitz, Nathan E.

    Sensitive Microelectromechanical System (MEMS) cantilever designs were modeled, fabricated, and tested to measure the photoacoustic (PA) response of gasses to terahertz (THz) radiation. Surface and bulk micromachining technologies were employed to create the extremely sensitive devices that could detect very small changes in pressure. Fabricated devices were then tested in a custom made THz PA vacuum test chamber where the cantilever deflections caused by the photoacoustic effect were measured with a laser interferometer and iris beam clipped methods. The sensitive cantilever designs achieved a normalized noise equivalent absorption coefficient of 2.83x10-10 cm-1 W Hz-½ using a 25 microW radiation source power and a 1 s sampling time. Traditional gas phase molecular spectroscopy absorption cells are large and bulky. The outcome of this research resulted was a photoacoustic detection method that was virtually independent of the absorption path-length, which allowed the chamber dimensions to be greatly reduced, leading to the possibility of a compact, portable chemical detection and spectroscopy system

  20. Vibration analysis of magnetostrictive thin-film composite cantilever actuator

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Shang, Xinchun

    2016-09-01

    The transverse vibration of a composed cantilever beam with magnetostrictive layer is analyzed, which is employed to simulate dynamic response of an actuator. The high-order shear deformation theory of beam and the coupling magnetoelastic constitutive relationship are introduced to construct the governing equations, all interface conditions between magnetostrictive film and elastic substrate as well as the free stress condition on the top and bottom surfaces of the beam can be satisfied. In order to demonstrate validity of the presented mathematical modeling, the verification examples are also given. Furthermore, the effect of geometry and material parameters on dynamic characteristics of magnetostrictive cantilever beam, such as the nature frequency and amplitude, is discussed. Moreover, through computing the magneto-mechanical coupling factor of the beam structure, the variation tendency curves of the factor along with different parameters and frequencies of magnetostrictive cantilever beam actuator have been presented. These numerical results should be useful for the design of beam-type with magnetostrictive thin-film actuators.

  1. Dynamic modelling and experimental study of cantilever beam with clearance

    NASA Astrophysics Data System (ADS)

    Li, B.; Jin, W.; Han, L.; He, Z.

    2012-05-01

    Clearances occur in almost all mechanical systems, typically such as the clearance between slide plate of gun barrel and guide. Therefore, to study the clearances of mechanisms can be very important to increase the working performance and lifetime of mechanisms. In this paper, rigid dynamic modelling of cantilever with clearance was done according to the subject investigated. In the rigid dynamic modelling, clearance is equivalent to the spring-dashpot model, the impact of beam and boundary face was also taken into consideration. In ADAMS software, the dynamic simulation was carried out according to the model above. The software simulated the movement of cantilever with clearance under external excitation. Research found: When the clearance is larger, the force of impact will become larger. In order to study how the stiffness of the cantilever's supporting part influences natural frequency of the system, A Euler beam which is restricted by a draught spring and a torsion spring at its end was raised. Through numerical calculation, the relationship between natural frequency and stiffness was found. When the value of the stiffness is close to the limit value, the corresponding boundary condition is illustrated. An ADAMS experiment was carried out to check the theory and the simulation.

  2. A cantilever-free approach to dot-matrix nanoprinting.

    PubMed

    Brown, Keith A; Eichelsdoerfer, Daniel J; Shim, Wooyoung; Rasin, Boris; Radha, Boya; Liao, Xing; Schmucker, Abrin L; Liu, Guoliang; Mirkin, Chad A

    2013-08-01

    Scanning probe lithography (SPL) is a promising candidate approach for desktop nanofabrication, but trade-offs in throughput, cost, and resolution have limited its application. The recent development of cantilever-free scanning probe arrays has allowed researchers to define nanoscale patterns in a low-cost and high-resolution format, but with the limitation that these are duplication tools where each probe in the array creates a copy of a single pattern. Here, we report a cantilever-free SPL architecture that can generate 100 nanometer-scale molecular features using a 2D array of independently actuated probes. To physically actuate a probe, local heating is used to thermally expand the elastomeric film beneath a single probe, bringing it into contact with the patterning surface. Not only is this architecture simple and scalable, but it addresses fundamental limitations of 2D SPL by allowing one to compensate for unavoidable imperfections in the system. This cantilever-free dot-matrix nanoprinting will enable the construction of surfaces with chemical functionality that is tuned across the nano- and macroscales. PMID:23861495

  3. Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework

    PubMed Central

    GRANDO, Antônio Francisco; REZENDE, Carlos Eduardo Edwards; SOUSA, Edson Antônio Capello; RUBO, José Henrique

    2014-01-01

    Knowing how stresses are dissipated on the fixed implant-supported complex allows adequate treatment planning and better choice of the materials used for prosthesis fabrication. Objectives The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant. PMID:25025562

  4. Cantilever Wings for Modern Aircraft: Some Aspects of Cantilever Wing Construction with Special Reference to Weight and Torsional Stiffness

    NASA Technical Reports Server (NTRS)

    Stieger, H J

    1929-01-01

    In the foregoing remarks I have made an attempt to touch on some of the structural problems met with in cantilever wings, and dealt rather fully with a certain type of single-spar construction. The experimental test wing was a first attempt to demonstrate the principles of this departure from orthodox methods. The result was a wing both torsionally stiff and of light weight - lighter than a corresponding biplane construction.

  5. Using the Finite Elements Method (FEM) for Nanotechnology Education. A rectangular cantilever as a mass sensor

    NASA Astrophysics Data System (ADS)

    Aya Baquero, H.

    2015-01-01

    The Finite Element Method FEM can be used in the context of physics engineering education, particularly in nanotechnology training. Cantilevers and cantilevers arrays have been implemented as sensors within lots of applications. In the present paper, FEM was used to assess validity of basic models where cantilevers are used as mass sensors. Resonance frequency of a cantilever transversal vibration was found; this was a silicon one-side clamped cantilever. A number of minor mass elements Am was added on the cantilever's free side. Then in each case, a new resonance frequency was found; this led to obtain the Am values from shifts of resonance frequencies. Finally, those values were compared with CAD model values.

  6. Nondestructive experimental determination of bimaterial rectangular cantilever spring constants in water

    SciTech Connect

    Snow, David E.; Kim, Dae Jung; Hope-Weeks, Louisa J.; Weeks, Brandon L.; Pitchimani, Rajasekar

    2008-08-15

    In order to address the issue of spring constant calibration in viscous fluids such as water, a new method is presented that allows for the experimental calibration of bimaterial cantilever spring constants. This method is based on modeling rectangular cantilever beam bending as a function of changing temperature. The temperature change is accomplished by heating water as it flows around the cantilever beams in an enclosed compartment. The optical static method of detection is used to measure the deflection of cantilever at the free end. Experimentally determined results are compared to Sader's method and to the Thermotune method most commonly used in cantilever calibrations. Results indicate that the new bimaterial thermal expansion method is accurate within 15%-20% of the actual cantilever spring constant, which is comparable to other nondestructive calibration techniques.

  7. Nondestructive experimental determination of bimaterial rectangular cantilever spring constants in water.

    PubMed

    Snow, David E; Weeks, Brandon L; Kim, Dae Jung; Pitchimani, Rajasekar; Hope-Weeks, Louisa J

    2008-08-01

    In order to address the issue of spring constant calibration in viscous fluids such as water, a new method is presented that allows for the experimental calibration of bimaterial cantilever spring constants. This method is based on modeling rectangular cantilever beam bending as a function of changing temperature. The temperature change is accomplished by heating water as it flows around the cantilever beams in an enclosed compartment. The optical static method of detection is used to measure the deflection of cantilever at the free end. Experimentally determined results are compared to Sader's method and to the Thermotune method most commonly used in cantilever calibrations. Results indicate that the new bimaterial thermal expansion method is accurate within 15%-20% of the actual cantilever spring constant, which is comparable to other nondestructive calibration techniques. PMID:19044356

  8. Piezoelectric energy harvester operated by noncontact mechanical frequency up-conversion using shell cantilever structure

    NASA Astrophysics Data System (ADS)

    Jang, Munseon; Song, Seunghwan; Park, Yong-Hee; Yun, Kwang-Seok

    2015-06-01

    In this study, we propose and demonstrate a piezoelectric energy harvester with a shell cantilever for mechanical frequency up-conversion to generate electric power in a low-frequency vibration environment. The proposed device is composed of a clamped semicylindrical shell cantilever as a driving beam and a piezoelectric cantilever attached to the proof mass of the shell cantilever as a generating beam. The shell cantilever bends downward when the external acceleration is over the threshold value for buckling transition. When the acceleration direction is reversed, the shell cantilever makes abrupt stop at its initial position, inducing impact-like force on the generating beam and resulting in free vibration at high resonance frequencies. Experimental results show that a maximum power of 101 µW at 20 Hz can be obtained.

  9. Performance of pre-deformed flexible piezoelectric cantilever in energy harvesting

    NASA Astrophysics Data System (ADS)

    Wang, Pengyingkai; Sui, Li; Shi, Gengchen; Liu, Guohua

    2016-05-01

    This paper proposes a novel structure for pre-rolled flexible piezoelectric cantilevers that use wind energy to power a submunition electrical device. Owing to the particular installation position and working environment, the submunition piezoelectric cantilever should be rolled when not working, but this pre-rolled state can alter the energy harvesting performance. Herein, a working principle and installation method for piezoelectric cantilevers used in submunitions are introduced. To study the influence of the pre-rolled state, pre-rolled piezoelectric cantilevers of different sizes were fabricated and their performances were studied using finite element analysis simulations and experiments. The simulation results show that the resonance frequency and stiffness of the pre-rolled structure is higher than that of a flat structure. Results show that, (1) for both the pre-rolled and flat cantilever, the peak voltage will increase with the wind speed. (2) The pre-rolled cantilever has a higher critical wind speed than the flat cantilever. (3) For identical wind speeds and cantilever sizes, the peak voltage of the flat cantilever (45 V) is less than that of the pre-rolled cantilever (56 V). (4) Using a full-bridge rectifier, the output of the pre-rolled cantilever can sufficiently supply a 10 μF capacitor, whose output voltage may be up to 23 V after 10 s. These results demonstrate that the pre-rolled piezoelectric cantilever and its installation position used in this work are more suitable for submunition, and its output sufficiently meets submunition requirements.

  10. Multi-directional energy harvesting by piezoelectric cantilever-pendulum with internal resonance

    SciTech Connect

    Xu, J.; Tang, J.

    2015-11-23

    This letter reports a piezoelectric cantilever-pendulum design for multi-directional energy harvesting. A pendulum is attached to the tip of a piezoelectric cantilever-type energy harvester. This design aims at taking advantage of the nonlinear coupling between the pendulum motion in 3-dimensional space and the beam bending vibration at resonances. Experimental studies indicate that, under properly chosen parameters, 1:2 internal resonance can be induced, which enables the multi-directional energy harvesting with a single cantilever. The advantages of the design with respect to traditional piezoelectric cantilever are examined.

  11. Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

    SciTech Connect

    Saraf, Laxmikant V.; Britt, David W.

    2011-09-14

    We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

  12. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy

    SciTech Connect

    Loganathan, Muthukumaran; Bristow, Douglas A.

    2014-04-15

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  13. Simultaneous position and mass determination of a nanoscale-thickness cantilever sensor in viscous fluids

    NASA Astrophysics Data System (ADS)

    Hong, Seongkyeol; Kim, Deokman; Park, Junhong; Jang, Jaesung

    2015-02-01

    We report simultaneous determination of the mass and position of micro-beads attached to a nanoscale-thickness cantilever sensor by analyzing wave propagations along the cantilever while taking into account viscous and inertial loading due to a surrounding fluid. The fluid-structure interaction was identified by measuring the change in the wavenumber under different fluid conditions. The predicted positions and masses agreed with actual measurements. Even at large mass ratios (6%-21%) of the beads to the cantilever, this wave approach enabled accurate determination of the mass and position, demonstrating the potential for highly accurate cantilever sensing of particle-based bio-analytes such as bacteria.

  14. Improving the quality factor of cantilevers in viscous fluids by the adaptation of their interface

    NASA Astrophysics Data System (ADS)

    Linden, J.; Oesterschulze, E.

    2012-03-01

    The adaptation of the fluid-microresonator interface enables the operation of cantilevers with high quality factor in viscous fluids. Partial wetting was proposed to implement the adapted interface by meniscus formation. An excellent quality factor of 79 was achieved in water applying the concept of partial wetting to thin film silicon nitride cantilevers. Compared to the quality factor calculated from Sader's theory of the hydrodynamic damping of fully immersed cantilevers, this is an improvement by more than one decade. As a first application the partially wetted cantilevers were employed as mass sensors in water revealing a sensitivity of 2.77 fg/Hz.

  15. Multi-directional energy harvesting by piezoelectric cantilever-pendulum with internal resonance

    NASA Astrophysics Data System (ADS)

    Xu, J.; Tang, J.

    2015-11-01

    This letter reports a piezoelectric cantilever-pendulum design for multi-directional energy harvesting. A pendulum is attached to the tip of a piezoelectric cantilever-type energy harvester. This design aims at taking advantage of the nonlinear coupling between the pendulum motion in 3-dimensional space and the beam bending vibration at resonances. Experimental studies indicate that, under properly chosen parameters, 1:2 internal resonance can be induced, which enables the multi-directional energy harvesting with a single cantilever. The advantages of the design with respect to traditional piezoelectric cantilever are examined.

  16. Note: Spring constant calibration of nanosurface-engineered atomic force microscopy cantilevers

    SciTech Connect

    Ergincan, O. Palasantzas, G.; Kooi, B. J.

    2014-02-15

    The determination of the dynamic spring constant (k{sub d}) of atomic force microscopy cantilevers is of crucial importance for converting cantilever deflection to accurate force data. Indeed, the non-destructive, fast, and accurate measurement method of the cantilever dynamic spring constant by Sader et al. [Rev. Sci. Instrum. 83, 103705 (2012)] is confirmed here for plane geometry but surface modified cantilevers. It is found that the measured spring constants (k{sub eff}, the dynamic one k{sub d}), and the calculated (k{sub d,1}) are in good agreement within less than 10% error.

  17. Self-driving capacitive cantilevers for high-frequency atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Brown, Keith A.; Yang, Benjamin H.; Westervelt, R. M.

    2012-01-01

    We demonstrate a simple way to actuate an atomic force microscope cantilever at high frequencies by electrically driving a thin-film capacitor on its surface. Capacitive driving directly actuates the vibrational mode of the cantilever, removing the effects of unwanted mechanical modes present in conventional driving systems and removing the need for a drive piezoelectric. Practical vibration amplitudes are attainable at drive voltages <5 V. We capacitively drive the first mechanical resonance of a tapping mode cantilever (243 kHz) and a high-frequency cantilever (1.5 MHz) with vibration amplitudes in agreement with our model of capacitive driving.

  18. Note: Lateral force microscope calibration using multiple location pivot loading of rectangular cantilevers

    SciTech Connect

    Chung, Koo-Hyun; Reitsma, Mark G.

    2010-02-15

    This note outlines a calibration method for atomic force microscope friction measurement that uses the ''pivot'' method of [Bogdanovic et al., Colloids Surf. B 19, 397 (2000)] to generate optical lever sensitivities for known torque applied to rectangular cantilevers. We demonstrate the key calibration parameter to be a linear function of the position at which it is determined along the length of the cantilevers. In this way the optical lever system can be calibrated for cantilever torque by applying loads at locations along the length of a cantilever, away from the integrated tip, so that issues such as tip damage or interference can be avoided.

  19. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy.

    PubMed

    Loganathan, Muthukumaran; Bristow, Douglas A

    2014-04-01

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields. PMID:24784614

  20. A barometric pressure sensor based on the air-gap scale effect in a cantilever

    NASA Astrophysics Data System (ADS)

    Minh-Dung, Nguyen; Takahashi, Hidetoshi; Uchiyama, Takeshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2013-09-01

    The most common structure for a conventional barometric pressure sensor consists of a vacuum-sealed cavity and a diaphragm. However, we hypothesize that a simple structure with an unsealed cavity and an ultra-thin cantilever can provide more sensitive measurements. We produced a 300-nm-thick cantilever with a small spring constant, which made the cantilever sensitive to low pressures. We demonstrated that miniaturizing the air-gap of the cantilever enables the sensor to measure barometric pressure changes at a low pressure change rate with a high resolution, which was 1 Pa at 0.05 Hz, and for a gap size of 1.7 μm.

  1. Probing model tumor interfacial properties using piezoelectric cantilevers.

    PubMed

    Yegingil, Hakki; Shih, Wan Y; Shih, Wei-Heng

    2010-09-01

    Invasive malignant breast cancers are typically branchy and benign breast tumors are typically smooth. It is of interest to characterize tumor branchiness (roughness) to differentiate invasive malignant breast cancer from noninvasive ones. In this study, we examined the shear modulus (G) to elastic modulus (E) ratio, G/E, as a quantity to describe model tumor interfacial roughness using a piezoelectric cantilever capable of measuring both tissue elastic modulus and tissue shear modulus. The piezoelectric cantilever used had two lead zirconate titanate layers to facilitate all-electrical elastic (shear) modulus measurements using one single device. We constructed model tissues with tumors by embedding one-dimensional (1D) corrugated inclusions and three-dimensional (3D) spiky-ball inclusions made of modeling clay in gelatin. We showed that for smooth inclusions, G/E was 0.3 regardless of the shear direction. In contrast, for a 1D corrugated rough inclusion G/E was 0.3 only when the shear was parallel to corrugation and G/E increased with an increasing angle between the shear direction and the corrugation. When the shear was perpendicular to corrugation, G/E became >0.7. For 3D isotropic spiky-ball inclusions we showed that the G/E depended on the degree of the roughness. Using the ratio s/r of the spike length (s) to the overall inclusion radius (r) as a roughness parameter, we showed that for inclusions with s/r larger than or equal to 0.28, the G/E ratio over the inclusions was larger than 0.7 whereas for inclusions with s/r less than 0.28, the G/E decreased with decreasing s/r to around 0.3 at s/r=0. In addition, we showed that the depth limit of the G/E measurement is twice the width of the probe area of the piezoelectric cantilever. PMID:20887005

  2. Cantilevers with integrated organic LEDs for scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    An, Kwang Hyup; O'Connor, Brendan; Zhao, Yiying; Loh, William; Pipe, Kevin P.; Shtein, Max

    2007-02-01

    Organic thin films which are based on Van der Waals-bonded molecular organic compounds can be deposited onto a variety of substrates including scanning probe cantilevers without the lattice-matching constraints of conventional covalently-bonded semiconductors. Here we demonstrate organic light-emitting devices (OLEDs) fabricated on scanning probe cantilevers using thermal evaporation of molecular organic compounds and metallic electrodes. Ion beam lithography was used to define the emissive region in the shape of a ring having a diameter of 5 micrometers. The width of the ring emission was less than a micron as measured in the far field. Stable light emission was observed from the device at forward bias, with a current-voltage response similar to that of archetypal OLEDs. Such a probe can enable a new form of electrically-pumped SNOM compatible with existing atomic force microscopy tools and techniques. The emission wavelength can be tuned across the entire visible spectrum, including white light emission, by altering the composition of the emissive layer with a wide range of luminescent dyes. Should the ring-shaped light emission be used for imaging, the sample image can be deconvolved using a ring filter to achieve high resolution. The OLED probe can also be used to transfer excitons through the cathode to a sample via plasmon-assisted energy transfer; such a probe would be valuable for studying exciton dynamics in organic or organic/inorganic hybrid photovoltaic devices. By demonstrating the first active organic device on a scanning probe cantilever, this work opens the door to a wide range of new scanning probe techniques based on this class of materials for areas such as biological imaging.

  3. Nonlinear Dynamics of Cantilever-Sample Interactions in Atomic Force Microscopy

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Cantrell, Sean A.

    2010-01-01

    The interaction of the cantilever tip of an atomic force microscope (AFM) with the sample surface is obtained by treating the cantilever and sample as independent systems coupled by a nonlinear force acting between the cantilever tip and a volume element of the sample surface. The volume element is subjected to a restoring force from the remainder of the sample that provides dynamical equilibrium for the combined systems. The model accounts for the positions on the cantilever of the cantilever tip, laser probe, and excitation force (if any) via a basis set of set of orthogonal functions that may be generalized to account for arbitrary cantilever shapes. The basis set is extended to include nonlinear cantilever modes. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a matrix iteration procedure. The effects of oscillatory excitation forces applied either to the cantilever or to the sample surface (or to both) are obtained from the solution set and applied to the to the assessment of phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) modalities. The influence of bistable cantilever modes of on AFM signal generation is discussed. The effects on the cantilever-sample surface dynamics of subsurface features embedded in the sample that are perturbed by surface-generated oscillatory excitation forces and carried to the cantilever via wave propagation are accounted by the Bolef-Miller propagating wave model. Expressions pertaining to signal generation and image contrast in A-AFM are obtained and applied to amplitude modulation (intermittent contact) atomic force microscopy and resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM). The influence of phase accumulation in A-AFM on image contrast is discussed, as is the effect of hard contact and maximum nonlinearity regimes of A-AFM operation.

  4. Influence of rotation and pretwist on cantilever fan blade flutter

    NASA Technical Reports Server (NTRS)

    Sisto, F.; Chang, A. T.

    1985-01-01

    The fundamental and lowest frequency natural modes in a cantilever fan blade exhibit significant amounts of flexure and torsion coupled by pretwist and operation in a rotational force field. Consequently the flutter estimation of such blades requires an accurate structural description that incorporates these two effects, amongst others. A beam-type finite element model is used in this study with up to six spanwise elements, each element being pretwisted. Coalescence-type flutter is found with subsonic aerodynamics. Evidence of the aerodynamic resonance phenomenon is exhibited and the importance of including radially varying aerodynamic forces is brought out.

  5. Double Cantilever Beam Fracture Toughness Testing of Several Composite Materials

    NASA Technical Reports Server (NTRS)

    Kessler, Jeff A.; Adams, Donald F.

    1992-01-01

    Double-cantilever beam fracture toughness tests were performed by the Composite Materials Research Group on several different unidirectional composite materials provided by NASA Langley Research Center. The composite materials consisted of Hercules IM-7 carbon fiber and various matrix resin formulations. Multiple formulations of four different families of matrix resins were tested: LaRC - ITPI, LaRC - IA, RPT46T, and RP67/RP55. Report presents the materials tested and pertinent details supplied by NASA. For each material, three replicate specimens were tested. Multiple crack extensions were performed on each replicate.

  6. On numerical nonlinear analysis of highly flexible spinning cantilevers

    NASA Technical Reports Server (NTRS)

    Utku, S.; El-Essawi, M.; Salama, M.

    1981-01-01

    The general nonlinear discretized equations of motion of spinning elastic solids and structures are derived as a set of nonlinear ordinary differential equations for the case when the strain-displacement and velocity-displacement relations are nonlinear up to the second order. It is shown that the cost of generation of such equations is proportional to the fourth power of the number of degrees of freedom. A computer program is written to automatically generate the equations for the case of spinning cantilevers with initial imperfections. The types and the number of the coordinate functions used in the trial solution are parameters of the program.

  7. Vibrations of twisted cantilever plates - A comparison of theoretical results

    NASA Technical Reports Server (NTRS)

    Kielb, R. E.; Leissa, A. W.; Macbain, J. C.

    1985-01-01

    As a result of significant differences in the published results for various methods of analysis involving the use of finite element techniques, there are now some questions regarding the adequacy of these methods to predict accurately the vibratory characteristics of highly twisted cantilever plates. In an attempt to help in a resolution of the arising problems, a joint government/industry/university research effort was initiated. The primary objective of the present paper is to summarize the theoretical methods used in the study and show samples of the obtained results. The study provided 19 sets of theoretical results which are derived from beam theory, shell theory, and finite element methods.

  8. Integrated optical dual-cantilever arrays in silica on silicon.

    PubMed

    Cooper, Peter A; Carpenter, Lewis G; Mennea, Paolo L; Holmes, Christopher; Gates, James C; Smith, Peter G R

    2014-12-29

    A dual cantilever device has been demonstrated which can operate as a force sensor or variable attenuator. The device is fabricated using physical micromachining techniques that do not require cleanroom class facilities. The response of the device to mechanical actuation is measured, and shown to be well described by conventional fiber optic angular misalignment theory. The device has the potential to be utilized within integrated optical components for sensors or attenuators. An array of devices was fabricated with potential for parallel operation. PMID:25607148

  9. Heater-Integrated Cantilevers for Nano-Samples Thermogravimetric Analysis

    PubMed Central

    Toffoli, Valeria; Carrato, Sergio; Lee, Dongkyu; Jeon, Sangmin; Lazzarino, Marco

    2013-01-01

    The design and characteristics of a micro-system for thermogravimetric analysis (TGA) in which heater, temperature sensor and mass sensor are integrated into a single device are presented. The system consists of a suspended cantilever that incorporates a microfabricated resistor, used as both heater and thermometer. A three-dimensional finite element analysis was used to define the structure parameters. TGA sensors were fabricated by standard microlithographic techniques and tested using milli-Q water and polyurethane microcapsule. The results demonstrated that our approach provides a faster and more sensitive TGA with respect to commercial systems.

  10. APPARATUS FOR NON-DESTRUCTIVE INSPECTION OF CANTILEVERED MEMBERS

    DOEpatents

    Taylor, E.R.; Mahoney, C.H.; Lay, C.R.

    1961-10-24

    An apparatus for non-destructive inspection of cantilevered members, such as compressor blades, is described. The member under inspection is vibrated with a regulated source of air under pressure. The amplitude of vibration of the member is maintained at its natural frequency. The frequency of vibration of the member is measured. An indication of an excessive decay or erratic shifting in the measured frequency above an allowable hysteretic decay is provided as an indication of a fault in the member. The member is vibrated for a selected test period. (AEC)

  11. [Advantages of fixed combinations].

    PubMed

    Lachkar, Y

    2008-07-01

    Fixed combinations are indicated in the treatment of glaucoma and ocular hypertension when monotherapy does not sufficiently reduce IOP. Fixed combinations show better efficacy than the instillation of each separate component and are at least equivalent to the administration of both components in a separate association. They simplify treatment, increase compliance and quality of life, and decrease exposure to preservatives. Although they are less aggressive for patients when a new drug needs to be added, the use of fixed combinations should not decrease the follow-up. PMID:18957922

  12. Structure–performance relationships for cantilever-type piezoelectric energy harvesters

    SciTech Connect

    Cho, Kyung-Hoon E-mail: spriya@vt.edu; Park, Hwi-Yeol; Heo, Jin S.; Priya, Shashank E-mail: spriya@vt.edu

    2014-05-28

    This study provides comprehensive analysis of the structure–performance relationships in cantilever-type piezoelectric energy harvesters. It provides full understanding of the effect of all the practical global control variables on the harvester performance. The control variables considered for the analysis were material parameters, areal and volumetric dimensions, and configuration of the inactive and active layers. Experimentally, the output power density of the harvester was maximum when the shape of the beam was close to a square for a constant bending stiffness and a fixed beam area. Through analytical modeling of the effective stiffness for the piezoelectric bimorph, the conditions for enhancing the bending stiffness within the same beam volume as that of a conventional bimorph were identified. The harvester configuration with beam aspect ratio of 0.86 utilizing distributed inactive layers exhibited an giant output power of 52.5 mW and power density of 28.5 mW cm{sup −3} at 30 Hz under 6.9 m s{sup −2} excitation. The analysis further indicates that the trend in the output power with varying damping ratio is dissimilar to that of the efficiency. In order to realize best performance, the harvester should be designed with respect to maximizing the magnitude of output power.

  13. Band-pass design optimization of piezoelectric cantilever bimorph energy harvester

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Williams, Keith A.

    2011-03-01

    Piezoelectric energy harvesting has become a feasible method for powering micro portable electronics and wireless sensor networks by converting ambient vibration energy into electrical energy. As a thumb of rule, it is critical to tune the resonant frequency of the generator to the frequency of the environmental vibrations in order to induce the maximum structural deformation and then the maximum converted electrical energy through piezoelectric effect. However, it is well-known that the ambient vibrations are not usually fixed in only one single frequency and could span over a limited frequency band. In this paper, a band-pass design optimization of piezoelectric cantilever bimorph (PCB) energy harvester is presented based on the system transfer function of the PCB generator presented in a previous literature. For such an energy harvester, a group of PCB with dimensions appropriately selected can be integrated into a band-pass energy harvester working over a limited frequency band if the dimensions of piezoelectric bimorphs and proof masses are appropriately chosen. Further, the finite element analysis (FEA) of such a band-pass energy harvester is performed in ANSYS to validate the theoretical proposal. The result shows that the band-pass design optimization leads to a piezoelectric generator working over a certain frequency band while keeping outputting the relatively stable open-circuit voltage.

  14. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  15. Ultrananocrystalline Diamond Cantilever Wide Dynamic Range Acceleration/Vibration /Pressure Sensor

    DOEpatents

    Krauss, Alan R.; Gruen, Dieter M.; Pellin, Michael J.; Auciello, Orlando

    2003-09-02

    An ultrananocrystalline diamond (UNCD) element formed in a cantilever configuration is used in a highly sensitive, ultra-small sensor for measuring acceleration, shock, vibration and static pressure over a wide dynamic range. The cantilever UNCD element may be used in combination with a single anode, with measurements made either optically or by capacitance. In another embodiment, the cantilever UNCD element is disposed between two anodes, with DC voltages applied to the two anodes. With a small AC modulated voltage applied to the UNCD cantilever element and because of the symmetry of the applied voltage and the anode-cathode gap distance in the Fowler-Nordheim equation, any change in the anode voltage ratio V1/V2 required to maintain a specified current ratio precisely matches any displacement of the UNCD cantilever element from equilibrium. By measuring changes in the anode voltage ratio required to maintain a specified current ratio, the deflection of the UNCD cantilever can be precisely determined. By appropriately modulating the voltages applied between the UNCD cantilever and the two anodes, or limit electrodes, precise independent measurements of pressure, uniaxial acceleration, vibration and shock can be made. This invention also contemplates a method for fabricating the cantilever UNCD structure for the sensor.

  16. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  17. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  18. Ultrananocrystalline diamond cantilever wide dynamic range acceleration/vibration/pressure sensor

    DOEpatents

    Krauss, Alan R.; Gruen, Dieter M.; Pellin, Michael J.; Auciello, Orlando

    2002-07-23

    An ultrananocrystalline diamond (UNCD) element formed in a cantilever configuration is used in a highly sensitive, ultra-small sensor for measuring acceleration, shock, vibration and static pressure over a wide dynamic range. The cantilever UNCD element may be used in combination with a single anode, with measurements made either optically or by capacitance. In another embodiment, the cantilever UNCD element is disposed between two anodes, with DC voltages applied to the two anodes. With a small AC modulated voltage applied to the UNCD cantilever element and because of the symmetry of the applied voltage and the anode-cathode gap distance in the Fowler-Nordheim equation, any change in the anode voltage ratio V1/N2 required to maintain a specified current ratio precisely matches any displacement of the UNCD cantilever element from equilibrium. By measuring changes in the anode voltage ratio required to maintain a specified current ratio, the deflection of the UNCD cantilever can be precisely determined. By appropriately modulating the voltages applied between the UNCD cantilever and the two anodes, or limit electrodes, precise independent measurements of pressure, uniaxial acceleration, vibration and shock can be made. This invention also contemplates a method for fabricating the cantilever UNCD structure for the sensor.

  19. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  20. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  1. Analysis of grating inscribed micro-cantilever for high resolution AFM probe

    NASA Astrophysics Data System (ADS)

    Balajee, N.; Mahapatra, D. R.; Hegde, G. M.

    2013-06-01

    We present a mathematical modelling and analysis of reflection grating etched Si AFM cantilever deflections under different loading conditions. A simple analysis of the effect of grating structures on cantilever deflection is carried out with emphasis on optimizing the beam and gratings such that maximum amount of diffracted light remains within the detector area.

  2. Decoupled cantilever arms for highly versatile and sensitive temperature and heat flux measurements.

    PubMed

    Burg, Brian R; Tong, Jonathan K; Hsu, Wei-Chun; Chen, Gang

    2012-10-01

    Microfabricated cantilever beams have been used in microelectromechanical systems for a variety of sensor and actuator applications. Bimorph cantilevers accurately measure temperature change and heat flux with resolutions several orders of magnitude higher than those of conventional sensors such as thermocouples, semiconductor diodes, as well as resistance and infrared thermometers. The use of traditional cantilevers, however, entails a series of important measurement limitations, because their interactions with the sample and surroundings often create parasitic deflection forces and the typical metal layer degrades the thermal sensitivity of the cantilever. The paper introduces a design to address these issues by decoupling the sample and detector section of the cantilever, along with a thermomechanical model, the fabrication, system integration, and characterization. The custom-designed bi-arm cantilever is over one order of magnitude more sensitive than current commercial cantilevers due to the significantly reduced thermal conductance of the cantilever sample arm. The rigid and immobile sample section offers measurement versatility ranging from photothermal absorption, near-field thermal radiation down to contact, conduction, and material thermal characterization measurements in nearly identical configurations. PMID:23126793

  3. Transmission electron microscopy of deformed Ti-6Al-4 V micro-cantilevers

    NASA Astrophysics Data System (ADS)

    Ding, Rengen; Gong, Jicheng; Wilkinson, Angus J.; Jones, Ian P.

    2012-09-01

    Single α-β colony micro-cantilevers were machined from a polycrystalline commercial Ti-6Al-4 V sample using a focussed ion beam. Each cantilever contained several alpha lamellae separated by thin fillets of beta. A nanoindenter was used to perform micro-bending tests. The a3 prismatic slip system was selectively activated in the cantilevers by controlling the crystal orientation along the micro-cantilever. Specimens for transmission electron microscopy (TEM) were prepared using a dual-beam focussed ion beam from a series of micro-cantilevers deformed to various extents. Bright field scanning transmission electron microscopy (BF-STEM) was used to investigate the processes of slip nucleation, propagation and transmission through the α/β interface. The cantilevers had an equilateral triangular cross-section with the bar at the top and the apex at the bottom. The compressive stresses developed near the apex were thus twice the tensile stresses near the top. Dislocations initiate first from the bottom and then from the top and move toward the neutral line. Even in the sample with a small deflection, i.e. 0.5 µm, dislocations were observed at the bottom of the cantilever, but dislocations were not observed at the top until the deflection reached 3 µm. Pile-ups pushed the dislocations past the neutral line when the micro-cantilevers were deflected to more than 4 µm.

  4. Silicon cantilever functionalization for cellulose-specific chemical force imaging of switchgrass

    DOE PAGESBeta

    Lee, Ida; Evans, Barbara R.; Foston, Marcus B.; Ragauskas, Arthur J.

    2015-05-08

    A method for direct functionalization of silicon and silicon nitride cantilevers with bifunctional silanes was tested with model surfaces to determine adhesive forces for different hydrogen-bonding chemistries. Application for biomass surface characterization was tested by mapping switchgrass and isolated switchgrass cellulose in topographic and force-volume mode using a cellulose-specific cantilever.

  5. Silicon cantilever functionalization for cellulose-specific chemical force imaging of switchgrass

    SciTech Connect

    Lee, Ida; Evans, Barbara R; Foston, Marcus B; Ragauskas, Arthur J

    2015-01-01

    A method for direct functionalization of silicon and silicon nitride cantilevers with bifunctional silanes was tested with model surfaces to determine adhesive forces for different hydrogen-bonding chemistries. Application for biomass surface characterization was tested by mapping switchgrass and isolated switchgrass cellulose in topographic and force-volume mode using a cellulose-specific cantilever.

  6. Assessment of insulated conductive cantilevers for biology and electrochemistry

    NASA Astrophysics Data System (ADS)

    Frederix, Patrick L. T. M.; Gullo, Maurizio R.; Akiyama, Terunobu; Tonin, Andreas; de Rooij, Nicolaas F.; Staufer, Urs; Engel, Andreas

    2005-08-01

    This paper describes the characterization and application of electrically insulated conductive tips mounted on a cantilever for use in an atomic force microscope and operated in liquid. These multifunctional probes were microfabricated and designed for measurements on biological samples in buffer solution, but they can also be employed for electrochemical applications, in particular scanning electrochemical microscopy. The silicon nitride based cantilevers had a spring constant <=0.1 N m-1 and a conductive tip, which was insulated except at the apex. The conductive core of the tip consisted of a metal, e.g. platinum silicide, and exhibited a typical radius of 15 nm. The mechanical and electrical characterization of the probe is presented and discussed. First measurements on the hexagonally packed intermediate layer of Deinococcus radiodurans demonstrated the possibility to adjust the image contrast by applying a voltage between a support and the conductive tip and to measure variations of less than 1 pA in faradaic current with a lateral resolution of 7.8 nm.

  7. The stress intensity factor for the double cantilever beam

    NASA Technical Reports Server (NTRS)

    Fichter, W. B.

    1983-01-01

    Fourier transforms and the Wiener-Hopf technique are used in conjunction with plane elastostatics to examine the singular crack tip stress field in the double cantilever beam (DCB) specimen. In place of the Dirac delta function, a family of functions which duplicates the important features of the concentrated forces without introducing unmanageable mathematical complexities is used as a loading function. With terms of order h-squared/a-squared retained in the series expansion, the dimensionless stress intensity factor is found to be K (h to the 1/2)/P = 12 to the 1/2 (a/h + 0.6728 + 0.0377 h-squared/a-squared), in which P is the magnitude of the concentrated forces per unit thickness, a is the distance from the crack tip to the points of load application, and h is the height of each cantilever beam. The result is similar to that obtained by Gross and Srawley by fitting a line to discrete results from their boundary collocation analysis.

  8. Surface effect on the nonlinear forced vibration of cantilevered nanobeams

    NASA Astrophysics Data System (ADS)

    Dai, H. L.; Zhao, D. M.; Zou, J. J.; Wang, L.

    2016-06-01

    The nonlinear forced vibration behavior of a cantilevered nanobeam is investigated in this paper, essentially considering the effect due to the surface elastic layer. The governing equation of motion for the nano-cantilever is derived, with consideration of the geometrical nonlinearity and the effects of additional flexural rigidity and residual stress of the surface layer. Then, the nonlinear partial differential equation (PDE) is discretized into a set of nonlinear ordinary differential equations (ODEs) by means of the Galerkin's technique. It is observed that surface effects on the natural frequency of the nanobeam is of significance, especially for the case when the aspect ratio of the nanobeam is large. The nonlinear resonant dynamics of the nanobeam system is evaluated by varying the excitation frequency around the fundamental resonance, showing that the nanobeam would display hardening-type behavior and hence the frequency-response curves bend to the right in the presence of positive residual surface stress. However, with the negative residual surface stress, this hardening-type behavior can be shifted to a softening-type one which becomes even more evident with increase of the aspect ratio parameter. It is also demonstrated that the combined effects of the residual stress and aspect ratio on the maximum amplitude of the nanobeam may be pronounced.

  9. Systematic design of cantilever beams for muscle research.

    PubMed

    McLaughlin, R J

    1977-05-01

    Experimental studies of muscle contraction often involve difficult problems in the design of cantilever beams for movable levers, transducers, or mechanical supports. Equations are presented for the calculation of mass, inertia, stress distribution, strain, deflection curve, compliance, and resonant frequency of uniform or nonuniform cantilever beams made of structural materials of different density or elastic modulus. Formulas are listed for solid, thick-wall, and thin-wall uniform beams of rectangular and circular cross section. Physical properties including density, elastic and torsional moduli, stress and strain limits, thermal expansion coefficients, Poisson's ratio, and certain elastic-modulus-to-density ratios are tabulated for structural materials including common metals, glass, plastic, and wood. A graphical design procedure is presented based on a chart containing loci of constant beam parameter values as a function of beam length and height or diameter, for the simple geometries. The choice of structural material is discussed for design problems with typical constraints, and examples are given of the design of beams of nonuniform cross section. Methods for extending the design chart to other geometries and materials are included. PMID:863848

  10. Instability of a cantilevered flexible plate in viscous channel flow

    NASA Astrophysics Data System (ADS)

    Balint, T. S.; Lucey, A. D.

    2005-10-01

    The stability of a flexible cantilevered plate in viscous channel flow is studied as a representation of the dynamics of the human upper airway. The focus is on instability mechanisms of the soft palate (flexible plate) that cause airway blockage during sleep. We solve the Navier Stokes equations for flow with Reynolds numbers up to 1500 fully coupled with the dynamics of the plate motion solved using finite-differences. The study is 2-D and based upon linearized plate mechanics. When both upper and lower airways are open, the plate is found to lose its stability through a flutter mechanism and a critical Reynolds number exists. When one airway is closed, the plate principally loses its stability through a divergence mechanism and a critical flow speed exists. However, below the divergence-onset flow speed, flutter can exist for low levels of structural damping in the flexible plate. Our results serve to extend understanding of flow-induced instability of cantilevered flexible plates and will ultimately improve the diagnosis and treatment of upper-airway disorders.