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Sample records for cantilever cross-arch fixed

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  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.

  7. 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.

  8. [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.

  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. [Elucidation of cross arch stabilization for the lower unilateral free end denture in terms of vibratory science].

    PubMed

    Hojyo, S

    1989-06-01

    Cases of lower unilateral free end defect are the source of many problems in clinical dentistry. The denture design method most commonly used is cross arch stabilization which involves creating a retainer on the side opposite the defect via a bar in order to stabilize the denture and protect the retaining teeth. Almost all research on this method involves experiments using a static load. Moreover, there are few studies that attempt to clarify the relationship between the major connector and the retaining teeth. As a means of clarifying these problems, the authors used the modal analysis method and a vibrometer, both of which have proven effective in general observation of lowr denture dynamics when dynamic force is applied. This allowed them to see the relationship between the metal framework configuration and the retainer in animation and thereby study displacement quantity and damping quantity. The following interesting were obtained. 1. There were four modes detected for fixed vibration on the individual metal frameworks: 500Hz band, 1kHz band 2kHz band and 4kHz band. 2. The dynamics of the individual metal frameworks were as follows: Mode 1 was a rigid body mode in a vertical direction with a fulcrum of angle 54. Mode 2 was a horizontal rigid body mode with a fulcrum of angle 54. Mode 3 was a mixture of a horizontal rigid bode and horizontal bend mode. There was a rolling type mode observed only from the plate type. Mode 4 consisted mainly of a horizontal bend mode. This showed that there were differences among the various modes. 3. Judging from the displacement rate computed at the 500Hz band, the rate of displacement decreases as the thickness and ratio decrease. 4. Judging from linear damping quantity and damping quantity in terms of frequency, the finishing line showed a greater tendency toward resonance. 5. Analysis in terms of vibratory science using modal analysis and octave band analysis hinted at the significance of cross arch stabilization.

  11. 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

  12. 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.

  13. Effect of proximal contact strength on the three-dimensional displacements of implant-supported cantilever fixed partial dentures under axial loading

    PubMed Central

    Peng, Zhen-zhen; Chen, Xin-min; Wang, Jun; Li, Ai-jie; Xu, Zu-jie

    2013-01-01

    Objective: This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture (CFPD) under vertically concentrated loading with digital laser speckle (DLS) technique. Methods: Fresh mandible of beagle dog was used to establish the implant-supported CFPD for specimen. DLS technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3 000 g. The effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact tightness. Results: When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD, the displacement of the CFPD was the greatest. The displacement of the prosthesis decreased with the increase of contact strength. When the contact strength was 0, 0.95, and 3.25 N, the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival direction. When the force on the contact area was 6.50 N, the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the smallest. Conclusions: The implant-supported CFPD is an effective therapy for fully or partially edentulous patients. The restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD, and get a better stress distribution. The most appropriate force value is 3.25 N in this study. PMID:23733430

  14. [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

  15. 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.

  16. Cross-arch arrangement in complete denture prosthesis to manage an edentulous patient with oral submucous fibrosis and abnormal jaw relation

    PubMed Central

    Tambe, Abhijit; Patil, Sanjayagouda B; Bhat, Sudhakara; Badadare, Mokshada M

    2014-01-01

    A patient with oral submucous fibrosis and resorbed ridges poses a challenge for prosthodontic rehabilitation because of the limited mouth opening and fibrotic mucosa. The fabrication of prosthesis is very difficult due to abnormal jaw relations, influencing the long-term prognosis of the patient. To present a case of oral submucous fibrosis with severely resorbed edentulous ridges which was successfully managed by adopting a modified technique in fabricating a complete denture prosthesis. A 55-year-old female patient with completely edentulous maxillary and mandibular arches diagnosed with oral submucous fibrosis was rehabilitated with complete dentures by recording neutral zone for resorbed mandibular ridge and by arranging the posterior teeth in cross arch relation for compensation of the abnormal jaw relations. The cross-arch arrangement of posterior teeth provides a more stable and retentive complete denture prosthesis for patients with severely resorbed ridges and a wider mandibular arch. PMID:25239981

  17. 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

  18. 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.

  19. 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.

  20. 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…

  1. 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

  2. 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

  3. Method for providing a compliant cantilevered micromold

    DOEpatents

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

    2008-12-16

    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.

  4. 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.

  5. 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.

  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. 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.

  8. 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.

  9. 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.

  10. 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.}

  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. High throughout reproducible cantilever functionalization

    SciTech Connect

    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.

  13. Influence of cantilever length and type of arch antagonist on bone loss in total implant-supported prostheses.

    PubMed

    Cid, Rafaella M O; Stanley, Kyle; Cordero, Ernesto B; Benfatti, Cesar A M; Bianchini, Marco A

    2014-01-01

    This study selected forty-two implants with full arch implantsupported fixed prostheses (with and without a cantilever) with at least five years' loading. Radiographic measurements were performed using Digimizer software (MedCalc Software, Belgium). Bone loss was measured on the distal side of the implant, from the surface of the platform to the edge of the bone crest, and the extent of the cantilever was measured from the distal surface of the last abutment to the end of the metal structure. Three groups were formed according the length of the cantilever: G1: cantilever ≤ 15 mm; G2: cantilever >15 mm; G3: no cantilever. Types of antagonists were grouped as: RP = removable complete denture; FP = fixed implant-supported prosthesis; ND = natural dentition. Data were analyzed according to the length of the cantilever and type of antagonist using Person's test to analyze normality and Student's t-test with P ≦ 0.05. No statistically significant difference was found between G1 and G2; however, increased bone loss was observed in both cantilever groups (G1 and G2) compared to G3 (P> 0.05). The antagonist showed no significant difference in bone loss ( P ≦ 0.05). Cantilevers showed increases in marginal bone loss. The type of antagonist did not influence bone loss.

  14. Orthodontic Traction of Impacted Canine Using Cantilever

    PubMed Central

    Gonçalves, João Roberto; Cassano, Daniel Serra; Bianchi, Jonas

    2016-01-01

    The impaction of the maxillary canines causes relevant aesthetic and functional problems. The multidisciplinary approach to the proper planning and execution of orthodontic traction of the element in question is essential. Many strategies are cited in the literature; among them is the good biomechanical control in order to avoid possible side effects. The aim of this paper is to present a case report in which a superior canine impacted by palatine was pulled out with the aid of the cantilever on the Segmented Arch Technique (SAT) concept. A 14.7-year-old female patient appeared at clinic complaining about the absence of the upper right permanent canine. The proposed treatment prioritized the traction of the upper right canine without changing the occlusion and aesthetics. For this, it only installed the upper fixed appliance (Roth with slot 0.018), opting for SAT in order to minimize unwanted side effects. The use of cantilever to the traction of the upper right canine has enabled an efficient and predictable outcome, because it is of statically determined mechanics. PMID:27800192

  15. 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.

  16. 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.

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

    PubMed

    Gates, Richard S; Reitsma, Mark G

    2007-08-01

    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.

  18. 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.

  19. 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

  20. 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

  1. Symmetrically arranged quartz tuning fork with soft cantilever for intermittent contact mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Akiyama, T.; Staufer, U.; de Rooij, N. F.; Frederix, P.; Engel, A.

    2003-01-01

    A self-sensing and -actuating probe for dynamic mode atomic force microscopy (AFM) based on a commercial quartz tuning fork and a microfabricated cantilever is presented. The U-shaped cantilever, exhibiting a sharp tip, is combined with the tuning fork in a symmetrical arrangement, such that each of the two legs of the cantilever is fixed to one of the prongs of the tuning fork. The tuning fork is used as an oscillatory force sensor. Its frequency and amplitude govern that of the tip vibration, while the cantilever determines the spring constant of the whole probe. The frequency of the tip vibration for AFM operations can be much higher than the resonance frequency of the cantilever. A probe comprising a silicon nitride cantilever (0.1 N/m) is used to image monoatomic terraces of graphite in the intermittent contact mode. A much softer cantilever (0.01 N/m) is used to analyze the topography of a microelectronic chip in the same mode. Moreover, a bacterial surface layer hexagonally packed intermediate layer of Deinococcus radiodurans is imaged in a buffer solution. The tip vibration was again generated by the tuning fork while the sample interaction was measured using the standard optical detection scheme in this experiment. These probes are suited for batch fabrication and assembly and, therefore, enlarge the applications for the tuning fork based AFM.

  2. 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.

  3. 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.

  4. Cantilevered probe detector with piezoelectric element

    SciTech Connect

    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.

  5. 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.

  6. 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.

  7. Tunnel junctions, cantilevers, and potentials

    NASA Astrophysics Data System (ADS)

    Tanner, Shawn

    We have developed a process for making sub-micrometer dimensional cantilevers, clamped beams, and more complicate electro-mechanical structures that carry integrated electrical leads. Such objects are perhaps useful as test structures for connecting to and measuring the electrical properties of molecular sized objects, as high frequency electromechanical components for radio and microwave frequency applications, and as sensor components for studying the fluctuation physics of small machines. Our process uses two realigned electron-beam lithography steps, a thin film angled deposition system, and differential removal of sacrificial aluminum layers to produce freely suspended sub-micron electromechanical components. We have produced cantilevers and beams on a variety of substrates (silica, silicon, and poly-imide) and have produced insulating, conductive, and multi-layer mechanical structures. We have measured mechanical resonances in the 10 MHz range by electrostatically actuating the cantilevers while in a magnetic field (3500 gauss) and measuring the voltage that results across the front edge of the cantilever. Two structures are fabricated sharing a common ground so that a balanced detection technique can be used to eliminate background signals. Due to the square dependence of the electrostatic force on the voltage, they can be resonated by a drive voltage of 1/2 the natural frequency or at the natural frequency. Two separate attempts have been made to apply these resonators. First, a process was developed to integrate a tunnel junction with the cantilever. These devices can possibly be used for probing small-scale systems such as molecules. We have verified the exponential variation of the tunneling resistance with both substrate flex and electrostatic gating. Second, a novel gate structure was developed to create a double potential well for resonator motion. This is accomplished by placing a multilayer structure in front of the hairpin cantilever consisting two

  8. 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

  9. 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.

  10. Optical fibre cantilever sensor for biological application

    NASA Astrophysics Data System (ADS)

    Li, J.; Zhou, Y. X.; Patterson, G.; Shu, W. M.; Maier, R. R. J.; Fowler, R.; Hand, D. P.; MacPherson, W. N.

    2014-05-01

    Micro-cantilever sensors have shown great promise in a wide range of application are as including chemical and biological sensing. However, many of these devices are based upon a sensor `chip' that requires careful alignment between the cantilever and the read-out system, which can be challenging. Furthermore, optical interrogation typically involves a bulky free-space system. Optical fibre addressed cantilevers have been reported previously in the literature and in this paper we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibres using laser machining. Low-cost optical sources and a fibre coupled spectrometer are employed to monitor the cantilever deflection and therefore observe biological binding between a species of interest and an activated cantilever. Proof-of-concept experiments show that the sensor is capable of detecting pathogen concentration with down to a level of 105cfu/ml.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. Improved cantilever profiles for sensor elements

    NASA Astrophysics Data System (ADS)

    Fernando, Sanchitha; Austin, Michael; Chaffey, Jason

    2007-12-01

    The problem of simultaneously enhancing sensitivity and noise immunity of microcantilevers is investigated. The dependence of deflection and resonant frequency of a microcantilever on its dimensions is studied. A principle to increase deflection and resonant frequency simultaneously is established. Several cantilevers agreeing with this principle are investigated using analytical models and are compared with FEM simulations. Using these results, a cantilever profile that achieves a larger deflection and a larger resonant frequency compared with uniform cantilevers is proposed to be used in sensor elements.

  20. 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.

  1. 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.

  2. 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.

  3. Cantilever noise in off-cantilever-resonance force-detected nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Harrell, Lee E.; Thurber, Kent R.; Smith, Doran D.

    2004-03-01

    Early work in force-detected nuclear magnetic resonance (FD-NMR) and magnetic resonance force microscopy was restricted to nuclei with a relatively large gyromagnetic ratio γ. Increasingly, as researchers look to apply FD-NMR to practical problems, observing isotopes with a small γ is becoming necessary. The small γ of these isotopes places severe restrictions on the radio frequency field strength necessary to flip the sample spins at practical cantilever frequencies by adiabatic rapid passage. These restrictions led us to investigate the feasibility of observing FD-NMR by flipping sample spins at a rate well below the cantilever frequency. In this article we show that there is no increase in thermomechanical force noise in off-cantilever-resonance FD-NMR relative to on-cantilever-resonance work. Further, we show that working off-cantilever resonance can reduce artifacts and decrease data acquisition time. The major disadvantage to working off-cantilever resonance—reduced cantilever response—increases the importance of low noise detection of cantilever oscillation.

  4. Three-dimensional vibrations of cantilevered right triangular plates

    NASA Astrophysics Data System (ADS)

    McGee, O. G.; Giaimo, G. T.

    1992-12-01

    The first known three-dimensional continuum vibration solutions for cantilevered right triangular plates with variable thickness are obtained using the Ritz method. Assumed displacement functions are in the form of algebraic polynomials, which satisfy the fixed face conditions exactly, and which are mathematically complete. Reasonably accurate natural frequencies are calculated for low aspect ratio, right triangular thin plates having arbitrary values of thickness taper ratios in the spanwise direction. Detailed numerical studies show that a three-dimensional analysis is essential to monitoring coupled-mode sensitivities in the variation of non-dimensional natural frequencies with increasing thickness taper ratio. Upper bound results, obtained using the present method, are compared with those obtained by other investigators using ordinary beam theories, two-dimensional finite element and finite difference procedures, and experimental methods. This unified comparison of upper and lower bound solutions is presented here with the aim of 'bracketing' the exact analytical solution of the subject problem.

  5. 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

  6. Cantilever piezoelectric energy harvester with multiple cavities

    NASA Astrophysics Data System (ADS)

    Srinivasulu Raju, S.; Umapathy, M.; Uma, G.

    2015-11-01

    Energy harvesting employing piezoelectric materials in mechanical structures such as cantilever beams, plates, diaphragms, etc, has been an emerging area of research in recent years. The research in this area is also focused on structural tailoring to improve the harvested power from the energy harvesters. Towards this aim, this paper presents a method for improving the harvested power from a cantilever piezoelectric energy harvester by introducing multiple rectangular cavities. A generalized model for a piezoelectric energy harvester with multiple rectangular cavities at a single section and two sections is developed. A method is suggested to optimize the thickness of the cavities and the number of cavities required to generate a higher output voltage for a given cantilever beam structure. The performance of the optimized energy harvesters is evaluated analytically and through experimentation. The simulation and experimental results show that the performance of the energy harvester can be increased with multiple cavities compared to the harvester with a single cavity.

  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. Piezoelectric cantilevers energy harvesting in MEMS technique

    NASA Astrophysics Data System (ADS)

    Shang, Yingqi; Qiu, Chengjun; Liu, Hongmei; Chen, Xiaojie; Qu, Wei; Dou, Yanwei

    2011-11-01

    Piezoelectric cantilevers energy harvesting made by micro-electromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed cantilevers energy harvesting are featured with resonate frequency and power output in microwatt level, which is sufficient to the self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. In this paper, piezoelectric energy harvesting based on thick-film piezoelectric cantilevers is investigated to resonate at specific frequencies of an external vibration energy source, which creating electrical energy via the piezoelectric effect. Our cantilever device has a multiple structure with a proof mass added to the end. The thick film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) coated on the top of Au/Cr/SiO2/Si substrates by sol-gel-spin method. The thickness of the PZT membrane was up to 2μm and the cantilevers substrates thickness 50μm, wideness 1.5mm, length 4mm. The Au/Ti top electrode is patterned on top of the sol-gel-spin coated PZT thick film in order to employ the d31 mode. The prototype energy generator has a measured performance of 0.74μW effective electrical power, and 4.93 DC output voltages to resistance load. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A multiple structure cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously. This device is promising to support networks of ultra-low-power sensor.

  9. Piezoelectric cantilevers energy harvesting in MEMS technique

    NASA Astrophysics Data System (ADS)

    Shang, Yingqi; Qiu, Chengjun; Liu, Hongmei; Chen, Xiaojie; Qu, Wei; Dou, Yanwei

    2012-04-01

    Piezoelectric cantilevers energy harvesting made by micro-electromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed cantilevers energy harvesting are featured with resonate frequency and power output in microwatt level, which is sufficient to the self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. In this paper, piezoelectric energy harvesting based on thick-film piezoelectric cantilevers is investigated to resonate at specific frequencies of an external vibration energy source, which creating electrical energy via the piezoelectric effect. Our cantilever device has a multiple structure with a proof mass added to the end. The thick film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) coated on the top of Au/Cr/SiO2/Si substrates by sol-gel-spin method. The thickness of the PZT membrane was up to 2μm and the cantilevers substrates thickness 50μm, wideness 1.5mm, length 4mm. The Au/Ti top electrode is patterned on top of the sol-gel-spin coated PZT thick film in order to employ the d31 mode. The prototype energy generator has a measured performance of 0.74μW effective electrical power, and 4.93 DC output voltages to resistance load. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A multiple structure cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously. This device is promising to support networks of ultra-low-power sensor.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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…

  15. 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.

  16. 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

  17. 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

  18. Nonlinear Vibrations of Ferroelectric Bimorph Cantilever

    NASA Astrophysics Data System (ADS)

    Ostrovskii, Igor; Nadtochiy, Andriy

    2008-06-01

    Nonlinear vibrations of a bimorph LiNbO3 microcantilever are investigated. A periodically poled LiNbO3 wafer is used as an initial chip. The cantilever is micro-machined near an interdomain wall between two inversely poled domains. The vibrations are excited by an applied rf-voltage, and motion of a cantilever tip is detected optically. Nonlinearity is revealed by measuring the changes in the dependencies of vibration amplitude versus frequency when amplitude increases, and by reading of sub-harmonic oscillations. A surface of the microcantilever may be modified with a silane, which is sensitive to certain biomolecules. This composite nonlinear micro-vibrator may be used for developing a smart biosensor operating in ambient atmosphere in a real time mode.

  19. Inner Crack Detection Method for Cantilever Beams

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Zhang, Wei; Li, Yixuan; Su, Xianyue

    2008-02-01

    In this paper, continuous wavelet transform has been performed to extract the inner crack information from the guided waves in cantilever beams, and the location and size of crack can be detected exactly. Considering its best time-frequency property, Gabor continuous wavelet transform is employed to analyze the complicated flexible wave signals in cantilever beam, which is inspirited by an impact on the free end. Otherwise, in order to enhance the sensitivity of detection for some small cracks, an improved method is discussed. Here, both computational and experimental methods are carried out for comparing the influence of different crack location in beam. Therefore, the method proposed can be expected to expand to a powerful damage detection method in a broad engineering application.

  20. Calibration of optical cantilever deflection readers

    NASA Astrophysics Data System (ADS)

    Hu, Zhiyu; Seeley, Tim; Kossek, Sebastian; Thundat, Thomas

    2004-02-01

    Because of its ultrahigh sensitivity, the optical lever detection method similar to that used in the atomic force microscope (AFM) has been widely employed as a standard technique for measuring microcantilever deflection. Along with the increasing interest in using the microcantilever as a sensing platform, there is also a requirement for a reliable calibration technique. Many researchers have used the concept of optical lever detection to construct microcantilever deflection readout instruments for chemical, physical, and biological detection. However, without an AFM piezo z scanner, it is very difficult to precisely calibrate these instruments. Here, we present a step-by-step method to conveniently calibrate an instrument using commercially available piezoresistive cantilevers. The experimental results closely match the theoretical calculation. Following this procedure, one can easily calibrate any optical cantilever deflection detection system with high reproducibility, precision, and reliability. A detailed discussion of the optical lever readout system design has been addressed in this article.

  1. 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

  2. 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.

  3. 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

  4. AFM cantilever vibration detection with a transmitted electron beam

    NASA Astrophysics Data System (ADS)

    Woehl, Taylor; Wagner, Ryan; Keller, Robert; Killgore, Jason

    Cantilever oscillations for dynamic atomic force microscopy (AFM) are conventionally measured with an optical lever system. The speed of AFM cantilevers can be increased by decreasing the size of the cantilever; however, the fastest AFM cantilevers are currently nearing the smallest size that can be detected with the current optical lever approach. Here we demonstrate an electron detection scheme in an SEM for detecting AFM cantilever oscillations. An oscillating AFM tip is positioned perpendicular to the propagation direction of a stationary ~ 1 nm diameter electron probe, and the oscillatory change in electron scattering resulting from the changing thickness of the electron irradiated area of the AFM tip is detected with a transmitted electron detector positioned below the AFM tip. We perform frequency sweep and ring-down experiments to determine the first resonant frequency and Q factor of an AFM cantilever.

  5. 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

  6. Imaging using lateral bending modes of atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Caron, A.; Rabe, U.; Reinstädtler, M.; Turner, J. A.; Arnold, W.

    2004-12-01

    Using scanning probe techniques, surface properties such as shear stiffness and friction can be measured with a resolution in the nanometer range. The torsional deflection or buckling of atomic force microscope cantilevers has previously been used in order to measure the lateral forces acting on the tip. This letter shows that the flexural vibration modes of cantilevers oscillating in their width direction parallel to the sample surface can also be used for imaging. These lateral cantilever modes exhibit vertical deflection amplitudes if the cantilever is asymmetric in thickness direction, e.g., by a trapezoidal cross section.

  7. Antibody-based protein detection using piezoresistive cantilever arrays

    NASA Astrophysics Data System (ADS)

    Dauksaite, Vita; Lorentzen, Martin; Besenbacher, Flemming; Kjems, Jørgen

    2007-03-01

    A piezoresistive cantilever array platform with electrical read-out was applied for protein detection using GST (glutathione-S-transferase) and GST antibodies as a model system. Sensing was performed in the static deflection mode under constant flow conditions. The GST antibodies were directly immobilized on the cantilever gold surface by means of free thiol groups. The setup allowed simultaneous deflection measurements with sensor and control-antibody-immobilized reference cantilevers and enabled detection of 1 ng µl-1 (40 nM) of GST protein, which is similar to the sensitivity reported for cantilever sensors using an optical read-out system.

  8. Fatigue strength of cantilevered metal frameworks for tissue-integrated prostheses.

    PubMed

    Stewart, R B; Desjardins, R P; Laney, W R; Chao, E Y

    1992-07-01

    The design of the metal alloy framework in cantilevered sections of fixed tissue-integrated prostheses, is critical. Several cross-sectional designs have been advocated, including the popular L-shaped beam, which permits the economical use of space for tooth placement. The fatigue strengths of 15 L-shaped cantilevered framework sections of the same metal alloy were tested. The castings were divided into three groups of five according to vertical wall heights of 4, 5, and 6 mm. Fatigue durability of each sample was determined by counting the number of cycles of vertical forces required to induce catastrophic failure. Statistical analysis revealed significant differences between all three groups in the cycles counted at failure (p less than 0.0019). Fatigue strengths improved significantly with increasing vertical wall height of the L-shaped cantilevered frameworks. In addition, beam flexure was shown to be indirectly proportional to fatigue strength. Theoretical beam deflection was calculated and shown to correlate with the actual beam deflection during the testing. Theoretical calculations in static bending specific for a cross-sectional design may aid in the predictability of fatigue strength.

  9. 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.

  10. Cantilever rib grafting in salvage rhinoplasty.

    PubMed

    Shubailat, Ghaith F

    2003-01-01

    Loss of nasal skeletal support, whether congenital, following trauma or secondary to multiple failed surgeries, calls for reconstruction aiming at restoring rigid dorsal stability, maintaining tip projection, and restoring respiratory function. Where septal and conchal grafts are inadequate to be used as building blocks, our procedure of choice has been the cantilever osseocartilagenous rib graft with microscrew fixation. In the past 10 years, 48 patients were candidates for this salvage procedure. Long-term functional and cosmetic results have been highly satisfactory. PMID:15058550

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. Calibration of atomic force microscope cantilevers using piezolevers.

    PubMed

    Aksu, Saltuk B; Turner, Joseph A

    2007-04-01

    The atomic force microscope (AFM) can provide qualitative information by numerous imaging modes, but it can also provide quantitative information when calibrated cantilevers are used. In this article a new technique is demonstrated to calibrate AFM cantilevers using a reference piezolever. Experiments are performed on 13 different commercially available cantilevers. The stiff cantilevers, whose stiffness is more than 0.4 N/m, are compared to the stiffness values measured using nanoindentation. The experimental data collected by the piezolever method is in good agreement with the nanoindentation data. Calibration with a piezolever is fast, easy, and nondestructive and a commercially available AFM is enough to perform the experiments. In addition, the AFM laser must not be calibrated. Calibration is reported here for cantilevers whose stiffness lies between 0.08 and 6.02 N/m.

  18. Experimental observation of contact mode cantilever dynamics with nanosecond resolution

    NASA Astrophysics Data System (ADS)

    Payton, O. D.; Picco, L.; Champneys, A. R.; Homer, M. E.; Miles, M. J.; Raman, A.

    2011-04-01

    We report the use of a laser Doppler vibrometer to measure the motion of an atomic force microscope contact mode cantilever during continuous line scans of a mica surface. With a sufficiently high density of measurement points the dynamics of the entire cantilever beam, from the apex to the base, can be reconstructed. We demonstrate nanosecond resolution of both rectangular and triangular cantilevers. This technique permits visualization and quantitative measurements of both the normal and lateral tip sample interactions for the first and higher order eigenmodes. The ability to derive quantitative lateral force measurements is of interest to the field of microtribology/nanotribology while the comprehensive understanding of the cantilever's dynamics also aids new cantilever designs and simulations.

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    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.

  1. 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.

  2. 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

    2015-07-22

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Thermo-magnetic behaviour of AFM-MFM cantilevers

    NASA Astrophysics Data System (ADS)

    Kumar, M.; Arinero, R.; Bergez, W.; Tordjeman, Ph

    2015-08-01

    Atomic force microscopy (AFM) experiments were performed to study the behaviour of AFM cantilevers under an external magnetic field B and temperature field produced by a coil with an iron core. Four cantilever types were studied. Forces were measured for different B values and at various coil-to-cantilever separation distances. The results were analysed on the basis of a phenomenological model. This model contains the contribution of two terms, one monopole-monopole interaction at short distance, and one apparent paramagnetic interaction in \

  10. Buckled cantilevers for out-of-plane platforms

    NASA Astrophysics Data System (ADS)

    Johnstone, R. W.; Ma, A. H.; Sameoto, D.; Parameswaran, M.; Leung, A. M.

    2008-04-01

    In this paper, we show how surface-micromachined buckled cantilevers can be used to construct out-of-plane structures. We include the relevant theory necessary to predict the height and angle of plates attached to buckled cantilevers, as well as the mechanical stresses involved in assembly. These platforms can be assembled to any angle between 0° and 90° with respect to the substrate by changing the attachment point and the amount of deflection. Example devices were fabricated using PolyMUMPs™ and assembled. Using these devices, the deflection of the buckled cantilevers was verified, as well as the placement for raised platforms.

  11. Optically Controlled Bimorph Cantilever of Poly(vinylidene difluoride)

    NASA Astrophysics Data System (ADS)

    Mizutani, Yasuhiro; Otani, Yukitoshi; Umeda, Norihiro

    2008-04-01

    Optically driven actuators are a non-contact method for the remote application of light energy. We propose a new optically driven actuator that employs bimorph poly(vinylidene difluoride) (PVDF) cantilevers. PVDF is an effective polymer from which to prepare actuators since it has both pyroelectric and piezoelectric properties. We have produced a bimorph cantilever from a PVDF film with a thin Ag electrode on one side. A bending model of the PVDF cantilever has been established and its bending characteristics have been experimentally measured. The mechanism can be explained by taking into consideration the model and its dielectric breakdown.

  12. 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.

  13. Dynamic performance analysis of a micro cantilever embedded in elastomer

    NASA Astrophysics Data System (ADS)

    Hosono, Minako; Noda, Kentaro; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-07-01

    This paper reports on the dynamic characteristics of a micro silicon standing cantilever embedded in a silicone elastomer, polydimethylsiloxane (PDMS). This combined structure, which consists of materials with significantly different Young’s moduli, is employed as a tactile sensor for shear-strain measurement. The frequency responses of the tactile sensor show no resonance near the intrinsic resonant frequency of the standing cantilever, whereas the resonant point was observed near the intrinsic resonant frequency of the PDMS covering. In addition, when the oscillation frequency is below the resonant frequency of the tactile sensor, the standing cantilever can follow the oscillating deformation of the PDMS covering with no delay, and the sensitivity of the tactile sensor does not change. The analytical and experimental results show that the PDMS covering has a dominant influence on the dynamic behavior of the embedded cantilever, and the tactile sensor can be applied to both static and oscillating input in the same way.

  14. 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

  15. 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

  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. 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

  18. 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

  19. 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

  20. 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

  1. Perspective view of cantilever truss over back channel, looking SW. ...

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

    Perspective view of cantilever truss over back channel, looking SW. - Bessemer & Lake Erie Railroad, Allegheny River Bridge, Spanning Allegheny River, East of Pennsylvania Turnpike (I-76), Oakmont, Allegheny County, PA

  2. 10. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWER, ...

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

    10. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWER, BACK TO SOUTH PORTAL. Note emergency bracing and crumpled vertical members. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  3. 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.

  4. 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

  5. 7. Detail of sidewalk cantilevers and walkway between viaduct and ...

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

    7. Detail of sidewalk cantilevers and walkway between viaduct and livestock exchange building. View to southwest. - South Omaha Union Stock Yards, Buckingham Road Viaduct, Twenty-ninth Street spanning Stockyard Cattle Pens, Omaha, Douglas County, NE

  6. DETAIL OF CANTILEVERED MEZZANINE OBSERVATION ROOM ON SOUTH WEST CORNER ...

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

    DETAIL OF CANTILEVERED MEZZANINE OBSERVATION ROOM ON SOUTH- WEST CORNER OF BUILDING. VIEW TO NORTHEAST. - Plattsburgh Air Force Base, Base Engineer Pavement & Grounds Facility, Off Colorado Street, Plattsburgh, Clinton County, NY

  7. 23. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER ...

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

    23. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM CHANNEL BELOW BRIDGE, FACING NORTHEAST - Grace Memorial Bridge, U.S. Highway 17 spanning Cooper River & Town Creek , Charleston, Charleston County, SC

  8. 31. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER ...

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

    31. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM WATER, PEARMAN BRIDGE ON LEFT, FACING WEST TOWARDS DRUM ISLAND - Grace Memorial Bridge, U.S. Highway 17 spanning Cooper River & Town Creek , Charleston, Charleston County, SC

  9. 30. SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM WATER, ...

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

    30. SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM WATER, FACING WEST TOWARDS DRUM ISLAND - Grace Memorial Bridge, U.S. Highway 17 spanning Cooper River & Town Creek , Charleston, Charleston County, SC

  10. 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.

  11. Atomic force microscope cantilever calibration using a focused ion beam.

    PubMed

    Slattery, Ashley D; Quinton, Jamie S; Gibson, Christopher T

    2012-07-20

    A calibration method is presented for determining the spring constant of atomic force microscope (AFM) cantilevers, which is a modification of the established Cleveland added mass technique. A focused ion beam (FIB) is used to remove a well-defined volume from a cantilever with known density, substantially reducing the uncertainty usually present in the added mass method. The technique can be applied to any type of AFM cantilever; but for the lowest uncertainty it is best applied to silicon cantilevers with spring constants above 0.7 N m(-1), where uncertainty is demonstrated to be typically between 7 and 10%. Despite the removal of mass from the cantilever, the calibration method presented does not impair the probes' ability to acquire data. The technique has been extensively tested in order to verify the underlying assumptions in the method. This method was compared to a number of other calibration methods and practical improvements to some of these techniques were developed, as well as important insights into the behavior of FIB modified cantilevers. These results will prove useful to research groups concerned with the application of microcantilevers to nanoscience, in particular for cases where maintaining pristine AFM tip condition is critical.

  12. 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

  13. 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

  14. 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

  15. Piezoresistive cantilever force-clamp system

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    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.

  16. 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.

  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. 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

  19. 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.

  20. 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.

  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. 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

  3. 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

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

    PubMed

    Kubba, Ali E; Jiang, Kyle

    2013-12-23

    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).

  5. Bimodal frequency-modulated atomic force microscopy with small cantilevers.

    PubMed

    Dietz, Christian; Schulze, Marcus; Voss, Agnieszka; Riesch, Christian; Stark, Robert W

    2015-02-01

    Small cantilevers with ultra-high resonant frequencies (1-3 MHz) have paved the way for high-speed atomic force microscopy. However, their potential for multi-frequency atomic force microscopy is unexplored. Because small cantilevers have small spring constants but large resonant frequencies, they are well-suited for the characterisation of delicate specimens with high imaging rates. We demonstrate their imaging capabilities in a bimodal frequency modulation mode in constant excitation on semi-crystalline polypropylene. The first two flexural modes of the cantilever were simultaneously excited. The detected frequency shift of the first eigenmode was held constant for topographical feedback, whereas the second eigenmode frequency shift was used to map the local properties of the specimen. High-resolution images were acquired depicting crystalline lamellae of approximately 12 nm in width. Additionally, dynamic force curves revealed that the contrast originated from different interaction forces between the tip and the distinct polymer regions. The technique uses gentle forces during scanning and quantified the elastic moduli Eam = 300 MPa and Ecr = 600 MPa on amorphous and crystalline regions, respectively. Thus, multimode measurements with small cantilevers allow one to map material properties on the nanoscale at high resolutions and increase the force sensitivity compared with standard cantilevers.

  6. 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.

  7. Influence of different cantilever extensions and glass or polyaramide reinforcement fibers on fracture strength of implant-supported temporary.

    PubMed

    Colán Guzmán, Paola; Freitas, Fernando Furtado Antunes de; Ferreira, Paulo Martins; Freitas, César Antunes de; 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.

  8. [Implant-supported fixed cantilever prosthesis: the impact on bone stress deformity].

    PubMed

    Ryakhovsky, A N; Kostyukova, V V

    2016-01-01

    The aim of this study was to compare the accuracy of digital impressions taken by different intraoral and laboratory scanners. For this purpose a synthetic jaw model with prepared tooth was scanned using intraoral scanning systems: 3D Progress (MHT S.P.A., IT - MHT Optic Research AG, CH); True Definition (3M ESPE, USA); Trios (3Shape A/S, DNK); CEREC AC Bluecam, CEREC Omnicam (Sirona Dental System GmbH, DE); Planscan (Planmeca, FIN); and laboratory scanning systems: s600 ARTI (Zirkonzahn GmbH, IT); Imetric Iscan D104, CH); D900 (3Shape A/S, DNK); Zfx Evolution (Zfx GmbH, DE) (each n=10). Reference-scanning was done by ATOS Core (GOM mbH, DE). The resulting digital impressions were superimposed with the master-scan. The measured deviations by points (trueness) for intraoral scanners were: True Definition - 15.0±2.85 μm (single tooth) and 45.0±19.11 µm (full arch); Trios - 17.1±1.44 and 58.8±27.36 µm; CEREC AC Bluecam - 22.3±5.58 and 20.3±4.13 µm; CEREC Omnicam - 25.0±1.06 and 78.5±27.03 µm; 3D Progress - 26.4±5.75 and 213.5±47.44 µm; Planscan - 54.6±11.58 and 205.2±21.73 µm. For laboratory scanners: Imetric Iscan D104 - 10.2±0.87 μm (stamp) and 65.3±5.36 µm (full arch); Zfx Evolution - 12.8±0.83 and 66.4±2.80 µm; Zirkonzahn s600 ARTI - 15.1±1.36 and 65.9±1.33 µm; 3Shape D900 - 19.9±0.53 and 63.6±0.83 µm. Precision was: True Definition - 19.9±2.77 μm (single tooth) and 40.1±11.04 µm (full arch); Trios - 25.8±2.49 and 69.9±18.95 µm; CEREC AC Bluecam - 36.4±2.78 and 46.6±3.44 µm; CEREC Omnicam - 37.6±3.29 and 76.2±13.36 µm; 3D Progress - 76.9±11.04 and 102.2±8.06 µm; Planscan - 74.3±6.58 and 93.9±15.32 µm. For laboratory scanners: Imetric Iscan D104 - 11.7±4.39 μm (stamp) and 31.2±5.58 µm (full arch); Zfx Evolution - 8.4±0.49 and 24.8±3.98 µm; Zirkonzahn s600 ARTI - 13.4±6.74 and 20.7±4.34 µm; 3Shape D900 - 10.4±0.93 and 17.8±0.62 µm. Whole deviation of the dental arch was: 3D Progress - 98.0±5.70 µm; True Definition - 47.1±9.61 µm; Trios - 59.6±18.77 µm; Omnicam - 77.8±8.79 µm; Planscan - 107.9±1.58 µm; Bluecam - 46.8±1.22 µm; Imetric - 36.4±1.62 µm; Zfx Evolution - 29.5±0.58 µm; S600 ARTI - 35.0±1.04 µm; 3Shape D900 - 32.7±0.29 µm. The results indicate that digital impressions provide enough accuracy for clinical application. PMID:27636766

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

    PubMed

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

    2013-11-01

    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.

  10. 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.

  11. 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

  12. 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.

  13. Normal and torsional spring constants of atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Green, Christopher P.; Lioe, Hadi; Cleveland, Jason P.; Proksch, Roger; Mulvaney, Paul; Sader, John E.

    2004-06-01

    Two methods commonly used to measure the normal spring constants of atomic force microscope cantilevers are the added mass method of Cleveland et al. [J. P. Cleveland et al., Rev. Sci. Instrum. 64, 403 (1993)], and the unloaded resonance technique of Sader et al. [J. E. Sader, J. W. M. Chon, and P. Mulvaney, Rev. Sci. Instrum. 70, 3967 (1999)]. The added mass method involves measuring the change in resonant frequency of the fundamental mode of vibration upon the addition of known masses to the free end of the cantilever. In contrast, the unloaded resonance technique requires measurement of the unloaded resonant frequency and quality factor of the fundamental mode of vibration, as well as knowledge of the plan view dimensions of the cantilever and properties of the fluid. In many applications, such as frictional force microscopy, the torsional spring constant is often required. Consequently, in this article, we extend both of these techniques to allow simultaneous calibration of both the normal and torsional spring constants. We also investigate the validity and applicability of the unloaded resonance method when a mass is attached to the free end of the cantilever due to its importance in practice.

  14. 9. VIEW, LOOKING SOUTHEAST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWER. ...

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

    9. VIEW, LOOKING SOUTHEAST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWER. Note emergency bracing installed beneath collapsed tower, and crumpled vertical members at right and left. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Optically controlled bimorph cantilever by Poly(vinylidene difluoride) and its application of optical actuator

    NASA Astrophysics Data System (ADS)

    Mizutani, Yasuhiro; Otani, Yukitoshi

    2008-11-01

    An optically driven actuator is a non-contact method for the remote application of light energy. A new method for optically driving actuators which uses a polyvinylidine difluoride (PVDF) cantilever is proposed. The PVDF cantilever is coated with silver on one surface. The PVDF is a ferroelectric polymer that has both pyroelectric and piezoelectric properties. When one side of the cantilever is irradiated by a laser beam, an electric field is produced along cross-section of the cantilever and mechanical displacement occurs by the piezoelectric effect. The response of the PVDF cantilever is analyzed mathematically.

  5. Tunable microwave generation based on a dual-wavelength single-longitudinal-mode fiber laser using a phase-shifted grating on a triangular cantilever.

    PubMed

    Jiang, Meng; Lin, Bo; Shum, Perry Ping; Tjin, Swee Chuan; Dong, Xinyong; Sun, Qizhen

    2011-05-01

    Frequency tunable microwave signal generation, based on a dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber (EDF) laser, incorporating a phase-shifted fiber Bragg grating (PS-FBG) with two π-phase shifts, is demonstrated. In the proposed configuration, the PS-FBG with two ultranarrow transmission bands is embedded in a triangular cantilever to serve as a wavelength spacing tunable filter with a fixed center wavelength by applying various strains on the cantilever. A section of unpumped EDF is employed as a saturable absorber to ensure SLM operation in each of the two lasing lines. By beating the two wavelengths at a photodiode, a tunable microwave signal ranging from 8.835 to 24.360 GHz is successfully achieved.

  6. 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.

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

    PubMed

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

    2007-04-01

    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 micros, 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 microVnm and the resolution is as good as 0.5 nmHz(1/2), depending on the cantilever power. The cantilever heating power ranges 0-7 mW, which corresponds to a temperature range of 25-700 degrees 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.

  8. 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.

  9. 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.

  10. Cantilever spring constant calibration using laser Doppler vibrometry.

    PubMed

    Ohler, Benjamin

    2007-06-01

    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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Apertureless cantilever-free pen arrays for scanning photochemical printing.

    PubMed

    Zhou, Yu; Xie, Zhuang; Brown, Keith A; Park, Daniel J; Zhou, Xiaozhu; Chen, Peng-Cheng; Hirtz, Michael; Lin, Qing-Yuan; Dravid, Vinayak P; Schatz, George C; Zheng, Zijian; Mirkin, Chad A

    2015-02-25

    A novel, apertureless, cantilever-free pen array can be used for dual scanning photochemical and molecular printing. Serial writing with light is enabled by combining self-focusing pyramidal pens with an opaque backing between pens. The elastomeric pens also afford force-tuned illumination and simultaneous delivery of materials and optical energy. These attributes make the technique a promising candidate for maskless high-resolution photopatterning and combinatorial chemistry. PMID:25315252

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Polymeric cantilever integrated with PDMS/graphene composite strain sensor

    NASA Astrophysics Data System (ADS)

    Choi, Young-Soo; Gwak, Min-Joo; Lee, Dong-Weon

    2016-10-01

    This paper describes the mechanical and electrical characteristics of a polydimethylsiloxane (PDMS) cantilever integrated with a high-sensitivity strain sensor. The strain sensor is fabricated using PDMS and graphene flakes that are uniformly distributed in the PDMS. In order to prepare PDMS/graphene composite with uniform resistance, a tetrahydrofuran solution is used to decrease the viscosity of a PDMS base polymer solution. A horn-type sonicator is then used to mix the base polymer with graphene flakes. Low viscosity of the base polymer solution improves the reliability and reproducibility of the PDMS/graphene composite for strain sensor applications. After dicing the composite into the desired sensor shape, a tensile test is performed. The experimental results show that the composite with a concentration of 30 wt.% exhibits a linear response up to a strain rate of 9%. The graphene concentration of the prepared materials affects the gauge factor, which at 20% graphene concentration reaches about 50, and with increasing graphene concentration to 30% decreases to 9. Furthermore, photolithography, PDMS casting, and a stencil process are used to fabricate a PDMS cantilever with an integrated strain sensor. The change in resistance of the integrated PDMS/graphene sensor is characterized with respect to the displacement of the cantilever of within 500 μm. The experimental results confirmed that the prepared PDMS/graphene based sensor has the potential for high-sensitive biosensor applications.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Optical nanomechanical sensor using a silicon photonic crystal cantilever embedded with a nanocavity resonator.

    PubMed

    Lee, Chengkuo; Thillaigovindan, Jayaraj

    2009-04-01

    We present in-depth discussion of the design and optimization of a nanomechanical sensor using a silicon cantilever comprising a two-dimensional photonic crystal (PC) nanocavity resonator arranged in a U-shaped silicon PC waveguide. For example, the minimum detectable strain, vertical deflection at the cantilever end, and force load are observed as 0.0133%, 0.37 mum, and 0.0625 muN, respectively, for a 30 mum long and 15 mum wide cantilever. In the graph of strain versus resonant wavelength shift, a rather linear relationship is observed for various data derived from different cantilevers. Both the resonant wavelength and the resonant wavelength shift of cantilevers under deformation or force loads are mainly a function of defect length change. Results point out that all these mechanical parameters are mainly dependent on the defect length of the PC nanocavity resonator. This new PC cantilever sensor shows promising linear characteristics as an optical nanomechanical sensor. PMID:19340132

  13. 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.

  14. 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.

  15. Feedback Cooling of a Cantilever's Fundamental Mode below 5mK

    NASA Astrophysics Data System (ADS)

    Poggio, M.; Degen, C. L.; Mamin, H. J.; Rugar, D.

    2007-07-01

    We cool the fundamental mechanical mode of an ultrasoft silicon cantilever from a base temperature of 2.2 K down to 2.9±0.3mK using active optomechanical feedback. The lowest observed mode temperature is consistent with limits determined by the properties of the cantilever and by the measurement noise. For high feedback gain, the driven cantilever motion is found to suppress or “squash” the optical interferometer intensity noise below the shot noise level.

  16. 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.

  17. 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.

  18. 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.

  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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Note: spring constant calibration of nanosurface-engineered atomic force microscopy cantilevers.

    PubMed

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

    2014-02-01

    The determination of the dynamic spring constant (kd) 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 (keff, the dynamic one kd), and the calculated (kd,1) are in good agreement within less than 10% error.

  6. 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.

  7. 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.

  8. Probing model tumor interfacial properties using piezoelectric cantilevers

    PubMed Central

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

    2010-01-01

    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

  9. On use of double cantilever beam for coatings and adhesion tests

    NASA Astrophysics Data System (ADS)

    Troczynski, Tom; Camire, Jean

    1995-05-01

    The compliance model of Double Cantilever Beam (DCB) for testing coatings and adhesion has been proposed and verified experimentally. The model is based on the assumption that the coating modifies the stiffness of a foundation of DCB onto which the beam is fixed, according to a simple series-spring law. The model includes multi-coated specimens, in particular the specimen with thermal sprayed ceramic coating, with an additional layer of epoxy adhesive for attachment of a symmetrical DCB arm. It was found, that the compliance of DCB specimens with a coating is significantly increased for a coating thickness larger than approximately 1% of the arm thickness, and a coating Young's modulus smaller than approximately 50% of the arm modulus. The model results, verified by experiment, have profound consequences on calculations of the strain energy release rate in fracture tests for coatings, brazed joints etc. The total compliance of the arm and coating assembly scales with the coating stiffness, and thus the model can be utilised for rigidity evaluation of a variety of coatings on standard substrates, e.g. paints or polymer coatings on metals.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. Study of laser excited vibration of silicon cantilever

    SciTech Connect

    Song Yaqin; Cretin, Bernard; Vairac, Pascal; Todorovic, D. M.

    2008-11-15

    In this paper an interferometric setup called 'thermoelastic microscopy' has been used to measure the vibration response of the semiconductor cantilevers under modulated laser thermal source. The small vibration amplitude has been detected well below 10 pm magnitude in accurate adjustment conditions. The results showed that experimental responses have a good agreement with the theoretical ones. Also from the analysis we could conclude that the signal amplitude has a power functional dependence on the modulation frequency and that the phase angle linearly depended on the square root of modulation frequency.

  17. An in-plane cantilever for wall shear stress measurement

    NASA Astrophysics Data System (ADS)

    Allen, N. J.; Sims-Williams, D. B.; Wood, D.

    2012-07-01

    A sensor capable of measuring small shear stresses in wind tunnel applications is presented. The sensor utilizes an in-plane cantilever concept for shear stress measurement, designed to minimize intrusiveness into the airflow and allow easy incorporation into wind tunnel test models. The sensor operates independently of input voltage, and can measure <1 Pa shear stresses with a sensitivity of 8.6 (mV V-1) Pa. Altering the geometry of the sensor has a direct effect on the sensitivity and so can be used to adapt the sensor for different applications.

  18. Piezoelectric Bimorph Cantilever for Vibration-Producing-Hydrogen

    PubMed Central

    Zhang, Jun; Wu, Zheng; Jia, Yanmin; Kan, Junwu; Cheng, Guangming

    2013-01-01

    A device composed of a piezoelectric bimorph cantilever and a water electrolysis device was fabricated to realize piezoelectrochemical hydrogen production. The obvious output of the hydrogen and oxygen through application of a mechanical vibration of ∼0.07 N and ∼46.2 Hz was observed. This method provides a cost-effective, recyclable, environment-friendly and simple way to directly split water for hydrogen fuels by scavenging mechanical waste energy forms such as noise or traffic vibration in the environment. PMID:23271601

  19. Experimental study of aerodynamic damping in arrays of vibrating cantilevers

    NASA Astrophysics Data System (ADS)

    Kimber, M.; Lonergan, R.; Garimella, S. V.

    2009-11-01

    Cantilever structures vibrating in a fluid are encountered in numerous engineering applications. The aerodynamic loading from a fluid can have a large effect on both the resonance frequency and damping, and has been the subject of numerous studies. The aerodynamic loading on a single beam is altered when multiple beams are configured in an array. In such situations, neighboring beams interact through the fluid and their dynamic behavior is modified. In this work, aerodynamic interactions between neighboring cantilever beams operating near their first resonance mode and vibrating at amplitudes comparable to their widths are experimentally explored. The degree to which two beams become coupled through the fluid is found to be sensitive to vibration amplitude and proximity of neighboring components in the array. The cantilever beams considered are slender piezoelectric fans (approximately 6 cm in length), and are caused to vibrate in-phase and out-of-phase at frequencies near their fundamental resonance values. Aerodynamic damping is expressed in terms of the quality factor for two different array configurations and estimated for both in-phase and out-of-phase conditions. The two array configurations considered are for neighboring fans placed face-to-face and edge-to-edge. It is found that the damping is greatly influenced by proximity of neighboring fans and phase difference. For the face-to-face configuration, a reduction in damping is observed for in-phase vibration, while it is greatly increased for out-of-phase vibration; the opposite effect is seen for the edge-to-edge configuration. The resonance frequencies also show a dependence on the phase difference, but these changes are small compared to those observed for damping. Correlations are developed based on the experimental data which can be used to predict the aerodynamic damping in arrays of vibrating cantilevers. The distance at which the beams no longer interact is quantified for both array configurations

  20. 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.

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. [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

  10. Detection of atomic force microscopy cantilever displacement with a transmitted electron beam

    NASA Astrophysics Data System (ADS)

    Wagner, R.; Woehl, T. J.; Keller, R. R.; Killgore, J. P.

    2016-07-01

    The response time of an atomic force microscopy (AFM) cantilever can be decreased by reducing cantilever size; however, the fastest AFM cantilevers are currently nearing the smallest size that can be detected with the conventional optical lever approach. Here, we demonstrate an electron beam detection scheme for measuring AFM cantilever oscillations. The oscillating AFM tip is positioned perpendicular to and in the path of a stationary focused nanometer sized electron beam. As the tip oscillates, the thickness of the material under the electron beam changes, causing a fluctuation in the number of scattered transmitted electrons that are detected. We demonstrate detection of sub-nanometer vibration amplitudes with an electron beam, providing a pathway for dynamic AFM with cantilevers that are orders of magnitude smaller and faster than the current state of the art.

  11. Sensorless enhancement of an atomic force microscope micro-cantilever quality factor using piezoelectric shunt control

    NASA Astrophysics Data System (ADS)

    Fairbairn, M.; Moheimani, S. O. R.

    2013-05-01

    The image quality and resolution of the Atomic Force Microscope (AFM) operating in tapping mode is dependent on the quality (Q) factor of the sensing micro-cantilever. Increasing the cantilever Q factor improves image resolution and reduces the risk of sample and cantilever damage. Active piezoelectric shunt control is introduced in this work as a new technique for modifying the Q factor of a piezoelectric self-actuating AFM micro-cantilever. An active impedance is placed in series with the tip oscillation voltage source to modify the mechanical dynamics of the cantilever. The benefit of using this control technique is that it removes the optical displacement sensor from the Q control feedback loop to reduce measurement noise in the loop and allows for a reduction in instrument size.

  12. Effect of tip mass on frequency response and sensitivity of AFM cantilever in liquid.

    PubMed

    Farokh Payam, Amir; Fathipour, Morteza

    2015-03-01

    The effect of tip mass on the frequency response and sensitivity of atomic force microscope (AFM) cantilever in the liquid environment is investigated. For this purpose, using Euler-Bernoulli beam theory and considering tip mass and hydrodynamic functions in a liquid environment, an expression for the resonance frequencies of AFM cantilever in liquid is derived. Then, based on this expression, the effect of the surface contact stiffness on the flexural mode of a rectangular AFM cantilever in fluid is investigated and compared with the case where the AFM cantilever operates in the air. The results show that in contrast with an air environment, the tip mass has no significant impact on the resonance frequency and sensitivity of the AFM cantilever in the liquid. Hence, analysis of AFM behaviour in liquid environment by neglecting the tip mass is logical. PMID:25562584

  13. Cantilever bending based on humidity-actuated mesoporous silica/silicon bilayers

    PubMed Central

    Ganser, Christian; Fritz-Popovski, Gerhard; Morak, Roland; Sharifi, Parvin; Marmiroli, Benedetta; Sartori, Barbara; Amenitsch, Heinz; Griesser, Thomas; Teichert, Christian

    2016-01-01

    Summary We use a soft templating approach in combination with evaporation induced self-assembly to prepare mesoporous films containing cylindrical pores with elliptical cross-section on an ordered pore lattice. The film is deposited on silicon-based commercial atomic force microscope (AFM) cantilevers using dip coating. This bilayer cantilever is mounted in a humidity controlled AFM, and its deflection is measured as a function of relative humidity. We also investigate a similar film on bulk silicon substrate using grazing-incidence small-angle X-ray scattering (GISAXS), in order to determine nanostructural parameters of the film as well as the water-sorption-induced deformation of the ordered mesopore lattice. The strain of the mesoporous layer is related to the cantilever deflection using simple bilayer bending theory. We also develop a simple quantitative model for cantilever deflection which only requires cantilever geometry and nanostructural parameters of the porous layer as input parameters. PMID:27335753

  14. Cantilever bending based on humidity-actuated mesoporous silica/silicon bilayers.

    PubMed

    Ganser, Christian; Fritz-Popovski, Gerhard; Morak, Roland; Sharifi, Parvin; Marmiroli, Benedetta; Sartori, Barbara; Amenitsch, Heinz; Griesser, Thomas; Teichert, Christian; Paris, Oskar

    2016-01-01

    We use a soft templating approach in combination with evaporation induced self-assembly to prepare mesoporous films containing cylindrical pores with elliptical cross-section on an ordered pore lattice. The film is deposited on silicon-based commercial atomic force microscope (AFM) cantilevers using dip coating. This bilayer cantilever is mounted in a humidity controlled AFM, and its deflection is measured as a function of relative humidity. We also investigate a similar film on bulk silicon substrate using grazing-incidence small-angle X-ray scattering (GISAXS), in order to determine nanostructural parameters of the film as well as the water-sorption-induced deformation of the ordered mesopore lattice. The strain of the mesoporous layer is related to the cantilever deflection using simple bilayer bending theory. We also develop a simple quantitative model for cantilever deflection which only requires cantilever geometry and nanostructural parameters of the porous layer as input parameters. PMID:27335753

  15. Controlling the opto-mechanics of a cantilever in an interferometer via cavity loss

    SciTech Connect

    Schmidsfeld, A. von Reichling, M.

    2015-09-21

    In a non-contact atomic force microscope, based on interferometric cantilever displacement detection, the optical return loss of the system is tunable via the distance between the fiber end and the cantilever. We utilize this for tuning the interferometer from a predominant Michelson to a predominant Fabry-Pérot characteristics and introduce the Fabry-Pérot enhancement factor as a quantitative measure for multibeam interference in the cavity. This experimentally easily accessible and adjustable parameter provides a control of the opto-mechanical interaction between the cavity light field and the cantilever. The quantitative assessment of the light pressure acting on the cantilever oscillating in the cavity via the frequency shift allows an in-situ measurement of the cantilever stiffness with remarkable precision.

  16. Fabrication of nanoscale magnet-tipped cantilevers for magnetic resonance force microscopy

    NASA Astrophysics Data System (ADS)

    Hickman, Steven A.; Garner, Sean R.; Harrell, Lee E.; Kuehn, Seppe; Marohn, John A.

    2006-03-01

    Magnetic resonance force microscopy(MRFM) is a promising new technique for acquiring magnetic resonance images of a single molecule; to date we have demonstrated a sensitivity of approximately 10,000 proton spins. In MRFM the force exerted on the cantilever, per spin, is proportional to the field gradient from the cantilever's magnetic tip. To increase the force requires shrinking the magnet size. Achieving the attonewton force sensitivity necessary to image single spins requires mitigating surface induced dissipation. We choose to meet both of these conditions by creating nanoscale magnets extending from the tips of silicon cantilevers. We will present a 50-nm wide overhanging cobalt magnet fabricated by a process involving electron beam lithography and anisotropic KOH etching. This process can be integrated into a fabrication protocol for ultrasensitive silicon cantilevers. With these cantilevers we expect a sensitivity of better than 1000 protons.

  17. Low frequency driven oscillations of cantilevers in viscous fluids at very low Reynolds number

    NASA Astrophysics Data System (ADS)

    Cranch, G. A.; Lane, J. E.; Miller, G. A.; Lou, J. W.

    2013-05-01

    The motion of submerged cantilevers driven by viscous fluids is experimentally investigated and a previously published theoretical model is verified over a broad range of Reynolds number covering 4×10-3≤Re≤2000 at frequencies up to 1 kHz. Both planar and cylindrical cantilevers are implemented using short length (few centimeters) fiber lasers, which are also used to measure the deflections. The driving forces are analyzed in detail illustrating how the dominant force transitions from a pressure related force to a viscous force depending on the Reynolds number of the fluid flow around the cantilever. Simplified, approximate expressions for the tip displacement of cantilevers oscillating in the highly viscous regime are also presented. These results will enable accurate, a priori, calculation of the motion of driven cantilevers over a range of dimensions, geometries, and fluid properties.

  18. Probing elastic modulus and depth of bottom-supported inclusions in model tissues using piezoelectric cantilevers.

    PubMed

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

    2007-11-01

    We have experimentally investigated the depth sensitivity limit of a piezoelectric cantilever tissue elastic modulus sensor and simultaneously determined the elastic modulus and the depth of a tumor directly. Using model tissues consisting of bottom-supported modeling clay inclusions of various depths in a gelatin matrix, we empirically determined that the depth sensitivity limit of a piezoelectric cantilever sensor was twice the linear dimension of the indentation area (or the cantilever width). Knowing the depth sensitivity limit of the individual cantilever sensor as input and treating a model tissue that has the gelatin matrix on top and the modeling clay inclusion at the bottom as two springs in series, we showed that the elastic moduli and depths of the hard inclusions could be simultaneously determined with the elastic modulus profiles measured by two cantilevers with different widths as input.

  19. Finite element modeling of atomic force microscopy cantilever dynamics during video rate imaging

    SciTech Connect

    Howard-Knight, J. P.; Hobbs, J. K.

    2011-04-01

    A dynamic finite element model has been constructed to simulate the behavior of low spring constant atomic force microscope (AFM) cantilevers used for imaging at high speed without active feedback as in VideoAFM. The model is tested against experimental data collected at 20 frame/s and good agreement is found. The complex dynamics of the cantilever, consisting of traveling waves coming from the tip sample interaction, reflecting off the cantilever-substrate junction, and interfering with new waves created at the tip, are revealed. The construction of the image from this resulting nonequilibrium cantilever deflection is also examined. Transient tip-sample forces are found to reach values up to 260 nN on a calibration grid sample, and the maximum forces do not always correspond to the position of steepest features as a result of energy stored in the cantilever.

  20. Accurate flexural spring constant calibration of colloid probe cantilevers using scanning laser Doppler vibrometry.

    PubMed

    Gates, Richard S; Osborn, William A; Shaw, Gordon A

    2015-06-12

    Calibration of the flexural spring constant for atomic force microscope (AFM) colloid probe cantilevers provides significant challenges. The presence of a large attached spherical added mass complicates many of the more common calibration techniques such as reference cantilever, Sader, and added mass. Even the most promising option, AFM thermal calibration, can encounter difficulties during the optical lever sensitivity measurement due to strong adhesion and friction between the sphere and a surface. This may cause buckling of the end of the cantilever and hysteresis in the approach-retract curves resulting in increased uncertainty in the calibration. Most recently, a laser Doppler vibrometry thermal method has been used to accurately calibrate the normal spring constant of a wide variety of tipped and tipless commercial cantilevers. This paper describes a variant of the technique, scanning laser Doppler vibrometry, optimized for colloid probe cantilevers and capable of spring constant calibration uncertainties near ±1%.

  1. Simultaneous determination of position and mass in the cantilever sensor using transfer function method

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    We present the simultaneous measurement of mass and position of micro-beads attached to the cantilever-based mass sensors using the transfer function method. 10 μm diameter micro-beads were placed on micro-cantilevers and the cantilevers were excited by lead-zirconate-titanate through low-pass filtered random voltages. The cantilever vibration was measured via a laser Doppler vibrometer before and after applying the beads. From the measured transfer function, the bead position was identified using its influence on the cantilever kinetic energy. The bead mass was then obtained by analyzing the wave propagation near the beads. The predicted position and mass agreed well with actual values.

  2. Note: Calibration of atomic force microscope cantilevers using only their resonant frequency and quality factor

    SciTech Connect

    Sader, John E.; Friend, James R.

    2014-11-15

    A simplified method for calibrating atomic force microscope cantilevers was recently proposed by Sader et al. [Rev. Sci. Instrum. 83, 103705 (2012); Sec. III D] that relies solely on the resonant frequency and quality factor of the cantilever in fluid (typically air). This method eliminates the need to measure the hydrodynamic function of the cantilever, which can be time consuming given the wide range of cantilevers now available. Using laser Doppler vibrometry, we rigorously assess the accuracy of this method for a series of commercially available cantilevers and explore its performance under non-ideal conditions. This shows that the simplified method is highly accurate and can be easily implemented to perform fast, robust, and non-invasive spring constant calibration.

  3. Vibration energy harvester with sustainable power based on a single-crystal piezoelectric cantilever array.

    PubMed

    Kim, Moonkeun; Lee, Sang-Kyun; Ham, Yong-Hyun; Yang, Yil Suk; Kwon, Jong-Kee; Kwon, Kwang-Ho

    2012-08-01

    We designed and fabricated a bimorph cantilever array for sustainable power with an integrated Cu proof mass to obtain additional power and current. We fabricated a cantilever system using single-crystal piezoelectric material and compared the calculations for single and arrayed cantilevers to those obtained experimentally. The vibration energy harvester had resonant frequencies of 60.4 and 63.2 Hz for short and open circuits, respectively. The damping ratio and quality factor of the cantilever device were 0.012 and 41.66, respectively. The resonant frequency at maximum average power was 60.8 Hz. The current and highest average power of the harvester array were found to be 0.728 mA and 1.61 mW, respectively. The sustainable maximum power was obtained after slightly shifting the short-circuit frequency. In order to improve the current and power using an array of cantilevers, we also performed energy conversion experiments.

  4. A cantilever based optical fiber acoustic sensor fabricated by femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Yuan, Lei; Huang, Jie; Xiao, Hai

    2016-04-01

    In this paper, we present a pure silica micro-cantilever based optical fiber sensor for acoustic wave detection. The cantilever is directly fabricated by fs laser micromachining on an optical fiber tip functioning as an inline Fabry-Perot interferometer (FPI). The applied acoustic wave pressurizes the micro-cantilever beam and the corresponding dynamic signals can be probed by the FPI. The thickness, length, and width of the micro-cantilever beam can be flexibly designed and fabricated so that the sensitivity, frequency response, and the total measurement range can be varied to fit many practical applications. Experimental results will be presented and analyzed. Due to the assembly free fabrication of the fs-laser, multiple micro-cantilever beams could be potentially fabricated in/on a single optical fiber for quasi-distributed acoustic mapping with high spatial resolution.

  5. Comparisons between Membrane, Bridge and Cantilever Miniaturized Resistive Vacuum Gauges

    PubMed Central

    Punchihewa, Kasun Gardiye; Zaker, Evan; Kuljic, Rade; Banerjee, Koushik; Dankovic, Tatjana; Feinerman, Alan; Busta, Heinz

    2012-01-01

    Using bulk micromachining, meander-shaped resistor elements consisting of 20 nm Cr and 200 nm Au were fabricated on 1 μm thick silicon nitride membranes, bridges, and cantilevers. The resistance change as a function of pressure depends strongly on the thermal resistance of the two metal lines connecting the heated resistor to the silicon bulk (cold junction) and on the thermal resistance of the silicon nitride. Relative resistance changes ranging from about 3% (small membrane) to 20% (bridge) per mW of input power were obtained when operating the devices in constant voltage mode. The pressure where maximum sensitivity of these gauges occurs depends on the distance ‘d’ between the periphery of the heated resistor element and the silicon cold junction. Devices with ‘d’ ranging from 50 μm to 1,200 μm were fabricated. Assuming that pressures can be reliably measured above the 10% and below the 90% points of the resistance versus pressure curve, the range of these devices is about two orders of magnitude. By integrating two devices, one with d = 65 μm and one with d = 1,200 μm on the same chip and connecting them in series, the range can be increased by about a factor of three. By fabricating the cantilever devices so that they curl upon release, it will be shown that these devices also exhibit larger range due to varying ‘d’. PMID:23012516

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Electromechanical decoupled model for cantilever-beam piezoelectric energy harvesters

    NASA Astrophysics Data System (ADS)

    Tan, T.; Yan, Z.; Hajj, M.

    2016-09-01

    Analysis of cantilever-based piezoelectric energy harvesting systems is usually performed using coupled equations that represent the mechanical displacement and the voltage output. These equations are then solved simultaneously. In contrast to this representation, we use analytical solutions of the governing equation to derive an algebraic equation of the power as a function of the beam displacement, electromechanical coefficients, and the load resistance. Such an equation can be more useful in the design of such harvesters. Particularly, the mechanical displacement is computed from a mechanical governing equation with modified natural frequency and damping ratio that account for the electromechanical coupling. The voltage and the harvested power are then obtained by relating them directly to the mechanical displacement. We validate the proposed analysis by comparing its solution including the tip displacement and harvested power with those of numerical simulations of the governing equations. To demonstrate the generality of the proposed approach, we consider the cases of base excitation, galloping, and autoparametric vibration. The model proposed in this study simplifies the electromechanical coupling problem for practical applications of cantilever-beam piezoelectric energy harvesting systems.

  11. Fixed Exit Monochromator with fixed Rotation Axis

    SciTech Connect

    Caliebe, W.A.; Cheung, S.; Lenhard, A.; Siddons, D.P.

    2004-05-12

    A new simple design for a fixed-exit monochromator has been developed. The set-up uses a linear slide to couple the rotation of the crystals to a translation of the second one to compensate for the 2hcos{theta} dependence of the beam-offset in a double crystal monochromator. This set-up requires just one motor for the rotation of the monochromator, and three piezo-actuators to tune the second crystal.The monochromator has been tested for Bragg-angles between 7 deg. and 70 deg.

  12. Effect of the location and size of a single crack on first fundamental frequency of a cantilever beam using fiber optic polarimetric sensors and characterisation of FBG sensors

    NASA Astrophysics Data System (ADS)

    Maheshwari, Muneesh; Asundi, A. K.; Tjin, Swee C.

    2013-08-01

    Fiber Optics Polarimetric Sensors (FOPS), utilizing first fundamental frequency mode and its harmonics, have already been used as damage detection tool. The FOPS technology is attractive in damage detection as it facilitates us with real time non-destructive health monitoring of different mechanical and civil structures. In this paper, the effects of the size and the location of a single crack on the frequency of first fundamental mode of a cantilever beam have been studied. A relation between the relative size of a crack and relative change in the first fundamental frequency has been established theoretically and then verified experimentally. Further, it has been shown that the cracks, close to the fixed end of the cantilever beam, have significant effect on the frequency of first fundamental mode and as the crack moves away from the fixed end, the effect on the frequency starts becoming diminished. Also the sensitivity of Fiber Bragg Grating (FBG) sensor against a single crack has been studied along both the directions; parallel to the axis of FBG sensor and perpendicular to the axis of FBG sensor. Experimental results show that the range of sensitivity in both the directions is almost the same bur FBG is more efficient along its axis.

  13. Nondestructive and noncontact method for determining the spring constant of rectangular cantilevers.

    PubMed

    Golovko, Dmytro S; Haschke, Thomas; Wiechert, Wolfgang; Bonaccurso, Elmar

    2007-04-01

    We present here an experimental setup and suggest an extension to the long existing added-mass method for the calibration of the spring constant of atomic force microscope cantilevers. Instead of measuring the resonance frequency shift that results from attaching particles of known masses to the end of cantilevers, we load them with water microdrops generated by a commercial inkjet dispenser. Such a device is capable of generating drops, and thus masses, of extremely reproducible size. This makes it an ideal tool for calibration tasks. Moreover, the major advantage of water microdrops is that they allow for a nearly contactless calibration: no mechanical micromanipulation of particles on cantilevers is required, neither for their deposition nor for removal. After some seconds the water drop is completely evaporated, and no residues are left on the cantilever surface or tip. We present two variants: we vary the size of the drops and deposit them at the free end of the cantilever, or we keep the size of the drops constant and vary their position along the cantilever. For the second variant, we implemented also numerical simulations. Spring constants measured by this method are comparable to results obtained by the thermal noise method, as we demonstrate for six different cantilevers.

  14. Nondestructive testing and hardness measurement based on contact resonance of piezoelectric cantilevers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Li, Faxin; Fu, Ji

    2016-04-01

    A suitable defect identification parameter is very important in the field of nondestructive testing (NDT). In this work, we proposed a NDT method which detects the sample's local contact stiffness (LCS) based on the contact resonance of a piezoelectric cantilever. Firstly, through finite element analysis we showed that LCS is quite sensitive to typical defects including debonding, voids, cracks and inclusions, making it a good identification parameter. Secondly, a homemade NDT system containing a piezoelectric unimorph cantilever was assembled to detect the sample's LCS by tracking the contact resonance frequency (CRF) of the cantilever-sample system based on strain signals. Testing results indicated that this NDT system could detect the above mentioned defects efficiently. The cantilever-stiffness dependent detection sensitivity was specially investigated and the stiffer cantilevers were found to be more sensitive to small defects. Then, a piezoelectric bimorph cantilever was fabricated and the electromechanical impedance, other than the strain signals, was measured to track the CRF of the cantilever-system. The LCS is then derived by using the equivalent-circuit model. The electromechanical impedance based NDT system is more compact and can be further developed to be a portable device. Finally, a Vicker indenter is fabricated onto the bimorph tip and the contact area is derived from the measured LCS. Thus the NDT system turns to be a hardness tester without any optical devices. It is very useful for in-situ testing or testing on inner surfaces where conventional hardness tester is not applicable.

  15. Imaging via complete cantilever dynamic detection: general dynamic mode imaging and spectroscopy in scanning probe microscopy.

    PubMed

    Somnath, Suhas; Collins, Liam; Matheson, Michael A; Sukumar, Sreenivas R; Kalinin, Sergei V; Jesse, Stephen

    2016-10-14

    We develop and implement a multifrequency spectroscopy and spectroscopic imaging mode, referred to as general dynamic mode (GDM), that captures the complete spatially- and stimulus dependent information on nonlinear cantilever dynamics in scanning probe microscopy (SPM). GDM acquires the cantilever response including harmonics and mode mixing products across the entire broadband cantilever spectrum as a function of excitation frequency. GDM spectra substitute the classical measurements in SPM, e.g. amplitude and phase in lock-in detection. Here, GDM is used to investigate the response of a purely capacitively driven cantilever. We use information theory techniques to mine the data and verify the findings with governing equations and classical lock-in based approaches. We explore the dependence of the cantilever dynamics on the tip-sample distance, AC and DC driving bias. This approach can be applied to investigate the dynamic behavior of other systems within and beyond dynamic SPM. GDM is expected to be useful for separating the contribution of different physical phenomena in the cantilever response and understanding the role of cantilever dynamics in dynamic AFM techniques. PMID:27607339

  16. Spring constant calibration of atomic force microscope cantilevers of arbitrary shape.

    PubMed

    Sader, John E; Sanelli, Julian A; Adamson, Brian D; Monty, Jason P; Wei, Xingzhan; Crawford, Simon A; Friend, James R; Marusic, Ivan; Mulvaney, Paul; Bieske, Evan J

    2012-10-01

    The spring constant of an atomic force microscope cantilever is often needed for quantitative measurements. The calibration method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] for a rectangular cantilever requires measurement of the resonant frequency and quality factor in fluid (typically air), and knowledge of its plan view dimensions. This intrinsically uses the hydrodynamic function for a cantilever of rectangular plan view geometry. Here, we present hydrodynamic functions for a series of irregular and non-rectangular atomic force microscope cantilevers that are commonly used in practice. Cantilever geometries of arrow shape, small aspect ratio rectangular, quasi-rectangular, irregular rectangular, non-ideal trapezoidal cross sections, and V-shape are all studied. This enables the spring constants of all these cantilevers to be accurately and routinely determined through measurement of their resonant frequency and quality factor in fluid (such as air). An approximate formulation of the hydrodynamic function for microcantilevers of arbitrary geometry is also proposed. Implementation of the method and its performance in the presence of uncertainties and non-idealities is discussed, together with conversion factors for the static and dynamic spring constants of these cantilevers. These results are expected to be of particular value to the design and application of micro- and nanomechanical systems in general.

  17. Spring constant calibration of atomic force microscope cantilevers of arbitrary shape

    SciTech Connect

    Sader, John E.; Sanelli, Julian A.; Adamson, Brian D.; Bieske, Evan J.; Monty, Jason P.; Marusic, Ivan; Wei Xingzhan; Mulvaney, Paul; Crawford, Simon A.; Friend, James R.

    2012-10-15

    The spring constant of an atomic force microscope cantilever is often needed for quantitative measurements. The calibration method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] for a rectangular cantilever requires measurement of the resonant frequency and quality factor in fluid (typically air), and knowledge of its plan view dimensions. This intrinsically uses the hydrodynamic function for a cantilever of rectangular plan view geometry. Here, we present hydrodynamic functions for a series of irregular and non-rectangular atomic force microscope cantilevers that are commonly used in practice. Cantilever geometries of arrow shape, small aspect ratio rectangular, quasi-rectangular, irregular rectangular, non-ideal trapezoidal cross sections, and V-shape are all studied. This enables the spring constants of all these cantilevers to be accurately and routinely determined through measurement of their resonant frequency and quality factor in fluid (such as air). An approximate formulation of the hydrodynamic function for microcantilevers of arbitrary geometry is also proposed. Implementation of the method and its performance in the presence of uncertainties and non-idealities is discussed, together with conversion factors for the static and dynamic spring constants of these cantilevers. These results are expected to be of particular value to the design and application of micro- and nanomechanical systems in general.

  18. Imaging via complete cantilever dynamic detection: general dynamic mode imaging and spectroscopy in scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Somnath, Suhas; Collins, Liam; Matheson, Michael A.; Sukumar, Sreenivas R.; Kalinin, Sergei V.; Jesse, Stephen

    2016-10-01

    We develop and implement a multifrequency spectroscopy and spectroscopic imaging mode, referred to as general dynamic mode (GDM), that captures the complete spatially- and stimulus dependent information on nonlinear cantilever dynamics in scanning probe microscopy (SPM). GDM acquires the cantilever response including harmonics and mode mixing products across the entire broadband cantilever spectrum as a function of excitation frequency. GDM spectra substitute the classical measurements in SPM, e.g. amplitude and phase in lock-in detection. Here, GDM is used to investigate the response of a purely capacitively driven cantilever. We use information theory techniques to mine the data and verify the findings with governing equations and classical lock-in based approaches. We explore the dependence of the cantilever dynamics on the tip-sample distance, AC and DC driving bias. This approach can be applied to investigate the dynamic behavior of other systems within and beyond dynamic SPM. GDM is expected to be useful for separating the contribution of different physical phenomena in the cantilever response and understanding the role of cantilever dynamics in dynamic AFM techniques.

  19. Imaging via complete cantilever dynamic detection: General dynamic mode imaging and spectroscopy in scanning probe microscopy

    DOE PAGESBeta

    Somnath, Suhas; Collins, Liam; Matheson, Michael A.; Sukumar, Sreenivas R.; Kalinin, Sergei V.; Jesse, Stephen

    2016-09-08

    We develop and implement a multifrequency spectroscopy and spectroscopic imaging mode, referred to as general dynamic mode (GDM), that captures the complete spatially- and stimulus dependent information on nonlinear cantilever dynamics in scanning probe microscopy (SPM). GDM acquires the cantilever response including harmonics and mode mixing products across the entire broadband cantilever spectrum as a function of excitation frequency. GDM spectra substitute the classical measurements in SPM, e.g. amplitude and phase in lock-in detection. Here, GDM is used to investigate the response of a purely capacitively driven cantilever. We use information theory techniques to mine the data and verify themore » findings with governing equations and classical lock-in based approaches. We explore the dependence of the cantilever dynamics on the tip–sample distance, AC and DC driving bias. This approach can be applied to investigate the dynamic behavior of other systems within and beyond dynamic SPM. In conclusion, GDM is expected to be useful for separating the contribution of different physical phenomena in the cantilever response and understanding the role of cantilever dynamics in dynamic AFM techniques.« less

  20. Spring constant calibration techniques for next-generation fast-scanning atomic force microscope cantilevers.

    PubMed

    Slattery, Ashley D; Blanch, Adam J; Ejov, Vladimir; Quinton, Jamie S; Gibson, Christopher T

    2014-08-22

    As a recent technological development, high-speed atomic force microscopy (AFM) has provided unprecedented insights into dynamic processes on the nanoscale, and is capable of measuring material property variation over short timescales. Miniaturized cantilevers developed specifically for high-speed AFM differ greatly from standard cantilevers both in size and dynamic properties, and calibration of the cantilever spring constant is critical for accurate, quantitative measurement. This work investigates specifically, the calibration of these new-generation cantilevers for the first time. Existing techniques are tested and the challenges encountered are reported and the most effective approaches for calibrating fast-scanning cantilevers with high accuracy are identified, providing a resource for microscopists in this rapidly developing field. Not only do these cantilevers offer faster acquisition of images and force data but due to their high resonant frequencies (up to 2 MHz) they are also excellent mass sensors. Accurate measurement of deposited mass requires accurate calibration of the cantilever spring constant, therefore the results of this work will also be useful for mass-sensing applications.

  1. Accurate calibration and uncertainty estimation of the normal spring constant of various AFM cantilevers.

    PubMed

    Song, Yunpeng; Wu, Sen; Xu, Linyan; Fu, Xing

    2015-03-10

    Measurement of force on a micro- or nano-Newton scale is important when exploring the mechanical properties of materials in the biophysics and nanomechanical fields. The atomic force microscope (AFM) is widely used in microforce measurement. The cantilever probe works as an AFM force sensor, and the spring constant of the cantilever is of great significance to the accuracy of the measurement results. This paper presents a normal spring constant calibration method with the combined use of an electromagnetic balance and a homemade AFM head. When the cantilever presses the balance, its deflection is detected through an optical lever integrated in the AFM head. Meanwhile, the corresponding bending force is recorded by the balance. Then the spring constant can be simply calculated using Hooke's law. During the calibration, a feedback loop is applied to control the deflection of the cantilever. Errors that may affect the stability of the cantilever could be compensated rapidly. Five types of commercial cantilevers with different shapes, stiffness, and operating modes were chosen to evaluate the performance of our system. Based on the uncertainty analysis, the expanded relative standard uncertainties of the normal spring constant of most measured cantilevers are believed to be better than 2%.

  2. Interdisciplinary cantilever physics: Elasticity of carrot, celery, and plasticware

    NASA Astrophysics Data System (ADS)

    Pestka, Kenneth A.

    2014-05-01

    This article presents several simple cantilever-based experiments using common household items (celery, carrot, and a plastic spoon) that are appropriate for introductory undergraduate laboratories or independent student projects. By applying Hooke's law and Euler beam theory, students are able to determine Young's modulus, fracture stress, yield stress, strain energy, and sound speed of these apparently disparate materials. In addition, a cellular foam elastic model is introduced—applicable to biologic materials as well as an essential component in the development of advanced engineering composites—that provides a mechanism to determine Young's modulus of the cell wall material found in celery and carrot. These experiments are designed to promote exploration of the similarities and differences between common inorganic and organic materials, fill a void in the typical undergraduate curriculum, and provide a foundation for more advanced material science pursuits within biology, botany, and food science as well as physics and engineering.

  3. Vibration Characteristics of Partially Covered Double-Sandwich Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Chen, Qinghua; Levy, Cesar

    1996-01-01

    The differential equations of motion together with the boundary conditions for a partially covered, double-sandwich cantilever beam are derived. Bending and extension, rotational and longitudinal inertia of damping layers, and shear deformation and rotational and longitudinal inertia of the constraining layers and the primary beam are included in the equations. The theory is applicable for long as well as short, soft, or stiff damping layer, double-sandwich beams. Also, the effects of different parameters on the system loss factor and resonance frequency are discussed. Differences are found to exist with the previous beam model (called the Euler beam model) when the damping layers are stiff, when the thickness of the damping layer is large compared to the primary-beam thickness, and in the case of higher modes of vibration.

  4. Behavior of a Cantilever Plate Under Rapid-heating Conditions

    NASA Technical Reports Server (NTRS)

    Vosteen, Louis F; Fuller, Kenneth E

    1955-01-01

    The temperature distributions encountered in thin solid wings subjected to aerodynamic heating induce thermal stresses that may effectively reduce the stiffness of the wing. The effects of this reduction in stiffness were investigated experimentally by rapidly heating the edges of a cantilever plate. The midplane thermal stresses imposed by the nonuniform temperature distribution caused the plate to buckle torsionally, increased the deformations of the plate under a constant applied torque, and reduced the frequency of the first two natural modes of vibration. By using small-deflection theory and employing energy methods, the effect of nonuniform heating on the plate stiffness was calculated. The theory predicts the general effects of the thermal stresses, but becomes inadequate as the temperature difference increases and plate deflections become large.

  5. 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. The goal of existing home high performing remodeling quality management systems (HPR-QMS) is to establish practices and processes that can be used throughout any remodeling project. The research presented in this document provides a comparison of a selected retrofit activity as typically done versus that same retrofit activity approached from an integrated high performance remodeling and quality management perspective. It highlights some key quality management tools and approaches that can be adopted incrementally by a high performance remodeler for this or any high performance retrofit. This example is intended as a template and establishes a methodology that can be used to develop a portfolio of high performance remodeling strategies.

  6. Bending stresses due to torsion in cantilever box beams

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1935-01-01

    The paper beings with a brief discussion on the origin of the bending stresses in cantilever box beams under torsion. A critical survey of existing theory is followed by a summary of design formulas; this summary is based on the most complete solution published but omits all refinements considered unnecessary at the present state of development. Strain-gage tests made by NACA to obtained some experimental verification of the formulas are described next. Finally, the formulas are applied to a series of box beams previously static-tested by the U.S. Army Air Corps; the results show that the bending stresses due to torsion are responsible to a large extent for the free-edge type of failure frequently experienced in these tests.

  7. Nonlinear finite amplitude torsional vibrations of cantilevers in viscous fluids

    NASA Astrophysics Data System (ADS)

    Aureli, Matteo; Pagano, Christopher; Porfiri, Maurizio

    2012-06-01

    In this paper, we study torsional vibrations of cantilever beams undergoing moderately large oscillations within a quiescent viscous fluid. The structure is modeled as an Euler-Bernoulli beam, with thin rectangular cross section, under base excitation. The distributed hydrodynamic loading experienced by the vibrating structure is described through a complex-valued hydrodynamic function which incorporates added mass and fluid damping elicited by moderately large rotations. We conduct a parametric study on the two dimensional computational fluid dynamics of a pitching rigid lamina, representative of a generic beam cross section, to investigate the dependence of the hydrodynamic function on the governing flow parameters. As the frequency and amplitude of the oscillation increase, vortex shedding and convection phenomena increase, thus resulting into nonlinear hydrodynamic damping. We derive a handleable nonlinear correction to the classical hydrodynamic function developed for small amplitude torsional vibrations for use in a reduced order nonlinear modal model and we validate theoretical results against experimental findings.

  8. Photothermal cantilever deflection spectroscopy of a photosensitive polymer

    SciTech Connect

    Yun, Minhyuk; Lee, Dongkyu; Jung, Namchul; Jeon, Sangmin; Kim, Seonghwan; Chae, Inseok; Thundat, Thomas

    2012-05-14

    The mechanical and chemical information of a poly(methyl methacrylate) (PMMA) film on a microcantilever were simultaneously acquired by photothermal cantilever deflection spectroscopy as a function of ultraviolet (UV) irradiation time. Nanomechanical infrared (IR) spectra from the PMMA-coated microcantilever agreed well with the Fourier transform infrared spectroscopy (FTIR) spectra of PMMA on gold-coated silicon wafer. The decreasing intensities of nanomechanical IR peaks represent chemical as well as mechanical information of UV radiation-induced photodegradation processes in the PMMA which cannot be obtained by a conventional FTIR technique. The observed decrease in the resonance frequency of the microcantilever is related to the change in the Young's modulus of the PMMA under UV exposure.

  9. Strain energy release rate distributions for double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Crews, J. H., Jr.; Shivakumar, K. N.; Raju, I. S.

    1991-01-01

    A 24-ply composite double cantilever-beam specimen under mode I (opening) loading has been analyzed by a 3D FEM code that calculated along a straight delamination starter for several different specimen materials. An isotropic specimen was found to have a strain-energy release rate distribution which varied along its delamination front due to the boundary-layer effect and another effect associated with the anticlastic curvature of the bent specimen arms. A 0-deg graphite-reinforced epoxy specimen had a nearly-uniform strain-energy release rate distribution which dropped only near the edge, due to the boundary-layer effect, and a +/- 45-deg graphite/epoxy specimen exhibited a pronounced strain-energy release rate variation across the specimen width.

  10. Strain engineering of diamond silicon vacancy centers in MEMS cantilevers

    NASA Astrophysics Data System (ADS)

    Meesala, Srujan; Sohn, Young-Ik; Atikian, Haig; Holzgrafe, Jeffrey; Zhang, Mian; Burek, Michael; Loncar, Marko

    2016-05-01

    The silicon vacancy (SiV) center in diamond has recently attracted attention as a solid state quantum emitter due to its attractive optical properties. We fabricate diamond MEMS cantilevers, and use electrostatic actuation to apply controlled strain fields to single SiV centers implanted in these devices. The strain response of the four electronic transitions of the SiV at 737 nm is measured via cryogenic (4 K) photoluminescence excitation. We demonstrate over 300 GHz of tuning for the mean transition frequency between the ground and excited states, and over 100 GHz of tuning for the orbital splittings within the ground and excited states. The interaction Hamiltonian for strain fields is inferred, and large strain susceptibilities of the order 1 PHz/strain are measured. We discuss prospects to utilize our device to reduce phonon-induced decoherence in SiV spin qubits, and to exploit the large strain susceptibilities for hybrid quantum systems based on nanomechanical resonators.

  11. Feedback cooling of cantilever motion using a quantum point contact transducer

    SciTech Connect

    Montinaro, M.; Mehlin, A.; Solanki, H. S.; Peddibhotla, P.; Poggio, M.; Mack, S.; Awschalom, D. D.

    2012-09-24

    We use a quantum point contact (QPC) as a displacement transducer to measure and control the low-temperature thermal motion of a nearby micromechanical cantilever. The QPC is included in an active feedback loop designed to cool the cantilever's fundamental mechanical mode, achieving a squashing of the QPC noise at high gain. The minimum achieved effective mode temperature of 0.2 K and the displacement resolution of 10{sup -11} m/{radical}(Hz) are limited by the performance of the QPC as a one-dimensional conductor and by the cantilever-QPC capacitive coupling.

  12. Spatial spectrograms of vibrating atomic force microscopy cantilevers coupled to sample surfaces

    SciTech Connect

    Wagner, Ryan; Raman, Arvind; Proksch, Roger

    2013-12-23

    Many advanced dynamic Atomic Force Microscopy (AFM) techniques such as contact resonance, force modulation, piezoresponse force microscopy, electrochemical strain microscopy, and AFM infrared spectroscopy exploit the dynamic response of a cantilever in contact with a sample to extract local material properties. Achieving quantitative results in these techniques usually requires the assumption of a certain shape of cantilever vibration. We present a technique that allows in-situ measurements of the vibrational shape of AFM cantilevers coupled to surfaces. This technique opens up unique approaches to nanoscale material property mapping, which are not possible with single point measurements alone.

  13. Characteristics of vibration energy harvesting using giant magnetostrictive cantilevers with resonant tuning

    NASA Astrophysics Data System (ADS)

    Mori, Kotaro; Horibe, Tadashi; Ishikawa, Shigekazu; Shindo, Yasuhide; Narita, Fumio

    2015-12-01

    This work deals with the dynamic bending and energy harvesting characteristics of giant magnetostrictive cantilevers with resonant tuning both numerically and experimentally. The giant magnetostrictive cantilever is fabricated using a thin Terfenol-D layer, SUS layer, movable proof mass, etc, and, is designed to automatically adjust its own resonant frequency to match the external vibration frequency in real time. Three-dimensional finite element analysis was conducted, and the resonant frequency, induced voltage and stress in the magnetostrictive cantilevers were predicted. The resonant frequency and induced voltage were also measured, and comparison was made between simulation and experiment. The time-varying behavior and self-tuning ability are discussed in detail.

  14. Photothermal Actuation of Cantilevered Multiwall Carbon Nanotubes with Bimaterial Configuration toward Calorimeter

    NASA Astrophysics Data System (ADS)

    Hiroshima, Seiya; Yoshinaka, Atsushi; Arie, Takayuki; Akita, Seiji

    2013-06-01

    We investigated the bimaterial effect on a multiwall carbon nanotube (CNT) cantilever by means of a photothermal actuation method toward sensitivity enhancement for calorimetry. The coating of a 10-nm-thick Ti layer on top of the CNT cantilever of 50 nm diameter successfully enhanced the photothermal vibration amplitude by 10-50 times. This implies that the expected resolution for the heat capacity measurement is as high as ˜0.1 fJ/K on the base of a simple lumped model for the photothermally excited Ti-coated CNT cantilever.

  15. Resonant interaction of trapped cold atoms with a magnetic cantilever tip

    NASA Astrophysics Data System (ADS)

    Montoya, Cris; Valencia, Jose; Geraci, Andrew; Eardley, Matthew; Kitching, John

    2015-05-01

    We report the resonant coupling of laser cooled trapped Rb atoms to a micro-cantilever with a magnetic tip. An atom chip is used to trap, cool, and transport the atoms to the tip of the cantilever. The capacitively-driven cantilever oscillation produces Zeeman state transitions which result in a loss of population in the trap. In a suitably scaled setup, mechanical resonators could be used to probe and manipulate atomic spins with nanometer spatial resolution and single-spin sensitivity; this technique may enable new approaches in neutral-atom quantum computation, quantum simulation, or precision sensing.

  16. Integrated MOSFET-Embedded-Cantilever-Based Biosensor Characteristic for Detection of Anthrax Simulant

    SciTech Connect

    Mostafa, Salwa; Lee, Ida; Islam, Syed K; Eliza, Sazia A.; Shekhawat, Gajendra; Dravid, Vinayak; Tulip, Fahmida S

    2011-01-01

    In this work, MOSFET-embedded cantilevers are configured as microbial sensors for detection of anthrax simulants, Bacillus thuringiensis. Anthrax simulants attached to the chemically treated gold-coated cantilever cause changes in the MOSFET drain current due to the bending of the cantilever which indicates the detection of anthrax simulant. Electrical properties of the anthrax simulant are also responsible for the change in the drain current. The test results suggest a detection range of 10 L of stimulant test solution (a suspension population of 1.3 107 colony-forming units/mL diluted in 40% ethanol and 60% deionized water) with a linear response of 31 A/ L.

  17. A Compact, Low-Power Cantilever-Based Sensor Array for Chemical Detection

    SciTech Connect

    Loui, A; Ratto, T; Wilson, T; Mukerjee, E; Hu, Z; Sulchek, T; Hart, B

    2007-02-22

    A compact and low-power cantilever-based sensor array has been developed and used to detect various vapor analytes. This device employs sorptive polymers that are deposited onto piezoresistive cantilevers. We have successfully detected several organic vapors, representing a breadth of chemical properties and over a range of concentrations. Comparisons of the polymer/vapor partition coefficient to the cantilever deflection responses show that a simple linear relationship does not exist, emphasizing the need to develop an appropriate functional model to describe the chemical-to-mechanical transduction that is unique to this sensing modality.

  18. Transient eigenmodes analysis of single-impact cantilever dynamics combining Fourier and wavelet transforms.

    PubMed

    Pukhova, Valentina; Banfi, Francesco; Ferrini, Gabriele

    2015-05-01

    The transient eigenmode structure of an interacting cantilever during a single impact on different surfaces evidences the excitation of higher flexural modes and low frequency oscillations. The frequency shift of the fundamental mode after the tip comes into contact with the sample surface allows calculating the tip-sample interaction stiffness and evidences the role of capillary condensation and surface wettability on the cantilever dynamics. Wavelet transforms are used to trace the origin of spectral features in the cantilever spectra and calculate force gradients of the tip-sample interaction.

  19. Fixing Dataset Search

    NASA Technical Reports Server (NTRS)

    Lynnes, Chris

    2014-01-01

    Three current search engines are queried for ozone data at the GES DISC. The results range from sub-optimal to counter-intuitive. We propose a method to fix dataset search by implementing a robust relevancy ranking scheme. The relevancy ranking scheme is based on several heuristics culled from more than 20 years of helping users select datasets.

  20. Fixed mount wavefront sensor

    DOEpatents

    Neal, Daniel R.

    2000-01-01

    A rigid mount and method of mounting for a wavefront sensor. A wavefront dissector, such as a lenslet array, is rigidly mounted at a fixed distance relative to an imager, such as a CCD camera, without need for a relay imaging lens therebetween.

  1. Indium phosphide-based monolithically integrated PIN waveguide photodiode readout for resonant cantilever sensors

    SciTech Connect

    Siwak, N. P.; Fan, X. Z.; Ghodssi, R.; Kanakaraju, S.; Richardson, C. J. K.

    2014-10-06

    An integrated photodiode displacement readout scheme for a microelectromechanical cantilever waveguide resonator sensing platform is presented. III-V semiconductors are used to enable the monolithic integration of passive waveguides with active optical components. This work builds upon previously demonstrated results by measuring the displacement of cantilever waveguide resonators with on-chip waveguide PIN photodiodes. The on-chip integration of the readout provides an additional 70% improvement in mass sensitivity compared to off-chip photodetector designs due to measurement stability and minimized coupling loss. In addition to increased measurement stability, reduced packaging complexity is achieved due to the simplicity of the readout design. We have fabricated cantilever waveguides with integrated photodetectors and experimentally characterized these cantilever sensors with monolithically integrated PIN photodiodes.

  2. Indium phosphide-based monolithically integrated PIN waveguide photodiode readout for resonant cantilever sensors

    NASA Astrophysics Data System (ADS)

    Siwak, N. P.; Fan, X. Z.; Kanakaraju, S.; Richardson, C. J. K.; Ghodssi, R.

    2014-10-01

    An integrated photodiode displacement readout scheme for a microelectromechanical cantilever waveguide resonator sensing platform is presented. III-V semiconductors are used to enable the monolithic integration of passive waveguides with active optical components. This work builds upon previously demonstrated results by measuring the displacement of cantilever waveguide resonators with on-chip waveguide PIN photodiodes. The on-chip integration of the readout provides an additional 70% improvement in mass sensitivity compared to off-chip photodetector designs due to measurement stability and minimized coupling loss. In addition to increased measurement stability, reduced packaging complexity is achieved due to the simplicity of the readout design. We have fabricated cantilever waveguides with integrated photodetectors and experimentally characterized these cantilever sensors with monolithically integrated PIN photodiodes.

  3. High resolution capabilities of all-silica cantilevered probes for near-field optical microscopy.

    PubMed

    Descrovi, Emiliano; Aeschimann, Laure; Soboleva, Irina; De Angelis, Francesco; Giorgis, Fabrizio; Di Fabrizio, Enzo

    2009-11-01

    We report on the possibility of performing Near-field Scanning Optical Microscopy in illumination mode by means of microfabricated, metal-coated silica probes based on transparent cantilevers. A low spring constant silica cantilever hosts a silica tip at its end showing an hyperbolic profile and a circular symmetry. After evaporation of 100 nm of aluminium on the tip and the cantilever we processed the tip apex by means of a FIB, thus obtaining either a probe apex with an optical aperture or an apertureless probe having a thin metal layer on the top. An excellent quality of near-field images of samples showing sub-wavelength features is obtained in both case. In particular, the apertureless probe allows highly resolved topographical and optical images to be collected at the same time. This work further demonstrates that the use of completely transparent, metal-coated cantilevers greatly simplify the light injection into the probe and the fabrication process consequently.

  4. Piezoelectric cantilever-pendulum for multi-directional energy harvesting with internal resonance

    NASA Astrophysics Data System (ADS)

    Xu, J.; Tang, J.

    2015-04-01

    Piezoelectric transducers are widely employed in vibration-based energy harvesting schemes. Simple piezoelectric cantilever for energy harvesting is uni-directional and has bandwidth limitation. In this research we explore utilizing internal resonances to harvest vibratory energy due to excitations from an arbitrary direction with the usage of a single piezoelectric cantilever. Specifically, it is identified that by attaching a pendulum to the piezoelectric cantilever, 1:2 internal resonances can be induced based on the nonlinear coupling. The nonlinear effect induces modal energy exchange between beam bending motion and pendulum motions in 3-dimensional space, which ultimately yield multidirectional energy harvesting by a single cantilever. Systematic analysis and experimental investigation are carried out to demonstrate this new concept.

  5. Electrothermally driven high-frequency piezoresistive SiC cantilevers for dynamic atomic force microscopy

    SciTech Connect

    Boubekri, R.; Cambril, E.; Couraud, L.; Bernardi, L.; Madouri, A.; Portail, M.; Chassagne, T.; Moisson, C.; Zielinski, M.; Jiao, S.; Michaud, J.-F.; Alquier, D.; Bouloc, J.; Nony, L.; Bocquet, F.; Loppacher, C.

    2014-08-07

    Cantilevers with resonance frequency ranging from 1 MHz to 100 MHz have been developed for dynamic atomic force microscopy. These sensors are fabricated from 3C-SiC epilayers grown on Si(100) substrates by low pressure chemical vapor deposition. They use an on-chip method both for driving and sensing the displacement of the cantilever. A first gold metallic loop deposited on top of the cantilever is used to drive its oscillation by electrothermal actuation. The sensing of this oscillation is performed by monitoring the resistance of a second Au loop. This metallic piezoresistive detection method has distinct advantages relative to more common semiconductor-based schemes. The optimization, design, fabrication, and characteristics of these cantilevers are discussed.

  6. A direct micropipette-based calibration method for atomic force microscope cantilevers

    PubMed Central

    Liu, Baoyu; Yu, Yan; Yao, Da-Kang; Shao, Jin-Yu

    2009-01-01

    In this report, we describe a direct method for calibrating atomic force microscope (AFM) cantilevers with the micropipette aspiration technique (MAT). A closely fitting polystyrene bead inside a micropipette is driven by precisely controlled hydrostatic pressures to apply known loads on the sharp tip of AFM cantilevers, thus providing a calibration at the most functionally relevant position. The new method is capable of calibrating cantilevers with spring constants ranging from 0.01 to hundreds of newtons per meter. Under appropriate loading conditions, this new method yields measurement accuracy and precision both within 10%, with higher performance for softer cantilevers. Furthermore, this method may greatly enhance the accuracy and precision of calibration for colloidal probes. PMID:19566228

  7. Label-free protein assay based on a nanomechanical cantilever array

    NASA Astrophysics Data System (ADS)

    Arntz, Y.; Seelig, J. D.; Lang, H. P.; Zhang, J.; Hunziker, P.; Ramseyer, J. P.; Meyer, E.; Hegner, M.; Gerber, Ch

    2003-01-01

    We demonstrate continuous label-free detection of two cardiac biomarker proteins (creatin kinase and myoglobin) using an array of microfabricated cantilevers functionalized with covalently anchored anti-creatin kinase and anti-myoglobin antibodies. This method allows biomarker proteins to be detected via measurement of surface stress generated by antigen-antibody molecular recognition. Reference cantilevers are used to eliminate thermal drifts, undesired chemical reactions and turbulences from injections of liquids by calculating differential deflection signals with respect to sensor cantilevers. The sensitivity achieved for myoglobin detection is below 20 µg ml-1. Both myoglobin and creatin kinase could be detected independently using cantilevers functionalized with the corresponding antibodies, in unspecific protein background. This approach permits the use of up to seven different antigen-antibody reactions simultaneously, including an additional thermomechanical and chemical in situ reference. Applications lie in the field of early and rapid diagnosis of acute myocardial infarction.

  8. Nanoscale deflection detection of a cantilever-based biosensor using MOSFET structure: A theoretical analysis

    NASA Astrophysics Data System (ADS)

    Paryavi, Mohsen; Montazeri, Abbas; Tekieh, Tahereh; Sasanpour, Pezhman

    2016-10-01

    A novel method for detection of biological species based on measurement of cantilever deflection has been proposed and numerically evaluated. Employing the cantilever as a moving gate of a MOSFET structure, its deflection can be analyzed via current characterization of the MOSFET consequently. Locating the cantilever as a suspended gate of a MOSFET on a substrate, the distance between cantilever and oxide layer will change the carrier concentration. Accordingly, it will be resulted in different current voltage characteristics of the device which can be easily measured using simple apparatuses. In order to verify the proposed method, the performance of system has been theoretically analyzed using COMSOL platform. The simulation results have confirmed the performance and sensitivity of the proposed method.

  9. Effect of cantilever length on stress distribution around implants in mandibular overdentures supported by two and three implants

    PubMed Central

    Ebadian, Behnaz; Mosharraf, Ramin; Khodaeian, Niloufar

    2016-01-01

    Objective: There is no definitive study comparing stress distribution around two versus three implants in implant-retained overdentures with different cantilever length. The purpose of this finite element study was to evaluate stress pattern around the implants of the 2 or 3 implant- supported mandibular overdenture with different cantilevered length. Materials and Methods: The models used in this study were 2 and 3 implant-supported overdenture with bar and clip attachment system on an edentulous mandibular arch. Each model was modified according to cantilever length (0 mm, 7 mm, and 13 mm); thus, 6 models were obtained. The vertical load of 15 and 30 pounds were applied unilaterally to the first molar and 15 pounds to the first premolar, and the stress in bone was analyzed. Results: With increasing cantilever length, no similar stress pattern changes were observed in different areas, but in most instances, an increase in cantilever length did not increase the stress around the implant adjacent to cantilever. Conclusions: Within the limitations of this study, it can be concluded that increasing of cantilever length in mandibular overdentures retained by 2–3 implants did not cause distinct increasing in stress, especially around the implant adjacent to cantilever, it may be helpful to use cantilever in cases of mandibular overdenture supported by splinted implants with insufficient retention and stability. Based on the findings of this study, optimal cantilever length in mandibular overdenture cannot be determined. PMID:27403049

  10. Quantitative measurement of in-plane cantilever torsion for calibrating lateral piezoresponse force microscopy.

    SciTech Connect

    Choi, H.; Hong, S.; No, K.

    2011-01-01

    A simple quantitative measurement procedure of in-plane cantilever torsion for calibrating lateral piezoresponse force microscopy is presented. This technique enables one to determine the corresponding lateral inverse optical lever sensitivity (LIOLS) of the cantilever on the given sample. Piezoelectric coefficient, d{sub 31} of BaTiO{sub 3} single crystal (-81.62 {+-} 40.22 pm/V) which was calculated using the estimated LIOLS was in good agreement with the reported value in literature.

  11. Double bi-material cantilever structures for complex surface plasmon modulation.

    PubMed

    Song, Eui-Young; Cho, Jaebum; Kim, Hwi; Choi, Woo Young; Lee, Byoungho

    2015-03-01

    A complex modulation structure of surface plasmon polaritons using double bi-material cantilevers is proposed. It is shown with numerical analysis that the thermally controlled mechanical actuation of double bi-material cantilevers can modulate the amplitude and phase of surface plasmon polaritons across a full complex modulation range independently and simultaneously. The complex modulation structures designed for visible wavelengths are presented and their multi-wavelength integration is discussed.

  12. Investigation of polymer derived ceramics cantilevers for application of high speed atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Chia-Yun

    High speed Atomic Force Microscopy (AFM) has a wide variety of applications ranging from nanomanufacturing to biophysics. In order to have higher scanning speed of certain AFM modes, high resonant frequency cantilevers are needed; therefore, the goal of this research is to investigate using polymer derived ceramics for possible applications in making high resonant frequency AFM cantilevers using complex cross sections. The polymer derived ceramic that will be studied, is silicon carbide. Polymer derived ceramics offer a potentially more economic fabrication approach for MEMS due to their relatively low processing temperatures and ease of complex shape design. Photolithography was used to make the desired cantilever shapes with micron scale size followed by a wet etching process to release the cantilevers from the substrates. The whole manufacturing process we use borrow well-developed techniques from the semiconducting industry, and as such this project also could offer the opportunity to reduce the fabrication cost of AFM cantilevers and MEMS in general. The characteristics of silicon carbide made from the precursor polymer, SMP-10 (Starfire Systems), were studied. In order to produce high qualities of silicon carbide cantilevers, where the major concern is defects, proper process parameters needed to be determined. Films of polymer derived ceramics often have defects due to shrinkage during the conversion process. Thus control of defects was a central issue in this study. A second, related concern was preventing oxidation; the polymer derived ceramics we chose is easily oxidized during processing. Establishing an environment without oxygen in the whole process was a significant challenge in the project. The optimization of the parameters for using photolithography and wet etching process was the final and central goal of the project; well established techniques used in microfabrication were modified for use in making the cantilever in the project. The techniques

  13. Soft-materials elastic and shear moduli measurement using piezoelectric cantilevers

    NASA Astrophysics Data System (ADS)

    Markidou, Anna; Shih, Wan Y.; Shih, Wei-Heng

    2005-06-01

    We have developed a soft-material elastic modulus and shear modulus sensor using piezoelectric cantilevers. A piezoelectric cantilever is consisted of a highly piezoelectric layer, e.g., lead-zirconate-titanate bonded to a nonpiezoelectric layer, e.g., stainless steel. Applying an electric field in the thickness direction causes a piezoelectric cantilever to bend, generating an axial displacement or force. When a piezoelectric cantilever is in contact with an object, this electric field-generated axial displacement is reduced due to the resistance by the object. With a proper design of the piezoelectric cantilever's geometry, its axial displacements with and without contacting the object could be accurately measured. From these measurements the elastic modulus of the object can be deduced. In this study, we tailored the piezoelectric cantilevers for measuring the elastic and shear moduli of tissue-like soft materials with forces in the submilli Newton to milliNewton range. Elastic moduli and shear moduli of soft materials were measured using piezoelectric cantilevers with a straight tip and an L-shaped tip, respectively. Using gelatin and commercial rubber material as model soft tissues, we showed that a piezoelectric cantilever 1.5-2cm long could measure the elastic modulus and the shear modulus of a small soft material sample (1-3mm wide) in the small strain range (<1%). For samples 5mm high, the resultant compressive (shear) strains were less than 0.5% (1%). The measurements were validated by (1) comparing the measured Young's modulus of the commercial rubber sample with its known value and (2) by measuring both the Young's modulus and shear modulus on the samples and confirming the thus deduced Poisson's ratios with the separately measured Poisson's ratios.

  14. A Novel Approach to the Sensing of Liquid Density Using a Plastic Optical Fibre Cantilever Beam

    ERIC Educational Resources Information Center

    Kulkarni, Atul; Kim, Youngjin; Kim, Taesung

    2009-01-01

    This article reports for the first time the use of a plastic optical fibre (POF) cantilever beam to measure the density of a liquid. The sensor is based on the Archimedes buoyancy principle. The sensor consists of a POF bonded on the surface of a metal beam in the form of a cantilever configuration, and at the free end of the beam a displacer is…

  15. Effect of finite width on deflection and energy release rate of an orthotropic double cantilever specimen

    NASA Technical Reports Server (NTRS)

    Schapery, R. A.; Davidson, B. D.

    1988-01-01

    The problem of an orthotropic cantilevered plate subjected to a uniformly distributed end load is solved by the Rayleigh-Ritz energy method. The result is applied to laminated composite, double cantilevered specimens to estimate the effect of crack tip constraint on the transverse curvature, deflection and energy release rate. The solution is also utilized to determined finite width correction factors for fracture energy characterization tests in which neither plane stress nor plane strain conditions apply.

  16. Cancelation of thermally induced frequency shifts in bimaterial cantilevers by nonlinear optomechanical interactions

    NASA Astrophysics Data System (ADS)

    Vy, Nguyen Duy; Tri Dat, Le; Iida, Takuya

    2016-08-01

    Bimaterial cantilevers have recently been used in, for example, the calorimetric analysis with picowatt resolution in microscopic space based on state-of-the-art atomic force microscopes. However, thermally induced effects usually change physical properties of the cantilevers, such as the resonance frequency, which reduce the accuracy of the measurements. Here, we propose an approach to circumvent this problem that uses an optical microcavity formed between a metallic layer coated on the back of the cantilever and one coated at the end of an optical fiber irradiating the cantilever. In addition to increasing the sensitivity, the optical rigidity of this system diminishes the thermally induced frequency shift. For a coating thickness of several tens of nanometers, the input power is 5-10 μW. These values can be evaluated from parameters derived by directly irradiating the cantilever in the absence of the microcavity. The system has the potential of using the cantilever both as a thermometer without frequency shifting and as a sensor with nanometer-controlled accuracy.

  17. A method for atomic force microscopy cantilever stiffness calibration under heavy fluid loading

    SciTech Connect

    Kennedy, Scott J.; Cole, Daniel G.; Clark, Robert L.

    2009-12-15

    This work presents a method for force calibration of rectangular atomic force microscopy (AFM) microcantilevers under heavy fluid loading. Theoretical modeling of the thermal response of microcantilevers is discussed including a fluid-structure interaction model of the cantilever-fluid system that incorporates the results of the fluctuation-dissipation theorem. This model is curve fit to the measured thermal response of a cantilever in de-ionized water and a cost function is used to quantify the difference between the theoretical model and measured data. The curve fit is performed in a way that restricts the search space to parameters that reflect heavy fluid loading conditions. The resulting fitting parameters are used to calibrate the cantilever. For comparison, cantilevers are calibrated using Sader's method in air and the thermal noise method in both air and water. For a set of eight cantilevers ranging in stiffness from 0.050 to 5.8 N/m, the maximum difference between Sader's calibration performed in air and the new method performed in water was 9.4%. A set of three cantilevers that violate the aspect ratio assumption associated with the fluid loading model (length-to-width ratios less than 3.5) ranged in stiffness from 0.85 to 4.7 N/m and yielded differences as high as 17.8%.

  18. A method for atomic force microscopy cantilever stiffness calibration under heavy fluid loading.

    PubMed

    Kennedy, Scott J; Cole, Daniel G; Clark, Robert L

    2009-12-01

    This work presents a method for force calibration of rectangular atomic force microscopy (AFM) microcantilevers under heavy fluid loading. Theoretical modeling of the thermal response of microcantilevers is discussed including a fluid-structure interaction model of the cantilever-fluid system that incorporates the results of the fluctuation-dissipation theorem. This model is curve fit to the measured thermal response of a cantilever in de-ionized water and a cost function is used to quantify the difference between the theoretical model and measured data. The curve fit is performed in a way that restricts the search space to parameters that reflect heavy fluid loading conditions. The resulting fitting parameters are used to calibrate the cantilever. For comparison, cantilevers are calibrated using Sader's method in air and the thermal noise method in both air and water. For a set of eight cantilevers ranging in stiffness from 0.050 to 5.8 N/m, the maximum difference between Sader's calibration performed in air and the new method performed in water was 9.4%. A set of three cantilevers that violate the aspect ratio assumption associated with the fluid loading model (length-to-width ratios less than 3.5) ranged in stiffness from 0.85 to 4.7 N/m and yielded differences as high as 17.8%.

  19. Electrothermal piezoresistive cantilever resonators for personal measurements of nanoparticles in workplace exposure

    NASA Astrophysics Data System (ADS)

    Wasisto, Hutomo Suryo; Wu, Wenze; Uhde, Erik; Waag, Andreas; Peiner, Erwin

    2015-05-01

    Low-cost and low-power piezoresistive cantilever resonators with integrated electrothermal heaters are developed to support the sensing module enhancement of the second generation of handheld cantilever-based airborne nanoparticle (NP) detector (CANTOR-2). These sensors are used for direct-reading of exposure to carbon engineered nanoparticles (ENPs) at indoor workplaces. The cantilever structures having various shapes of free ends are created using silicon bulk micromachining technologies (i.e, rectangular, hammer-head, triangular, and U-shaped cantilevers). For a complete wearable CANTOR-2, all components of the proposed detector can be grouped into two main units depending on their packaging placements (i.e., the NP sampler head and the electronics mounted in a handy-format housing). In the NP sampler head, a miniaturized electrophoretic aerosol sampler and a resonant silicon cantilever mass sensor are employed to collect the ENPs from the air stream to the cantilever surfaces and measuring their mass concentration, respectively. After calibration, the detected ENP mass concentrations of CANTOR-2 show a standard deviation from fast mobility particle sizer (FMPS, TSI 3091) of 8-14%.

  20. Study of node and mass sensitivity of resonant mode based cantilevers with concentrated mass loading

    NASA Astrophysics Data System (ADS)

    Zhang, Kewei; Chai, Yuesheng; Fu, Jiahui

    2015-12-01

    Resonant-mode based cantilevers are an important type of acoustic wave based mass-sensing devices. In this work, the governing vibration equation of a bi-layer resonant-mode based cantilever attached with concentrated mass is established by using a modal analysis method. The effects of resonance modes and mass loading conditions on nodes and mass sensitivity of the cantilever were theoretically studied. The results suggested that the node did not shift when concentrated mass was loaded on a specific position. Mass sensitivity of the cantilever was linearly proportional to the square of the point displacement at the mass loading position for all the resonance modes. For the first resonance mode, when mass loading position xc satisfied 0 < xc < ˜ 0.3l (l is the cantilever beam length and 0 represents the rigid end), mass sensitivity decreased as the mass increasing while the opposite trend was obtained when mass loading satisfied ˜0.3l ≤ xc ≤ l. Mass sensitivity did not change when concentrated mass was loaded at the rigid end. This work can provide scientific guidance to optimize the mass sensitivity of a resonant-mode based cantilever.

  1. Study of node and mass sensitivity of resonant mode based cantilevers with concentrated mass loading

    SciTech Connect

    Zhang, Kewei Chai, Yuesheng; Fu, Jiahui

    2015-12-15

    Resonant-mode based cantilevers are an important type of acoustic wave based mass-sensing devices. In this work, the governing vibration equation of a bi-layer resonant-mode based cantilever attached with concentrated mass is established by using a modal analysis method. The effects of resonance modes and mass loading conditions on nodes and mass sensitivity of the cantilever were theoretically studied. The results suggested that the node did not shift when concentrated mass was loaded on a specific position. Mass sensitivity of the cantilever was linearly proportional to the square of the point displacement at the mass loading position for all the resonance modes. For the first resonance mode, when mass loading position x{sub c} satisfied 0 < x{sub c} < ∼ 0.3l (l is the cantilever beam length and 0 represents the rigid end), mass sensitivity decreased as the mass increasing while the opposite trend was obtained when mass loading satisfied ∼0.3l ≤ x{sub c} ≤ l. Mass sensitivity did not change when concentrated mass was loaded at the rigid end. This work can provide scientific guidance to optimize the mass sensitivity of a resonant-mode based cantilever.

  2. Development of Multi-Degree-Of-Freedom Piezoelectric Energy Harvester Using Interdigital Shaped Cantilevers.

    PubMed

    Cho, Hyunok; Park, Jongcheol; Park, Jae Yeong

    2016-05-01

    A piezoelectric vibration energy harvester with interdigital shaped cantilever was developed by using silicon bulk micromachining technology. The proposed energy harvester was designed to obtain multi degree-of-freedom (m-DOF). Most of the piezoelectric vibration energy harvesters are comprised of mass-loaded cantilever beams having several resonant frequencies. The second resonant frequency of such a device has lower amplitude compared to its first resonant frequency (fundamental frequency). Therefore, the interdigital shaped cantilever has been proposed for multiple fundamental resonant frequencies. The fabricated piezoelectric vibration energy harvester is composed of main cantilever (MC), sub-main cantilever (SMC), and secondary cantilevers (SC). MC surrounds SMC and SC which have same dimension of 5600 x 800 x 10 μm3. The fabricated piezoelectric energy harvester can generate 51.4 mV(p-p) and 11 mV(p-p) of output voltages at 24.2 Hz and 33 Hz of its resonant frequencies by MC. Moreover, it can generate 8 mV(p-p) and 6.6 mV(p-p) of output voltages at 24.2 Hz and 33.2 Hz of its resonant frequencies by SMC; and 364 mV(p-p) of output voltage at 33.6 Hz of its resonant frequency by SC. PMID:27483909

  3. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    PubMed

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever. PMID:25971046

  4. Control of curvature in highly compliant probe cantilevers during carbon nanotube growth.

    PubMed

    Chen, I-Chen; Chen, Li-Han; Orme, Christine A; Jin, Sungho

    2007-10-01

    Direct growth of a sharp carbon nanotube (CNT) probe on a very thin and highly flexible cantilever by plasma-enhanced chemical vapor deposition (PECVD) is desirable for atomic force microscopy (AFM) of nanoscale features on soft or fragile materials. Plasma-induced surface stresses in such fabrication processes, however, tend to cause serious bending of these cantilevers, which makes the CNT probe unsuitable for AFM measurements. Here, we report a new tunable CNT growth technique that controls cantilever bending during deposition, thereby enabling the creation of either flat or deliberately curved AFM cantilevers containing a CNT probe. By introducing hydrogen gas to the (acetylene + ammonia) feed gas during CNT growth and adjusting the ammonia to hydrogen flow ratio, the cantilever surface stress can be altered from compressive to tensile stress, and in doing so controlling the degree of cantilever bending. The CNT probes grown under these conditions have high aspect ratios and are robust. Contact-mode imaging has been demonstrated using these probe tips. Such CNT probes can be useful for bio-imaging involving DNA and other delicate biological features in a liquid environment. PMID:17887798

  5. Atomic force microscope cantilever spring constant evaluation for higher mode oscillations: A kinetostatic method

    SciTech Connect

    Tseytlin, Yakov M.

    2008-02-15

    Our previous study of the particle mass sensor has shown a large ratio (up to thousands) between the spring constants of a rectangular cantilever in higher mode vibration and at the static bending or natural mode vibration. This has been proven by us through the derived nodal point position equation. That solution is good for a cantilever with the free end in noncontact regime and the probe shifted from the end to an effective section and contacting a soft object. Our further research shows that the same nodal position equation with the proper frequency equations may be used for the same spring constant ratio estimation if the vibrating at higher mode cantilever's free end has a significant additional mass clamped to it or that end is in permanent contact with an elastic or hard measurand object (reference cantilever). However, in the latter case, the spring constant ratio is much smaller (in tens) than in other mentioned cases at equal higher (up to fourth) vibration modes. We also present the spring constant ratio for a vibrating at higher eigenmode V-shaped cantilever, which is now in wide use for atomic force microscopy. The received results on the spring constant ratio are in good (within a few percent) agreement with the theoretical and experimental data published by other researchers. The knowledge of a possible spring constant transformation is important for the proper calibration and use of an atomic force microscope with vibrating cantilever in the higher eigenmodes for measurement and imaging with enlarged resolution.

  6. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    PubMed

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever.

  7. Development of Multi-Degree-Of-Freedom Piezoelectric Energy Harvester Using Interdigital Shaped Cantilevers.

    PubMed

    Cho, Hyunok; Park, Jongcheol; Park, Jae Yeong

    2016-05-01

    A piezoelectric vibration energy harvester with interdigital shaped cantilever was developed by using silicon bulk micromachining technology. The proposed energy harvester was designed to obtain multi degree-of-freedom (m-DOF). Most of the piezoelectric vibration energy harvesters are comprised of mass-loaded cantilever beams having several resonant frequencies. The second resonant frequency of such a device has lower amplitude compared to its first resonant frequency (fundamental frequency). Therefore, the interdigital shaped cantilever has been proposed for multiple fundamental resonant frequencies. The fabricated piezoelectric vibration energy harvester is composed of main cantilever (MC), sub-main cantilever (SMC), and secondary cantilevers (SC). MC surrounds SMC and SC which have same dimension of 5600 x 800 x 10 μm3. The fabricated piezoelectric energy harvester can generate 51.4 mV(p-p) and 11 mV(p-p) of output voltages at 24.2 Hz and 33 Hz of its resonant frequencies by MC. Moreover, it can generate 8 mV(p-p) and 6.6 mV(p-p) of output voltages at 24.2 Hz and 33.2 Hz of its resonant frequencies by SMC; and 364 mV(p-p) of output voltage at 33.6 Hz of its resonant frequency by SC.

  8. Torsion/cantilever-based MEMS bistable mechanisms with different support configurations: structure design and comparison

    NASA Astrophysics Data System (ADS)

    Wu, Yibo; Zhang, Congchun; Wang, Hong; Ding, Guifu

    2011-04-01

    Three types of torsion/cantilever-based MEMS bistable mechanisms (BMs) with different support configurations have been constructed, modeled and experimented. For the support configuration, there is a crisscross-shaped, a ring-shaped and a diamond-shaped support beam, respectively. The proposed MEMS BMs consist of a free-free torsion-based cantilever which forms a symmetrical rocker lever. The free-free cantilever is suspended by a support skeleton which in turn is attached to a torsion cantilever. A permanent magnet is attached beside for holding the closed state with a permalloy soft magnetic circuit. The different special support configurations account for a low torsional compliance with the overhanging beams. In order to deduce the equivalent stiffness coefficient of BM systems, mechanical modeling of three types of torsion/cantilever-based MEMS BMs was performed by the classical beam theorem. Meanwhile, the magnetostatic latching force was also deduced by the Maxwell electromagnetism theory. The performances of these MEMS BMs have been compared by the evaluation of static deformation variations, equivalent stiffness coefficients and dynamical switching characterizations. Finally, mechanical performance was characterized by atomic force microscopy, combined with a Nanoindentation Tester. In addition, bistabilities of the MEMS BMs were proved by theoretical analysis as well as experimental results. Among these BMs, the ring-shaped MEMS BM is extremely prone to deflect due to relatively low stiffness compared with other types. The torsion/cantilever-based MEMS BMs have potential application in the field of latching relays with low power consumption.

  9. Resonant frequencies of cantilevered sheets under various clamping configurations immersed in fluid

    NASA Astrophysics Data System (ADS)

    Shen, Naijian; Chakraborty, Debadi; Sader, John E.

    2016-10-01

    Immersion of an elastic cantilevered sheet in a fluid can strongly affect its dynamic response. While significant effort has been expended in studying slender cantilevered sheets, the behavior of wide sheets has received far less attention. Here we study the clamping configuration's effect on the vibrational dynamics of wide cantilever sheets of macroscopic size, which naturally generate inviscid flows. Three practically relevant clamping configurations are investigated: clamping into (i) a thin and rigid horizontal plate, (ii) a rigid vertical wall, and (iii) a rigid line. These are found to produce different resonant frequencies, as expected from the nonlocal flows generated by these cantilevers. The resulting formulas are joined to an existing expression for slender cantilevers, leading to a universal formula valid for all aspect ratios (cantilever length/width) and mode numbers; accuracy is verified using finite element analysis. This study is expected to be of practical value in a host of engineering applications, such as those that utilize fluid-structure interactions for energy harvesting and aerodynamic design.

  10. Model-based Processing of Micro-cantilever Sensor Arrays

    SciTech Connect

    Tringe, J W; Clague, D S; Candy, J V; Lee, C L; Rudd, R E; Burnham, A K

    2004-11-17

    We develop a model-based processor (MBP) for a micro-cantilever array sensor to detect target species in solution. After discussing the generalized framework for this problem, we develop the specific model used in this study. We perform a proof-of-concept experiment, fit the model parameters to the measured data and use them to develop a Gauss-Markov simulation. We then investigate two cases of interest: (1) averaged deflection data, and (2) multi-channel data. In both cases the evaluation proceeds by first performing a model-based parameter estimation to extract the model parameters, next performing a Gauss-Markov simulation, designing the optimal MBP and finally applying it to measured experimental data. The simulation is used to evaluate the performance of the MBP in the multi-channel case and compare it to a ''smoother'' (''averager'') typically used in this application. It was shown that the MBP not only provides a significant gain ({approx} 80dB) in signal-to-noise ratio (SNR), but also consistently outperforms the smoother by 40-60 dB. Finally, we apply the processor to the smoothed experimental data and demonstrate its capability for chemical detection. The MBP performs quite well, though it includes a correctable systematic bias error. The project's primary accomplishment was the successful application of model-based processing to signals from micro-cantilever arrays: 40-60 dB improvement vs. the smoother algorithm was demonstrated. This result was achieved through the development of appropriate mathematical descriptions for the chemical and mechanical phenomena, and incorporation of these descriptions directly into the model-based signal processor. A significant challenge was the development of the framework which would maximize the usefulness of the signal processing algorithms while ensuring the accuracy of the mathematical description of the chemical-mechanical signal. Experimentally, the difficulty was to identify and characterize the non

  11. Research of fiber Bragg grating geophone based on cantilever beam

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Chen, Shao-hua; Tao, Guo; Lu, Gui-wu; Zhao, Kun

    2009-07-01

    Along with the development of seismic exploration, the demand of frequency, dynamic range, precision and resolution ration is increased. However, the traditional geophone has disadvantages of narrower bandwidth, lower dynamic range and resolution, and cannot meet the new needs of seismic exploration. Geophone technology is a choke point, which constrains the development of petroleum prospecting in recent years. Fiber Bragg Grating seism demodulation technology is the newest kind of seism demodulation technology. The sensing probe of the Fiber Bragg Grating geophone is made up of Fiber Bragg Gating. The information which it collects is embodied by wavelength. The modulation-demodulation is accomplished by Fiber Bragg Gating geophone directly. In this paper, we design different size Fiber Bragg Grating geophones based on the transmission properties of Fiber Bragg Grating and cantilever beam method. Beryllium bronze and stainless steel are chosen as the elastic beam and shell materials, respectively. The parameters such as response function and sensitivity are given theoretically. In addition, we have simulated the transmission characteristics of Fiber Bragg Grating geophone by virtue of finite element analysis. The influences of wavelength, mass block, fiber length on the characteristics of geophones are discussed in detail, and finally the appropriate structural parameters are presented.

  12. Droplet Impacting a Cantilever: A Leaf-Raindrop System

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Mates, Joseph E.; Megaridis, Constantine M.; Jung, Sunghwan

    2015-04-01

    Previous studies show that air pollution and wind erosion, which damage a leaf's epicuticular wax layer, can change leaf surface properties from hydrophobic to hydrophilic. However, the dynamic response of a damaged leaf to a raindrop impact has not been investigated and could clarify the direct influence of changes in wettability on early leaf abscission. In this article, we investigate how leaves with different surface properties respond to falling raindrops, viewing this as a unique system of coupled elasticity and drop dynamics. An elastic beam with tunable surface wettability properties is used as a simple leaf model. We find that wettable beams experience much higher torque and bending energy than nonwettable beams. This is because a drop sticks to a wettable beam, while a drop falls off a nonwettable beam. An analytical model using momentum balance and simple cantilever beam theory quantifies the bending energy and torque experienced by wettable and nonwettable beams. The results elucidate the potential damage caused by raindrops impacting a leaf as a function of its surface wettability and are correlated with environmental factors contributing to premature changes of leaf surface properties.

  13. Factors influencing elastic stresses in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Crews, J. H., Jr.; Shivakumar, K. N.; Raju, I. S.

    1986-01-01

    An elastic stress analysis was conducted for a double cantilever beam (DCB) specimen using finite-element methods. The purpose of this study was to identify the important parameters that influence stresses ahead of the delamination front. The study focused on an aluminum DCB specimen, typical of adhesively-bonded joints, and on a graphite/epoxy specimen representing a cocured composite. Opening mode sigma sub y stresses ahead of the crack tip were calculated and compared with those for a monolithic reference specimen. Beyond the singularity-dominated region very near the crack tip, the sigma sub y distribution was elevated compared to the monolithic case. Both the adhesive thickness and the adherend transverse (thickness-direction) stiffness were found to influence the elevation of sigma sub y. In contrast, adherend thickness and longitudinal stiffness has very little effect on this stress distribution. Estimates for adhesive yielding beyond the aluminum DCB crack tip showed that both the area and height of the plastic zone increased to a peak value for increasing adhesive thicknesses. Results from this study would provide insight for comparing data from different DCB specimens and for designing new DCB specimens.

  14. Factors influencing elastic stresses in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Crews, J. H., Jr.; Shivakumar, K. N.; Raju, I. S.

    1988-01-01

    An elastic stress analysis was conducted for a double cantilever beam (DCB) specimen using finite-element methods. The purpose of this study was to identify the important parameters that influence stresses ahead of the delamination front. The study focused on an aluminum DCB specimen, typical of adhesively-bonded joints, and on a graphite/epoxy specimen representing a cocured composite. Opening mode sigma sub y stresses ahead of the crack tip were calculated and compared with those for a monolithic reference specimen. Beyond the singularity-dominated region very near the crack tip, the sigma sub y distribution was elevated compared to the monolithic case. Both the adhesive thickness and the adherend transverse (thickness-direction) stiffness were found to influence the elevation of sigma sub y. In contrast, adherend thickness and longitudinal stiffness has very little effect on this stress distribution. Estimates for adhesive yielding beyond the aluminum DCB crack tip showed that both the area and height of the plastic zone increased to a peak value for increasing adhesive thicknesses. Results from this study would provide insight for comparing data from different DCB specimens and for designing new DCB specimens.

  15. Advanced structural optimization of a heliostat with cantilever arms

    NASA Astrophysics Data System (ADS)

    Bogdanov, Dimitar; Zlatanov, Hristo

    2016-05-01

    The weight of the support structure of heliostats, CPV and PV trackers is important cost element of a solar plant and reducing it will improve the economic viability of a solar project. Heliostats with rectangular area (1 to 5 in 1 m² steps; 5 to 150 in 5 m² steps) and aspect ratios (0.5, 1.0, 1.2, 1.5, 2.0) were investigated under various winds speeds (0, 5 to 100 in 5 m/s steps), wind direction (0 to 180° in 15° steps) and elevation positions (0 to 90° in 10° steps). Each load case was run with three different cantilever arms. The inclination angle of the chords and bracings was chosen so as to fulfill the geometrical boundary condition. Stress and buckling validations were performed according to Eurocode. The results of research carried out can be used to determine the specific weight of a heliostat in kg/m² as a function of the wind speed, tracker area and tracker aspect ratio. Future work should investigate the impact of using cold formed structural hollow sections and cross sections with thinner wall thickness which is not part of EN 10210.

  16. Investigation of fiber bridging in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Managalgiri, P. D.

    1986-01-01

    The possibility to eliminate fiber bridging or at least to reduce it, and to evaluate an alternative approach for determination of in situ mode 7 fracture toughness values of composite matrix materials were investigated. Double cantilever beam (DCB) specimens were made using unidirectional lay-ups of T6C/Hx205 composite material in which the delaminating halves were placed at angles of 0, 1.5, and 3 degrees to each other. The small angles between the delaminating plies were used to avoid fiber nesting without significantly affecting mode I teflon insert. The DCB specimens were fabricated and it was found that: (1) the extent which fiber bridging and interlaminar toughness increase with crack length can be reduced by slight cross ply at the delamination plane to reduce fiber nesting; (2) some fiber bridging may occur even in the absence of fiber nesting; (3) the first values of toughness measured ahead of the thin teflon insert are very close to the toughness of the matrix material with no fiber bridging; (4) thin adhesive bondline of matrix material appears to give toughness values equal to the interlaminar toughness of the composite matrix without fiber bridging.

  17. Event parameters - fixed target

    SciTech Connect

    Poskanzer, A.; Ritter, H.G.; Ludewigt, B.; Foley, K.; Borenstein, S.; Platner, E.; Love, W.; Keane, D.; Plasil, F.

    1984-06-15

    This subgroup has focussed on detectors for fixed target experiments which have full azimuthal coverage. The general scope of the working group was to consider (1) the configuration of an idealized detector, and (2) various configurations of practical detectors that could be implemented on a relatively short time scale. The second category includes possible upgrades and modifications of existing experimental facilities. Beams of both 15 GeV/A sulphur at the AGS and 200 GeV/A oxygen at the SPS were considered.

  18. Calibration of the effective spring constant of ultra-short cantilevers for a high-speed atomic force microscope

    NASA Astrophysics Data System (ADS)

    Song, Yun-Peng; Wu, Sen; Xu, Lin-Yan; Zhang, Jun-Ming; Dorantes-Gonzalez, Dante J.; Fu, Xing; Hu, Xiao-Dong

    2015-06-01

    Ultra-short cantilevers are a new type of cantilever designed for the next generation of high-speed atomic force microscope (HS-AFM). Ultra-short cantilevers have smaller dimensions and higher resonant frequency than conventional AFM cantilevers. Moreover, their geometry may also be different from the conventional beam-shape or V-shape. These changes increase the difficulty of determining the spring constant for ultra-short cantilevers, and hence limit the accuracy and precision of force measurement based on a HS-AFM. This paper presents an experimental method to calibrate the effective spring constant of ultra-short cantilevers. By using a home-made AFM head, the cantilever is bent against an electromagnetic compensation balance under servo control. Meanwhile the bending force and the cantilever deflection are synchronously measured by the balance and the optical lever in the AFM head, respectively. Then the effective spring constant is simply determined as the ratio of the force to the corresponding deflection. Four ultra-short trapezoid shape cantilevers were calibrated using this method. A quantitative uncertainty analysis showed that the combined relative standard uncertainty of the calibration result is less than 2%, which is better than the uncertainty of any previously reported techniques.

  19. Calibration of the spring constant of cantilevers of arbitrary shape using the phase signal in an atomic force microscope.

    PubMed

    Rawlings, Colin; Durkan, Colm

    2012-12-01

    The measurement of cantilever parameters is an essential part of performing a calibrated measurement with an atomic force microscope (AFM). The thermal motion method is a widely used technique for calibrating the spring constant of an AFM cantilever, which can be applied to non-rectangular cantilevers. Given the trend towards high frequency scanning, calibration of non-rectangular cantilevers is of increasing importance. This paper presents two results relevant to cantilever calibration via the thermal motion method. We demonstrate the possibility of using the AFM's phase signal to acquire the thermal motion. This avoids the challenges associated with connecting the raw photodiode signal to a separate spectrum analyser. We also describe how numerical calculations may be used to calculate the parameters needed in a thermal motion calibration of a non-rectangular cantilever. Only accurate knowledge of the relative size of the in-plane dimensions of the cantilever is needed in this computation. We use this pair of results in the calibration of a variety of rectangular and non-rectangular cantilevers. We observe an average difference between the Sader and thermal motion values of cantilever stiffness of 10%. PMID:23137943

  20. Calibration of the spring constant of cantilevers of arbitrary shape using the phase signal in an atomic force microscope.

    PubMed

    Rawlings, Colin; Durkan, Colm

    2012-12-01

    The measurement of cantilever parameters is an essential part of performing a calibrated measurement with an atomic force microscope (AFM). The thermal motion method is a widely used technique for calibrating the spring constant of an AFM cantilever, which can be applied to non-rectangular cantilevers. Given the trend towards high frequency scanning, calibration of non-rectangular cantilevers is of increasing importance. This paper presents two results relevant to cantilever calibration via the thermal motion method. We demonstrate the possibility of using the AFM's phase signal to acquire the thermal motion. This avoids the challenges associated with connecting the raw photodiode signal to a separate spectrum analyser. We also describe how numerical calculations may be used to calculate the parameters needed in a thermal motion calibration of a non-rectangular cantilever. Only accurate knowledge of the relative size of the in-plane dimensions of the cantilever is needed in this computation. We use this pair of results in the calibration of a variety of rectangular and non-rectangular cantilevers. We observe an average difference between the Sader and thermal motion values of cantilever stiffness of 10%.

  1. ‘Living cantilever arrays’ for characterization of mass of single live cells in fluids†

    PubMed Central

    Park, Kidong; Jang, Jaesung; Irimia, Daniel; Sturgis, Jennifer; Lee, James; Robinson, J. Paul; Toner, Mehmet; Bashir, Rashid

    2013-01-01

    The size of a cell is a fundamental physiological property and is closely regulated by various environmental and genetic factors. Optical or confocal microscopy can be used to measure the dimensions of adherent cells, and Coulter counter or flow cytometry (forward scattering light intensity) can be used to estimate the volume of single cells in a flow. Although these methods could be used to obtain the mass of single live cells, no method suitable for directly measuring the mass of single adherent cells without detaching them from the surface is currently available. We report the design, fabrication, and testing of ‘living cantilever arrays’, an approach to measure the mass of single adherent live cells in fluid using silicon cantilever mass sensor. HeLa cells were injected into microfluidic channels with a linear array of functionalized silicon cantilevers and the cells were subsequently captured on the cantilevers with positive dielectrophoresis. The captured cells were then cultured on the cantilevers in a microfluidic environment and the resonant frequencies of the cantilevers were measured. The mass of a single HeLa cell was extracted from the resonance frequency shift of the cantilever and was found to be close to the mass value calculated from the cell density from the literature and the cell volume obtained from confocal microscopy. This approach can provide a new method for mass measurement of a single adherent cell in its physiological condition in a non-invasive manner, as well as optical observations of the same cell. We believe this technology would be very valuable for single cell time-course studies of adherent live cells. PMID:18584076

  2. Fixed sagittal plane imbalance.

    PubMed

    Savage, Jason W; Patel, Alpesh A

    2014-12-01

    Study Design Literature review. Objective To discuss the evaluation and management of fixed sagittal plane imbalance. Methods A comprehensive literature review was performed on the preoperative evaluation of patients with sagittal plane malalignment, as well as the surgical strategies to address sagittal plane deformity. Results Sagittal plane imbalance is often caused by de novo scoliosis or iatrogenic flat back deformity. Understanding the etiology and magnitude of sagittal malalignment is crucial in realignment planning. Objective parameters have been developed to guide surgeons in determining how much correction is needed to achieve favorable outcomes. Currently, the goals of surgery are to restore a sagittal vertical axis < 5 cm, pelvic tilt < 20 degrees, and lumbar lordosis equal to pelvic incidence ± 9 degrees. Conclusion Sagittal plane malalignment is an increasingly recognized cause of pain and disability. Treatment of sagittal plane imbalance varies according to the etiology, location, and severity of the deformity. Fixed sagittal malalignment often requires complex reconstructive procedures that include osteotomy correction. Reestablishing harmonious spinopelvic alignment is associated with significant improvement in health-related quality-of-life outcome measures and patient satisfaction.

  3. Fixed and Sunk Costs Revisited.

    ERIC Educational Resources Information Center

    Wang, X. Henry; Yang, Bill Z.

    2001-01-01

    Attempts to clarify the concepts of, and the link between, fixed costs and sunk costs. Argues that the root of confusion is the inconsistency in defining the term fixed costs. Consistently defines fixed and sunk costs, and describes how instructors must teach under these definitions. (RLH)

  4. Characterizing the free and surface-coupled vibrations of heated-tip atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Killgore, Jason P.; Tung, Ryan C.; Hurley, Donna C.

    2014-08-01

    Combining heated-tip atomic force microscopy (HT-AFM) with quantitative methods for determining surface mechanical properties, such as contact resonance force microscopy, creates an avenue for nanoscale thermomechanical property characterization. For nanomechanical methods that employ an atomic force microscope cantilever’s vibrational modes, it is essential to understand how the vibrations of the U-shaped HT-AFM cantilever differ from those of a more traditional rectangular lever, for which analytical techniques are better developed. Here we show, with a combination of finite element analysis (FEA) and experiments, that the HT-AFM cantilever exhibits many more readily-excited vibrational modes over typical AFM frequencies compared to a rectangular cantilever. The arms of U-shaped HT-AFM cantilevers exhibit two distinct forms of flexural vibrations that differ depending on whether the two arms are vibrating in-phase or out-of-phase with one another. The in-phase vibrations are qualitatively similar to flexural vibrations in rectangular cantilevers and generally show larger sensitivity to surface stiffness changes than the out-of-phase vibrations. Vibration types can be identified from their frequency and by considering vibration amplitudes in the horizontal and vertical channels of the AFM at different laser spot positions on the cantilever. For identifying contact resonance vibrational modes, we also consider the sensitivity of the resonant frequencies to a change in applied force and hence to tip-sample contact stiffness. Finally, we assess how existing analytical models can be used to accurately predict contact stiffness from contact-resonance HT-AFM results. A simple two-parameter Euler-Bernoulli beam model provided good agreement with FEA for in-phase modes up to a contact stiffness 500 times the cantilever spring constant. By providing insight into cantilever vibrations and exploring the potential of current analysis techniques, our results lay the

  5. MicroCantilever (MC) based nanomechanical sensor for detection of molecular interactions

    SciTech Connect

    Kang, Kyung

    2011-01-01

    Specific aims of this study are to investigate the mechanism governing surface stress generation associated with chemical or molecular binding on functionalized microcantilevers. Formation of affinity complexes on cantilever surfaces leads to charge redistribution, configurational change and steric hindrance between neighboring molecules resulting in surface stress change and measureable cantilever deformation. A novel interferometry technique employing two adjacent micromachined cantilevers (a sensing/reference pair) was utilized to measure the cantilever deformation. The sensing principle is that binding/reaction of specific chemical or biological species on the sensing cantilever transduces to mechanical deformation. The differential bending of the sensing cantilever respect to the reference cantilever ensures that measured response is insensitive to environmental disturbances. As a proof of principle for the measurement technique, surface stress changes associated with: self-assembly of alkanethiol, hybridization of ssDNA, and the formation of cocaine-aptamer complexes were measured. Dissociation constant (Kd) for each molecular reaction was utilized to estimate the surface coverage of affinity complexes. In the cases of DNA hybridization and cocaine-aptamer binding, measured surface stress was found to be dependent on the surface coverage of the affinity complexes. In order to achieve a better sensitivity for DNA hybridization, immobilization of receptor molecules was modified to enhance the deformation of underlying surface. Single-stranded DNA (ssDNA) strands with thiol-modification on both 3-foot and 5-foot ends were immobilized on the gold surface such that both ends are attached to the gold surface. Immobilization condition was controlled to obtain similar receptor density as single-thiolated DNA strands. Hybridization of double-thiolated DNA strands leads to an almost two orders of magnitude increase in cantilever deformation. In both DNA

  6. Measurement and reliability issues in resonant mode cantilever for bio-sensing application in fluid medium

    NASA Astrophysics Data System (ADS)

    Kathel, G.; Shajahan, M. S.; Bhadra, P.; Prabhakar, A.; Chadha, A.; Bhattacharya, E.

    2016-09-01

    Cantilevers immersed in liquid experience viscous damping and hydrodynamic loading. We report on the use of such cantilevers, operating in the dynamic mode with, (i) frequency sweeping and (ii) phase locked loop methods. The solution to reliability issues such as random drift in the resonant peak values, and interference of spurious modes in the resonance frequency spectrum, are explained based on the actuation signal provided and laser spot size. The laser beam spot size and its position on the cantilever were found to have an important role, on the output signal and resonance frequency. We describe a method to distinguish the normal modes from the spurious modes for a cantilever. Uncertainties in the measurements define the lower limit of mass detection (m min). The minimum detection limits of the two measurement methods are investigated by measuring salt adsorption from phosphate buffer solution, as an example, a mass of 14 pg was measured using the 14th transverse mode of a 500~μ m  ×  100 μm  ×  1 μm silicon cantilever. The optimized measurement was used to study the interaction between antibody and antigen.

  7. Development of the magnetic force-induced dual vibration energy harvester using a unimorph cantilever

    NASA Astrophysics Data System (ADS)

    Umaba, M.; Nakamachi, E.; Morita, Y.

    2015-12-01

    In this study, a high frequency piezoelectric energy harvester converted from the human low vibrated motion energy was newly developed. This hybrid energy harvester consists of the unimorph piezoelectric cantilever, the pendulum and a pair of permanent magnets. One magnet was attached at the edge of cantilever, and the counterpart magnet at the edge of pendulum. The mechanical energy provided through the human walking motion, which is a typical ubiquitous existence of vibration, is converted to the electric energy via the piezoelectric unimorph cantilever vibration. At first, we studied the energy convert mechanism and analyze the performance of novel energy harvester, where the resonance free vibration of unimorph piezoelectric cantilever generated a high electric power. Next, we equipped the counterpart permanent magnet at the edge of pendulum, which vibrates with a very low frequency caused by the human walking. Then the counterpart magnet was set at the edge of unimorph piezoelectric cantilever, which vibrated with a high frequency. This low-to-high frequency convert "dual vibration system" can be characterized as an enhanced energy harvester. We examined and obtained average values of voltage and power in this system, as 8.31 mV and 0.33 μW. Those results show the possibility to apply for the energy harvester in the portable and implantable Bio-MEMS devices.

  8. Design Optimization of PZT-Based Piezoelectric Cantilever Beam by Using Computational Experiments

    NASA Astrophysics Data System (ADS)

    Kim, Jihoon; Park, Sanghyun; Lim, Woochul; Jang, Junyong; Lee, Tae Hee; Hong, Seong Kwang; Song, Yewon; Sung, Tae Hyun

    2016-08-01

    Piezoelectric energy harvesting is gaining huge research interest since it provides high power density and has real-life applicability. However, investigative research for the mechanical-electrical coupling phenomenon remains challenging. Many researchers depend on physical experiments to choose devices with the best performance which meet design objectives through case analysis; this involves high design costs. This study aims to develop a practical model using computer simulations and to propose an optimized design for a lead zirconate titanate (PZT)-based piezoelectric cantilever beam which is widely used in energy harvesting. In this study, the commercial finite element (FE) software is used to predict the voltage generated from vibrations of the PZT-based piezoelectric cantilever beam. Because the initial FE model differs from physical experiments, the model is calibrated by multi-objective optimization to increase the accuracy of the predictions. We collect data from physical experiments using the cantilever beam and use these experimental results in the calibration process. Since dynamic analysis in the FE analysis of the piezoelectric cantilever beam with a dense step size is considerably time-consuming, a surrogate model is employed for efficient optimization. Through the design optimization of the PZT-based piezoelectric cantilever beam, a high-performance piezoelectric device was developed. The sensitivity of the variables at the optimum design is analyzed to suggest a further improved device.

  9. Flexible tactile sensor for shear stress measurement using transferred sub-µm-thick Si piezoresistive cantilevers

    NASA Astrophysics Data System (ADS)

    Noda, Kentaro; Onoe, Hiroaki; Iwase, Eiji; Matsumoto, Kiyoshi; Shimoyama, Isao

    2012-11-01

    We propose a flexible tactile sensor using sub-µm-thick Si piezoresistive cantilevers for shear stress detection. The thin Si piezoresistive cantilevers were fabricated on the device layer of a silicon on insulator (SOI) wafer. By using an adhesion-based transfer method, only these thin and fragile cantilevers were transferred from the rigid handling layer of the SOI wafer to the polydimethylsiloxane layer without damage. Because the thin Si cantilevers have high durability of bending, the proposed sensor can be attached to a thin rod-type structure serving as the finger of a robotic hand. The cantilevers were arrayed in orthogonal directions to measure the X and Y directional components of applied shear stresses independently. We evaluated the bending durability of our flexible tactile sensor and confirmed that the sensor can be attached to a rod with a radius of 10 mm. The sensitivity of the flexible tactile sensor attached to a curved surface was 1.7 × 10-6 Pa-1 on average for a range of shear stresses from -1.8 × 103 to 1.8 × 103 Pa applied along its surface. It independently detected the X and Y directional components of the applied shear stresses.

  10. Calibration of the lateral spring constant of atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Song, Yunpeng; Wu, Sen; Xu, Linyan; Fu, Xing

    2015-10-01

    Atomic force microscope (AFM) is very useful in nano-scale force measurement. Lateral force is typically used in nanoscratch and surface friction measurement based on AFM. As one of the most important parameters to obtain lateral force, the lateral spring constant of AFM cantilever probe is of great significance and needs to be quantitative calibrated. Lateral torsion and lateral force of the cantilever are two parameters need to be measured in lateral spring constant calibration. In this article, we develop a calibration system and introduce a calibration method using an AFM head and an electromagnetic balance. An aluminium column with a known angel on top is placed on the weighing pan of the balance. The cantilever is precisely positioned in the AFM head, then approaches and bends on the aluminium column. During this procedure, the bending force and the lateral torsion of the cantilever are synchronously measured by the balance and an optical lever system, respectively. Then the lateral spring constant is calculated with a formula. By using this method, three kinds of rectangular cantilever are calibrated. The relative standard deviations of the calibration results are smaller than 2%.

  11. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials

    PubMed Central

    Qureshi, Awais; Li, Bing; Tan, K. T.

    2016-01-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes. PMID:27329828

  12. Damping analysis of a flexible cantilever beam containing an internal fluid channel: Experiment, modeling and analysis

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Masoumi, Masoud; Gaucher-Petitdemange, Matthias

    2015-03-01

    Passive structural damping treatments have been applied with the use of high-viscosity fillings (in practice) and have been the focus of numerous research studies and papers. However, internal viscoelastic fluid leading to passive damping of flexible cantilever beams, has not yet been investigated in the literature. Although structures containing internal fluid channels provide multifunctional solutions to many engineering issues, they also raise damping control requests caused by unacceptable vibrations due to ambient environmental changes. In this paper, we examine ambient effects on damping properties of flexible cantilever beams, each conveying an internal high-viscosity fluid channel. Experiments are conducted to investigate how the internal fluids provide damping to the system under varied temperatures, frequencies and base-acceleration levels. While the vibration analysis of pipes conveying internal flow has been extensively studied, internal high-viscosity fluids in relation to passive damping of flexible cantilever beams and their ambient, environment-dependent behaviors have not been well-investigated. Originally motivated by research, which uses internal fluid channels to provide the cooling of multifunctional composite structures, we aim to research the damping behaviors of cantilever beams. We will conduct an experimental study and modeling analysis, examining the vibrations and frequency responses of the cantilever beams when filled with three types of internal fluids.

  13. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials

    NASA Astrophysics Data System (ADS)

    Qureshi, Awais; Li, Bing; Tan, K. T.

    2016-06-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes.

  14. Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor.

    PubMed

    Körner, Julia; Reiche, Christopher F; Gemming, Thomas; Büchner, Bernd; Gerlach, Gerald; Mühl, Thomas

    2016-01-01

    Cantilever magnetometry is a measurement technique used to study magnetic nanoparticles. With decreasing sample size, the signal strength is significantly reduced, requiring advances of the technique. Ultrathin and slender cantilevers can address this challenge but lead to increased complexity of detection. We present an approach based on the co-resonant coupling of a micro- and a nanometer-sized cantilever. Via matching of the resonance frequencies of the two subsystems we induce a strong interplay between the oscillations of the two cantilevers, allowing for a detection of interactions between the sensitive nanocantilever and external influences in the amplitude response curve of the microcantilever. In our magnetometry experiment we used an iron-filled carbon nanotube acting simultaneously as nanocantilever and magnetic sample. Measurements revealed an enhancement of the commonly used frequency shift signal by five orders of magnitude compared to conventional cantilever magnetometry experiments with similar nanomagnets. With this experiment we do not only demonstrate the functionality of our sensor design but also its potential for very sensitive magnetometry measurements while maintaining a facile oscillation detection with a conventional microcantilever setup. PMID:27547621

  15. Design of piezoelectric MEMS cantilever for low-frequency vibration energy harvester

    NASA Astrophysics Data System (ADS)

    Takei, Ryohei; Makimoto, Natsumi; Okada, Hironao; Itoh, Toshihiro; Kobayashi, Takeshi

    2016-06-01

    We report the design of piezoelectric MEMS cantilevers formed on a silicon-on-insulator wafer to efficiently harvest electrical power from harmonic vibration with a frequency of approximately 30 Hz. Numerical simulation indicates that a >4-µm-thick top silicon layer and >3-µm-thick piezoelectric film are preferable to maximize the output electrical power. An in-plane structure of the cantilever is also designed retaining the footprint of the cantilever. The simulation results indicate that the output power is maximized when the length ratio of the proof mass to the cantilever beam is 1.5. To ensure the accuracy of the simulation, we fabricated and characterized cantilevers with a 10-µm-thick top silicon layer and a 1.8-µm-thick piezoelectric film, resulting in 0.21 µW at a vibration of 0.5 m/s2 and 25.1 Hz. The measured output power is in agreement with the simulated value, meaning that the design is significantly reliable for low-frequency vibration energy harvesters.

  16. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials.

    PubMed

    Qureshi, Awais; Li, Bing; Tan, K T

    2016-01-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes. PMID:27329828

  17. Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

    NASA Astrophysics Data System (ADS)

    Ngo, D. Q.; Petković, I.; Lollo, A.; Castellanos-Beltran, M. A.; Harris, J. G. E.

    2014-10-01

    We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 105 rings. The rings have a circumference of 1 μm, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current ⟨I⟩ in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of ⟨I⟩.

  18. Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

    SciTech Connect

    Ngo, D. Q.; Petković, I. Lollo, A.; Castellanos-Beltran, M. A.; Harris, J. G. E.

    2014-10-15

    We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 10{sup 5} rings. The rings have a circumference of 1 μm, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of .

  19. Surface-patterned SU-8 cantilever arrays for preliminary screening of cardiac toxicity.

    PubMed

    Kim, Jong Yun; Choi, Young-Soo; Lee, Bong-Kee; Lee, Dong-Weon

    2016-06-15

    Arrays of a μgrooved SU-8 cantilever were utilized to analyze changes in the contraction force and beating frequency of cardiomyocytes in vitro. The longitudinally patterned μgrooves facilitates alignment of cardiomyocytes on top of the SU-8 cantilever, which increases the contraction force of cardiomyocytes by a factor of about 2.5. The bending displacement of the SU-8 cantilever was precisely measured in nanoscale using a laser-based measurement system combined with a motorized xyz stage. The cantilever displacement due to contraction of the cardiomyocytes showed the maximum on day 8 after their cultivation. Following preliminary experiments, Isoproterenol, Verapamil, and Astemizole were used to investigate the effect of drug toxicity on the physiology of cardiomyocytes. The experimental results indicated that 1 µM of Isoproterenol treatment increased contraction force and beating frequencies of cardiomyocytes by 30% and 200%, respectively, whereas 500 nM of Verapamil treatment decreased contraction force and beating frequencies of cardiomyocytes by 56% and 42%, respectively. A concentration of less than 5 nM of the hERG channel suppression drug Astemizole did not change the contraction forces in the displacement but slightly decreased the beating frequencies. However, irregular or abnormal heartbeats were observed at Astemizole concentrations of 5 nM and higher. We experimentally conformed that the proposed SU-8 cantilever arrays combined with the laser-based measurement systems has the great potential for a high-throughput drug toxicity screening system in future. PMID:26878482

  20. Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

    PubMed Central

    Körner, Julia; Reiche, Christopher F; Gemming, Thomas; Büchner, Bernd; Gerlach, Gerald

    2016-01-01

    Summary Cantilever magnetometry is a measurement technique used to study magnetic nanoparticles. With decreasing sample size, the signal strength is significantly reduced, requiring advances of the technique. Ultrathin and slender cantilevers can address this challenge but lead to increased complexity of detection. We present an approach based on the co-resonant coupling of a micro- and a nanometer-sized cantilever. Via matching of the resonance frequencies of the two subsystems we induce a strong interplay between the oscillations of the two cantilevers, allowing for a detection of interactions between the sensitive nanocantilever and external influences in the amplitude response curve of the microcantilever. In our magnetometry experiment we used an iron-filled carbon nanotube acting simultaneously as nanocantilever and magnetic sample. Measurements revealed an enhancement of the commonly used frequency shift signal by five orders of magnitude compared to conventional cantilever magnetometry experiments with similar nanomagnets. With this experiment we do not only demonstrate the functionality of our sensor design but also its potential for very sensitive magnetometry measurements while maintaining a facile oscillation detection with a conventional microcantilever setup. PMID:27547621

  1. Calibration of the torsional and lateral spring constants of cantilever sensors.

    PubMed

    Parkin, John D; Hähner, Georg

    2014-06-01

    A method suitable for the calibration of the spring constants of all torsional and lateral eigenmodes of micro- and nanocantilever sensors is described. Such sensors enable nanomechanical measurements and the characterization of nanomaterials, for example with atomic force microscopy. The method presented involves the interaction of a flow of fluid from a microchannel with the cantilever beam. Forces imparted by the flow cause the cantilever to bend and induce a measurable change of the torsional and lateral resonance frequencies. From the frequency shifts the cantilever spring constants can be determined. The method does not involve physical contact between the cantilever or its tip and a hard surface. As such it is non-invasive and does not risk damage to the cantilever. Experimental data is presented for two rectangular microcantilevers with fundamental flexural spring constants of 0.046 and 0.154 N m(-1). The experimentally determined torsional stiffness values are compared with those obtained by the Sader method. We demonstrate that the torsional spring constants can be readily calibrated using the method with an accuracy of around 15%.

  2. Micromechanical cantilever array sensors for selective fungal immobilization and fast growth detection.

    PubMed

    Nugaeva, Natalia; Gfeller, Karin Y; Backmann, Natalija; Lang, Hans Peter; Düggelin, Marcel; Hegner, Martin

    2005-12-15

    We demonstrate the use of micromechanical cantilever arrays for selective immobilization and fast quantitative detection of vital fungal spores. Micro-fabricated uncoated as well as gold-coated silicon cantilevers were functionalized with concanavalin A, fibronectin or immunoglobulin G. In our experiments two major morphological fungal forms were used--the mycelial form Aspergillus niger and the unicellular yeast form Saccharomyces cerevisiae, as models to explore a new method for growth detection of eukaryotic organisms using cantilever arrays. We exploited the specific biomolecular interactions of surface grafted proteins with the molecular structures on the fungal cell surface. It was found that these proteins have different affinities and efficiencies to bind the spores. Maximum spore immobilization, germination and mycelium growth was observed on the immunoglobulin G functionalized cantilever surfaces. We show that spore immobilization and germination of the mycelial fungus A. niger and yeast S. cerevisiae led to shifts in resonance frequency within a few hours as measured by dynamically operated cantilever arrays, whereas conventional techniques would require several days. The biosensor could detect the target fungi in a range of 10(3) - 10(6) CFUml(-1). The measured shift is proportional to the mass of single fungal spores and can be used to evaluate spore contamination levels. Applications lie in the field of medical and agricultural diagnostics, food- and water-quality monitoring.

  3. A calibration method for lateral forces for use with colloidal probe force microscopy cantilevers

    SciTech Connect

    Quintanilla, M. A. S.; Goddard, D. T.

    2008-02-15

    A calibration method is described for colloidal probe cantilevers that enables friction force measurements obtained using lateral force microscopy (LFM) to be quantified. The method is an adaptation of the lever method of Feiler et al. [A. Feiler, P. Attard, and I. Larson, Rev. Sci. Instum. 71, 2746 (2000)] and uses the advantageous positioning of probe particles that are usually offset from the central axis of the cantilever. The main sources of error in the calibration method are assessed, in particular, the potential misalignment of the long axis of the cantilever that ideally should be perpendicular to the photodiode detector. When this is not taken into account, the misalignment is shown to have a significant effect on the cantilever torsional stiffness but not on the lateral photodiode sensitivity. Also, because the friction signal is affected by the topography of the substrate, the method presented is valid only against flat substrates. Two types of particles, 20 {mu}m glass beads and UO{sub 3} agglomerates attached to silicon tapping mode cantilevers were used to test the method against substrates including glass, cleaved mica, and UO{sub 2} single crystals. Comparisons with the lateral compliance method of Cain et al. [R. G. Cain, S. Biggs, and N. W. Page, J. Colloid Interface Sci. 227, 55 (2000)] are also made.

  4. Role of implant configurations supporting three-unit fixed partial denture on mandibular bone response: biological-data-based finite element study.

    PubMed

    Yoda, N; Liao, Z; Chen, J; Sasaki, K; Swain, M; Li, Q

    2016-09-01

    Implant-supported fixed partial denture with cantilever extension can transfer the excessive load to the bone around implants and stress/strain concentration potentially leading to bone resorption. This study investigated the effects of implant configurations supporting three-unit fixed partial denture (FPD) on the stress and strain distribution in the peri-implant bone by combining clinically measured time-dependent loading data and finite element (FE) analysis. A 3-dimensional mandibular model was constructed based on computed tomography (CT) images. Four different configurations of implants supporting 3-unit FPDs, namely three implant-supported FPD, conventional three-unit bridge FPD, distal cantilever FPD and mesial cantilever FPD, were modelled. The FPDs were virtually inserted to the molar area in the mandibular FE models. The FPDs were loaded according to time-dependent in vivo-measured 3-dimensional loading data during chewing. The von Mises stress (VMS) and equivalent strain (EQS) in peri-implant bone regions were evaluated as mechanical stimuli. During the chewing cycles, the regions near implant necks and bottom apexes experienced high VMS and EQS than the middle regions in all implant-supported FPD configurations. Higher VMS and EQS values were also observed at the implant neck region adjacent to the cantilever extension in the cantilevered configurations. The patient-specific dynamic loading data and CT-based reconstruction of full 3D mandibular allowed us to model the biomechanical responses more realistically. The results provided data for clinical assessment of implant configuration to improve longevity and reliability of the implant-supported FPD restoration. PMID:27224022

  5. Apparatus for fixing latency

    DOEpatents

    Hall, David R.; Bartholomew, David B.; Moon, Justin; Koehler, Roger O.

    2009-09-08

    An apparatus for fixing computational latency within a deterministic region on a network comprises a network interface modem, a high priority module and at least one deterministic peripheral device. The network interface modem is in communication with the network. The high priority module is in communication with the network interface modem. The at least one deterministic peripheral device is connected to the high priority module. The high priority module comprises a packet assembler/disassembler, and hardware for performing at least one operation. Also disclosed is an apparatus for executing at least one instruction on a downhole device within a deterministic region, the apparatus comprising a control device, a downhole network, and a downhole device. The control device is near the surface of a downhole tool string. The downhole network is integrated into the tool string. The downhole device is in communication with the downhole network.

  6. [Fixed-dose combination].

    PubMed

    Nagai, Yoshio

    2015-03-01

    Many patients with type 2 diabetes mellitus(T2DM) do not achieve satisfactory glycemic control by monotherapy alone, and often require multiple oral hypoglycemic agents (OHAs). Combining OHAs with complementary mechanisms of action is fundamental to the management of T2DM. Fixed-dose combination therapy(FDC) offers a method of simplifying complex regimens. Efficacy and tolerability appear to be similar between FDC and treatment with individual agents. In addition, FDC can enhance adherence and improved adherence may result in improved glycemic control. Four FDC agents are available in Japan: pioglitazone-glimepiride, pioglitazone-metformin, pioglitazone-alogliptin, and voglibose-mitiglinide. In this review, the advantages and disadvantages of these four combinations are identified and discussed. PMID:25812374

  7. Fixed Access Network Sharing

    NASA Astrophysics Data System (ADS)

    Cornaglia, Bruno; Young, Gavin; Marchetta, Antonio

    2015-12-01

    Fixed broadband network deployments are moving inexorably to the use of Next Generation Access (NGA) technologies and architectures. These NGA deployments involve building fiber infrastructure increasingly closer to the customer in order to increase the proportion of fiber on the customer's access connection (Fibre-To-The-Home/Building/Door/Cabinet… i.e. FTTx). This increases the speed of services that can be sold and will be increasingly required to meet the demands of new generations of video services as we evolve from HDTV to "Ultra-HD TV" with 4k and 8k lines of video resolution. However, building fiber access networks is a costly endeavor. It requires significant capital in order to cover any significant geographic coverage. Hence many companies are forming partnerships and joint-ventures in order to share the NGA network construction costs. One form of such a partnership involves two companies agreeing to each build to cover a certain geographic area and then "cross-selling" NGA products to each other in order to access customers within their partner's footprint (NGA coverage area). This is tantamount to a bi-lateral wholesale partnership. The concept of Fixed Access Network Sharing (FANS) is to address the possibility of sharing infrastructure with a high degree of flexibility for all network operators involved. By providing greater configuration control over the NGA network infrastructure, the service provider has a greater ability to define the network and hence to define their product capabilities at the active layer. This gives the service provider partners greater product development autonomy plus the ability to differentiate from each other at the active network layer.

  8. Lateral force microscope calibration using a modified atomic force microscope cantilever

    SciTech Connect

    Reitsma, M. G.

    2007-10-15

    A proof-of-concept study is presented for a prototype atomic force microscope (AFM) cantilever and associated calibration procedure that provide a path for quantitative friction measurement using a lateral force microscope (LFM). The calibration procedure is based on the method proposed by Feiler et al. [Rev. Sci. Instrum. 71, 2746 (2000)] but allows for calibration and friction measurements to be carried out in situ and with greater precision. The modified AFM cantilever is equipped with lateral lever arms that facilitate the application of normal and lateral forces, comparable to those acting in a typical LFM friction experiment. The technique allows the user to select acceptable precision via a potentially unlimited number of calibration measurements across the full working range of the LFM photodetector. A microfabricated version of the cantilever would be compatible with typical commercial AFM instrumentation and allow for common AFM techniques such as topography imaging and other surface force measurements to be performed.

  9. Accurate and precise calibration of AFM cantilever spring constants using laser Doppler vibrometry.

    PubMed

    Gates, Richard S; Pratt, Jon R

    2012-09-21

    Accurate cantilever spring constants are important in atomic force microscopy both in control of sensitive imaging and to provide correct nanomechanical property measurements. Conventional atomic force microscope (AFM) spring constant calibration techniques are usually performed in an AFM. They rely on significant handling and often require touching the cantilever probe tip to a surface to calibrate the optical lever sensitivity of the configuration. This can damage the tip. The thermal calibration technique developed for laser Doppler vibrometry (LDV) can be used to calibrate cantilevers without handling or touching the tip to a surface. Both flexural and torsional spring constants can be measured. Using both Euler-Bernoulli modeling and an SI traceable electrostatic force balance technique as a comparison we demonstrate that the LDV thermal technique is capable of providing rapid calibrations with a combination of ease, accuracy and precision beyond anything previously available.

  10. Wide frequency range capacitive detection of loss in a metallic cantilever using resonance and relaxation modes.

    PubMed

    Richert, Ranko

    2007-05-01

    The impedance of a capacitor which embraces a charged cantilever is used to measure the mechanical properties of the cantilever material. The technique has been tested with an amorphous metallic specimen, but is applicable for many other solids. The material damping can be measured at the resonance frequency of the cantilever via the width of the resonance curve or by recording the ring-down behavior. Additionally, several decades in frequency are accessible below the resonance frequency, where values as low as nu=0.03 Hz are achieved easily. The data are analyzed with a single equation that captures the damping at all frequencies in terms of the material specific Young's modulus E and its loss angle tan delta=E"/E'.

  11. Fabrication of high-aspect-ratio nanotips integrated with single-crystal silicon cantilevers

    NASA Astrophysics Data System (ADS)

    Chen, Henry J. H.; Hung, C. S.

    2007-09-01

    This work presents a novel fabrication technique for an atomic force microscope (AFM) nanotip. The high-aspect-ratio silicon nanotip on a single-crystal silicon cantilever was manufactured using inductive coupling plasma (ICP) anisotropic etching and XeF2 isotropic silicon etching processes. The cantilever shape was defined and the high-aspect-ratio silicon nanotip structure was fabricated by ICP anisotropic deep silicon etching (~50-80 µm deep). Nanotip sharpening and single-crystal Si cantilever undercutting were achieved simultaneously via two-step XeF2 isotropic silicon etching. The final structures were observed by a scanning electron microscope (SEM) and the diameter of the nanotip was about ~30 nm. This process is simple, easy to use, CMOS post-process-compatible and suitable for the future IC integrated AFM nanotip applications.

  12. Design optimization of piezoresistive cantilevers for force sensing in air and water

    PubMed Central

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

    2009-01-01

    Piezoresistive cantilevers fabricated from doped silicon or metal films are commonly used for force, topography, and chemical sensing at the micro- and macroscales. Proper design is required to optimize the achievable resolution by maximizing sensitivity while simultaneously minimizing the integrated noise over the bandwidth of interest. Existing analytical design methods are insufficient for modeling complex dopant profiles, design constraints, and nonlinear phenomena such as damping in fluid. Here we present an optimization method based on an analytical piezoresistive cantilever model. We use an existing iterative optimizer to minimimize a performance goal, such as minimum detectable force. The design tool is available as open source software. Optimal cantilever design and performance are found to strongly depend on the measurement bandwidth and the constraints applied. We discuss results for silicon piezoresistors fabricated by epitaxy and diffusion, but the method can be applied to any dopant profile or material which can be modeled in a similar fashion or extended to other microelectromechanical systems. PMID:19865512

  13. Quantitative displacement measurement of a nanotube cantilever with nanometer accuracy using epifluorescence microscopy

    SciTech Connect

    Park, Hyojun; Kwon, Soongeun; Kim, Soohyun

    2009-05-15

    A method to measure the deflection of a nanotube cantilever with nanometer accuracy in an air or liquid environment is presented. We attached fluorescent dyes at the end of a nanotube to detect its deflection. The nanotube cantilever was fabricated with a multiwalled carbon nanotube that is attached to the end of an electrochemically etched tungsten tip, and it was imaged in an epifluorescence microscope system. The fluorescence intensity distribution of the fluorescent particles at the end of the nanotube was approximated with a Gaussian and fitted by least-squares method. Finally, we were able to measure the displacement of the nanotube cantilever during electrostatic actuation with positional accuracy of a few nanometers. This technique can be applied to a manipulator or a force transducer on related a few piconewton forces.

  14. Active vibration control of flexible cantilever plates using piezoelectric materials and artificial neural networks

    NASA Astrophysics Data System (ADS)

    Abdeljaber, Osama; Avci, Onur; Inman, Daniel J.

    2016-02-01

    The study presented in this paper introduces a new intelligent methodology to mitigate the vibration response of flexible cantilever plates. The use of the piezoelectric sensor/actuator pairs for active control of plates is discussed. An intelligent neural network based controller is designed to control the optimal voltage applied on the piezoelectric patches. The control technique utilizes a neurocontroller along with a Kalman Filter to compute the appropriate actuator command. The neurocontroller is trained based on an algorithm that incorporates a set of emulator neural networks which are also trained to predict the future response of the cantilever plate. Then, the neurocontroller is evaluated by comparing the uncontrolled and controlled responses under several types of dynamic excitations. It is observed that the neurocontroller reduced the vibration response of the flexible cantilever plate significantly; the results demonstrated the success and robustness of the neurocontroller independent of the type and distribution of the excitation force.

  15. High-speed imaging upgrade for a standard sample scanning atomic force microscope using small cantilevers

    SciTech Connect

    Adams, Jonathan D.; Nievergelt, Adrian; Erickson, Blake W.; Yang, Chen; Dukic, Maja; Fantner, Georg E.

    2014-09-15

    We present an atomic force microscope (AFM) head for optical beam deflection on small cantilevers. Our AFM head is designed to be small in size, easily integrated into a commercial AFM system, and has a modular architecture facilitating exchange of the optical and electronic assemblies. We present two different designs for both the optical beam deflection and the electronic readout systems, and evaluate their performance. Using small cantilevers with our AFM head on an otherwise unmodified commercial AFM system, we are able to take tapping mode images approximately 5–10 times faster compared to the same AFM system using large cantilevers. By using additional scanner turnaround resonance compensation and a controller designed for high-speed AFM imaging, we show tapping mode imaging of lipid bilayers at line scan rates of 100–500 Hz for scan areas of several micrometers in size.

  16. Frequency dependence of viscous and viscoelastic dissipation in coated micro-cantilevers from noise measurement.

    PubMed

    Paolino, P; Bellon, L

    2009-10-01

    We measure the mechanical thermal noise of soft silicon atomic force microscope cantilevers. Using an interferometric setup, we obtain a resolution down to 10(-14) m Hz(-1/2) on a wide spectral range (3-10(5) Hz). The low frequency behavior depends dramatically on the presence of a reflective coating: almost flat spectra for uncoated cantilevers versus a 1/f like trend for coated ones. The addition of a viscoelastic term in models of the mechanical system can account for this observation. Use of Kramers-Kronig relations validate this approach with a complete determination of the response of the cantilever: a power law with a small coefficient is found for the frequency dependence of viscoelasticity due to the coating, whereas the viscous damping due to the surrounding atmosphere is accurately described by the Sader model. PMID:19738311

  17. Fabrication of high-density cantilever arrays and through-wafer interconnects

    SciTech Connect

    A. Harley, J.; Abdollahi-Alibeik, S.; Chow, E. M.; Kenney, T. W.; McCarthy, A. M.; McVittie, J. P.; Partridge; Quate, C. F.; Soh, H. T.

    1998-11-03

    Processes to fabricate dense, dry released microstructures with electrical connections on the opposite side of the wafer are described. A 10 x 10 array of silicon and polysilicon cantilevers with high packing density (5 tips/mm2) and high uniformity (<10 µm length variation across the wafer) are demonstrated. The cantilever release process uses a deep SF6/C4F8, plasma etch followed by a HBr plasma etch to accurately release cantilevers. A process for fabricating electrical contacts through the backside of the wafer is also described. Electrodeposited resist, conformal CVD metal deposition and deep SF6/C4F8 plasma etching are used to make 30 µm/side square vias each of which has a resistance of 50 m(omega).

  18. Dynamic analysis and temperature measurements of concrete cantilever beam using fibre Bragg gratings

    NASA Astrophysics Data System (ADS)

    da Silva, Jean Carlos Cardozo; Martelli, Cicero; Kalinowski, Hypolito José; Penner, Elisabeth; Canning, John; Groothoff, Nathaniel

    2007-01-01

    We analyzed the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure was fitted with two fibre Bragg gratings (FBG) sensors. One of them measured vibration and the other measured the temperature inside of the cantilever beam, while the beam was exposed to fire. A high-temperature probe based on a simple packaging system, which isolates the sensing FBG from any mechanical action, was developed. A low-cost fibre Bragg grating interrogation system, including easy assembly and maintenance, was used for the measurements. The temperature in the cantilever beam increased until 150 °C and a reduction in the strength of concrete was observed through modal analysis. Results reveal a considerable reduction in strength occurs even with exposures to moderate temperatures (less than 90 °C).

  19. Effect of Centrifugal Force on the Elastic Curve of a Vibrating Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Simpkinson, Scott H; Eatherton, Laurel J; Millenson, Morton B

    1948-01-01

    A study was made to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. The results of a mathematical analysis are presented together with experimental results obtained by means of stroboscopic photographs and strain gages. The theoretical analysis was confined to uniform cantilever beams; the experimental work was extended to include a tapered cantilever beam to simulate an aircraft propeller blade. Calculations were made on nondimensional basis for second and third mode vibration; the experiments were conducted on beams of various lengths, materials, and cross sections for second-mode vibration. From this investigation it was concluded that high vibratory-stress positions are unaffected by the addition of centrifugal force. Nonrotating vibration surveys of blades therefore are valuable in predicting high vibratory-stress locations under operating conditions.

  20. Method and apparatus for sensing the natural frequency of a cantilevered body

    DOEpatents

    Duncan, Michael G.

    2000-01-01

    A method and apparatus for measuring the natural resonant frequency of a spring element by monitoring a phase difference between an output signal from the spring element and an input signal to the spring element and by adjusting frequency of the input signal until a detected phase difference signals that the natural resonant frequency has been reached. The method and apparatus are applied to a micro-cantilevered elements used to measure gas compositions and concentrations. Such elements are provided with coatings that absorb gas to cause deflections and changes in the mass or spring constant of the cantilevered element. These changes correspond to changes in the natural resonant frequency of the cantilevered element which are measured using the method and apparatus described herein.

  1. Highly sensitive polymer-based cantilever-sensors for DNA detection.

    PubMed

    Calleja, M; Nordström, M; Alvarez, M; Tamayo, J; Lechuga, L M; Boisen, A

    2005-11-01

    We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers.

  2. Design and experimental evaluation of flextensional-cantilever based piezoelectric transducers for flow energy harvesting

    NASA Astrophysics Data System (ADS)

    Lee, Hyeong Jae; Sherrit, Stewart; Tosi, Luis Phillipe; Colonius, Tim

    2016-04-01

    Cantilever type piezoelectric harvesters, such as bimorphs, are typically used for vibration induced energy harvesting. However, a major drawback of a piezoelectric bimorph is its brittle nature in harsh environments, precipitating short life-times as well as output power degradation. The emphasis in this work is to design robust, highly efficient piezoelectric harvesters that are capable of generating electrical power in the milliwatt range. Various harvesters were modeled, designed and prototyped, and the flextensional actuator based harvester, where the metal cantilever is mounted and coupled between two flextensional actuators, was found to be a viable alternative to the cantilever type piezoelectric harvesters. Preliminary tests show that these devices equipped with 5x5x36 mm two piezoelectric PZT stacks can produce greater than 50 mW of power under air flow induced vibrations.

  3. Growth and sculpting of Co nano-strings on Si micro-cantilevers: magneto-mechanical properties.

    PubMed

    Madurga, V; Favieres, C; Vergara, J

    2010-03-01

    Si micro-cantilevers were coated with Co nano-strings, which were simultaneously grown and sculpted during off-normal pulsed laser deposition. The surface morphology of micro-cantilevers with longitudinal or transverse nano-strings was analysed by scanning tunnelling microscopy. Magnetic anisotropy was detected with a magnetization direction parallel to the nano-strings. The two micro-cantilever types exhibited different mechanical behaviours when placed in a non-uniform magnetic field. By varying the relative position of the micro-cantilever with respect to the gradient direction of this field, a split in the resonant frequency shift of the micro-cantilevers was generated, depending on the direction of magnetic anisotropy. Discrimination was achieved between the micro-cantilevers with transverse nano-strings and the micro-cantilevers with longitudinal nano-strings. The lowest limit of magnetic moment for distinction between these covered micro-cantilevers was 10(-8) emu. The possible benefits of these magneto-mechanical properties for the biological, chemical and physical applications of some nano-mechanical devices are pointed out.

  4. Study on the design method of the jack-up's x-type cantilever allowable load nephogram

    NASA Astrophysics Data System (ADS)

    Zhu, Yazhou; Sun, Chengmeng; Qin, Hongde; Jiang, Bin; Fan, Yansong

    2014-09-01

    The extending of a cantilever and transverse moving of a drilling floor enable the jack-up to operate in several well positions after the Jack-up has pitched. The cantilever allowable load nephogram is the critical reference which can evaluate the jack-up's drilling ability, design the cantilever structure and instruct a jack-up manager to make the operations safe. The intent of this paper is to explore the interrelationships between the cantilever position, drilling floor and the loads including wind force, the stand set-back weight etc., through analyzing the structure and load characteristics of the x-type cantilever and the simplified mechanics model with the restriction of the maximum moment capacity of the cantilever single side beam. Referring to several typical position designs load values, the cantilever allowable load nephogram is obtained by using the suitable interpolation method. The paper gives a method for cantilever allowable load design, which is proved reliable and effective by the calculation example.

  5. Dynamic characterization of small fibers based on the flexural vibrations of a piezoelectric cantilever probe

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaofei; Ye, Xuan; Li, Xide

    2016-08-01

    In this paper, we present a cantilever-probe system excited by a piezoelectric actuator, and use it to measure the dynamic mechanical properties of a micro- and nanoscale fiber. Coupling the fiber to the free end of the cantilever probe, we found the dynamic stiffness and damping coefficient of the fiber from the resonance frequency and the quality factor of the fiber-cantilever-probe system. The properties of Bacillus subtilis fibers measured using our proposed system agreed with tensile measurements, validating our method. Our measurements show that the piezoelectric actuator coupled to cantilever probe can be made equivalent to a clamped cantilever with an effective length, and calculated results show that the errors of measured natural frequency of the system can be ignored if the coupled fiber has an inclination angle of alignment of less than 10°. A sensitivity analysis indicates that the first or second resonant mode is the sensitive mode to test the sample’s dynamic stiffness, while the damping property has different sensitivities for the first four modes. Our theoretical analysis demonstrates that the double-cantilever probe is also an effective sensitive structure that can be used to perform dynamic loading and characterize dynamic response. Our method has the advantage of using amplitude-frequency curves to obtain the dynamic mechanical properties without directly measuring displacements and forces as in tensile tests, and it also avoids the effects of the complex surface structure and deformation presenting in contact resonance method. Our method is effective for measuring the dynamic mechanical properties of fiber-like one-dimensional (1D) materials.

  6. Study of Effects of Sweep on the Flutter of Cantilever Wings

    NASA Technical Reports Server (NTRS)

    Barmby, J G; Cunningham, H J; Garrick, I E

    1951-01-01

    An experimental and analytical investigation of the flutter of sweptback cantilever wings is reported. The experiments employed groups of wings swept back by rotating and by shearing. The angle of sweep range from 0 degree to 60 degrees and Mach numbers extended to approximately 0.85. A theoretical analysis of the air forces on an oscillating swept wing of high length-chord ratio is developed, and the approximations inherent in the assumptions are discussed. Comparison with experiment indicates that the analysis developed in the present report is satisfactory for giving the main effects of sweep, at least for nearly uniform cantilever wings of high and moderate length-chord ratios.

  7. Fast optical cooling of nanomechanical cantilever with the dynamical Zeeman effect.

    PubMed

    Zhang, Jian-Qi; Zhang, Shuo; Zou, Jin-Hua; Chen, Liang; Yang, Wen; Li, Yong; Feng, Mang

    2013-12-01

    We propose an efficient optical electromagnetically induced transparency (EIT) cooling scheme for a cantilever with a nitrogen-vacancy center attached in a non-uniform magnetic field using dynamical Zeeman effect. In our scheme, the Zeeman effect combined with the quantum interference effect enhances the desired cooling transition and suppresses the undesired heating transitions. As a result, the cantilever can be cooled down to nearly the vibrational ground state under realistic experimental conditions within a short time. This efficient optical EIT cooling scheme can be reduced to the typical EIT cooling scheme under special conditions. PMID:24514521

  8. Note: Simultaneous determination of local temperature and thickness of heated cantilevers using two-wavelength thermoreflectance.

    PubMed

    Park, Heeseung; Lee, Bong Jae; Lee, Jungchul

    2014-03-01

    In this work, we have demonstrated that two-wavelength thermoreflectance technique can be used to characterize the local thickness and temperature of heated cantilevers at steady-state operation. By taking the ratio of reflectances for two lasers with different wavelengths, the geometrical factor causing the mismatch between experimentally measured and theoretically calculated reflectances was eliminated. Based on the fitting analysis of the reflectance ratio of two wavelengths at various input powers to the heated cantilevers, the local temperature and thickness could be unambiguously determined.

  9. In vacuo elastodynamics of a flexible cantilever for wideband energy harvesting

    NASA Astrophysics Data System (ADS)

    Tan, D.; Erturk, A.

    2016-04-01

    We explore the potential for bandwidth enhancement by merely exploiting the hardening nonlinearity of a flexible cantilever. To date, this cubic hardening behavior has been minor due to dissipative effects, especially fluid drag. The goal here is to minimize the fluid damping and thereby achieve the jump phenomenon. A vacuum setup that is compatible with the armature of a long-stroke shaker is employed. Experiments are conducted for a range of air pressure and base excitation levels. The overall nonlinear non-conservative elastodynamics of the cantilever is also modeled and experimentally validated by empirically accounting for fluid damping.

  10. Forced response of a cantilever beam with a dry friction damper attached. I - Theory. II - Experiment

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.; Schwartz, H. B.

    1983-01-01

    A theoretical and experimental study of the forced vibration response of a cantilevered beam with Coulomb damping nonlinearity is described. Viscous damping in the beam is neglected. Beam and dry friction damper configurations of interest for applications to turbine blade vibrations are considered. It is shown that the basic phenomena found by Dowell (1983) for a simply supported beam with an attached dry friction damper of specific geometry also apply to a cantilevered beam and a more general representation of the dry friction damper and its associated mass and stiffness.

  11. Performance evaluation and parametric analysis on cantilevered ramp injector in supersonic flows

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Li, Shi-bin; Yan, Li; Wang, Zhen-guo

    2013-03-01

    The cantilevered ramp injector is one of the most promising candidates for the mixing enhancement between the fuel and the supersonic air, and its parametric analysis has drawn an increasing attention of researchers. The flow field characteristics and the drag force of the cantilevered ramp injector in the supersonic flow with the freestream Mach number 2.0 have been investigated numerically, and the predicted injectant mole fraction and static pressure profiles have been compared with the available experimental data in the open literature. At the same time, the grid independency analysis has been performed by using the coarse, the moderate and the refined grid scales, and the influence of the turbulence model on the flow field of the cantilevered ramp injector has been carried on as well. Further, the effects of the swept angle, the ramp angle and the length of the step on the performance of the cantilevered ramp injector have been discussed subsequently. The obtained results show that the grid scale has only a slight impact on the flow field of the cantilevered ramp injector except in the region near the fuel injector, and the predicted results show reasonable agreement with the experimental data. Additionally, the turbulence model makes a slight difference to the numerical results, and the results obtained by the RNG k-ɛ and SST k-ω turbulence models are almost the same. The swept angle and the ramp angle have the same impact on the performance of the cantilevered ramp injector, and the kidney-shaped plume is formed with shorter distance with the increase of the swept and ramp angles. At the same time, the shape of the injectant mole fraction contour at X/H=6 goes through a transition from a peach-shaped plume to a kidney-shaped plume, and the cantilevered ramp injector with larger swept and ramp angles has the higher mixing efficiency and the larger drag force. The length of the step has only a slight impact on the drag force performance of the cantilevered

  12. Self-excited coupled cantilevers for mass sensing in viscous measurement environments

    NASA Astrophysics Data System (ADS)

    Yabuno, Hiroshi; Seo, Yasuhiro; Kuroda, Masaharu

    2013-08-01

    The eigenstate shift in two nearly identical and weakly coupled cantilevers provides a means to realize much higher-sensitivity mass detection compared with the eigenfrequency shift approach. We propose using self-excited oscillations for eigenstate detection without using frequency response or resonance curve normally used in conventional methods. Mass sensing thus becomes possible even in high-viscosity environments, where the peak of the frequency response curve is ambiguous or does not exist. The feedback control method is theoretically clarified to produce self-excited oscillation and the validity of the proposed method is investigated experimentally using macroscale coupled cantilevers.

  13. Resonant interaction of trapped cold atoms with a magnetic cantilever tip

    NASA Astrophysics Data System (ADS)

    Montoya, Cris; Valencia, Jose; Geraci, Andrew A.; Eardley, Matthew; Moreland, John; Hollberg, Leo; Kitching, John

    2015-06-01

    Magnetic resonance in an ensemble of laser-cooled trapped Rb atoms is excited using a microcantilever with a magnetic tip. The cantilever is mounted on a multilayer chip designed to capture, cool, and magnetically transport cold atoms. The coupling is observed by measuring the loss from a magnetic trap as the oscillating cantilever induces Zeeman-state transitions in the atoms. Interfacing cold atoms with mechanical devices could enable probing and manipulating atomic spins with nanometer spatial resolution and single-spin sensitivity, leading to new capabilities in quantum computation, quantum simulation, and precision sensing.

  14. Fast optical cooling of nanomechanical cantilever with the dynamical Zeeman effect.

    PubMed

    Zhang, Jian-Qi; Zhang, Shuo; Zou, Jin-Hua; Chen, Liang; Yang, Wen; Li, Yong; Feng, Mang

    2013-12-01

    We propose an efficient optical electromagnetically induced transparency (EIT) cooling scheme for a cantilever with a nitrogen-vacancy center attached in a non-uniform magnetic field using dynamical Zeeman effect. In our scheme, the Zeeman effect combined with the quantum interference effect enhances the desired cooling transition and suppresses the undesired heating transitions. As a result, the cantilever can be cooled down to nearly the vibrational ground state under realistic experimental conditions within a short time. This efficient optical EIT cooling scheme can be reduced to the typical EIT cooling scheme under special conditions.

  15. Nonlinear output properties of cantilever driving low frequency piezoelectric energy harvester

    NASA Astrophysics Data System (ADS)

    Xu, Chundong; Ren, Bo; Liang, Zhu; Chen, Jianwei; Zhang, Haiwu; Yue, Qingwen; Xu, Qing; Zhao, Xiangyong; Luo, Haosu

    2012-11-01

    Cantilever driving low frequency piezoelectric energy harvester (CANDLE) has been found as a promising structure for vibration energy harvesting. This paper presents the nonlinear output properties of the CANDLE to optimize the performance of the device. Simulation results of the finite element method illustrate that nonlinear contacts between the cymbal transducers and the cantilever beam are main reasons of the nonlinear output. However, high excitation acceleration of the nonlinear leap point limits the application of the device. Based on the simulation results and theory analysis, the excitation acceleration is reduced to 30 m/s2 by increasing the proof mass.

  16. Integrated cantilever-based flow sensors with tunable sensitivity for in-line monitoring of flow fluctuations in microfluidic systems.

    PubMed

    Noeth, Nadine; Keller, Stephan Sylvest; Boisen, Anja

    2013-12-23

    For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN) and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL/min and the thinnest SU-8 cantilevers a detection limit below 5 nL/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.

  17. A study of fixed prosthodontics performed at a university clinic 18 years after insertion.

    PubMed

    Sundh, B; Odman, P

    1997-01-01

    This study obtained information on the long-term efficiency of prosthetic rehabilitation with fixed partial dentures performed by undergraduate students. From a list of discharged patients treated from 1975 to 1976 by undergraduate students at a dental school, 101 were recalled for free clinical examinations after 6, 11, and 18 years. A total of 163 fixed partial dentures were inserted. The majority (85%) of the fixed partial dentures were acrylic resin veneer-gold restorations; 15% were metal ceramic restorations. During this study period, 14 individuals died, leaving 138 fixed partial dentures to be examined. Of these, 35 (25%) were removed after a mean of 11 years in function, which left 75% in place and functioning after 18 years. The main causes for removal included caries, periodontitis, root fracture, and endodontic complications. Fewer metal ceramic restorations than acrylic resin veneer-gold restorations were removed. The removal rate for abutments with cast posts and cores was higher than the removal rate of total abutments. There was no difference in removal frequency between fixed partial dentures with moderate cantilever extensions and those with end-supported extensions.

  18. The Resin-Bonded Fixed Partial Denture as the First Treatment Consideration to Replace a Missing Tooth.

    PubMed

    Kuijs, Ruud; van Dalen, Andy; Roeters, Joost; Wismeijer, Daniel

    2016-01-01

    The resin-bonded fixed partial denture (RB-FPD) is the first restorative treatment option to be considered in cases where one or more teeth are missing. The indications for implants, conventional FPDs, and adhesive FPDs, considering the general and dental conditions of the patient, are discussed in this article. When the RB-FPD is the chosen option, a direct or indirect technique, a cantilever-type or fixed-fixed design, and materials to be used need to be selected. The choice will depend on a variety of factors, such as interproximal space at the connector area, anterior or posterior location, the skills of the dentist, esthetics, and the patient's wishes. The RB-FPD can be made using various techniques and materials. PMID:27479338

  19. Fixed points of quantum gravity.

    PubMed

    Litim, Daniel F

    2004-05-21

    Euclidean quantum gravity is studied with renormalization group methods. Analytical results for a nontrivial ultraviolet fixed point are found for arbitrary dimensions and gauge fixing parameters in the Einstein-Hilbert truncation. Implications for quantum gravity in four dimensions are discussed.

  20. Quick and easy microfabrication of T-shaped cantilevers to generate arrays of microtissues.

    PubMed

    Kalman, Benoît; Picart, Catherine; Boudou, Thomas

    2016-06-01

    Over the past decade, a major effort was made to miniaturize engineered tissues, as to further improve the throughput of such approach. Most existing methods for generating microtissues thus rely on T-shaped cantilevers made by soft lithography and based on the use of negative SU-8 photoresist. However, photopatterning T-shaped microstructures with these negative photoresists is fastidious and time-consuming. Here we introduce a novel method to quickly generate T-shaped cantilevers dedicated to generation of cellular microtissues, based on the use of positive photoresist. With only two layers of photoresist and one photomask, we were able to fabricate arrays of microwells in less than 3 h, each containing two T-shaped cantilevers presenting either a rectangular or a circular geometry. As a proof of concept, these arrays were then replicated in poly(dimethylsiloxane) and microtissues composed of NIH 3T3 fibroblasts encapsulated in collagen I were generated, while the two cantilevers simultaneously constrain and report forces generated by the microtissues. Immunostainings showed longitudinally aligned and elongated fibroblasts over the whole microtissue after 8 days of culture. The method described here opens the potential to quick prototyping platforms for high-throughput, low-volume screening applications.

  1. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves

    NASA Astrophysics Data System (ADS)

    Al-Musawi, R. S. J.; Brousseau, E. B.; Geng, Y.; Borodich, F. M.

    2016-09-01

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves.

  2. Piezoresistive AFM cantilevers surpassing standard optical beam deflection in low noise topography imaging

    PubMed Central

    Dukic, Maja; Adams, Jonathan D.; Fantner, Georg E.

    2015-01-01

    Optical beam deflection (OBD) is the most prevalent method for measuring cantilever deflections in atomic force microscopy (AFM), mainly due to its excellent noise performance. In contrast, piezoresistive strain-sensing techniques provide benefits over OBD in readout size and the ability to image in light-sensitive or opaque environments, but traditionally have worse noise performance. Miniaturisation of cantilevers, however, brings much greater benefit to the noise performance of piezoresistive sensing than to OBD. In this paper, we show both theoretically and experimentally that by using small-sized piezoresistive cantilevers, the AFM imaging noise equal or lower than the OBD readout noise is feasible, at standard scanning speeds and power dissipation. We demonstrate that with both readouts we achieve a system noise of ≈0.3 Å at 20 kHz measurement bandwidth. Finally, we show that small-sized piezoresistive cantilevers are well suited for piezoresistive nanoscale imaging of biological and solid state samples in air. PMID:26574164

  3. Stress distribution in implant-supported prostheses using different connection systems and cantilever lengths: digital photoelasticity.

    PubMed

    Goiato, Marcelo Coelho; Shibayama, Ricardo; Gennari Filho, Humberto; de Medeiros, Rodrigo Antonio; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline; de Araújo, Cleudmar Amaral

    2016-01-01

    Photoelastic analysis was used to evaluate the biomechanical behaviour of implant-supported, double-screwed crowns with different connection systems and cantilever lengths. Three models were made in PL-2 photoelastic resin and divided into six groups, on the basis of the implant connection system (external hexagon [EH] or Morse taper [MT]), type of abutment (Mini Pilar [Neodent, Curitiba, Paraná, Brazil] or "UCLA") and number of crowns in the cantilever (one or two). The implant-prosthesis unit was placed in a circular polariscope. Occlusal surfaces of the crowns were subjected to 100-N loads in the axial and oblique (45°) directions in a universal testing machine (EMIC). Generated stresses were recorded and analysed qualitatively in a graphics program (Adobe Photoshop). Under axial loading, all of the groups had similar numbers of fringes, which were increased when the crowns were subjected to oblique loading. The highest number of fringes was found during oblique loading in the EH + Mini Pilar group. In conclusion, although the type of implant connection system did not have a direct influence on the stress distribution for axial loading, the cantilever length did have a direct influence on stress distribution. Models with two crowns in the cantilever showed more stress, with a greater concentration of force on the cervical part of the implant.

  4. Maximizing Output Power in a Cantilevered Piezoelectric Vibration Energy Harvester by Electrode Design

    NASA Astrophysics Data System (ADS)

    Du, Sijun; Jia, Yu; Seshia, Ashwin

    2015-12-01

    A resonant vibration energy harvester typically comprises of a clamped anchor and a vibrating shuttle with a proof mass. Piezoelectric materials are embedded in locations of high strain in order to transduce mechanical deformation into electric charge. Conventional design for piezoelectric vibration energy harvesters (PVEH) usually utilizes piezoelectric material and metal electrode layers covering the entire surface area of the cantilever with no consideration provided to examining the trade-off involved with respect to maximizing output power. This paper reports on the theory and experimental verification underpinning optimization of the active electrode area of a cantilevered PVEH in order to maximize output power. The analytical formulation utilizes Euler-Bernoulli beam theory to model the mechanical response of the cantilever. The expression for output power is reduced to a fifth order polynomial expression as a function of the electrode area. The maximum output power corresponds to the case when 44% area of the cantilever is covered by electrode metal. Experimental results are also provided to verify the theory.

  5. High-Gradient Nanomagnets on Cantilevers for Sensitive Detection of Nuclear Magnetic Resonance

    PubMed Central

    Longenecker, Jonilyn G.; Mamin, H. J.; Senko, Alexander W.; Chen, Lei; Rettner, Charles T.; Rugar, Daniel; Marohn, John A.

    2012-01-01

    Detection of magnetic resonance as a force between a magnetic tip and nuclear spins has previously been shown to enable sub-10 nm resolution 1H imaging. Maximizing the spin force in such a magnetic resonance force microscopy (MRFM) experiment demands a high field gradient. In order to study a wide range of samples, it is equally desirable to locate the magnetic tip on the force sensor. Here we report the development of attonewton-sensitivity cantilevers with high gradient cobalt nanomagnet tips. The damage layer thickness and saturation magnetization of the magnetic material were characterized by X-ray photoelectron spectroscopy and superconducting quantum interference device magnetometry. The coercive field and saturation magnetization of an individual tip were quantified in situ using frequency-shift cantilever magnetometry. Measurements of cantilever dissipation versus magnetic field and tip-sample separation were conducted. MRFM signals from protons in a polystyrene film were studied versus rf irradiation frequency and tip-sample separation, and from this data the tip field and tip-field gradient were evaluated. Magnetic tip performance was assessed by numerically modeling the frequency dependence of the magnetic resonance signal. We observed a tip-field gradient ∂Bztip∕∂z estimated to be between 4.4 and 5.4 MT m−1, which is comparable to the gradient used in recent 4 nm resolution 1H imaging experiments and larger by nearly an order of magnitude than the gradient achieved in prior magnet-on-cantilever MRFM experiments. PMID:23033869

  6. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves.

    PubMed

    Al-Musawi, R S J; Brousseau, E B; Geng, Y; Borodich, F M

    2016-09-23

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves. PMID:27532247

  7. A case study of analysis methods for large deflections of a cantilever beam

    NASA Technical Reports Server (NTRS)

    Craig, L. D.

    1994-01-01

    A load case study of geometric nonlinear large deflections of a cantilever beam is presented. The bending strain must remain elastic. Closed form solution and finite element methods of analysis are illustrated and compared for three common load cases. A nondimensional nomogram for each case is presented in the summary.

  8. Comparison of Theory with Experimental Data For a Partially Covered Double-Sandwich Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Chen, Qinghua; Levy, Cesar

    1998-01-01

    In this paper, vibration characteristics of a partially covered, double-sandwich cantilever beam are evaluated experimentally and compared to the theoretical results of Levy and Chen for partially covered beams with and without end mass. The results obtained indicate that the theoretical models serve very well in providing the frequency factors and loss factors for the system being investigated.

  9. An analytic model for accurate spring constant calibration of rectangular atomic force microscope cantilevers.

    PubMed

    Li, Rui; Ye, Hongfei; Zhang, Weisheng; Ma, Guojun; Su, Yewang

    2015-10-29

    Spring constant calibration of the atomic force microscope (AFM) cantilever is of fundamental importance for quantifying the force between the AFM cantilever tip and the sample. The calibration within the framework of thin plate theory undoubtedly has a higher accuracy and broader scope than that within the well-established beam theory. However, thin plate theory-based accurate analytic determination of the constant has been perceived as an extremely difficult issue. In this paper, we implement the thin plate theory-based analytic modeling for the static behavior of rectangular AFM cantilevers, which reveals that the three-dimensional effect and Poisson effect play important roles in accurate determination of the spring constants. A quantitative scaling law is found that the normalized spring constant depends only on the Poisson's ratio, normalized dimension and normalized load coordinate. Both the literature and our refined finite element model validate the present results. The developed model is expected to serve as the benchmark for accurate calibration of rectangular AFM cantilevers.

  10. Note: curve fit models for atomic force microscopy cantilever calibration in water.

    PubMed

    Kennedy, Scott J; Cole, Daniel G; Clark, Robert L

    2011-11-01

    Atomic force microscopy stiffness calibrations performed on commercial instruments using the thermal noise method on the same cantilever in both air and water can vary by as much as 20% when a simple harmonic oscillator model and white noise are used in curve fitting. In this note, several fitting strategies are described that reduce this difference to about 11%.

  11. Fabrication Challenges in Producing Magnet-tipped Cantilevers for Magnetic Resonance Force Microscopy

    NASA Astrophysics Data System (ADS)

    Hickman, Steven A.; Garner, Sean R.; Harrell, Lee E.; Ong, Jeremy C.; Kuehn, Seppe; Marohn, John A.

    2008-03-01

    Magnetic resonance force microscopy (MRFM) is a technique that may allow MR imaging of single molecules -- an extremely exciting prospect. To date we have demonstrated MRFM sensitivity of ˜10^5 proton spins. By making improved magnetic tips and increasing force sensitivity, it may be possible to achieve single-proton sensitivity necessary for molecular imaging. In MRFM the force exerted on the cantilever, per spin, is proportional to the field gradient from the cantilever's magnetic tip. Achieving single proton sensitivity thus requires dramatically reducing magnet size. We have developed an e-beam lithography process for batch fabricating nanoscale magnets on silicon cantilevers. With these sized magnets we will still require attonewton force sensitivity. Research by our group has shown that surface induced dissipation is a major noise source. We believe this can be minimized by producing magnets overhanging the cantilever end. As proof of concept, we will show a 50-nm overhanging cobalt magnet made by a process involving KOH etching, as well as preliminary work on making overhanging magnets by dry fabrication methods. Our current challenge appears to be preventing the formation of metal silicides.

  12. Comparison of Five Topologies of Cantilever-based MEMS Piezoelectric Vibration Energy Harvesters

    NASA Astrophysics Data System (ADS)

    Jia, Y.; Seshia, A. A.

    2014-11-01

    In the realm of MEMS piezoelectric vibration energy harvesters, cantilever-based designs are by far the most popular. Despite being deceptively simple, the active piezoelectric area near the clamped end is able to accumulate maximum strain-generated-electrical-charge, while the free end is able to accommodate a proof mass without compromising the effective area of the piezoelectric generator since it experiences minimal strain anyway. While other contending designs do exist, this paper investigates five micro-cantilever (MC) topologies, namely: a plain MC, a tapered MC, a lined MC, a holed MC and a coupled MC, in order to assess their relative performance as an energy harvester. Although a classical straight and plain MC offers the largest active piezoelectric area, alternative MC designs can potentially offer higher average mechanical strain distribution for a given mechanical loading. Numerical simulation and experimental comparison of these 5 MCs (0.5 μ AlN on 10 μm Si) with the same practical dimensions of 500 μm and 2000 μm, suggest a cantilever with a coupled subsidiary cantilever yield the best power performance, closely followed by the classical plain topology.

  13. Free vibration analysis of cantilever plate partially submerged into a fluid

    NASA Astrophysics Data System (ADS)

    Kwak, Moon K.; Yang, Dong-Ho

    2013-07-01

    The free flexural vibration of a cantilever plate partially submerged in a fluid is investigated. The fluid is assumed to be inviscid and irrotational. The virtual mass matrix is derived by solving the boundary-value problem related to the fluid motion using elliptical coordinates. The introduction of the elliptical coordinates naturally leads to the use of the Mathieu function. Hence, the virtual mass matrix which reflects the effect of the fluid on the natural vibration characteristics is expressed in analytical form in terms of the Mathieu functions. The virtual mass matrix is then combined with the dynamic model of a thin rectangular plate obtained by using the Rayleigh-Ritz method. This combination is used to analyze the natural vibration characteristics of a partially submerged cantilever plate qualitatively. Also, the non-dimensionalized added virtual mass incremental factors for a partially submerged cantilever plate are presented to facilitate the easy estimation of natural frequencies of a partially submerged cantilever plate. It is found that the numerical results are in good agreement with the previous results, thus validating the proposed approach.

  14. Piezoresistive AFM cantilevers surpassing standard optical beam deflection in low noise topography imaging

    NASA Astrophysics Data System (ADS)

    Dukic, Maja; Adams, Jonathan D.; Fantner, Georg E.

    2015-11-01

    Optical beam deflection (OBD) is the most prevalent method for measuring cantilever deflections in atomic force microscopy (AFM), mainly due to its excellent noise performance. In contrast, piezoresistive strain-sensing techniques provide benefits over OBD in readout size and the ability to image in light-sensitive or opaque environments, but traditionally have worse noise performance. Miniaturisation of cantilevers, however, brings much greater benefit to the noise performance of piezoresistive sensing than to OBD. In this paper, we show both theoretically and experimentally that by using small-sized piezoresistive cantilevers, the AFM imaging noise equal or lower than the OBD readout noise is feasible, at standard scanning speeds and power dissipation. We demonstrate that with both readouts we achieve a system noise of ≈0.3 Å at 20 kHz measurement bandwidth. Finally, we show that small-sized piezoresistive cantilevers are well suited for piezoresistive nanoscale imaging of biological and solid state samples in air.

  15. Flexural Vibration Test of a Cantilever Beam with a Force Sensor: Fast Determination of Young's Modulus

    ERIC Educational Resources Information Center

    Digilov, Rafael M.

    2008-01-01

    We describe a simple and very inexpensive undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures with the aid of a force sensor. A strip-shaped specimen rigidly bolted to the force sensor forms a clamped-free cantilever beam. Placed in a furnace, it is subjected to free-bending vibrations followed by…

  16. Analysis of dynamic cantilever behavior in tapping mode atomic force microscopy.

    PubMed

    Deng, Wenqi; Zhang, Guang-Ming; Murphy, Mark F; Lilley, Francis; Harvey, David M; Burton, David R

    2015-10-01

    Tapping mode atomic force microscopy (AFM) provides phase images in addition to height and amplitude images. Although the behavior of tapping mode AFM has been investigated using mathematical modeling, comprehensive understanding of the behavior of tapping mode AFM still poses a significant challenge to the AFM community, involving issues such as the correct interpretation of the phase images. In this paper, the cantilever's dynamic behavior in tapping mode AFM is studied through a three dimensional finite element method. The cantilever's dynamic displacement responses are firstly obtained via simulation under different tip-sample separations, and for different tip-sample interaction forces, such as elastic force, adhesion force, viscosity force, and the van der Waals force, which correspond to the cantilever's action upon various different representative computer-generated test samples. Simulated results show that the dynamic cantilever displacement response can be divided into three zones: a free vibration zone, a transition zone, and a contact vibration zone. Phase trajectory, phase shift, transition time, pseudo stable amplitude, and frequency changes are then analyzed from the dynamic displacement responses that are obtained. Finally, experiments are carried out on a real AFM system to support the findings of the simulations. PMID:26303510

  17. Shape effect of torsional resonance mode AFM cantilevers operated in fluids

    NASA Astrophysics Data System (ADS)

    Haochih Liu, Bernard; Chuang, Sheng-Kai; Lowai Huang, Allison

    2014-09-01

    Nanoscale resolution, high scanning rate, and non-destructive measurement are highly desirable attributes for imagining living cells in fluids. Torsional resonance (TR) mode is a promising approach that can satisfy these requirements. In this study, we have fabricated scanning probes with suitable cantilever designs for use in TR mode in fluids, using computer simulation as an aid in the design and fabrication iterations. Several geometrical parameters of cantilevers were considered and simulated for mechanical properties and dynamic characteristics, and selected designs were fabricated for performance evaluation. The influences of design parameters on scan performance were investigated by statistical analysis. Based on this approach, we designed and fabricated optimal cantilevers that can be operated in TR mode in water with high quality (Q) factor (˜60), high resonance frequency (˜240 kHz), and low spring constant (˜0.14 N m-1). Overall, O-shape cantilevers have demonstrated superior Q factors to typical rectangular shape, A-shape and V-shape designs.

  18. An analytic model for accurate spring constant calibration of rectangular atomic force microscope cantilevers

    PubMed Central

    Li, Rui; Ye, Hongfei; Zhang, Weisheng; Ma, Guojun; Su, Yewang

    2015-01-01

    Spring constant calibration of the atomic force microscope (AFM) cantilever is of fundamental importance for quantifying the force between the AFM cantilever tip and the sample. The calibration within the framework of thin plate theory undoubtedly has a higher accuracy and broader scope than that within the well-established beam theory. However, thin plate theory-based accurate analytic determination of the constant has been perceived as an extremely difficult issue. In this paper, we implement the thin plate theory-based analytic modeling for the static behavior of rectangular AFM cantilevers, which reveals that the three-dimensional effect and Poisson effect play important roles in accurate determination of the spring constants. A quantitative scaling law is found that the normalized spring constant depends only on the Poisson’s ratio, normalized dimension and normalized load coordinate. Both the literature and our refined finite element model validate the present results. The developed model is expected to serve as the benchmark for accurate calibration of rectangular AFM cantilevers. PMID:26510769

  19. Spring constant calibration of atomic force microscopy cantilevers with a piezosensor transfer standard

    SciTech Connect

    Langlois, E. D.; Shaw, G. A.; Kramar, J. A.; Pratt, J. R.; Hurley, D. C.

    2007-09-15

    We describe a method to calibrate the spring constants of cantilevers for atomic force microscopy (AFM). The method makes use of a ''piezosensor'' composed of a piezoresistive cantilever and accompanying electronics. The piezosensor was calibrated before use with an absolute force standard, the NIST electrostatic force balance (EFB). In this way, the piezosensor acts as a force transfer standard traceable to the International System of Units. Seven single-crystal silicon cantilevers with rectangular geometries and nominal spring constants from 0.2 to 40 N/m were measured with the piezosensor method. The values obtained for the spring constant were compared to measurements by four other techniques: the thermal noise method, the Sader method, force loading by a calibrated nanoindentation load cell, and direct calibration by force loading with the EFB. Results from different methods for the same cantilever were generally in agreement, but differed by up to 300% from nominal values. When used properly, the piezosensor approach provides spring-constant values that are accurate to {+-}10% or better. Methods such as this will improve the ability to extract quantitative information from AFM methods.

  20. Reduction of nonspecific protein adsorption on cantilever biosensors caused by transverse resonant mode vibration.

    PubMed

    Johnson, Blake N; Mutharasan, Raj

    2014-03-01

    We examine if vibration of millimeter-sized cantilever sensors can release nonspecifically adsorbed proteins. Integrated electrochemical and mass-change measurement as well as fluorescence assays showed transverse surface vibration released nonspecifically bound proteins in samples prepared at 0.2-3.6 mg bovine serum albumin (BSA) per mL. Extent of release was directly related to magnitude of excitation voltage (Vex) applied to the self-actuating lead zirconate titanate (PZT) cantilever over three log units (0, 10 mV, 100 mV, and 1 V). Vibration-induced release was not instantaneous, but had an apparent first-order rate constant (kapp) which ranged from 0.02-0.1 min(-1). Results suggest significant serum albumin protein release could be achieved using excitation voltages of 1 V in millimeter-sized cantilever sensors. Complementary experiments with thiolated DNA, which binds to surface gold 〈111〉 sites with ∼ four times higher binding energy than BSA, showed negligible release under the same vibration magnitude. The results of the study suggest a direct correlation between surface-adsorbate binding energy and the effectiveness of vibration-induced release. We suggest that the release mechanism includes contributions from surface strain energy, body force, and acoustic streaming-associated hydrodynamic effects. The primary contribution of this study suggests that surface vibration of cantilever sensors may be useful in reducing nonspecific adsorption, especially for biosensing of analytes present in a complex background. PMID:24416758

  1. Monitoring the formation of self-assembled monolayers of alkanedithiols using a micromechanical cantilever sensor.

    PubMed

    Kohale, Swapnil; Molina, Sara M; Weeks, Brandon L; Khare, Rajesh; Hope-Weeks, Louisa J

    2007-01-30

    Using a micromechanical cantilever device, the surface stress induced during the growth of alkanedithiol (HS(CH2)nSH) monolayers on gold in solution is continuously monitored and reported. Adsorption of alkanedithiols of varying chain lengths is observed and compared to each other, as well as to the adsorption of hydroxyalkanethiols (HS(CH2)nOH) and alkanethiols (HS(CH2)nCH3). The results have revealed a significant change in surface stress on the basis of the chain length of the alkanedithiol. The long-chain (n > 10) alkanedithiol adsorption imposes a tensile stress on the gold-coated surface of the cantilever rather than the compressive stress exhibited by both alkanethiols and short-chain dithiols. Our results suggest a phenomenon in which the two thiols of the alkanedithiol adsorb onto the gold surface forming a loop inducing a tensile stress on the cantilever for long chain lengths. This study shows that micromechanical cantilever sensors can be very valuable tools in the exploration and characterization of self-assembled monolayers.

  2. Direct-write nanoscale printing of nanogranular tunnelling strain sensors for sub-micrometre cantilevers

    PubMed Central

    Dukic, Maja; Winhold, Marcel; Schwalb, Christian H.; Adams, Jonathan D.; Stavrov, Vladimir; Huth, Michael; Fantner, Georg E.

    2016-01-01

    The sensitivity and detection speed of cantilever-based mechanical sensors increases drastically through size reduction. The need for such increased performance for high-speed nanocharacterization and bio-sensing, drives their sub-micrometre miniaturization in a variety of research fields. However, existing detection methods of the cantilever motion do not scale down easily, prohibiting further increase in the sensitivity and detection speed. Here we report a nanomechanical sensor readout based on electron co-tunnelling through a nanogranular metal. The sensors can be deposited with lateral dimensions down to tens of nm, allowing the readout of nanoscale cantilevers without constraints on their size, geometry or material. By modifying the inter-granular tunnel-coupling strength, the sensors' conductivity can be tuned by up to four orders of magnitude, to optimize their performance. We show that the nanoscale printed sensors are functional on 500 nm wide cantilevers and that their sensitivity is suited even for demanding applications such as atomic force microscopy. PMID:27666316

  3. SEMICONDUCTOR TECHNOLOGY Supercritical carbon dioxide process for releasing stuck cantilever beams

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Chaoqun, Gao; Lei, Wang; Yupeng, Jing

    2010-10-01

    The multi-SCCO2 (supercritical carbon dioxide) release and dry process based on our specialized SCCO2 semiconductor process equipment is investigated and the releasing mechanism is discussed. The experiment results show that stuck cantilever beams were held up again under SCCO2 high pressure treatment and the repeatability of this process is nearly 100%.

  4. Solid-State Lighting: Cantilever Epitaxy Process Wins R&D 100 Award

    SciTech Connect

    2012-04-19

    Sandia National Laboratories received an R&D 100 Award from R&D Magazine for development of a new process for growing gallium nitride on an etched sapphire substrate. The process, called cantilever epitaxy, promises to make brighter and more efficient green, blue, and white LEDs.

  5. Comment on ‘Longest reach of a cantilever with a tip load’

    NASA Astrophysics Data System (ADS)

    Batista, Milan

    2016-09-01

    In this contribution, the longest horizontal reach of a cantilever subject to a dead load is analysed in terms of Jacobi elliptical functions. The problem is reduced to finding the solution of a system of transcendental equations. Several analytical results that cannot be obtained using pure numerical methods are discussed.

  6. Optimal placement and active vibration control for piezoelectric smart flexible cantilever plate

    NASA Astrophysics Data System (ADS)

    Qiu, Zhi-cheng; Zhang, Xian-min; Wu, Hong-xin; Zhang, Hong-hua

    2007-04-01

    Some flexible appendages of spacecraft are cantilever plate structures, such as sun plate and satellite antenna. Thus, vibration problem will be caused by parameter uncertainties and environmental disturbances. In this paper, piezoelectric ceramics patches are used as sensors and actuators to suppress the vibration of the smart flexible clamped plate. Firstly, modal equations and piezoelectric control equations of cantilever plate are derived. Secondly, an optimal placement method for the locations of piezoelectric actuators and sensors is developed based on the degree of observability and controllability indices for cantilever plate. The bending and torsional modes are decoupled by the proposed method using bandwidth Butterworth filter. Thirdly, an efficient control method by combining positive position feedback and proportional-derivative control is proposed for vibration reduction. The analytical results for modal frequencies, transient responses and control responses are carried out. Finally, an experimental setup of piezoelectric smart plate is designed and built up. The modal frequencies and damping ratios of the plate setup are obtained by identification method. Also, the experimental studies on vibration control of the cantilever plate including bending modes and torsional modes are conducted. The analytical and experimental results demonstrate that the presented control method is feasible, and the optimal placement method is effective.

  7. Flap/Lag/Torsion Dynamics of a Uniform, Cantilever Rotor Blade in Hover

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1977-01-01

    The dynamic stability of the flap/lag/torsion motion of a uniform, cantilever rotor blade in hover is calculated. The influence of blade collective pitch, lag frequency, torsional flexibility, structural coupling, and precone angle on the stability is examined. Good agreement is found with the results of an independent analytical investigation.

  8. Real-time measurement of flow rate in microfluidic devices using a cantilever-based optofluidic sensor.

    PubMed

    Cheri, Mohammad Sadegh; Latifi, Hamid; Sadeghi, Jalal; Moghaddam, Mohammadreza Salehi; Shahraki, Hamidreza; Hajghassem, Hasan

    2014-01-21

    Real-time and accurate measurement of flow rate is an important reqirement in lab on a chip (LOC) and micro total analysis system (μTAS) applications. In this paper, we present an experimental and numerical investigation of a cantilever-based optofluidic flow sensor for this purpose. Two sensors with thin and thick cantilevers were fabricated by engraving a 2D pattern of cantilever/base on two polymethylmethacrylate (PMMA) slabs using a CO2 laser system and then casting a 2D pattern with polydimethylsiloxane (PDMS). The basic working principle of the sensor is the fringe shift of the Fabry-Pérot (FP) spectrum due to a changing flow rate. A Finite Element Method (FEM) is used to solve the three dimensional (3D) Navier-Stokes and structural deformation equations to simulate the pressure distribution, velocity and cantilever deflection results of the flow in the channel. The experimental results show that the thin and thick cantilevers have a minimum detectable flow change of 1.3 and 4 (μL min(-1)) respectively. In addition, a comparison of the numerical and experimental deflection of the cantilever has been done to obtain the effective Young's modulus of the thin and thick PDMS cantilevers. PMID:24291805

  9. Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers

    SciTech Connect

    Johnson, Raegan Lynn

    2005-01-01

    In Atomic Force Microscopy (AFM), a microcantilever is raster scanned across the surface of a sample in order to obtain a topographical image of the sample's surface. In a traditional, optical AFM, the sample rests on a bulk piezoelectric tube and a control loop is used to control the tip-sample separation by actuating the piezo-tube. This method has several disadvantages--the most noticeable one being that response time of the piezo-tube is rather long which leads to slow imaging speeds. One possible solution aimed at improving the speed of imaging is to incorporate a thin piezoelectric film on top of the cantilever beam. This design not only improves the speed of imaging because the piezoelectric film replaces the piezo-tube as an actuator, but the film can also act as a sensor. In addition, the piezoelectric film can excite the cantilever beam near its resonance frequency. This project aims to fabricate piezoelectric microcantilevers for use in the AFM. Prior to fabricating the cantilevers and also part of this project, a systematic study was performed to examine the effects of deposition conditions on the quality of piezoelectric ZnO thin films deposited by RF sputtering. These results will be presented. The deposition parameters that produced the highest quality ZnO film were used in the fabrication of the piezoelectric cantilevers. Unfortunately, the fabricated cantilevers warped due to the intrinsic stress of the ZnO film and were therefore not usable in the AFM. The complete fabrication process will be detailed, the results will be discussed and reasons for the warping will be examined.

  10. Theoretical and experimental study on the transverse vibration properties of an axially moving nested cantilever beam

    NASA Astrophysics Data System (ADS)

    Duan, Ying-Chang; Wang, Jian-Ping; Wang, Jing-Quan; Liu, Ya-Wen; Shao, Fei

    2014-06-01

    An axially moving nested cantilever beam is a type of time-varying nonlinear system that can be regarded as a cantilever stepped beam. The transverse vibration equation for the axially moving nested cantilever beam with a tip mass is derived by D'Alembert's principle, and the modified Galerkin's method is used to solve the partial differential equation. The theoretical model is modified by adjusting the theoretical beam length with the measured results of its first-order vibration frequencies under various beam lengths. It is determined that the length correction value of the second segment of the nested beam increases as the structural length increases, but the corresponding increase in the amplitude becomes smaller. The first-order decay coefficients are identified by the logarithmic decrement method, and the decay coefficient of the beam decreases with an increase in the cantilever length. The calculated responses of the modified model agree well with the experimental results, which verifies the correctness of the proposed calculation model and indicates the effectiveness of the methods of length correction and damping determination. Further studies on non-damping free vibration properties of the axially moving nested cantilever beam during extension and retraction are investigated in the present paper. Furthermore, the extension movement of the beam leads the vibration displacement to increase gradually, and the instantaneous vibration frequency and the vibration speed decrease constantly. Moreover, as the total mechanical energy becomes smaller, the extension movement of the nested beam remains stable. The characteristics for the retraction movement of the beam are the reverse.

  11. Optical and mechanical detection of near-field light by atomic force microscopy using a piezoelectric cantilever

    NASA Astrophysics Data System (ADS)

    Satoh, Nobuo; Kobayashi, Kei; Watanabe, Shunji; Fujii, Toru; Matsushige, Kazumi; Yamada, Hirofumi

    2016-08-01

    In this study, we developed an atomic force microscopy (AFM) system with scanning near-field optical microscopy (SNOM) using a microfabricated force-sensing cantilever with a lead zirconate titanate (PZT) thin film. Both optical and mechanical detection techniques were adopted in SNOM to detect scattered light induced by the interaction of the PZT cantilever tip apex and evanescent light, and SNOM images were obtained for each detection scheme. The mechanical detection technique did allow for a clear observation of the light scattered from the PZT cantilever without the interference observed by the optical detection technique, which used an objective lens, a pinhole, and a photomultiplier tube.

  12. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: combining normal spring constant and classical beam theory.

    PubMed

    Álvarez-Asencio, R; Thormann, E; Rutland, M W

    2013-09-01

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.

  13. A surface-micromachining-based inertial micro-switch with compliant cantilever beam as movable electrode for enduring high shock and prolonging contact time

    NASA Astrophysics Data System (ADS)

    Xu, Qiu; Yang, Zhuoqing; Fu, Bo; Li, Jianhua; Wu, Hao; Zhang, Qihuan; Sun, Yunna; Ding, Guifu; Zhao, Xiaolin

    2016-11-01

    A novel laterally-driven inertial micro-switch with two L-shaped elastic cantilever beams as the movable electrode, which is attached to the proof mass, is proposed in this paper. The advantage of this design is that the contact time of the inertial micro-switch can be prolonged. Meanwhile, the micro-switch can withstand a higher shock than the traditional designs whose cantilever beams are attached to the fixed electrode. The designed inertial micro-switch was simulated and optimized with ANSYS software and fabricated on a quartz substrate by surface micromachining technology. The simulated result demonstrates that the threshold acceleration (aths) under stable switch-on state is about 288 g and the contact time is about 198 μs when the pulse width of acceleration loads is 1 ms. At the same time, it indicates that the threshold acceleration, the response time and the contact time of designed micro-switch all increase with the pulse width of acceleration loads. The simulation of impact process in non-sensitive direction shows that the introduced constraint sleeve structure in the novel inertial micro-switch can lower the off-axis sensitivity. The fabricated micro-switch prototype has been tested by a standard dropping hammer system under shock accelerations with various amplitudes and pulse widths. The experimental measurements show that the contact time is about 150 μs when the threshold acceleration is about 288 g. It also indicates that the response time and the contact time both increase with the pulse width, which is consistent with the simulation ones.

  14. A femtogram resolution mass sensor platform, based on SOI electrostatically driven resonant cantilever. Part I: electromechanical model and parameter extraction.

    PubMed

    Teva, J; Abadal, G; Torres, F; Verd, J; Pérez-Murano, F; Barniol, N

    2006-01-01

    A microcantilever based platform for mass detection in the femtogram range has been integrated in the doped top silicon layer of a SOI substrate. The on-plane fundamental resonance mode of the cantilever is excited electrostatically and detected capacitively by means of two parallel placed electrodes in a two port configuration. An electromechanical model of the cantilever-electrodes transducer and its implementation in a SPICE environment are presented. The model takes into account non-linearities from variable cantilever-electrode gap, fringing field contributions and real deflection shape of the cantilever for the calculation of the driving electrostatic force. A fitting of the model to the measured S(21) transmitted power frequency response is performed to extract the characteristic sensor parameters as Young modulus, Q factor, electrical parasitics and mass responsivity.

  15. Precise and direct method for the measurement of the torsion spring constant of the atomic force microscopy cantilevers

    SciTech Connect

    Jarząbek, D. M.

    2015-01-15

    A direct method for the evaluation of the torsional spring constants of the atomic force microscope cantilevers is presented in this paper. The method uses a nanoindenter to apply forces at the long axis of the cantilever and in the certain distance from it. The torque vs torsion relation is then evaluated by the comparison of the results of the indentations experiments at different positions on the cantilever. Next, this relation is used for the precise determination of the torsional spring constant of the cantilever. The statistical analysis shows that the standard deviation of the calibration measurements is equal to approximately 1%. Furthermore, a simple method for calibration of the photodetector’s lateral response is proposed. The overall procedure of the lateral calibration constant determination has the accuracy approximately equal to 10%.

  16. Investigation of shear force of a single adhesion cell using a self-sensitive cantilever and fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Hashimoto, Shigetaka; Adachi, Makoto; Iwata, Futoshi

    2015-08-01

    In this paper, we describe a measurement system based on an atomic force microscope (AFM) for the measurement of the shear force and detachment energy of a single adhesion cell on a substrate. The shear force was quantitatively measured from the deflection of a self-sensitive cantilever that was employed for the simple configuration of the AFM manipulator. The shear force behavior of a single cell detaching from the substrate was observed. By staining cells with a fluorescence dye, the deformation shape of the cell being pushed with the cantilever could be clearly observed. The shear force and detachment energy of the cell increased with the size of the cell. The difference in the shear force of single cells on different substrates with different surface energies was quantitatively evaluated. The loading force applied to a single cell increased with the feed speed of the cantilever. The viability of cells after measurement under different feed speeds of the cantilever was also evaluated.

  17. Mass determination and sensitivity based on resonance frequency changes of the higher flexural modes of cantilever sensors

    SciTech Connect

    Parkin, John D.; Haehner, Georg

    2011-03-15

    Micro- and nanocantilevers are increasingly employed as mass sensors. Most studies consider the first flexural mode and adsorbed masses that are either discretely attached or homogeneously distributed along the entire length of the cantilever. We derive general expressions that allow for the determination of the total attached mass with any mass distribution along the cantilever length and all flexural modes. The expressions are valid for all cantilevers whose flexural deflection can be described by a one-dimensional function. This approach includes the most common types of microcantilevers, namely, rectangular, picket, and V-shaped. The theoretical results are compared with experimental data up to the fourth flexural mode obtained from thermal noise spectra of rectangular and V-shaped cantilevers.

  18. Investigation of static and dynamic behavior of functionally graded piezoelectric actuated Poly-Si micro cantilever probe

    NASA Astrophysics Data System (ADS)

    Pandey, Vibhuti Bhushan; Parashar, Sandeep Kumar

    2016-04-01

    In the present paper a novel functionally graded piezoelectric (FGP) actuated Poly-Si micro cantilever probe is proposed for atomic force microscope. The shear piezoelectric coefficient d15 has much higher value than coupling coefficients d31 and d33, hence in the present work the micro cantilever beam actuated by d15 effect is utilized. The material properties are graded in the thickness direction of actuator by a simple power law. A three dimensional finite element analysis has been performed using COMSOL Multiphysics® (version 4.2) software. Tip deflection and free vibration analysis for the micro cantilever probe has been done. The results presented in the paper shall be useful in the design of micro cantilever probe and their subsequent utilization in atomic force microscopes.

  19. Flexible SiO2 cantilevers for torsional self-aligning micro scale four-point probes

    NASA Astrophysics Data System (ADS)

    Kjær, D.; Gammelgaard, L.; Bøggild, P.; Hansen, O.; Petersen, P. R. E.; Hansen, J. E.

    2007-09-01

    In order to successfully measure the conductivity of a sample with a four-point probe, good alignment of the electrodes to the sample is important to establish even contact pressure and contact areas of the electrodes. By incorporating a hinge in a microfabricated SiO2 mono-cantilever the ability to compensate for misalignment is improved at a cost of reduced spring constant. Analytical calculations, numerical simulations on cantilever deflection and comparison with experimental results indicate that a reasonable compromise between torsional flexibility and overall spring constant can be achieved by proper dimensioning and placement of the hinge. Furthermore, it is shown that polymeric macro scale cantilever models can provide a fast and reliable understanding of the mechanical deflection properties of microfabricated SiO2 cantilevers.

  20. Precise and direct method for the measurement of the torsion spring constant of the atomic force microscopy cantilevers.

    PubMed

    Jarząbek, D M

    2015-01-01

    A direct method for the evaluation of the torsional spring constants of the atomic force microscope cantilevers is presented in this paper. The method uses a nanoindenter to apply forces at the long axis of the cantilever and in the certain distance from it. The torque vs torsion relation is then evaluated by the comparison of the results of the indentations experiments at different positions on the cantilever. Next, this relation is used for the precise determination of the torsional spring constant of the cantilever. The statistical analysis shows that the standard deviation of the calibration measurements is equal to approximately 1%. Furthermore, a simple method for calibration of the photodetector's lateral response is proposed. The overall procedure of the lateral calibration constant determination has the accuracy approximately equal to 10%.

  1. Sensitivity analysis of rectangular atomic force microscope cantilevers immersed in liquids based on the modified couple stress theory.

    PubMed

    Lee, Haw-Long; Chang, Win-Jin

    2016-01-01

    The modified couple stress theory is adopted to study the sensitivity of a rectangular atomic force microscope (AFM) cantilever immersed in acetone, water, carbon tetrachloride (CCl4), and 1-butanol. The theory contains a material length scale parameter and considers the size effect in the analysis. However, this parameter is difficult to obtain via experimental measurements. In this study, a conjugate gradient method for the parameter estimation of the frequency equation is presented. The optimal method provides a quantitative approach for estimating the material length scale parameter based on the modified couple stress theory. The results show that the material length scale parameter of the AFM cantilever immersed in acetone, CCl4, water, and 1-butanol is 0, 25, 116.3, and 471 nm, respectively. In addition, the vibration sensitivities of the AFM cantilever immersed in these liquids are investigated. The results are useful for the design of AFM cantilevers immersed in liquids.

  2. Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid

    NASA Astrophysics Data System (ADS)

    Hoof, Sebastian; Nand Gosvami, Nitya; Hoogenboom, Bart W.

    2012-12-01

    Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here, we show that a high-quality resonance (Q >20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity—as expressed via the minimum detectable force gradient—is hardly affected, because of the enhanced quality factor. Through the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up that includes magnetic actuation of the cantilevers and that can be easily implemented in any AFM system that is compatible with an inverted optical microscope.

  3. Study of thermal and acoustic noise interferences in low stiffness atomic force microscope cantilevers and characterization of their dynamic properties

    SciTech Connect

    Boudaoud, Mokrane; Haddab, Yassine; Le Gorrec, Yann; Lutz, Philippe

    2012-01-15

    The atomic force microscope (AFM) is a powerful tool for the measurement of forces at the micro/nano scale when calibrated cantilevers are used. Besides many existing calibration techniques, the thermal calibration is one of the simplest and fastest methods for the dynamic characterization of an AFM cantilever. This method is efficient provided that the Brownian motion (thermal noise) is the most important source of excitation during the calibration process. Otherwise, the value of spring constant is underestimated. This paper investigates noise interference ranges in low stiffness AFM cantilevers taking into account thermal fluctuations and acoustic pressures as two main sources of noise. As a result, a preliminary knowledge about the conditions in which thermal fluctuations and acoustic pressures have closely the same effect on the AFM cantilever (noise interference) is provided with both theoretical and experimental arguments. Consequently, beyond the noise interference range, commercial low stiffness AFM cantilevers are calibrated in two ways: using the thermal noise (in a wide temperature range) and acoustic pressures generated by a loudspeaker. We then demonstrate that acoustic noises can also be used for an efficient characterization and calibration of low stiffness AFM cantilevers. The accuracy of the acoustic characterization is evaluated by comparison with results from the thermal calibration.

  4. A pressure gauge based on gas density measurement from analysis of the thermal noise of an atomic force microscope cantilever

    SciTech Connect

    Seo, Dongjin; Ducker, William A.; Paul, Mark R.

    2012-05-15

    We describe a gas-density gauge based on the analysis of the thermally-driven fluctuations of an atomic force microscope (AFM) cantilever. The fluctuations are modeled as a ring-down of a simple harmonic oscillator, which allows fitting of the resonance frequency and damping of the cantilever, which in turn yields the gas density. The pressure is obtained from the density using the known equation of state. In the range 10-220 kPa, the pressure readings from the cantilever gauge deviate by an average of only about 5% from pressure readings on a commercial gauge. The theoretical description we use to determine the pressure from the cantilever motion is based upon the continuum hypothesis, which sets a minimum pressure for our analysis. It is anticipated that the cantilever gauge could be extended to measure lower pressures given a molecular theoretical description. Alternatively, the gauge could be calibrated for use in the non-continuum range. Our measurement technique is similar to previous AFM cantilever measurements, but the analysis produces improved accuracy.

  5. Study of thermal and acoustic noise interferences in low stiffness atomic force microscope cantilevers and characterization of their dynamic properties.

    PubMed

    Boudaoud, Mokrane; Haddab, Yassine; Le Gorrec, Yann; Lutz, Philippe

    2012-01-01

    The atomic force microscope (AFM) is a powerful tool for the measurement of forces at the micro/nano scale when calibrated cantilevers are used. Besides many existing calibration techniques, the thermal calibration is one of the simplest and fastest methods for the dynamic characterization of an AFM cantilever. This method is efficient provided that the Brownian motion (thermal noise) is the most important source of excitation during the calibration process. Otherwise, the value of spring constant is underestimated. This paper investigates noise interference ranges in low stiffness AFM cantilevers taking into account thermal fluctuations and acoustic pressures as two main sources of noise. As a result, a preliminary knowledge about the conditions in which thermal fluctuations and acoustic pressures have closely the same effect on the AFM cantilever (noise interference) is provided with both theoretical and experimental arguments. Consequently, beyond the noise interference range, commercial low stiffness AFM cantilevers are calibrated in two ways: using the thermal noise (in a wide temperature range) and acoustic pressures generated by a loudspeaker. We then demonstrate that acoustic noises can also be used for an efficient characterization and calibration of low stiffness AFM cantilevers. The accuracy of the acoustic characterization is evaluated by comparison with results from the thermal calibration.

  6. Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope.

    PubMed

    Sader, John E; Lu, Jianing; Mulvaney, Paul

    2014-11-01

    Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied - in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry - neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

  7. Batch-fabrication of cantilevered magnets on attonewton-sensitivity mechanical oscillators for scanned-probe nanoscale magnetic resonance imaging.

    PubMed

    Hickman, Steven A; Moore, Eric W; Lee, SangGap; Longenecker, Jonilyn G; Wright, Sarah J; Harrell, Lee E; Marohn, John A

    2010-12-28

    We have batch-fabricated cantilevers with ∼100 nm diameter nickel nanorod tips and force sensitivities of a few attonewtons at 4.2 K. The magnetic nanorods were engineered to overhang the leading edge of the cantilever, and consequently the cantilevers experience what we believe is the lowest surface noise ever achieved in a scanned probe experiment. Cantilever magnetometry indicated that the tips were well magnetized, with a ≤ 20 nm dead layer; the composition of the dead layer was studied by electron microscopy and electron energy loss spectroscopy. In what we believe is the first demonstration of scanned probe detection of electron-spin resonance from a batch-fabricated tip, the cantilevers were used to observe electron-spin resonance from nitroxide spin labels in a film via force-gradient-induced shifts in cantilever resonance frequency. The magnetic field dependence of the magnetic resonance signal suggests a nonuniform tip magnetization at an applied field near 0.6 T.

  8. A theoretical study of a nano-opto-mechanical sensor using a photonic crystal-cantilever cavity

    NASA Astrophysics Data System (ADS)

    Mao, Depeng; Liu, Peng; Ho, Kai-Ming; Dong, Liang

    2012-07-01

    In this simulation study, integration of a nanocantilever inside a two-dimensional (2D) photonic crystal (PC) cavity resulted in a unique photonic crystal-cantilever cavity (PC3), where the cantilever served as a tunable mechanical defect of the PC slab. Strong nano-opto-mechanical interactions between the cantilever and the defect-mode field inside the PC3 gave rise to a high sensitivity of the resonance wavelength to surface stress-induced cantilever deflection. Mechanical and optical responses of the PC3 to surface stress changes on the cantilever surface were studied by using a finite-element method (FEM) and a finite-difference time-domain (FDTD) method, respectively. Theoretical analysis revealed that the devised PC3 sensor could resolve a conservative minimum surface stress at the level of ˜0.8 mN m-1, representing state-of-the-art cantilever sensor performance. Also, the PC3 sensor design used an ultracompact structure with an on-chip optical length of only several microns, while a conventional reflected laser beam detection scheme requires a ˜1 m long free-space optical path.

  9. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  10. Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes

    PubMed Central

    Zizys, Darius; Gaidys, Rimvydas; Dauksevicius, Rolanas; Ostasevicius, Vytautas; Daniulaitis, Vytautas

    2015-01-01

    The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines. PMID:26703623

  11. Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes.

    PubMed

    Zizys, Darius; Gaidys, Rimvydas; Dauksevicius, Rolanas; Ostasevicius, Vytautas; Daniulaitis, Vytautas

    2015-01-01

    The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines. PMID:26703623

  12. A theoretical study of a nano-opto-mechanical sensor using a photonic crystal-cantilever cavity

    SciTech Connect

    Mao, Depeng; Liu, Peng; Ho, Kai-Ming; Dong, Liang

    2012-07-09

    In this simulation study, integration of a nanocantilever inside a two-dimensional (2D) photonic crystal (PC) cavity resulted in a unique photonic crystal-cantilever cavity (PC3), where the cantilever served as a tunable mechanical defect of the PC slab. Strong nano-opto-mechanical interactions between the cantilever and the defect-mode field inside the PC3 gave rise to a high sensitivity of the resonance wavelength to surface stress-induced cantilever deflection. Mechanical and optical responses of the PC3 to surface stress changes on the cantilever surface were studied by using a finite-element method (FEM) and a finite-difference time-domain (FDTD) method, respectively. Theoretical analysis revealed that the devised PC3 sensor could resolve a conservative minimum surface stress at the level of ~0.8 mN m−1, representing state-of-the-art cantilever sensor performance. Also, the PC3 sensor design used an ultracompact structure with an on-chip optical length of only several microns, while a conventional reflected laser beam detection scheme requires a ~1 m long free-space optical path.

  13. Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope

    SciTech Connect

    Sader, John E.; Lu, Jianing; Mulvaney, Paul

    2014-11-15

    Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied – in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry – neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

  14. Rapid serial prototyping of magnet-tipped attonewton-sensitivity cantilevers by focused ion beam manipulation1

    PubMed Central

    Longenecker, Jonilyn G.; Moore, Eric W.; Marohn, John A.

    2011-01-01

    The authors report a method for rapidly prototyping attonewton-sensitivity cantilevers with custom-fabricated tips and illustrate the method by preparing tips consisting of a magnetic nanorod overhanging the leading edge of the cantilevers. Micron-long nickel nanorods with widths of 120–220 nm were fabricated on silicon chips by electron beam lithography, deposition, and lift-off. Each silicon chip, with its integral nanomagnet, was attached serially to a custom-fabricated attonewton-sensitivity cantilever using focused ion beam manipulation. The magnetic nanorod tips were prepared with and without an alumina capping layer, and the minimum detectable force and tip magnetic moment of the resulting cantilevers was characterized by cantilever magnetometry. The results indicate that this serial but high-yield approach is an effective way to rapidly prepare and characterize magnetic tips for the proposed single-electron-spin and single-proton magnetic resonance imaging experiments. The approach also represents a versatile route for affixing essentially any vacuum-compatible sample to the leading edge of an attonewton-sensitivity cantilever. PMID:23028212

  15. Dynamically forced cantilever system: A piezo-polymer characterization tool with possible application for micromechanical HF resonator devices

    NASA Astrophysics Data System (ADS)

    Schwödiauer, Reinhard

    2005-04-01

    A cantilever system, driven to a dynamically forced oscillation by a small piezoelectric specimen is presented as a simple and accurate tool to determine the converse dynamic piezocoefficient up to several kHz. The piezoelectric sample is mounted on top of a reflective cantilever where it is free to oscillate without any mechanical constraint. A Nomarsky-interferometer detects the induced cantilever displacement. The presented technique is especially suited for a precise characterization of small and soft piezoelectric polymer-samples with rough surfaces. The capability of the dynamically forced cantilever principle is demonstrated with a LiNbO3 crystal and with a porous ferroelectretic polypropylene foam. Results from measurements between 400 Hz and 5 kHz were found to be in excellent agreement with published values. Additionally, the dynamically forced cantilever principle may possibly improve the sensitivity of some micromechanical cantilever-sensors and it could also be interesting for the design of enhanced micromechanical high frequency mixer filters. Some ideas about are briefly presented.

  16. Dynamically forced cantilever system: A piezo-polymer characterization tool with possible application for micromechanical HF resonator devices

    SciTech Connect

    Schwoediauer, Reinhard

    2005-04-01

    A cantilever system, driven to a dynamically forced oscillation by a small piezoelectric specimen is presented as a simple and accurate tool to determine the converse dynamic piezocoefficient up to several kHz. The piezoelectric sample is mounted on top of a reflective cantilever where it is free to oscillate without any mechanical constraint. A Nomarsky-interferometer detects the induced cantilever displacement. The presented technique is especially suited for a precise characterization of small and soft piezoelectric polymer-samples with rough surfaces. The capability of the dynamically forced cantilever principle is demonstrated with a LiNbO{sub 3} crystal and with a porous ferroelectretic polypropylene foam. Results from measurements between 400 Hz and 5 kHz were found to be in excellent agreement with published values. Additionally, the dynamically forced cantilever principle may possibly improve the sensitivity of some micromechanical cantilever-sensors and it could also be interesting for the design of enhanced micromechanical high frequency mixer filters. Some ideas about are briefly presented.

  17. Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes.

    PubMed

    Zizys, Darius; Gaidys, Rimvydas; Dauksevicius, Rolanas; Ostasevicius, Vytautas; Daniulaitis, Vytautas

    2015-12-23

    The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines.

  18. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam

    PubMed Central

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m3), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  19. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-09-22

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively.

  20. A Comparison Simulation of Fixed-fixed Type MEMS Switches

    NASA Astrophysics Data System (ADS)

    Rezazadeh, G.; Sadeghian, H.; Malekpour, E.

    2006-04-01

    In the present work pull-in voltage of fixed-fixed end type MEMS switches with variative electrostatic area has been calculated using a distributed model and applying a full nonlinear finite difference discretizing method. The governing nonlinear differential equation has been derived using of the variational principle for multi domain electromechanical coupled system. The numerical results of the beam with variative electrostatic area with the results of Coupled-Domain Finite Element method have been compared and very good agreement has been achieved.

  1. A performance-enhanced energy harvester for low frequency vibration utilizing a corrugated cantilevered beam

    NASA Astrophysics Data System (ADS)

    Kim, In-Ho; Jin, SeungSeop; Jang, Seon-Jun; Jung, Hyung-Jo

    2014-03-01

    This note proposes a performance-enhanced piezoelectric energy harvester by replacing a conventional flat cantilevered beam with a corrugated beam. It consists of a proof mass and a sinusoidally or trapezoidally corrugated cantilevered beam covered by a polyvinylidene fluoride (PVDF) film. Compared to the conventional energy harvester of the same size, it has a more flexible bending stiffness and a larger bonding area of the PVDF layer, so higher output voltage from the device can be expected. In order to investigate the characteristics of the proposed energy harvester, analytical developments and numerical simulations on its natural frequency and tip displacement are carried out. Shaking table tests are also conducted to verify the performance of the proposed device. It is clearly shown from the tests that the proposed energy harvester not only has a lower natural frequency than an equivalent sized standard energy harvester, but also generates much higher output voltage than the standard one.

  2. An ultra-high Q silicon compound cantilever resonator for Young's modulus measurements.

    PubMed

    Metcalf, Thomas H; Liu, Xiao

    2013-07-01

    We describe the design of ultra-high Q mechanical cantilever resonators, fabricated from single-crystal silicon wafers. The mechanical resonance mode at f ≈ 8.5 kHz achieves a background damping of Q(-1) cantilever resonator shares several design elements. The new resonator can be used for accurate measurements of the Young's modulus and internal friction of thin films. It is compatible with both the mounting apparatus and measurement electronics of the torsional resonator, and the two resonators together can be used to provide a complete description of the elastic properties of isotropic thin films. PMID:23902093

  3. The influence of the parasitic current on the nonlinear electrical response of capacitively sensed cantilever resonators

    NASA Astrophysics Data System (ADS)

    Vidal-Álvarez, Gabriel; Torres, Francesc; Barniol, Núria; Gottlieb, Oded

    2015-04-01

    The influence of the parasitic feedthrough current on the nonlinear electrical response of capacitively sensed cantilever resonators is analyzed theoretically and experimentally. We show that the parasitic current strongly affects the shape of the nonlinear electrical frequency response of such devices. Specifically, we demonstrate that in the electrical measurement, the directions of the jumps from the different transitions between branches of stable solutions depend on the parasitic current and are independent of the jumps directions in the mechanical domain. As a consequence, the nonlinear electrical frequency response of cantilevers with capacitive readout presents three different hysteretic cycle topologies: counterclockwise, bow tie, and clockwise. This is in contrast with the only one topology (counterclockwise) that appears in the nonlinear mechanical frequency response.

  4. Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Montanini, Roberto; Quattrocchi, Antonino

    2016-06-01

    A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d31 mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

  5. Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

    SciTech Connect

    Wu, Meng; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie; Ou, Yi; Ou, Wen

    2015-07-15

    This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

  6. Thermal imaging with tapping mode using a bimetal oscillator formed at the end of a cantilever.

    PubMed

    Kim, Sang-Jin; Ono, Takahito; Esashi, Masayoshi

    2009-03-01

    Thermal detection based on the thermal shift of the resonant frequency of a bimetal resonator (Al/Si) is presented and demonstrated. The bimetal oscillator with a tip is fabricated at the end of a commercial silicon cantilever. The bimetal oscillator and the silicon cantilever have a resonance frequency of 441 and 91 kHz, respectively, and the measured temperature coefficients of the resonant frequency are -127x10(-6)/K and -115x10(-6)/K, respectively. It is demonstrated that self-oscillated resonant frequency of the bimetal oscillator changes in response to heat from a microheat source. Simultaneous measurements of topography and temperature profile with the temperature resolution of 0.12 K on a glass substrate heated using a thin chromium film microheater are successfully demonstrated. These results show potential abilities of the mechanical resonant thermal sensor.

  7. Thermal imaging with tapping mode using a bimetal oscillator formed at the end of a cantilever

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Jin; Ono, Takahito; Esashi, Masayoshi

    2009-03-01

    Thermal detection based on the thermal shift of the resonant frequency of a bimetal resonator (Al/Si) is presented and demonstrated. The bimetal oscillator with a tip is fabricated at the end of a commercial silicon cantilever. The bimetal oscillator and the silicon cantilever have a resonance frequency of 441 and 91 kHz, respectively, and the measured temperature coefficients of the resonant frequency are -127×10-6/K and -115×10-6/K, respectively. It is demonstrated that self-oscillated resonant frequency of the bimetal oscillator changes in response to heat from a microheat source. Simultaneous measurements of topography and temperature profile with the temperature resolution of 0.12 K on a glass substrate heated using a thin chromium film microheater are successfully demonstrated. These results show potential abilities of the mechanical resonant thermal sensor.

  8. A virtual instrument to standardise the calibration of atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Sader, John E.; Borgani, Riccardo; Gibson, Christopher T.; Haviland, David B.; Higgins, Michael J.; Kilpatrick, Jason I.; Lu, Jianing; Mulvaney, Paul; Shearer, Cameron J.; Slattery, Ashley D.; Thorén, Per-Anders; Tran, Jim; Zhang, Heyou; Zhang, Hongrui; Zheng, Tian

    2016-09-01

    Atomic force microscope (AFM) users often calibrate the spring constants of cantilevers using functionality built into individual instruments. This calibration is performed without reference to a global standard, hindering the robust comparison of force measurements reported by different laboratories. Here, we describe a virtual instrument (an internet-based initiative) whereby users from all laboratories can instantly and quantitatively compare their calibration measurements to those of others—standardising AFM force measurements—and simultaneously enabling non-invasive calibration of AFM cantilevers of any geometry. This global calibration initiative requires no additional instrumentation or data processing on the part of the user. It utilises a single website where users upload currently available data. A proof-of-principle demonstration of this initiative is presented using measured data from five independent laboratories across three countries, which also allows for an assessment of current calibration.

  9. A method to measure cellular adhesion utilizing a polymer micro-cantilever

    NASA Astrophysics Data System (ADS)

    Gaitas, Angelo; Malhotra, Ricky; Pienta, Kenneth

    2013-09-01

    In the present study we engineered a micro-machined polyimide cantilever with an embedded sensing element to investigate cellular adhesion, in terms of its relative ability to stick to a cross-linker, 3,3'-dithiobis[sulfosuccinimidylpropionate], coated on the cantilever surface. To achieve this objective, we investigated adhesive properties of three human prostate cancer cell lines, namely, a bone metastasis derived human prostate cancer cell line (PC3), a brain metastasis derived human prostate cancer cell line (DU145), and a subclone of PC3 (PC3-EMT14). We found that PC3-EMT14, which displays a mesenchymal phenotype, has the least adhesion compared to PC3 and DU145, which exhibit an epithelial phenotype.

  10. High-speed force mapping on living cells with a small cantilever atomic force microscope

    SciTech Connect

    Braunsmann, Christoph; Seifert, Jan; Rheinlaender, Johannes; Schäffer, Tilman E.

    2014-07-15

    The imaging speed of the wide-spread force mapping mode for quantitative mechanical measurements on soft samples in liquid with the atomic force microscope (AFM) is limited by the bandwidth of the z-scanner and viscous drag forces on the cantilever. Here, we applied high-speed, large scan-range atomic force microscopy and small cantilevers to increase the speed of force mapping by ≈10−100 times. This allowed resolving dynamic processes on living mouse embryonic fibroblasts. Cytoskeleton reorganization during cell locomotion, growth of individual cytoskeleton fibers, cell blebbing, and the formation of endocytic pits in the cell membrane were observed. Increasing the force curve rate from 2 to 300 Hz increased the measured apparent Young's modulus of the cells by about 10 times, which facilitated force mapping measurements at high speed.

  11. Recording oscillations of sub-micron size cantilevers by extreme ultraviolet Fourier transform holography.

    PubMed

    Monserud, Nils C; Malm, Erik B; Wachulak, Przemyslaw W; Putkaradze, Vakhtang; Balakrishnan, Ganesh; Chao, Weilun; Anderson, Erik; Carlton, David; Marconi, Mario C

    2014-02-24

    We recorded the fast oscillation of sub-micron cantilevers using time-resolved extreme ultraviolet (EUV) Fourier transform holography. A tabletop capillary discharge EUV laser with a wavelength of 46.9 nm provided a large flux of coherent illumination that was split using a Fresnel zone plate to generate the object and the reference beams. The reference wave was produced by the first order focus while a central opening in the zone plate provided a direct illumination of the cantilevers. Single-shot holograms allowed for the composition of a movie featuring the fast oscillation. Three-dimensional displacements of the object were determined as well by numerical back-propagation, or "refocusing" of the electromagnetic fields during the reconstruction of a single hologram. PMID:24663740

  12. Nanoporous-Gold-Based Hybrid Cantilevered Actuator Dealloyed and Driven by A Modified Rotary Triboelectric Nanogenerator

    PubMed Central

    Li, Xuequan; Liu, Mengmeng; Huang, Baisheng; Liu, Hong; Hu, Weiguo; Shao, Li-Hua; Wang, Zhong Lin

    2016-01-01

    We firstly designed an electrochemical system for dealloying to synthesize nanoporous gold (NPG) and also driving the novel NPG based actuator by utilizing a modified rotary triboelectric nanogenerator (TENG). Compared to the previous reported TENG whose outputs decline due to temperature rising resulting from electrodes friction, the modified TENG with a cooling system has stable output current and voltage increased by 14% and 20%, respectively. The novel cantilevered hybrid actuator characterised by light-weight (ca. 3 mg) and small volume (ca. 30 mm × 2 mm × 10 μm) is driven by a microcontroller modulated TENG with the displacement of 2.2 mm, which is about 106 times larger than that of traditional cantilever using planar surfaces. The energy conversion efficiencies defined as the energy consumed during dealloying and actuation compared with the output of TENG are 47% and 56.7%, respectively. PMID:27063987

  13. An analytical investigation of delamination front curvature in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Davidson, B. D.

    1990-01-01

    An analytical investigation is conducted to determine the shape of a growing delamination and the distribution of the energy release rate along the delamination front in a laminated composite double cantilever beam specimen. Distributions of the energy release rate for specimens with straight delamination fronts and delamination front contours for delaminations whose growth is governed by the fracture criterion that G = Gc at all points are predicted as a function of material properties and delamination length. The predicted delamination front contours are utilized to ascertain the effect of the changing shape of the delamination front on the value of the critical strain energy release rate as computed from double cantilever beam fracture toughness test data.

  14. Computational model for noncontact atomic force microscopy: energy dissipation of cantilever.

    PubMed

    Senda, Yasuhiro; Blomqvist, Janne; Nieminen, Risto M

    2016-09-21

    We propose a computational model for noncontact atomic force microscopy (AFM) in which the atomic force between the cantilever tip and the surface is calculated using a molecular dynamics method, and the macroscopic motion of the cantilever is modeled by an oscillating spring. The movement of atoms in the tip and surface is connected with the oscillating spring using a recently developed coupling method. In this computational model, the oscillation energy is dissipated, as observed in AFM experiments. We attribute this dissipation to the hysteresis and nonconservative properties of the interatomic force that acts between the atoms in the tip and sample surface. The dissipation rate strongly depends on the parameters used in the computational model. PMID:27420398

  15. Characterization of Mechanical Properties of Cantilevered Nd2Fe14B/Ta Magnetic Microstructures

    NASA Astrophysics Data System (ADS)

    Jiang, Yonggang; Fujita, Takayuki; Uehara, Minoru; Zhang, Deyuan; Cai, Jun; Higuchi, Kohei; Maenaka, Kazusuke

    2011-11-01

    The mechanical properties of low-stress cantilevered Nd2Fe14B/Ta multilayered microstructures are characterized. The cantilevered microstructures are fabricated using silicon molding technique and XeF2 gas-phase silicon etching process. The magnetic microcantilevers show relatively high quality factors varying from 75 to 135. The Young's modulus of the Nd2Fe14B/Ta multilayered film is evaluated by fitting the resonance response of the microcantilevers, which is smaller than those of bulk Nd2Fe14B magnets due to the texture effect. The good mechanical properties of the microcantilevers indicate that Nd2Fe14B/Ta multilayered films can be used as a structural material for microsystem applications. In addition, the electromagnetic driving of the Nd2Fe14B/Ta magnetic microcantilever is also demonstrated.

  16. Development of low noise cantilever deflection sensor for multienvironment frequency-modulation atomic force microscopy

    SciTech Connect

    Fukuma, Takeshi; Kimura, Masayuki; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2005-05-15

    We have developed a low noise cantilever deflection sensor with a deflection noise density of 17 fm/{radical}(Hz) by optimizing the parameters used in optical beam deflection (OBD) method. Using this sensor, we have developed a multienvironment frequency-modulation atomic force microscope (FM-AFM) that can achieve true molecular resolution in various environments such as in moderate vacuum, air, and liquid. The low noise characteristic of the deflection sensor makes it possible to obtain a maximum frequency sensitivity limited by the thermal Brownian motion of the cantilever in every environment. In this paper, the major noise sources in OBD method are discussed in both theoretical and experimental aspects. The excellent noise performance of the deflection sensor is demonstrated in deflection and frequency measurements. True molecular-resolution FM-AFM images of a polydiacetylene single crystal taken in vacuum, air, and water are presented.

  17. Performances analysis of piezoelectric cantilever based energy harvester devoted to mesoscale intra-body robot

    NASA Astrophysics Data System (ADS)

    Rabenorosoa, Kanty; Rakotondrabe, Micky

    2015-06-01

    Mesoscale robots, including active capsules, are a promising and well suited approach for minimal invasive intrabody intervention. However, within the numerous works, the main limitation in these robots is the embedded energy used for their locomotion and for the tasks they should accomplish. The limited autonomy and the limited power make them finally unusable for real situations such as active capsules inside body during several tens of minutes. In this paper, we propose an approach to power mesoscale robots by using energy harvesting techniques through a piezoelectric cantilever structure embedded on the robot and through an oscillating magnetic excitation. The physical model of the proposed system is carried out and simulation results are yielded and analyzed accordingly to the influencing parameters such as the number of layers in the cantilever and its dimensions. Finally, the feasability of this solution is proved and perspectives are discussed.

  18. Device for filamentous fungi growth monitoring using the multimodal frequency response of cantilevers

    NASA Astrophysics Data System (ADS)

    Maloney, N.; Lukacs, G.; Ball, S. L.; Hegner, M.

    2014-01-01

    Filamentous fungi cause opportunistic infections in hospital patients. A fast assay to detect viable spores is of great interest. We present a device that is capable of monitoring fungi growth in real time via the dynamic operation of cantilevers in an array. The ability to detect minute frequency shifts for higher order flexural resonance modes is demonstrated using hydrogel functionalised cantilevers. The use of higher order resonance modes sees the sensor dependent mass responsivity enhanced by a factor of 13 in comparison to measurements utilizing the fundamental resonance mode only. As a proof of principle measurement, Aspergillus niger growth is monitored using the first two flexural resonance modes. The detection of single spore growth within 10 h is reported for the first time. The ability to detect and monitor the growth of single spores, within a small time frame, is advantageous in both clinical and industrial settings.

  19. Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers

    NASA Astrophysics Data System (ADS)

    Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

    2015-12-01

    We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations.

  20. Computational model for noncontact atomic force microscopy: energy dissipation of cantilever.

    PubMed

    Senda, Yasuhiro; Blomqvist, Janne; Nieminen, Risto M

    2016-09-21

    We propose a computational model for noncontact atomic force microscopy (AFM) in which the atomic force between the cantilever tip and the surface is calculated using a molecular dynamics method, and the macroscopic motion of the cantilever is modeled by an oscillating spring. The movement of atoms in the tip and surface is connected with the oscillating spring using a recently developed coupling method. In this computational model, the oscillation energy is dissipated, as observed in AFM experiments. We attribute this dissipation to the hysteresis and nonconservative properties of the interatomic force that acts between the atoms in the tip and sample surface. The dissipation rate strongly depends on the parameters used in the computational model.

  1. Catalyst-induced growth of carbon nanotubes on tips of cantilevers and nanowires

    DOEpatents

    Lee, James Weifu; Lowndes, Douglas H.; Merkulov, Vladimir I.; Eres, Gyula; Wei, Yayi; Greenbaum, Elias; Lee, Ida

    2004-06-29

    A method is described for catalyst-induced growth of carbon nanotubes, nanofibers, and other nanostructures on the tips of nanowires, cantilevers, conductive micro/nanometer structures, wafers and the like. The method can be used for production of carbon nanotube-anchored cantilevers that can significantly improve the performance of scaning probe microscopy (AFM, EFM etc). The invention can also be used in many other processes of micro and/or nanofabrication with carbon nanotubes/fibers. Key elements of this invention include: (1) Proper selection of a metal catalyst and programmable pulsed electrolytic deposition of the desired specific catalyst precisely at the tip of a substrate, (2) Catalyst-induced growth of carbon nanotubes/fibers at the catalyst-deposited tips, (3) Control of carbon nanotube/fiber growth pattern by manipulation of tip shape and growth conditions, and (4) Automation for mass production.

  2. Active H ∞ control of the vibration of an axially moving cantilever beam by magnetic force

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Chen, Huai-hai; He, Xu-dong

    2011-11-01

    An H ∞ method for the vibration control of an iron cantilever beam with axial velocity using the noncontact force by permanent magnets is proposed in the paper. The transverse vibration equation of the axially moving cantilever beam with a tip mass is derived by D'Alembert's principle and then updated by experiments. An experimental platform and a magnetic control system are introduced. The properties of the force between the magnet and the beam have been determined by theoretic analysis and tests. The H ∞ control strategy for the suppression of the beam transverse vibration by initial deformation excitations is put forward. The control method can be used for the beam with constant length or varying length. Numerical simulation and actual experiments are implemented. The results show that the control method is effective and the simulations fit well with the experiments.

  3. Measuring the resonant vibration of a sessile droplet using MEMS based cantilevers

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh-Vinh; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-11-01

    We directly measure the normal force distribution on the contact area during the 1st mode resonant vibration of a droplet using an array of MEMS based cantilever. The measurement result shows that the normal force change is the largest at the periphery of the contact area. The ratio between the amplitude of the normal force change at the periphery of the contact area over that at the center of the contact area was approximately 20 times, in the case of 1.8 μL water droplet whose equilibrium contact angle is 140 degrees. We also demonstrate a method to estimate viscosity based on the measurement of the droplet vibration using MEMS cantilevers. The proposed method is able to estimate viscosity using less than 3 μL sample and has a simple operating principle. We believe that this method is suitable for point-of-care testing and characterization of chemical and biological solutions.

  4. High-speed force mapping on living cells with a small cantilever atomic force microscope.

    PubMed

    Braunsmann, Christoph; Seifert, Jan; Rheinlaender, Johannes; Schäffer, Tilman E

    2014-07-01

    The imaging speed of the wide-spread force mapping mode for quantitative mechanical measurements on soft samples in liquid with the atomic force microscope (AFM) is limited by the bandwidth of the z-scanner and viscous drag forces on the cantilever. Here, we applied high-speed, large scan-range atomic force microscopy and small cantilevers to increase the speed of force mapping by ≈10-100 times. This allowed resolving dynamic processes on living mouse embryonic fibroblasts. Cytoskeleton reorganization during cell locomotion, growth of individual cytoskeleton fibers, cell blebbing, and the formation of endocytic pits in the cell membrane were observed. Increasing the force curve rate from 2 to 300 Hz increased the measured apparent Young's modulus of the cells by about 10 times, which facilitated force mapping measurements at high speed. PMID:25085142

  5. High-speed force mapping on living cells with a small cantilever atomic force microscope

    NASA Astrophysics Data System (ADS)

    Braunsmann, Christoph; Seifert, Jan; Rheinlaender, Johannes; Schäffer, Tilman E.

    2014-07-01

    The imaging speed of the wide-spread force mapping mode for quantitative mechanical measurements on soft samples in liquid with the atomic force microscope (AFM) is limited by the bandwidth of the z-scanner and viscous drag forces on the cantilever. Here, we applied high-speed, large scan-range atomic force microscopy and small cantilevers to increase the speed of force mapping by ≈10-100 times. This allowed resolving dynamic processes on living mouse embryonic fibroblasts. Cytoskeleton reorganization during cell locomotion, growth of individual cytoskeleton fibers, cell blebbing, and the formation of endocytic pits in the cell membrane were observed. Increasing the force curve rate from 2 to 300 Hz increased the measured apparent Young's modulus of the cells by about 10 times, which facilitated force mapping measurements at high speed.

  6. Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

    NASA Astrophysics Data System (ADS)

    Wu, Meng; Ou, Yi; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie; Ou, Wen

    2015-07-01

    This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

  7. Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy

    PubMed Central

    Ghoraishi, M. S.; Hawk, J. E.; Phani, Arindam; Khan, M. F.; Thundat, T.

    2016-01-01

    The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20–100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures. PMID:27046089

  8. Computational model for noncontact atomic force microscopy: energy dissipation of cantilever

    NASA Astrophysics Data System (ADS)

    Senda, Yasuhiro; Blomqvist, Janne; Nieminen, Risto M.

    2016-09-01

    We propose a computational model for noncontact atomic force microscopy (AFM) in which the atomic force between the cantilever tip and the surface is calculated using a molecular dynamics method, and the macroscopic motion of the cantilever is modeled by an oscillating spring. The movement of atoms in the tip and surface is connected with the oscillating spring using a recently developed coupling method. In this computational model, the oscillation energy is dissipated, as observed in AFM experiments. We attribute this dissipation to the hysteresis and nonconservative properties of the interatomic force that acts between the atoms in the tip and sample surface. The dissipation rate strongly depends on the parameters used in the computational model.

  9. Readout of micromechanical cantilever sensor arrays by Fabry-Perot interferometry

    SciTech Connect

    Wehrmeister, Jana; Fuss, Achim; Saurenbach, Frank; Berger, Ruediger; Helm, Mark

    2007-10-15

    The increasing use of micromechanical cantilevers in sensing applications causes a need for reliable readout techniques of micromechanical cantilever sensor (MCS) bending. Current optical beam deflection techniques suffer from drawbacks such as artifacts due to changes in the refraction index upon exchange of media. Here, an adaptation of the Fabry-Perot interferometer is presented that allows simultaneous determination of MCS bending and changes in the refraction index of media. Calibration of the instrument with liquids of known refraction index provides an avenue to direct measurement of bending with nanometer precision. Versatile construction of flow cells in combination with alignment features for substrate chips allows simultaneous measurement of two MCS situated either on the same, or on two different support chips. The performance of the instrument is demonstrate in several sensing applications, including adsorption experiments of alkanethioles on MCS gold surfaces, and measurement of humidity changes in air.

  10. Effect of thermal stresses on the vibration of composite cantilevered plates

    NASA Astrophysics Data System (ADS)

    Klosner, J. M.; Cheng, T.-H.

    This study explores the effects of thermal stresses on the dynamic characteristics of composite cantilevered plates. The induced thermal stresses are determined by appealing to the principle of minimum strain energy, while the Raleigh-Ritz procedure is used to obtain the plate frequencies. Extensive numerical calculations were carried out in order to gain quantitative understanding of how different choices of aspect ratios and temperature change intensities (T0) influence the natural frequencies of composite cantilevered plates. It is shown that the first bending mode frequencies are unaffected by the induced stresses, while the first torsional mode frequencies decrease quite significantly with increasing values of T0, and therefore with increased magnitudes of the thermal stresses.

  11. Rapid detection of bacterial resistance to antibiotics using AFM cantilevers as nanomechanical sensors

    NASA Astrophysics Data System (ADS)

    Longo, G.; Alonso-Sarduy, L.; Rio, L. Marques; Bizzini, A.; Trampuz, A.; Notz, J.; Dietler, G.; Kasas, S.

    2013-07-01

    The widespread misuse of drugs has increased the number of multiresistant bacteria, and this means that tools that can rapidly detect and characterize bacterial response to antibiotics are much needed in the management of infections. Various techniques, such as the resazurin-reduction assays, the mycobacterial growth indicator tube or polymerase chain reaction-based methods, have been used to investigate bacterial metabolism and its response to drugs. However, many are relatively expensive or unable to distinguish between living and dead bacteria. Here we show that the fluctuations of highly sensitive atomic force microscope cantilevers can be used to detect low concentrations of bacteria, characterize their metabolism and quantitatively screen (within minutes) their response to antibiotics. We applied this methodology to Escherichia coli and Staphylococcus aureus, showing that live bacteria produced larger cantilever fluctuations than bacteria exposed to antibiotics. Our preliminary experiments suggest that the fluctuation is associated with bacterial metabolism.

  12. High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

    SciTech Connect

    Duden, Thomas; Radmilovic, Velimir

    2009-03-04

    We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.

  13. Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers.

    PubMed

    Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

    2015-12-01

    We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations. PMID:26684144

  14. Dynamic behaviour of dagger-shaped cantilevers for atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Shen, Kangzhi; Hurley, Donna C.; Turner, Joseph A.

    2004-11-01

    Experimental techniques based on the atomic force microscope (AFM) have been developed for characterizing mechanical properties at the nanoscale and applied to a variety of materials and structures. Atomic force acoustic microscopy (AFAM) is one such technique that uses spectral information of the AFM cantilever as it vibrates in contact with a sample. In this paper, the dynamic behaviour of AFM cantilevers that have a dagger shape is investigated using a power-series method. Dagger-shaped cantilevers have plan-view geometry consisting of a rectangular section at the clamped end and a triangular section at the tip. Their geometry precludes modelling using closed-form expressions. The convergence of the series is demonstrated and the convergence radius is shown to be related to the given geometry. The accuracy and efficiency of the method are investigated by comparison with finite element results for several different cases. AFAM experiments are modelled by including a linear spring at the tip that represents the contact stiffness. The technique developed is shown to be very effective for inversion of experimental frequency information into contact stiffness results for AFAM. In addition, the sensitivities of the frequencies to the contact stiffness are discussed in terms of the various geometric parameters of the problem including the slope, the ratio of the rectangular to triangular lengths and the tip location. Calculations of contact stiffness from experimental data using this model are shown to be very good in comparison with other models. It is anticipated that this approach may be useful for other cantilever geometries as well, such that AFAM accuracy may be improved.

  15. Operating characteristics of a cantilever-mounted resilient-pad gas-lubricated thrust bearing

    NASA Technical Reports Server (NTRS)

    Nemeth, Z. N.

    1979-01-01

    A resilient-pad gas thrust bearing consisting of pads mounted on cantilever beams was tested to determine its operating characteristic. The bearing was run at a thrust load of 74 newtons to a speed of 17000 rpm. The pad film thickness and bearing friction torque were measured and compared with theory. The measured film thickness was less than that predicted by theory. The bearing friction torque was greater than that predicted by theory.

  16. Mechanics of cantilever beam: Implementation and comparison of FEM and MLPG approach

    NASA Astrophysics Data System (ADS)

    Trobec, Roman

    2016-06-01

    Two weak form solution approaches for partial differential equations, the well known meshbased finite element method and the newer meshless local Petrov Galerkin method are described and compared on a standard test case - mechanics of cantilever beam. The implementation, solution accuracy and calculation complexity are addressed for both approaches. We found out that FEM is superior in most standard criteria, but MLPG has some advantages because of its flexibility that results from its general formulation.

  17. Four-beam model for vibration analysis of a cantilever beam with an embedded horizontal crack

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Zhu, Weidong; Charalambides, Panos G.; Shao, Yimin; Xu, Yongfeng; Wu, Kai; Xiao, Huifang

    2016-01-01

    As one of the main failure modes, embedded cracks occur in beam structures due to periodic loads. Hence it is useful to investigate the dynamic characteristics of a beam structure with an embedded crack for early crack detection and diagnosis. A new four-beam model with local flexibilities at crack tips is developed to investigate the transverse vibration of a cantilever beam with an embedded horizontal crack; two separate beam segments are used to model the crack region to allow opening of crack surfaces. Each beam segment is considered as an Euler-Bernoulli beam. The governing equations and the matching and boundary conditions of the four-beam model are derived using Hamilton's principle. The natural frequencies and mode shapes of the four-beam model are calculated using the transfer matrix method. The effects of the crack length, depth, and location on the first three natural frequencies and mode shapes of the cracked cantilever beam are investigated. A continuous wavelet transform method is used to analyze the mode shapes of the cracked cantilever beam. It is shown that sudden changes in spatial variations of the wavelet coefficients of the mode shapes can be used to identify the length and location of an embedded horizontal crack. The first three natural frequencies and mode shapes of a cantilever beam with an embedded crack from the finite element method and an experimental investigation are used to validate the proposed model. Local deformations in the vicinity of the crack tips can be described by the proposed four-beam model, which cannot be captured by previous methods.

  18. Multi-material bio-fabrication of hydrogel cantilevers and actuators with stereolithography.

    PubMed

    Chan, Vincent; Jeong, Jae Hyun; Bajaj, Piyush; Collens, Mitchell; Saif, Taher; Kong, Hyunjoon; Bashir, Rashid

    2012-01-01

    Cell-based biohybrid actuators are integrated systems that use biological components including proteins and cells to power material components by converting chemical energy to mechanical energy. The latest progress in cell-based biohybrid actuators has been limited to rigid materials, such as silicon and PDMS, ranging in elastic moduli on the order of mega (10(6)) to giga (10(9)) Pascals. Recent reports in the literature have established a correlation between substrate rigidity and its influence on the contractile behavior of cardiomyocytes (A. J. Engler, C. Carag-Krieger, C. P. Johnson, M. Raab, H. Y. Tang and D. W. Speicher, et al., J. Cell Sci., 2008, 121(Pt 22), 3794-3802, P. Bajaj, X. Tang, T. A. Saif and R. Bashir, J. Biomed. Mater. Res., Part A, 2010, 95(4), 1261-1269). This study explores the fabrication of a more compliant cantilever, similar to that of the native myocardium, with elasticity on the order of kilo (10(3)) Pascals. 3D stereolithographic technology, a layer-by-layer UV polymerizable rapid prototyping system, was used to rapidly fabricate multi-material cantilevers composed of poly(ethylene glycol) diacrylate (PEGDA) and acrylic-PEG-collagen (PC) mixtures. The incorporation of acrylic-PEG-collagen into PEGDA-based materials enhanced cell adhesion, spreading, and organization without altering the ability to vary the elastic modulus through the molecular weight of PEGDA. Cardiomyocytes derived from neonatal rats were seeded on the cantilevers, and the resulting stresses and contractile forces were calculated using finite element simulations validated with classical beam equations. These cantilevers can be used as a mechanical sensor to measure the contractile forces of cardiomyocyte cell sheets, and as an early prototype for the design of optimal cell-based biohybrid actuators.

  19. A macroscopic non-destructive testing system based on the cantilever-sample contact resonance

    NASA Astrophysics Data System (ADS)

    Fu, Ji; Lin, Lizhi; Zhou, Xilong; Li, Yingwei; Li, Faxin

    2012-12-01

    Detecting the inside or buried defects in materials and structures is always a challenge in the field of nondestructive testing (NDT). In this paper, enlightened by the operation principle of the contact resonance force microscopy or atomic force acoustic microscopy (AFAM), we proposed a macroscopic NDT system based on contact resonance of the cantilever-sample surface to detect the local stiffness variations in materials or structures. We fabricated a piezoelectric unimorph with the dimension typically of 150 mm × 8 mm × 2 mm to act as a macroscopic cantilever, whose flexural mode vibration was driven by a wideband power amplifier together with a signal generator. The vibration signal of the macroscopic cantilever is detected by a high sensitive strain gauge bonded on the cantilever surface which is much more stable than the laser diode sensor in AFAM, thus making it very suitable for outdoor operations. Scanning is realized by a three-dimensional motorized stage with the Z axis for pressing force setting. The whole system is controlled by a LabVIEW-based homemade software. Like the AFAM, this NDT system can also work in two modes, i.e., the single-frequency mode and the resonance-tracking mode. In the latter mode, the contact stiffness at each pixel of the sample can be obtained by using the measured contact resonance frequency and a beam dynamics model. Testing results of this NDT system on a grid structure with an opaque panel show that in both modes the prefabricated defect beneath the panel can be detected and the grid structures can be clearly "seen," which indicates the validity of this NDT system. The sensitivity of this NDT system was also examined.

  20. An approximate solution for the free vibrations of rotating uniform cantilever beams

    NASA Technical Reports Server (NTRS)

    Peters, D. A.

    1973-01-01

    Approximate solutions are obtained for the uncoupled frequencies and modes of rotating uniform cantilever beams. The frequency approximations for flab bending, lead-lag bending, and torsion are simple expressions having errors of less than a few percent over the entire frequency range. These expressions provide a simple way of determining the relations between mass and stiffness parameters and the resultant frequencies and mode shapes of rotating uniform beams.

  1. Large deflections of a cantilever beam under arbitrarily directed tip load

    NASA Technical Reports Server (NTRS)

    Mccomb, H. E., Jr.

    1985-01-01

    The nonlinear beam equation was integrated numerically in a direct fashion to obtain results for large deflections of cantilevers under tip loads of arbitrary direction. A short BASIC computer program for performing this integration is presented. Results for selected load cases are presented. The numerical process is performed rapidly on a modern microcomputer, and comparisons with results from closed form solutions show that the process is accurate.

  2. Analysis and design of a cantilever-mounted resilient-pad gas-lubricated thrust bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    A thrust bearing consisting of pads mounted on resilient, metallic, cantilever beams is described and analyzed. Compliance and stiffness of the bearing assembly are discussed, and the effects of bearing design parameters on performance are shown. After the general analysis, a design example is presented for a flat sector-shaped gas bearing. A special case where zero axial movement of the runner can be obtained is pointed out.

  3. Response of long, flexible cantilever beams applied root motions. [spacecraft structures

    NASA Technical Reports Server (NTRS)

    Fralich, R. W.

    1976-01-01

    Results are presented for an analysis of the response of long, flexible cantilever beams to applied root rotational accelerations. Maximum values of deformation, slope, bending moment, and shear are found as a function of magnitude and duration of acceleration input. Effects of tip mass and its eccentricity and rotatory inertia on the response are also investigated. It is shown that flexible beams can withstand large root accelerations provided the period of applied acceleration can be kept small relative to the beam fundamental period.

  4. Piezoresistor-equipped fluorescence-based cantilever probe for near-field scanning

    NASA Astrophysics Data System (ADS)

    Kan, Tetsuo; Matsumoto, Kiyoshi; Shimoyama, Isao

    2007-08-01

    Scanning near-field optical microscopes (SNOMs) with fluorescence-based probes are promising tools for evaluating the optical characteristics of nanoaperture devices used for biological investigations, and this article reports on the development of a microfabricated fluorescence-based SNOM probe with a piezoresistor. The piezoresistor was built into a two-legged root of a 160-μm-long cantilever. To improve the displacement sensitivity of the cantilever, the piezoresistor's doped area was shallowly formed on the cantilever surface. A fluorescent bead, 500nm in diameter, was attached to the bottom of the cantilever end as a light-intensity-sensitive material in the visible-light range. The surface of the scanned sample was simply detected by the probe's end being displaced by contact with the sample. Measuring displacements piezoresistively is advantageous because it eliminates the noise arising from the use of the optical-lever method and is free of any disturbance in the absorption or the emission spectrum of the fluorescent material at the probe tip. The displacement sensitivity was estimated to be 6.1×10-6nm-1, and the minimum measurable displacement was small enough for near-field measurement. This probe enabled clear scanning images of the light field near a 300×300nm2 aperture to be obtained in the near-field region where the tip-sample distance is much shorter than the light wavelength. This scanning result indicates that the piezoresistive way of tip-sample distance regulation is effective for characterizing nanoaperture optical devices.

  5. A soft-polymer piezoelectric bimorph cantilever-actuated peristaltic micropump.

    PubMed

    Graf, Neil J; Bowser, Michael T

    2008-10-01

    A peristaltic micropump was fabricated and characterized. The micropump was fabricated using soft lithography, and actuated using piezoelectric bimorph cantilevers. The micropump channel was formed by bonding two layers of PDMS, mixed at 5:1 and 30:1 ratios. The channel was fabricated in the 5:1 layer using replica molding (REM), where a very simple and inexpensive template was made by straddling a 75 microm wire over a glass substrate, followed by covering and smoothing over the wire with a piece of aluminium foil. Not only was this template inexpensive and extremely simple to fabricate, it also created a rounded cross-sectional geometry which is favorable for complete valve shutoff. The cantilevers were driven at Vp=+/-90 V with amplified square wave signals generated by a virtual function generator created in LabVIEW. Connections to the micropump were made by placing capillary tubes in the channel, and then sealed between the two layers of PDMS. Machined aluminium clamps were adhered to the tips of the cantilevers with general purpose adhesive. These clamps allowed for aluminium valves, with finely machined tips of dimensions 3 mm by 200 microm, to be held firmly in place. The variables characterized for this micropump were flow rate, maximum attainable backpressure, free cantilever deflection, valve shutoff, and valve leakage. Three actuation patterns with phase differences of 60, 90, and 120 degrees were compared for flow rate and maximum backpressure. It was determined that the 120 degrees signal outperformed the 60 degrees and 90 degrees signals for both maximum flowrate and maximum attainable backpressure. The maximum and minimum flowrates demonstrated by the micropump were 289 nL min(-1) and 53 nL min(-1), respectively. The maximum backpressure attained was 35 300 Pa. It was also demonstrated that the valves fully closed the channels upon actuation, with minimal observed leakage.

  6. A Cantilever-based apparatus for detecting micron-scale deviations from Newtonian gravity

    NASA Astrophysics Data System (ADS)

    Kapitulnik, Aharon

    2009-03-01

    To test new theories of physics beyond the Standard Model, we have built a low temperature probe to measure forces as small as 10-18 N between masses separated by distances on the order of 20 microns. Our experiment is fundamentally a Cavendish-type experiment in the sense that its purpose is to directly measure the force between two masses [1]. A cryogenic helium gas bearing is used to rotate a disc containing a drive mass pattern of alternating density under a small test mass mounted on a micromachined cantilever. Any mass-dependent force between the two will produce a time-varying force on the test mass, and consequently a time-varying displacement of the cantilever. This displacement is read out with a laser interferometer, and the position of the drive mass is simultaneously recorded using an optical encoder. The displacement is then averaged over many cycles and converted to a force using measured properties of the cantilever. This AC ``lock-in'' type measurement enables significant noise rejection and allows us to operate on resonance to take advantage of the cantilever's high quality factor. A novel feature of the apparatus is the utilization of feedback regulation of the response of the microcantilever using the radiation pressure of a laser. Our approach does not require a high-finesse cavity, and the feedback force is due solely to the momentum of the photons in the second laser. [4pt] [1] D.M. Weld, J. Xia, B. Cabrera, and A. Kapitulnik, Phys. Rev. D 77, 062006 (2008).

  7. Biomechanical aspects of the optimal number of implants to carry a cross-arch full restoration.

    PubMed

    Brunski, John B

    2014-01-01

    A proper definition of the 'optimal' number of implants to support a full arch prosthesis should go beyond solely a listing of the number of implants used in a treatment plan; it should be based upon a biomechanical analysis that takes into account several factors: the locations of the implants in the jaw; the quality and quantity of bone into which they are placed; the loads (forces and moments) that develop on the implants; the magnitudes of stress and strain that develop in the interfacial bone as well as in the implants and prosthesis; and the relationship of the stresses and strains to limits for the materials involved. Overall, determining an 'optimal' number of implants to use in a patient is a biomechanical design problem. This paper discusses some of the approaches that are already available to aid biomechanically focused clinical treatment planning. A number of examples are presented to illustrate how relatively simple biomechanical analyses - e.g. the Skalak model - as well as more complex analyses (e.g. finite element modelling) can be used to assess the pros and cons of various arrangements of implants to support fullarch prostheses. Some of the examples considered include the use of 4 rather than 6 implants to span the same arc-length in a jaw, and the pros and cons of using tilted implants as in the 'all-on-4' approach. In evaluating the accuracy of the various biomechanical analyses, it is clear that our current prediction methods are not always perfectly accurate in vivo, although they can provide a reasonably approximate analysis of a treatment plan in many situations. In the current era of cone beam computerised tomography (CT) scans of patients in the dental office, there is significant promise for finite element analyses (FEA) based on anatomically-accurate input data. However, at the same time it has to be recognised that effective use of FEA software requires a reasonable engineering background, especially insofar as interpretations of the clinical significance of stresses and strains in bone and prosthetic materials. PMID:24977245

  8. A paper-based cantilever array sensor: Monitoring volatile organic compounds with naked eye.

    PubMed

    Fraiwan, Arwa; Lee, Hankeun; Choi, Seokheun

    2016-09-01

    Volatile organic compound (VOC) detection is critical for controlling industrial and commercial emissions, environmental monitoring, and public health. Simple, portable, rapid and low-cost VOC sensing platforms offer the benefits of on-site and real-time monitoring anytime and anywhere. The best and most practically useful approaches to monitoring would include equipment-free and power-free detection by the naked eye. In this work, we created a novel, paper-based cantilever sensor array that allows simple and rapid naked-eye VOC detection without the need for power, electronics or readout interface/equipment. This simple VOC detection method was achieved using (i) low-cost paper materials as a substrate and (ii) swellable thin polymers adhered to the paper. Upon exposure to VOCs, the polymer swelling adhered to the paper-based cantilever, inducing mechanical deflection that generated a distinctive composite pattern of the deflection angles for a specific VOC. The angle is directly measured by the naked eye on a 3-D protractor printed on a paper facing the cantilevers. The generated angle patterns are subjected to statistical algorithms (linear discriminant analysis (LDA)) to classify each VOC sample and selectively detect a VOC. We classified four VOC samples with 100% accuracy using LDA. PMID:27343578

  9. A paper-based cantilever array sensor: Monitoring volatile organic compounds with naked eye.

    PubMed

    Fraiwan, Arwa; Lee, Hankeun; Choi, Seokheun

    2016-09-01

    Volatile organic compound (VOC) detection is critical for controlling industrial and commercial emissions, environmental monitoring, and public health. Simple, portable, rapid and low-cost VOC sensing platforms offer the benefits of on-site and real-time monitoring anytime and anywhere. The best and most practically useful approaches to monitoring would include equipment-free and power-free detection by the naked eye. In this work, we created a novel, paper-based cantilever sensor array that allows simple and rapid naked-eye VOC detection without the need for power, electronics or readout interface/equipment. This simple VOC detection method was achieved using (i) low-cost paper materials as a substrate and (ii) swellable thin polymers adhered to the paper. Upon exposure to VOCs, the polymer swelling adhered to the paper-based cantilever, inducing mechanical deflection that generated a distinctive composite pattern of the deflection angles for a specific VOC. The angle is directly measured by the naked eye on a 3-D protractor printed on a paper facing the cantilevers. The generated angle patterns are subjected to statistical algorithms (linear discriminant analysis (LDA)) to classify each VOC sample and selectively detect a VOC. We classified four VOC samples with 100% accuracy using LDA.

  10. Utilization of microscale silicon cantilevers to assess cellular contractile function in vitro

    PubMed Central

    Smith, Alec S.T.; Long, Christopher J.; McAleer, Christopher; Bobbitt, Nathaniel; Srinivasan, Balaji; Hickman, James J.

    2016-01-01

    The development of more predictive and biologically relevant in vitro assays is predicated on the advancement of versatile cell culture systems which facilitate the functional assessment of the seeded cells. To that end, microscale cantilever technology offers a platform with which to measure the contractile functionality of a range of cell types, including skeletal, cardiac and smooth muscle cells, through assessment of contraction induced substrate bending. Application of multiplexed cantilever arrays provides the means to develop moderate to high-throughput protocols for assessing drug efficacy and toxicity, disease phenotype and progression, as well as neuromuscular and other cell-cell interactions. This manuscript provides the details for fabricating reliable cantilever arrays for this purpose, and the methods required to successfully culture cells on these surfaces. Further description is provided on the steps necessary to perform functional analysis of contractile cell types maintained on such arrays using a novel laser and photo-detector system. The representative data provided highlights the precision and reproducible nature of the analysis of contractile function possible using this system, as well as the wide range of studies to which such technology can be applied. Successful widespread adoption of this system could provide investigators with the means to perform rapid, low cost functional studies in vitro, leading to more accurate predictions of tissue performance, disease development and response to novel therapeutic treatment. PMID:25350792

  11. Microfluidic cantilever detects bacteria and measures their susceptibility to antibiotics in small confined volumes

    PubMed Central

    Etayash, Hashem; Khan, M. F.; Kaur, Kamaljit; Thundat, Thomas

    2016-01-01

    In the fight against drug-resistant bacteria, accurate and high-throughput detection is essential. Here, a bimaterial microcantilever with an embedded microfluidic channel with internal surfaces chemically or physically functionalized with receptors selectively captures the bacteria passing through the channel. Bacterial adsorption inside the cantilever results in changes in the resonance frequency (mass) and cantilever deflection (adsorption stress). The excitation of trapped bacteria using infrared radiation (IR) causes the cantilever to deflect in proportion to the infrared absorption of the bacteria, providing a nanomechanical infrared spectrum for selective identification. We demonstrate the in situ detection and discrimination of Listeria monocytogenes at a concentration of single cell per μl. Trapped Escherichia coli in the microchannel shows a distinct nanomechanical response when exposed to antibiotics. This approach, which combines enrichment with three different modes of detection, can serve as a platform for the development of a portable, high-throughput device for use in the real-time detection of bacteria and their response to antibiotics. PMID:27698375

  12. Estimating the transfer function of the cantilever in atomic force microscopy: A system identification approach

    NASA Astrophysics Data System (ADS)

    Stark, Martin; Guckenberger, Reinhard; Stemmer, Andreas; Stark, Robert W.

    2005-12-01

    Dynamic atomic force microscopy (AFM) offers many opportunities for the characterization and manipulation of matter on the nanometer scale with a high temporal resolution. The analysis of time-dependent forces is basic for a deeper understanding of phenomena such as friction, plastic deformation, and surface wetting. However, the dynamic characteristics of the force sensor used for such investigations are determined by various factors such as material and geometry of the cantilever, detection alignment, and the transfer characteristics of the detector. Thus, for a quantitative investigation of surface properties by dynamic AFM an appropriate system identification procedure is required, characterizing the force sensor beyond the usual parameters spring constant, quality factor, and detection sensitivity. Measurement of the transfer function provides such a characterization that fully accounts for the dynamic properties of the force sensor. Here, we demonstrate the estimation of the transfer function in a bandwidth of 1MHz from experimental data. To this end, we analyze the signal of the vibrations induced by snap-to-contact and snap-off-contact events. For the free cantilever, we determine both a parameter-free estimate [empirical transfer function estimate (ETFE)] and a parametric estimate of the transfer function. For the surface-coupled cantilever the ETFE is obtained. These identification procedures provide an intrinsic calibration as they dispense largely with a priori knowledge about the force sensor.

  13. Cantilever energy effects on bimodal AFM: phase and amplitude contrast of multicomponent samples

    NASA Astrophysics Data System (ADS)

    Chakraborty, Ishita; Yablon, Dalia G.

    2013-11-01

    Bimodal atomic force microscopy (AFM) is a recently developed technique of dynamic AFM where a higher eigenmode of the cantilever is simultaneously excited along with the fundamental eigenmode. The effects of different operating parameters while imaging an impact copolymer blend of polypropylene (PP) and ethylene-propylene (E-P) rubber in bimodal mode are explored through experiments and numerical simulations. The higher mode amplitude and phase contrasts between the two components of the sample reverse at different points as the free amplitude of the higher eigenmode is increased. Three different regimes are identified experimentally depending on the relative contrast between the PP and the E-P rubber. It is observed that the kinetic energy and free air drive input energy of the two cantilever eigenmodes play a role in determining the regimes of operation. Numerical simulations conducted with appropriate tip-sample interaction forces support the experimental results. An understanding of these regimes and the associated cantilever dynamics will guide a rational approach towards selecting appropriate operating parameters.

  14. Research on vibration measurement of a cantilever beam by twin-core fiber

    NASA Astrophysics Data System (ADS)

    Geng, Tao; Liu, Tao; Peng, Feng; Dai, Qiang; Yang, Yuan

    2009-05-01

    A novel interference transducer based on the measurement principle of multicore fiber interference for vibration measurement of a cantilever beam is designed in the paper. Twin-core fiber is special designed fiber, which contains a pair of parallel fiber core. Two paths integrated in one fiber not only greatly decreases sensor's volume, but also makes environment temperature effect approximately equal to each. A twin-core fiber which is pasted on the cantilever beam with epoxy resin is used as the sensing element. The twin-core fiber act as a two-beam in-fiber integrated interferometer that has a far-field interferometric fringe pattern which shift thereupon with the cantilever beam oscillates. CCD was used to measure the displacement of interferometer fringes instead of the traditional photodetector. The continuous capture of interference fringes was realized. The design of low pass filter and image smoothing were finished according to the characteristics of interference fringes. Orientation error of interference fringe center was removed. Displacement of fringe center was calculated and the spectrum of the displacement was analyzed with Fourier Transform. The system uses high-speed CCD camera as the photoelectric transformer. By using the high sensitivity twin-core fiber, the system realizes high precision measurement of vibration frequency, and ensures real-time performance. The experiment results show that the vibration measurement method is feasible and possesses potential application prospect in tiny vibration measure.

  15. Coupled molecular and cantilever dynamics model for frequency-modulated atomic force microscopy.

    PubMed

    Klocke, Michael; Wolf, Dietrich E

    2016-01-01

    A molecular dynamics model is presented, which adds harmonic potentials to the atomic interactions to mimic the elastic properties of an AFM cantilever. It gives new insight into the correlation between the experimentally monitored frequency shift and cantilever damping due to the interaction between tip atoms and scanned surface. Applying the model to ionic crystals with rock salt structure two damping mechanisms are investigated, which occur separately or simultaneously depending on the tip position. These mechanisms are adhesion hysteresis on the one hand and lateral excitations of the cantilever on the other. We find that the short range Lennard-Jones part of the atomic interaction alone is sufficient for changing the predominant mechanism. When the long range ionic interaction is switched off, the two damping mechanisms occur with a completely different pattern, which is explained by the energy landscape for the apex atom of the tip. In this case the adhesion hysteresis is always associated with a distinct lateral displacement of the tip. It is shown how this may lead to a systematic shift between the periodic patterns obtained from the frequency and from the damping signal, respectively. PMID:27335760

  16. Microfluidic cantilever detects bacteria and measures their susceptibility to antibiotics in small confined volumes

    NASA Astrophysics Data System (ADS)

    Etayash, Hashem; Khan, M. F.; Kaur, Kamaljit; Thundat, Thomas

    2016-10-01

    In the fight against drug-resistant bacteria, accurate and high-throughput detection is essential. Here, a bimaterial microcantilever with an embedded microfluidic channel with internal surfaces chemically or physically functionalized with receptors selectively captures the bacteria passing through the channel. Bacterial adsorption inside the cantilever results in changes in the resonance frequency (mass) and cantilever deflection (adsorption stress). The excitation of trapped bacteria using infrared radiation (IR) causes the cantilever to deflect in proportion to the infrared absorption of the bacteria, providing a nanomechanical infrared spectrum for selective identification. We demonstrate the in situ detection and discrimination of Listeria monocytogenes at a concentration of single cell per μl. Trapped Escherichia coli in the microchannel shows a distinct nanomechanical response when exposed to antibiotics. This approach, which combines enrichment with three different modes of detection, can serve as a platform for the development of a portable, high-throughput device for use in the real-time detection of bacteria and their response to antibiotics.

  17. Utilization of Microscale Silicon Cantilevers to Assess Cellular Contractile Function In Vitro

    PubMed Central

    Smith, Alec S.T.; Long, Christopher J.; McAleer, Christopher; Bobbitt, Nathaniel; Srinivasan, Balaji; Hickman, James J.

    2014-01-01

    The development of more predictive and biologically relevant in vitro assays is predicated on the advancement of versatile cell culture systems which facilitate the functional assessment of the seeded cells. To that end, microscale cantilever technology offers a platform with which to measure the contractile functionality of a range of cell types, including skeletal, cardiac, and smooth muscle cells, through assessment of contraction induced substrate bending. Application of multiplexed cantilever arrays provides the means to develop moderate to high-throughput protocols for assessing drug efficacy and toxicity, disease phenotype and progression, as well as neuromuscular and other cell-cell interactions. This manuscript provides the details for fabricating reliable cantilever arrays for this purpose, and the methods required to successfully culture cells on these surfaces. Further description is provided on the steps necessary to perform functional analysis of contractile cell types maintained on such arrays using a novel laser and photo-detector system. The representative data provided highlights the precision and reproducible nature of the analysis of contractile function possible using this system, as well as the wide range of studies to which such technology can be applied. Successful widespread adoption of this system could provide investigators with the means to perform rapid, low cost functional studies in vitro, leading to more accurate predictions of tissue performance, disease development and response to novel therapeutic treatment. PMID:25350792

  18. Coupled molecular and cantilever dynamics model for frequency-modulated atomic force microscopy.

    PubMed

    Klocke, Michael; Wolf, Dietrich E

    2016-01-01

    A molecular dynamics model is presented, which adds harmonic potentials to the atomic interactions to mimic the elastic properties of an AFM cantilever. It gives new insight into the correlation between the experimentally monitored frequency shift and cantilever damping due to the interaction between tip atoms and scanned surface. Applying the model to ionic crystals with rock salt structure two damping mechanisms are investigated, which occur separately or simultaneously depending on the tip position. These mechanisms are adhesion hysteresis on the one hand and lateral excitations of the cantilever on the other. We find that the short range Lennard-Jones part of the atomic interaction alone is sufficient for changing the predominant mechanism. When the long range ionic interaction is switched off, the two damping mechanisms occur with a completely different pattern, which is explained by the energy landscape for the apex atom of the tip. In this case the adhesion hysteresis is always associated with a distinct lateral displacement of the tip. It is shown how this may lead to a systematic shift between the periodic patterns obtained from the frequency and from the damping signal, respectively.

  19. Thrust measurements and flow field analysis of a piezoelectrically actuated oscillating cantilever

    NASA Astrophysics Data System (ADS)

    Eastman, Andrew; Kiefer, Jacob; Kimber, Mark

    2012-11-01

    Although not identical to the motion employed by nature's swimmers and flyers, the simple harmonic oscillations of cantilever-like structures have been shown to provide efficient low-power solutions for applications ranging from thermal management to propulsion. However, in order to quantify their true potential, the resulting flow field and corresponding thrust must be better understood. In this work, a thin, flexible cantilever is actuated via a piezoelectric patch mounted near its base and caused to vibrate in its first resonance mode in air. The flow field is experimentally measured with particle image velocimetry while the thrust produced from the oscillatory motion is quantified using a high-resolution scale. The trends observed in the data are captured using an oscillating Reynolds number, and a clear relationship is defined between the operating parameters and the resulting thrust. Two-dimensional flow fields are extracted from the x- y and y- z planes and are primarily used to motivate future geometry and sidewall configurations that could greatly enhance the thrust capabilities of the cantilever by directing the flow downstream in a more effective manner.

  20. Coupled molecular and cantilever dynamics model for frequency-modulated atomic force microscopy

    PubMed Central

    Klocke, Michael

    2016-01-01

    Summary A molecular dynamics model is presented, which adds harmonic potentials to the atomic interactions to mimic the elastic properties of an AFM cantilever. It gives new insight into the correlation between the experimentally monitored frequency shift and cantilever damping due to the interaction between tip atoms and scanned surface. Applying the model to ionic crystals with rock salt structure two damping mechanisms are investigated, which occur separately or simultaneously depending on the tip position. These mechanisms are adhesion hysteresis on the one hand and lateral excitations of the cantilever on the other. We find that the short range Lennard-Jones part of the atomic interaction alone is sufficient for changing the predominant mechanism. When the long range ionic interaction is switched off, the two damping mechanisms occur with a completely different pattern, which is explained by the energy landscape for the apex atom of the tip. In this case the adhesion hysteresis is always associated with a distinct lateral displacement of the tip. It is shown how this may lead to a systematic shift between the periodic patterns obtained from the frequency and from the damping signal, respectively. PMID:27335760