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Mechanical and electronic approaches to improve the sensitivity of microcantilever sensors

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Acta Mechanica Sinica 2009年第1期25卷 1-12页

作者： Madhu Santosh Ku Mutyala Deepika Bandhanadham Vijaya Rohini Pendyala Institute for Micromanufacturing Louisiana Tech University

Advances in the field of micro electro mechanical systems and their uses now offer unique opportunities in the design of ultrasensitive analytical tools. The analytical community continues to search for cost-effective, reliable, and even portable analytical techniques that can give reliable and fast response results for a variety of chemicals and biomolecules. microcantilevers （MCLs） have emerged as a unique platform for label-free chem-sensor or bioassay. Several electronic designs, including piezoresistive, piezoelectric, and capacitive approaches, have been applied to measure the bending or frequency change of the MCLs upon exposure to chemicals. This review summarizes mechanical, fabrication, and electronics approaches to increase the sensitivity of MCL sensors.

关键词： microcantilever Sensor MEMS Sensitivity

Development of novel and sensitive sensors based on microcantilever of atomic force microscope

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Progress in Natural Science:Materials International 2006年第5期16卷 445-451页

作者： JIN Yan, WANG Kemin and JIN Rong (State Key Laboratory of Chemo/Biosensing and Chernometrics, Institute of Biological Technology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China) State Key Laboratory of Chemo Biosensing and Chemometrics Institute of Biological Technology College of Chemistry and Chemical Engineering Hunan University Changsha 410082 China

Recently, the development of sensors based on microfabricated cantilevers of atomic force microscope (AFM) has attracted considerable attention from the designers of novel physical, chemical, and biological sensors. Many kinds of sensors have been developed taking the advantages of its high-resolution imaging, force measurement and force sensitivity, such as immunosensor and DNA biosensor and the sensors for detection of intermolecular interaction. This paper reviews the progress made in this field and discusses the signal transfer principles by which the design of the sensors is achieved.

关键词： atomic force microscopy microcantilever sensor.

Resonance-mode effect on piezoelectric microcantilever performance in air,with a focus on the torsional modes

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Chinese Physics B 2014年第2期23卷 481-485页

作者：邱华诚 Dara Feili 吴学忠 Helmut Seidel Saarland University Chair of MicromechanicsMicrofluidics/Microactuators66123 Saarbrücken National University of Defense Technology College of Mechanical Engineering and Automation

A high quality factor is preferred for a microresonator sensor to improve the sensitivity and resolution. In this paper we systematically investigate the performance of the microcantilever in different resonance modes, which are the first three flexural modes, the first lateral mode, and the first and the second torsional modes. An aluminum nitride-based piezoelectric cantilever is fabricated and tested under controlled pressure from an ultra-high vacuum to a normal atmosphere, using a custom-built vacuum chamber. From the experiment results, it can be seen that the torsional modes exhibit better quality factors than those of the flexural and lateral ones. Finally, an analytical model for the air damping characteristics of the torsional mode cantilever is derived and verified by comparing with experimental results.

关键词： microcantilever aluminum nitride torsional mode quality factor

Electrothermal Driving microcantilever Resonator as a Platform for Chemical Gas Sensing

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Tsinghua Science and Technology 2010年第5期15卷 481-488页

作者：董瑛高伟郑义尤政 Department of Precision Instruments and Mechanology Tsinghua University State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University

In the current research,the use of a micromachined cantilever resonator as a platform for chemical gas sensing was *** microcantilever resonator integrates an electrothermal driving unit and a piezoresistive detecting unit,and it is fabricated by direct bonding a silicon-on-insulator（SOI） *** a particular polymer layer coated on the surface of the microcantilever,a gas sensor for volatile organic components（VOCs） detection can be *** operation mechanism provides the microcantilever resonator with integrated circuit（IC） compatibility in terms of both the fabrication process and operating *** configuration of the microcantilever resonator can optimize the performance of the gas *** SOI wafer provides a solution for the integrated fabrication of the microstructure,transducers,electronics,and the precise control of the resonator *** this paper,the principles,design,analysis,process,and demonstration of the gas sensor based on the microcantilever resonator are *** experimental results provide confirmation that the polymer-coated microcantilever resonator has excellent performance with regard to VOC detection.

关键词： microcantilever resonator gas sensor electrothermal driving volatile organic component

A ZnO thin-film driven microcantilever for nanoscale actuation and sensing

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International Journal of Smart and Nano Materials 2013年第2期4卷 128-141页

作者： Yanhui Yuan Kun Shyong Chow Hejun Du Peihong Wang Mingsheng Zhang Shengkai Yu k Bo Liu School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingaporeSingapore Data Storage Institute SingaporeSingapore

Zinc oxide(ZnO)thin film as a piezoelectric material for microelectromechanical system(MEMS)actuators and sensors was *** thin films were deposited using radio frequency(RF)magnetron *** parameters such as gas ratio,working pressure,and RF power were optimized for crystalline *** ZnO thin films were characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).Good quality of ZnO thin films was further confirmed by a high transverse piezoelectric coefficient d31.A microcantilever was then designed,fabricated,and *** formulas of resonant frequency,actuation,and sensing sensitivities were *** resonant frequency was determined by an impedance *** deflection on nanometer level was demonstrated with the cantilever used as an *** actuation sensitivity was found to be 12.2 nm/*** a sensor,the cantilever was calibrated against a reference *** sensing sensitivity was characterized to be 46 mV/*** characterization results were compared with design *** differences were caused mainly by thickness control in *** study showed that ZnO is a promising piezoelectric material for MEMS actuators and sensors in terms of excellent process compatibility and good piezoelectric performance.

关键词： ZnO actuation sensing microcantilever MEMS

Nonlinear Response of Multi-Segmented Photodetectors Used for Measurements of microcantilever Motion over Large Dynamic Ranges

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Journal of Sensor Technology 2012年第4期2卷 196-205页

作者： Asit Kar Michael George Laboratory for Materials and Surface Science Department of Chemistry University of Alabama in Huntsville Huntsville AL 35899 USA

The use of multi-segmented Position Sensitive Photodiodes (PSD) to measure microcantilever deflections have been found to produce nonlinear signal output, especially when the dynamic range is large. The reflected beam of the microcantilever may undergo intensity and shape modifications prior to reaching the PSD. In a multi-microcantilever sensor system the variation in the size of the individual spots plays an additional role contributing to the nonlinearities of detector output. Irrespective of the range of operation the merits of intensity normalization have been discussed. We show that the output is proportional to the width of the spot along the split line of the detector. This enables the determination of the shape of a spot. We show that the microcantilever vibrational spectrum can be obtained just using a single segment photodetector instead of using multiple segmented PSDs. These concepts will greatly facilitate interpretation of sensor data acquired from either single or multi-microcantilever experimental platforms.

关键词： Photodetectors microcantilever Sensors Signal Artifacts Laser Spot Shape AFM

Measurement of Temperature Induced Unfolding of DNA Hairpins by microcantilever Sensors

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Open Journal of Applied Biosensor 2013年第3期2卷 78-82页

作者： Joseph D. Ng Jeffrey J. Dowell Asit K. Kar Karolyn Hansen Thomas Thundat Michael A. George Department of Biology University of Dayton Dayton USA Department of Chemical and Materials Engineering University of Alberta Edmonton Canada Department of Chemistry University of Alabama Huntsville USA Laboratory for Structural Biology and the Department of Biological Science University of Alabama Huntsville USA

The technical feasibility of monitoring DNA melting and cooling transitions using a microcantilever substrate has been demonstrated and these results were compared with those measured in solution by circular dichroism. DNA hairpins have been immobilized on the surface of gold-coated microcantilever surfaces and their DNA melting and cooling transitions were monitored by nanomechanical deflections. The hairpins comprised of a 16 base-pair GACA repeat motif stem duplex with a 29 nucleotide variable region. microcantilever deflection profiles, measured by the microcantilever response as a function of temperature, were unique to different hairpins indicative of the molecules’ general stability and denaturation characteristics. The major melting and cooling transition temperatures for all three immobilized oligonucleotides were between 41。C - 52。C. The composition and flexibility of the DNA stem loops were shown to influence the thermal transitions.

关键词： Hairpin DNA microcantilever Thermal Melting Unfolding

Residual Strains in a Nanometer Thick Cr Film Measured on Micromachined Beams

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Journal of Materials Science & Technology 2009年第1期25卷 77-80页

作者： Z.M. Zhou Yong Zhou Ying Cao Haiping Mao Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education Research Institute of Micro/Nano Science and Technology Shanghai Jiao Tong University Shanghai 200030 China

A Cr film with a 75 nm thickness sputtered on a Si substrate was used to fabricate microbridge and microcantilever samples with the MEMS （microelectromechanical system） technique. The profile of the buckled beams was measured by using the interference technique with white light and fitted with a theoretical result. The uniform residual strain in the bridge samples was deduced from the variation of buckling amplitude with the beam length. On the other hand, the gradient residual strain was determined from the deflection profile of the cantilever. The residual uniform and gradient strain in the Cr film are about 4.96×10^-3 and 4.2967×10^-5, respectively.

关键词： Residual Strain Microelectromechanical system (MEMS) Microbridge microcantilever

A NANOMECHANICAL DEVICE BASED ON LIGHT-DRIVEN PROTON PUMPS

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A NANOMECHANICAL DEVICE BASED ON LIGHT-DRIVEN PROTON PUMPS