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A PIPETTE TIP INTEGRATED WITH A capacitive microsensor FABRICATED BY COMBINED 3D PRINTING AND MEMS PROCESS FOR CELL DETECTION AND TRANSPORTATION 36

A PIPETTE TIP INTEGRATED WITH A CAPACITIVE MICROSENSOR FABRI...

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36th IEEE International Conference on Micro Electro Mechanical Systems (MEMS)

作者： Amaya, Satoshi Sugiura, Hirotaka Turan, Bilal Kaneko, Shingo Arai, Fumihito Univ Tokyo Bunkyo City Japan

ISBN: (纸本)9781665493086

This paper reports on the detection and manipulation of cells using a pipette tip with a capacitive microsensor fabricated by combined 3D printing and MEMS processes. This pipette tip with microsensor was fabricated by 3D printing directly onto a MEMS device. First, a pair of comb electrode capacitive sensor was fabricated using the traditional MEMS process. Then, the pipette tip structure was 3D-printed directly on the sensor substrate by projection micro stereolithography. This process is possible to form nm- to cm-scale structures integrally with high precision and three-dimensionally. The fabricated device successfully detected cell suction and ejection. In addition, cell transfer was performed to show the possibility of applying the device to cell manipulation by a robot.

关键词： capacitive microsensor 3D printing Cell Detection

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THE MODELLING OF A capacitive microsensor FOR BIOSENSING APPLICATIONS

THE MODELLING OF A CAPACITIVE MICROSENSOR FOR BIOSENSING APP...

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3rd South African Conference on Sensors, MEMS, and Electro-Optical Systems (SMEOS)

作者： Bezuidenhout, P. H. Schoeman, J. Joubert, T. H. Univ Pretoria Dept Elect Engn & Comp Engn ZA-0002 Pretoria South Africa CSIR Mat Sci & Mfg Pretoria South Africa

ISBN: (纸本)9781628413243

Microsensing is a leading field in technology due to its wide application potential, not only in bio-engineering, but in other fields as well. microsensors have potentially low-cost manufacturing processes, while a single device type can have various uses, and this consequently helps with the ever-growing need to provide better health conditions in rural parts of the world. capacitive biosensors detect a change in permittivity (or dielectric constant) of a biological material, usually within a parallel plate capacitor structure which is often implemented with integrated electrodes of an inert metal such as gold or platinum on a microfluidic substrate typically with high dielectric constant. There exist parasitic capacitance components in these capacitive sensors, which have large influence on the capacitive measurement. Therefore, they should be considered for the development of sensitive and accurate sensing devices. An analytical model of a capacitive sensor device is discussed, which accounts for these parasitic factors. The model is validated with a laboratory device of fixed geometry, consisting of two parallel gold electrodes on an alumina (Al2O3) substrate mounted on a glass microscope slide, and with a windowed cover layer of poly-dimethyl-siloxane (PDMS). The thickness of the gold layer is 1 mu m and the electrode spacing is 300 mu m. The alumina substrate has a thickness of 200 mu m, and the high relative permittivity of 11.5 is expected to be a significantly contributing factor to the total device capacitance. The 155 mu m thick PDMS layer is also expected to contribute substantially to the total device capacitance since the relative permittivity for PDMS is 2.7. The wideband impedance analyser evaluation of the laboratory device gives a measurement result of 2pF, which coincides with the model results;while the handheld RLC meter readout of 4pF at a frequency of 10kHz is acceptable within the measurement accuracy of the instrument. This validated model w

关键词： capacitive biosensor parasitic capacitances capacitive microsensor microsensor

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Low-power, parasitic-insensitive interface circuit for capacitive microsensors

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IET CIRCUITS DEVICES & SYSTEMS 2016年第2期10卷 104-110页

作者： Aezinia, Fatemeh Bahreyni, Behraad Simon Fraser Univ Sch Mechatron Syst Engn Surrey BC V3T 0A3 Canada

capacitive transduction is ubiquitously employed at macro- and especially micro-scales due to their simple structure and stability. This study proposes a topology for a low-power readout circuit for differential capacitive sensors. The circuit includes two switched-capacitor blocks that produce signals that are proportional to the difference and sum of the sense capacitors. Outputs of these two blocks are fed to an analogue divider to produce a pulse whose width is proportional to the ratio of the difference to sum of the sense capacitors. In addition to providing adjustable sensitivity and noise levels, this also reduces the sensitivity of the sensor to common-mode parasitics at the circuit input. The circuit topology was realised in a standard CMOS 0.35 mu m technology with a total chip area of 330 mu m x 600 mu m. The performance of the fabricated circuit was evaluated by pairing it with a micromechanical variable capacitor. Experimental results demonstrated the capability of the circuit to resolve 160 aF of differential capacitance with a total power consumption of 720 mu W while remaining insensitive to common-mode parasitic capacitances.

关键词： capacitance 160 aF sensor sensitivity reduction low-power readout circuit complementary metal oxide semiconductor capacitive transduction low-power electronics differential capacitive sensor capacitive sensors circuit topology common-mode parasitic capacitance microsensors parasitic-insensitive interface circuit size 0.35 mum sense capacitor CMOS technology power 720 muW CMOS integrated circuits readout electronics switched-capacitor block sensitivity analysis capacitive microsensor analogue divider micromechanical variable capacitor

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Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital Converter

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MICROMACHINES 2018年第7期9卷 347-347页

作者： Kim, Hyungseup Lee, Byeoncheol Mun, Yeongjin Kim, Jaesung Han, Kwonsang Roh, Youngtaek Song, Dongkyu Huh, Seounghoon Ko, Hyoungho Chungnam Natl Univ Dept Elect Engn Daejeon 34134 South Korea LeoLSI Co Ltd Seoul 06728 South Korea

This paper proposes a reconfigurable sensor analog front-end using low-noise chopper-stabilized delta-sigma capacitance-to-digital converter (CDC) for capacitive microsensors. The proposed reconfigurable sensor analog front-end can drive both capacitive microsensors and voltage signals by direct conversion without a front-end amplifier. The reconfigurable scheme of the front-end can be implemented in various multi-mode applications, where it is equipped with a fully integrated temperature sensor. A chopper stabilization technique is implemented here to achieve a low-noise characteristic by reducing unexpected low-frequency noises such as offsets and flicker noise. The prototype chip of the proposed sensor analog front-end is fabricated by a standard 0.18-mu m 1-poly-6-metal (1P6M) complementary metal-oxide-semiconductor (CMOS) process. It occupies a total active area of 5.37 mm(2) and achieves an effective resolution of 16.3-bit. The total power consumption is 0.843 mW with a 1.8 V power supply.

关键词： capacitive microsensor analog front-end (AFE) capacitive sensor interface circuit reconfigurable sensor readout circuit delta-sigma modulation capacitance-to-digital converter (CDC) temperature sensor low-noise technique chopper stabilization

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Fully Integrated Low-Noise Readout Circuit with Automatic Offset Cancellation Loop for capacitive microsensors

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SENSORS 2015年第10期15卷 26009-26017页

作者： Song, Haryong Park, Yunjong Kim, Hyungseup Cho, Dong-il Dan Ko, Hyoungho Chungnam Natl Univ Dept Elect Taejon 305764 South Korea Seoul Natl Univ Dept Elect Engn & Comp Sci ASRI ISRC Seoul 151744 South Korea

capacitive sensing schemes are widely used for various microsensors;however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 m complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm(2). The power consumption is 220 W with 3.3 V supply. The input parasitic capacitances within the range of -250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

关键词： capacitive sensing circuit automatic offset cancellation loop (AOCL) correlated double sampling (CDS) capacitive microsensor

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Use of capacitive microsensors and ultrasonic time-domain reflectometry for in-situ quantification of concentration polarization and membrane fouling in pressure-driven membrane filtration

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SENSORS AND ACTUATORS B-CHEMICAL 2006年第2期117卷 323-331页

作者： Zhang, Zhongxia Bright, Victor M. Greenberg, Alan R. Univ Colorado Dept Mech Engn Boulder CO 80309 USA Univ Colorado Dept Chem Engn Boulder CO 80309 USA

In membrane separation processes, the presence of the concentration polarization boundary layer (CPBL) often leads to a decline in the permeate flux and an increased risk of membrane fouling. Although the study of membrane fouling has benefited from the recent development of real-time, non-invasive acoustic measurements of the fouling process under realistic conditions, measurement of concentration polarization is still difficult and rather limited. This paper describes the development of interdigitated capacitive microsensors for real-time in-situ monitoring of CPBL growth in a cross-flow nanofiltration membrane module using calcium sulfate (CaSO4) solution as the feed. The developed capacitive sensors respond to changes in solute concentration as a function of distance from the membrane surface. Detection capability was determined in a series of comprehensive experiments with systematic changes in feed concentration and module operating parameters including upstream pressure, flow rate, and feed composition. The specially designed microscale capacitor assembly provides a unique capability for real-time characterization of the transient and steady-state concentration boundary layer polarization behavior. The capacitive microsensor concentration polarization measurements were corroborated via independent membrane morphological analysis and standard performance metrics. The experimental data were in excellent qualitative agreement with theoretical predictions from a mathematical model of concentration polarization behavior. In addition, the use of microcapacitor sensors in combination with ultrasonic time-domain reflectometry, enabled real-time observation of the development of scaling from the initiation of concentration polarization through the onset of membrane fouling. These results clearly demonstrate the advantages of a multisensor approach to the measurement of membrane phenomena, and provide a basis for the development of "smart" membranes. (c) 2005 Elsevier

关键词： membrane filtration concentration polarization capacitive microsensor ultrasonic time-domain reflectometry

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capacitive microsensors for biochemical sensing based on porous silicon technology

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SENSORS AND ACTUATORS B-CHEMICAL 2000年第1-3期64卷 59-64页

作者： Schöning, MJ Kurowski, A Thust, M Kordos, P Schultze, JW Lüth, H Res Ctr Julich Inst Thin Film & Ion Technol D-52425 Julich Germany Univ Appl Sci Aachen D-52428 Julich Germany Univ Dusseldorf AGEF EV Inst D-40225 Dusseldorf Germany

Porous EIS (electrolyte-insulator-semiconductor) structures of n-Si/SiO2/Si3N4 with a mean pore diameter of about 1 mu m and a mean pore depth of about 2 mu m have been realized for capacitive pH sensors. For the fabrication of the porous microsensors (down to "spot'' sizes of 10 mu m X 10 mu m), the n-doped silicon substrates have been photolithographically patterned by means of mask-matching technique using polyimide as a passivation material. The average pH sensitivity of the porous pH microsensor amounts about 56 mV/pH in the concentration range between pH 4 and pH 8. In order to prepare porous EIS biosensors the enzyme penicillinase has been adsorptively immobilized inside the porous structure. In the case of the porous biosensors an average penicillin sensitivity of about 90 mV/mM in the concentration range from 0.01 to 1 mM exists. Microreference electrodes, also prepared by the same porous silicon technology as for the pH- and biosensors, show a potential stability of more than 1 week in the long term. (C) 2000 Elsevier Science S.A. All rights reserved.

关键词： EIS sensor porous silicon capacitive microsensor pH/penicillin determination microreference electrode

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Discrimination of volatile organic compounds using CMOS capacitive chemical microsensors with thickness adjusted polymer coating

Discrimination of volatile organic compounds using CMOS capa...

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Smart Structures and Materials 1999 Conference

作者： Koll, A Kummer, A Brand, O Baltes, H ETH Zurich Phys Elect Lab CH-8093 Zurich Switzerland

ISBN: (纸本)0819431478

We present a new method for discriminating organic vapors based on the variation of capacitance changes of an interdigitated CMOS capacitor with the thickness of the sensitive polymer layer. By carefully adjusting the thickness of the polymer layer, discrimination potential in addition to the chemical selectivity of the polymer is provided by the fact that the interdigitated capacitor signals depend on the layer thickness. At polymer thicknesses small compared to the center-to-center spacing of the electrodes, an increase in capacitance is observed for all analytes, whereas for thick layers,the direction of the capacitance changes depends on the dielectric constant of the analyte. Sensors can be designed to be insensitive towards a certain analyte by varying the polymer thickness. Measurements for volatile organic compounds (VOCs) using CMOS capacitors coated with different polymer thicknesses are presented to demonstrate the new way of increasing sensor selectivity.

关键词： CMOS chemical microsensor volatile organic compounds polymer thickness control capacitive microsensor polymer spray coating chemical microsensor

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