Development of a CMOS-Based Capacitive Tactile Sensor With Adjustable Sensing Range and Sensitivity Using Polymer Fill-In

This paper reports a capacitive-type CMOSmicroelectromechanical system tactile sensor containing a capacitance-sensing gap filled with polymer. Thus, the equivalent stiffness of the tactile sensor can be modulated by the polymer fill-in, so as to further tune its sensing range. Moreover, the polymer fill-in has a higher dielectric constant to increase the sensitivity of the tactile sensor. In short, the sensing range and sensitivity of the proposed tactile sensor can be easily changed by using the polymer fill-in. In application, the tactile sensor and sensing circuits have been designed and implemented using the 1) TSMC 0.35 μm 2P4M CMOS process and the 2) in-house post-CMOS releasing and polymer-filling processes. The polydimethylsiloxane (PDMS) material with different curing agent ratios has been exploited as the fill-in polymers. The experiment results demonstrate that the equivalent stiffness of tactile sensors can be adjusted from 16.85 to 124.43 kN/m. Thus, the sensitivity of the tactile sensor increases from 1.5 to 42.7 mV/mN by varying the PDMS filling. Moreover, the maximum sensing load is also improved.

[1]  Weileun Fang,et al.  A tunable range/sensitivity CMOS-MEMS capacitive tactile sensor with polymer fill-in technique , 2009, TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference.

[2]  Hyung-Kew Lee,et al.  A Flexible Polymer Tactile Sensor: Fabrication and Modular Expandability for Large Area Deployment , 2006, Journal of Microelectromechanical Systems.

[3]  Joost Conrad Lötters,et al.  Polydimethylsiloxane as an elastic material applied in a capacitive accelerometer , 1996 .

[4]  Weileun Fang,et al.  Design and application of a metal wet-etching post-process for the improvement of CMOS-MEMS capacitive sensors , 2009 .

[5]  M.-Y. Cheng,et al.  A flexible capacitive tactile sensing array with floating electrodes , 2009 .

[6]  T. Kamei,et al.  Novel surface structure and its fabrication process for MEMS fingerprint sensor , 2005, IEEE Transactions on Electron Devices.

[7]  I. Bársony,et al.  CMOS integrated tactile sensor array by porous Si bulk micromachining , 2008 .

[8]  Kensall D. Wise,et al.  CAPACITIVE SILICON TACTILE IMAGING ARRAY. , 1985 .

[9]  Chang Liu,et al.  Institute of Physics Publishing Journal of Micromechanics and Microengineering Development of Polyimide Flexible Tactile Sensor Skin , 2022 .

[10]  A. Erdman,et al.  Flexible Tactile Sensor for Tissue Elasticity Measurements , 2009, Journal of Microelectromechanical Systems.

[11]  Weileun Fang,et al.  A novel CMOS out-of-plane accelerometer with fully differential gap-closing capacitance sensing electrodes , 2007 .

[12]  Anurat Wisitsoraat,et al.  Low cost thin film based piezoresistive MEMS tactile sensor , 2007 .

[13]  S. Middelhoek,et al.  Silicon three-axial tactile sensor , 1996 .

[14]  Tayfun Akin,et al.  Low-cost uncooled infrared detectors in CMOS process , 2003 .

[15]  C. Hagleitner,et al.  CMOS MEMS - present and future , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[16]  M. Haider,et al.  Flexible capacitive sensors for high resolution pressure measurement , 2008, 2008 IEEE Sensors.

[17]  Christoph Hagleitner,et al.  CMOS single-chip gas detection system comprising capacitive, calorimetric and mass-sensitive microsensors , 2002, IEEE J. Solid State Circuits.

[18]  Chih-Chieh Wen,et al.  Tuning the sensing range and sensitivity of three axes tactile sensors using the polymer composite membrane , 2008 .

[19]  Sarah S. Bedair,et al.  CMOS-MEMS Capacitive Humidity Sensor , 2010 .

[20]  H. Baltes,et al.  CMOS-Based Tactile Microsensor for Medical Instrumentation , 2007, IEEE Sensors Journal.

[21]  U. Kleine,et al.  A novel class of complementary folded-cascode opamps for low voltage , 2002 .

[22]  P. Veltink,et al.  The mechanical properties of the rubber elastic polymer polydimethylsiloxane for sensor applications , 1997 .

[23]  G. Abadal,et al.  Monolithic CMOS MEMS Oscillator Circuit for Sensing in the Attogram Range , 2008, IEEE Electron Device Letters.

[24]  C. Ko,et al.  A CMOS Micromachined Capacitive Tactile Sensor With High-Frequency Output , 2006, Journal of Microelectromechanical Systems.

[25]  M. Schulz,et al.  Flexible Dome and Bump Shape Piezoelectric Tactile Sensors Using PVDF-TrFE Copolymer , 2008, Journal of Microelectromechanical Systems.