Investigation into the pressure sensing properties of PVDF and PVB thick film capacitors

This paper examines the sensitivity of polyvinylidene fluoride (PVDF) and polyvinyl butyral (PVB) capacitors to pressures ranging from 0-100 kPa. The capacitors were formed by screen-printing onto flexible substrates and have an active area of 2 times 3 mm2. There are no moving parts and as a result the complexity of sensor design, fabrication and packaging issues may be reduced. After fabrication, sensors were adhered to planar and cylindrical surfaces and interfaced with an AD7746 24-bit capacitance to digital converter. This allowed precise measurements to be taken. It has high linearity and accuracy and can accept up to 17 pF absolute capacitance. The pressure was applied by housing the sensor in an airtight container and pumping air into the system to increase the pressure. It was found that PVDF devices on planar surfaces exhibited the largest response to the application of pressure. This was further increased for devices placed on cylindrical surfaces. It is thought that this is due to cracking of the thick film upon bending of the substrate. The results suggest that PVDF and PVB are suitable candidate materials for use in a pressure monitoring system.

[1]  P. Harrop,et al.  The temperature coefficient of capacitance , 1968 .

[2]  P. A. Payne,et al.  Piezoelectric polymers and copolymers and their applications , 1990 .

[3]  P. A. Payne,et al.  Polymer materials for pressure measurement , 1990 .

[4]  N. D. Duffy,et al.  PVDF touch sensors and time-of-flight force sensors for robot gripper applications , 1991 .

[5]  C.C. Liu,et al.  Fabricating biomedical sensors with thin-film technology , 1994, IEEE Engineering in Medicine and Biology Magazine.

[6]  P. Hauptmann.  Sensors: A Comprehensive Survey , 1996 .

[7]  Javad Dargahi,et al.  A micromachined piezoelectric tactile sensor for use in endoscopic graspers , 1998, Proceedings. 1998 IEEE/RSJ International Conference on Intelligent Robots and Systems. Innovations in Theory, Practice and Applications (Cat. No.98CH36190).

[8]  J. Knapp,et al.  Measurement of shock events by means of strain gauges and accelerometers , 1998 .

[9]  S. Urry.  Plantar pressure-measurement sensors , 1999 .

[10]  Rainer Laur,et al.  Advanced hybrid integrated low-power telemetric pressure monitoring system for biomedical applications , 2000, Proceedings IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems (Cat. No.00CH36308).

[11]  Khalil Arshak,et al.  Development of new capacitive strain sensors based on thick film polymer and cermet technologies , 2000 .

[12]  Horst Richter,et al.  Initial investigations on systems for measuring intraocular pressure , 2000 .

[13]  Kenton R Kaufman,et al.  Biocompatibility of a physiological pressure sensor. , 2003, Biosensors & bioelectronics.

[14]  O. Korostynska,et al.  Novel silicone-based capacitive pressure sensors with high sensitivity for biomedical applications , 2004 .

[15]  Khalil Arshak,et al.  Development Of PVDF Thick Film Interdigitated Capacitors For Pressure Measurement On Flexible Melinex Substrates , 2005 .

[16]  O. Korostynska,et al.  Cerium and Titanium Oxide Interdigitated Capacitors for Pressure Sensing Applications , 2005 .

[17]  Khalil Arshak,et al.  Investigation of TiO2 thick film capacitors for use as strain gauge sensors , 2005 .

[18]  Portable Real-Time Gamma Radiation Dosimetry System Using MgO and CeO 2 Thick Film Capacitors , 2005 .

[19]  A Arshak,et al.  Review of the potential of a wireless MEMS and TFT microsystems for the measurement of pressure in the GI tract. , 2005, Medical engineering & physics.

[20]  Sergio Callegari,et al.  A non-invasive capacitive sensor strip for aerodynamic pressure measurement , 2005 .

[22]  Khalil Arshak,et al.  PVB, PVAc and PS pressure sensors with interdigitated electrodes , 2006 .