Sensitivity of polyvinyl butyral/carbon-black sensors to pressure

Interdigitated capacitors have the potential to be used in pressure sensing applications requiring small size, high reliability and cost effective production. Such sensors have applications in wireless pressure monitoring of bodily fluids for the research and diagnosis of a number of medical conditions in cardiology, pulmonology and gastroenterology. In this work, the sensitivity of Polyvinyl Butyral (PVB)/carbon-black composites to pressure is evaluated with these applications in mind. The devices are fabricated by drop coating solutions containing PVB and 5, 10, 15 and 20% carbon black onto interdigitated electrodes. The optimum carbon loading for pressure sensing applications up to 2500 kPa was determined for these composites using a tensile tester. The highest sensitivity was recorded for samples with 5% carbon black. These devices were successfully integrated into a prototype wireless interface, transmitter and receiver system. The response (25 mV), hysteresis (4.78%) and repeatability (10.76%) under hydrostatic pressure ranging from 0-17 kPa were measured. Finally, the devices temperature dependence was investigated. (c) 2007 Elsevier B.V. All rights reserved.