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A Flexible Capacitive Sensor with Encapsulated Liquids as Dielectrics
Department of Mechanical Engineering, Keio University/3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
JST PRESTO, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
* Author to whom correspondence should be addressed.
Received: 1 February 2012; in revised form: 2 March 2012 / Accepted: 2 March 2012 / Published: 13 March 2012
Abstract: Flexible and high-sensitive capacitive sensors are demanded to detect pressure distribution and/or tactile information on a curved surface, hence, wide varieties of polymer-based flexible MEMS sensors have been developed. High-sensitivity may be achieved by increasing the capacitance of the sensor using solid dielectric material while it deteriorates the flexibility. Using air as the dielectric, to maintain the flexibility, sacrifices the sensor sensitivity. In this paper, we demonstrate flexible and highly sensitive capacitive sensor arrays that encapsulate highly dielectric liquids as the dielectric. Deionized water and glycerin, which have relative dielectric constants of approximately 80 and 47, respectively, could increase the capacitance of the sensor when used as the dielectric while maintaining flexibility of the sensor with electrodes patterned on flexible polymer substrates. A reservoir of liquids between the electrodes was designed to have a leak path, which allows the sensor to deform despite of the incompressibility of the encapsulated liquids. The proposed sensor was microfabricated and demonstrated successfully to have a five times greater sensitivity than sensors that use air as the dielectric.
Keywords: capacitive sensor; flexible; tactile sensor; liquid encapsulation; polymer MEMS
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MDPI and ACS Style
Hotta, Y.; Zhang, Y.; Miki, N. A Flexible Capacitive Sensor with Encapsulated Liquids as Dielectrics. Micromachines 2012, 3, 137-149.
Hotta Y, Zhang Y, Miki N. A Flexible Capacitive Sensor with Encapsulated Liquids as Dielectrics. Micromachines. 2012; 3(1):137-149.
Hotta, Yasunari; Zhang, Yuhua; Miki, Norihisa. 2012. "A Flexible Capacitive Sensor with Encapsulated Liquids as Dielectrics." Micromachines 3, no. 1: 137-149.