Fabrication of Comb-Structured Acceleration Sensors by Roll-to-Roll Gravure Printing

As a common type of microelectromechanical systems (MEMS) inertial sensors, comb-structured air-gap acceleration sensors have been applied to various industrial devices and systems. Printed electronics technology has emerged recently as an alternative for fabrication of flexible electronic devices with superior productivity and eco-friendliness to MEMS technology. However, air-gap structures are hard to realize through printing without etching process, and thus comb-structured acceleration sensors have been rarely reported in the printed electronics field in spite of many advantages. This study presents design of a comb-structured air-gap acceleration sensor and materials and processes for highly productive roll-to-roll printed electronic fabrication of the sensor. The sensor is designed to have multiple layers in two parts: fixed fingers are in the lower part while the movable mass and movable fingers in the upper part. Both parts are processed separately on different flexible PET substrates by roll-to-roll gravure printing and drying. Then the upper part is transferred and bonded to the lower one and air-gap structure is formed as a result. This paper also provides electrical characteristics of the proposed comb-structured acceleration sensor by testing capacitance change as a function of acceleration.