Design and Fabrication of Non-silicon-based Piezoresistive MEMS Tactile Sensor

In this work, we develop a new non-silicon-based piezoresistive MEMS tactile sensor by a low-cost fabrication process. Prior to fabrication, the structure was designed and simulated by finite element simulation software to predict the device behaviors. The MEMS tactile sensor with a trampoline membrane structure has been fabricated by successive sputtering of Cr, Al, AlN, indium tin oxide (ITO), and Au layers through electroplated Ni micro-shadow masks over an 8 mm-thick photoresist sacrificial layer on a glass substrate. In addition, the gauge factor of the ITO piezoresistive material was studied as a function of sputtering parameter including oxygen flow rate and film thickness to optimize the sensitivity of the sensor. It was found that the 0.4 mm-thick ITO film deposited with no oxygen flow provide an optimum gauge factor of ~650. The fabricated tactile sensor has been tested for displacement and force sensing and a high sensitivity of 0.2 mV/muN has been achieved.