Packaging-Induced Range Tunability of Tactile Sensors for Physiological Signal Monitoring Applications

Packaging-induced performance changes of microelectromechanical systems (MEMS) usually are detrimental in the device development. This paper presents a methodology of tuning the force range of a designated MEMS tactile sensor for broader application potentials by packaging this millinewton-level force sensor with different polymers. The force range of the tactile sensor has been enhanced from 30 mN to 400 mN and 100 N, respectively, which are more than tenfolds or 1000 folds of its original capability, by ruggedizing with the polydimethylsiloxane and polyurethane. Numerical analysis and experimental characterization have verified the tuned force range by these two packaging approaches. Three potential applications for the physiological signal monitoring have been revealed by preliminary emulation test results, including emulated lip pressure measurement, heart rate monitoring, and the finger strength evaluation. This methodology sheds light on reconciling the sensitivity changes induced by the packaging phase from defects to merits for broader application potentials in the MEMS development, accelerating the fabrication flow and lowering the cost with the reusability of concurrent devices.