A high-performance strain sensing microsystem with remote RF power capability

This paper describes a high-performance strain sensing microsystem with a remote RF powering capability. A MEMS capacitive strain sensor converts an input strain to a capacitance change with a sensitivity of 26.5 aF per 0.1 /spl mu//spl epsiv/. Low-noise integrated sensing electronics, employing a continuous time synchronous detection architecture, convert the capacitive signal to an output voltage for further signal processing. An RF to DC converter, based on inductive coupled coils, converts a 50 MHz AC signal to a stable DC supply of 2.8 V with a current driving capability of 2 mA, sufficient to power the interface sensing electronics. The prototype microsystem achieves a minimum detectable strain of 0.09 /spl mu//spl epsiv/ over a 10 kHz bandwidth with a dynamic range of 81 dB. The sensing electronics consume 1.5 mA from a 2.8 V supply.