Low power strain sensing using tunneling current through MOS capacitors

Abstract

Although MEMS pressure sensors and accelerometers have been widely researched and commercialized for decades, the recently increasing requirement for low power sensors is motivating research on new techniques. We present a new technology to make very low power sensors by measuring the tunneling current (Ig) through a MOS capacitor. The tunneling current can be in the nano-amp range, which is a good alternative for low power sensing. We demonstrate a power consumption of couple of nano-Walts (nW) with a minimum detectable strain of 0.0005%. This method can be used to create very low power sensors compared to typical piezoresistive and capacitive sensors whose power is typically in the μW to mW range. Our fabrication process is very simple and compatible with CMOS processes.