MOS tunneling strain sensor using an AC measurement technique

The increasing requirement for low power sensors is motivating research on new techniques. MOS tunneling sensors consume only nW of power, compared to typical piezoresistive and capacitive sensors which consumes μW to mW. The strain was measured by measuring the tunneling current through a Metal-Oxide-Semiconductor sandwich from a DC voltage. To overcome the electronic noise, substantial averaging was utilized. In this paper an improved method of measuring the strain from the tunneling current is demonstrated in which an AC signal is utilized, and the AC current is measured. This approach substantially reduces the noise by avoiding the 1/f noise. The optimal conditions for the AC technique are to use a high frequency to avoid 1/f noise and a low DC bias.