Stochastic strain sensor using pull-in probability under white-noise-applied bistable state with reliable pull-in release mechanism

This paper describes a MEMS based stochastic sensor, which will be used in low S/N environments like high temperature plants. The mass which vibrates between two counter electrodes by white noise voltage is “pulled-in” to either of the counter electrodes by applying pulse voltage to the mass. The direction of the pull-in is determined stochastically, and the probability that the mass is pulled in to a particular side depends on mechanical strain applied to the sensor. Therefore, strain can be measured just by counting the number of pull-in to a particular side, which is easy even in low S/N environments. We demonstrated this sensing principle using an SOI-based sensor, which had a reliable pull-in release mechanism using a non-linear spring structure. We also demonstrated that the pull-in probability could be tuned by bias voltage applied to the counter electrodes, as predicted by simulation.