Assessment of the Security of MEMS Gyroscopes under Acoustic Attacks

In this work, we assess the vulnerability of MEMS-based gyroscopes to targeted acoustic attacks and show that such attacks can impose high security risks. In particular, we demonstrate via theory and experiments that, a surface micromachined MEMS gyroscope produces false angular velocity readings when subjected to an ultrasonic harmonic wave with a frequency near its driving resonance. The false angular velocity measurement is of low frequency, and hence, cannot be easily attenuated by adding a low-pass filter. To better understand the main reason behind the susceptibility of the gyroscope to ultrasonic attacks, we develop a physics-based mathematical model of the gyroscope and use it to illustrate that the demodulator in the readout circuit, and the misalignment between the sensing and driving axes, are the primary factors behind the deceptive angular velocity readings.