​Inertial sensors made of a single layer of silicon must reach a compromise between mechanical performance and electrical transduction* performance. Leti, a CEA Tech institute, recently came up with a way to eliminate this compromise. They combined a "thick" silicon layer that serves as a mass with a "thin" layer onto which facing interdigital combs are etched.

The combs, produced using a partial etching (dual-mask) process, expose varying amounts of their surfaces as they move in relation to each other depending on the perceived acceleration. The development combines the advantages of high mass with the small gaps of the thin silicon combs. The architecture can measure accelerations 20 times greater than those that can be measured by conventional single-silicon-layer accelerometers with five times better resolution. Therefore, the detection dynamics achieved are 100 times higher than conventional sensors; bandwidth (the resonance frequency) is four times greater.

This remarkable performance could be used for the preventive maintenance of industrial machines. It could also substantially improve devices like gyrometers. The concept, protected by three patents, was presented at the MEMS 2019 conference. 

*The conversion of movement into an electrical signal