A passive microsystem for detecting multiple acceleration events beyond a threshold

Display Omitted Passive MEMS for detecting numerous acceleration threshold violations is presented.Fully mechanical layout for passive sensing of acceleration events.A ratcheting mechanism is built in silicon-on-insulator (SOI) technology.The ratcheting state can be re-initialized by a comb drive actuator. A fully mechanical microsystem for detecting multiple acceleration threshold violations is presented. It combines a seismic mass as a part of a ratcheting mechanism so that discrete positions are enabled depending on the external acceleration forces.A numerical model describing the dynamic system behavior has been developed. The fabricated system demonstrator is investigated utilizing impact tests, and the numerical model is verified by comparing the model with the measurement values. Various acceleration thresholds between 5g and 30g could safely be measured. Additionally, the counter can be re-initialized utilizing an electrostatic actuator for releasing the ratcheting mechanism.This recording of acceleration events does not require electrical energy for detection nor for storage; hence it is suitable for monitoring of sparse but critical acceleration or impact events over large time periods. The system design is prepared for an electrical read-out by, e.g. RFID transponders or comparable systems that transmit the position of the seismic mass within the ratcheting mechanism.