A thermoresponsive electromechanical microchip for temperature control in biomedical smart implants

This paper reports an electromechanical micro circuit breaker device developed for self-temperature regulation and safe operation of electronic implants that produce heat in vivo. A micromachined cantilever actuator made of nitinol is used as a normally closed thermoresponsive switch to prevent the host implant from overheating. The device is packaged to be a biocompatible microchip with a footprint of 0.7×1.9 mm
²
. The testing of fabricated microchips shows their contact resistance of ~35 Ω at the cold state and rapid rise to the open state as temperature reaches ~54 °C. Their electromechanical responses to heat and related threshold temperatures are measured to be well consistent with those of the particular nitinol material used. These preliminary results illustrate the desired functionality of the micro circuit breaker, validating the effectiveness of the adopted design-fabrication approach.