Implantable low-g accelerometer for the telemetric monitoring of micro-movements in fracture zones

The development of a low-g accelerometer for the use in medical applications is presented. Commercial available accelerometers fulfill the required specifications in terms of resolution using closed-loop operation. Due to the high energy consumption in closed-loop operation, these sensors are not suitable in implantable devices. New technologies enable lateral moving accelerometers with high aspect ratios. Therefore, the required damping constant (d>0,7) for an open-loop operation can be achieved by using interdigital comb structures and transversal deflection. A sensing element suitable for open-loop operation has been simulated and designed. Furthermore, a process flow for the fabrication of high aspect accelerometers is presented. Characterizations on fabricated prototypes show the performance of the devices.