Novel Ultrasound Read-Out for a Wireless Implantable Passive Strain Sensor (WIPSS)

Monitoring the deformation of orthopedic implants during rehabilitation exercises helps preventing their possible failure due to repeated overloads. For this reason we propose a completely new sensor concept, which consist of a passive load sensor and its associated ultrasound-based read-out unit. The measurement principle is based on the transformation of a force into a varying amount of fluid in a micro channel integrated into the sensor. A novel ultrasound read-out method is applied to monitor the fill level of the micro channel.