A New Capacitive Sensor for Histomorphometry Evaluation of Dental Implants

Knowing information about the internal functions of the human body has always been the subject of scientific research. Processing of the data from inside of the body gives access to valuable information for the therapist. In this paper, an implantable capacitive sensor has been designed and implemented inside the bone to evaluate the new bone growth. Reducing the medical x-ray imaging dose during a jaw scan is a motivation for the design of the sensor. The new capacitive sensor can replace multiple x-ray imaging sessions. Low energy consumption, stable performance, and information processing rate are some of the engineering challenges for implanted sensors. The designed sensor is a zero power module, which can easily be implemented in dental tooth implants without any active component. The capacitive sensor information can be transmitted to a reader device via a wireless inductive link. The sensor simulation results from COMSOL confirm experimental measurements. The fabricated sensor has been tested on the femur (thigh) bone and mandible bone (lower jaw). The sensor capacitance changes from 20nF to 1.57 μF for the fabricated sensor and amount of the surrounding bone. Fabrication results show that variation of sensor capacitance from the early stage of the dental implant to full recovery and bone development is more than seven times. The wide range of sensor capacitance variation allows for better bone development characterization.