A self-powered sensor designed to monitor progress during knee operations, has been developed by a student from The University of Southampton’s School of Electronics and Computer Science.

Serial In-vivo Transducer (SIT), developed by Fauzan Baharudin, uses thick film technology to measure tendon force during Anterior Cruciate Ligament (ACL) reconstruction. The ACL is the most commonly injured ligament and is commonly damaged by athletes.

Fauzan’s project was supervised by Professor Neil White at ECS, who, in 1991 developed thick film piezoelectric material which made it possible to produce a sensor which could power itself if it was installed in a device that vibrates, and would be suitable for appliances where physical connections to the outside world were difficult.

Professor White said: “Although this work is still in its infancy, our earlier research in thick-film sensors has shown that it is feasible to apply the technology to medical applications such as prosthetic hands. We have also shown that it is possible to harvest energy from the human body using piezoelectric materials and the knee is subjected to very high levels of force during everyday activities. It therefore seems logical to combine the two approaches to deliver a new type of embedded, self-powered sensor.”

Before developing SIT, Fauzan reviewed the existing devices in this field and concluded that due to its flexibility in fabrication, low capital cost, fast lead time and its suitability for use in the body, thick film technology is the best solution for ACL surgery. Assessment of the energy harvesting feature revealed that the device could produce more than enough energy to power itself.

Fauzan concluded: “It remains a mystery to me, given how common knee injuries are among athletes, that devices like ours have not been developed before now. A sensible assumption for this is that thick film technology does not reach medical researchers as quickly as it does within the microelectronics community hence the delay in realising the huge potential in developing in vivo transducers.”