06 Load sensing surgical instruments and implants

		Top: ligament balancing device for total knee arthroplasty. Bottom: bone repair fixtures, with load measurement based on purely passive mechanical movement and external ultrasonic readout (WIPSS), or more classical thick-film piezoresistive bridge + RFID electronics.

This projects aims to develop and apply force and pressure sensor technology and integrate it into instruments to assist surgical operations as well as implants to monitor patient recovery in-situ. In the field of devices, we plan to build intelligent instruments for the spine and knee, and achieve significant progress in building a technology platform for implants.

The following technologies will be developed:

• ultra low-power wireless telemetry for cordless, battery-less instruments and for implants
  
• biocompatible piezoresistive thick-film technology for load measurement in sensor structures
  
• fully novel wireless in-situ passive strain sensors (WIPSS)
  

Sub Projects

06/1 Intraoperative force measurement system for ligament balancing in unliateral knee prostheses

The aim of this project is to develop an intraoperative force measurement system for ligament balancing in unilateral knee prostheses, and to pursue development of the existing system for total prostheses. The device will be entirely wireless, in order to maximise convenience for the surgeon and minimise invasiveness.

06/2 Intelligent surgical instruments in spinal surgeries

We intend to build intelligent instruments for spinal surgery, where load sensing and ultra low-power telemetry are combined to achieve inexpensive, reliable and commercially viable instruments: an instrumented distraction forceps to treat spinal deformities and a high pressure cement injection system for restoration and reinforcement of vertebrae (vertebroplasty and kyphoplasty).

06/3 Thick films

Piezoresistive thick-film strain sensor technology, where mechanical strains translate into a change of electrical resistance, is known to be robust and reliable. We aim to adapt it to biomechanical applications, namely to render it compatible with deposition onto high-strength medical alloys such as stainless steels and titanium, and to make progress in moving away from existing lead-based materials (which have to be appropriately shielded from contact with the patient) to environmentally and biologically more benign materials, combined with appropriate packaging methods.

06/4 WIPSS - polymer - ETHZ

This subproject addresses the development of an implantable wireless in-situ passive strain sensor (WIPSS), including the option for complete biodegradability of the whole sensor unit, whereby the mechanical strain is transposed into a remotely monitorable mechanical displacement (e.g. of a micromechanical structure or of a liquid-solid interface).

06/5 WIPSS - polymer - EMPA

This part aims at developing the ultrasound imaging and signal processing technology needed to remotely image the abovementioned WIPSS sensors and transpose their mechanical output into a measurement of strain.

Project Coordination