Following head injuries, traumatic brain injuries or surgery, monitoring intracranial pressure accurately is vital. Wired probes are currently used that can however give rise to contamination and infection from the skull-probe-environment interface. In cooperation with UNISENSOR, the leading microsensor manufacturer for medical products, research was carried out into an implantable, passive SAW microsensor. The sensor is inserted just under the cranium and an antenna placed under the scalp, which transmits radio signals through it. This approach ensures a high level of sterility, greatly reducing the risk of infection. Transmitting the data wirelessly enables continuous and above all careful patient monitoring. The objective is to use the principle of a membrane sensor to create the basis for force and pressure diagnostics for applications in neurology as well as gastroenterology, urology and orthopaedics. In addition to medical products, other applications could be developed in laboratory technology, diagnostics or even in industrial use. What poses particular challenges in development are the high demands placed on resolution and the wireless sensor’s sensitivity. A first prototype has already been developed. It features good sensitivity and resolution of the intended 100 mbar pressure range. In 2013 important progress was made in radio transmission. Together with FH Joanneum in Kapfenberg, a 2.4 GHz antenna was developed that transmits signals through 4 cm thick artificial tissue without any trouble. The antenna was successfully tested in connection with the pressure sensor. Passive wireless sensors have many potential uses in medical telemetry, which will be the subject of future research.
Impact and Effects
CTR is one of the first teams worldwide to be researching into implantable pressure sensors. The potential for medical technology is highly promising and wide ranging. Further projects and clinical studies will be aimed at following on from the research results already achieved and providing stimulus for new international cooperation in similar areas.