Pressure-Monitoring Stockings Prevent Diabetic Foot

Novel pressure stockings could help protect against diabetic foot ulcers via an integrated sensor system that sends a warning when pressure is too high.

Developed by researchers at the Fraunhofer Institute for Silicate Research (ISC; Würzburg, Germany), with support from industry partners and colleagues from the Fraunhofer Institute for Integrated Circuits (IIS; Erlangen, Germany), the special diabetic monitoring stockings are each equipped with 40 very fine, dielectric elastomer sensors that measure three-dimensional (3D) compression load and distribution, assuming a function usually performed by the nerves in the feet.

The sensors are made from a soft elastomer silicone film that is coated on both sides with highly flexible electrodes of graphite. When the film deforms as a result of compression or stretching, its thickness decreases and its surface area simultaneously increases; the resulting pressure measurably raises electrical capacitance. The measurement is sent via a conductive thread to an application-specific integrated circuit (ASIC) chip controller, which then transmits it wirelessly to a smartphone or tablet, informing the diabetes patient that it is time to change foot position or weight distribution.

The stockings themselves are made from a blend of cotton and synthetic fibers, with the sensors either stitched or glued between two layers of fabric, which makes them more comfortable to put on or take off. The range of potential applications is broad, and includes sports and fitness; joggers and runners could use the integrated sensor stockings to analyze their running style and foot positioning. According to the researchers, a pair of stockings should cost no more than EUR 250, since they can be cost-effectively manufactured in series.

“Existing systems on the market measure the pressure distribution only on the bottom of the foot using shoe inserts,” said Bernhard Brunner, PhD, of the Fraunhofer ISC. “Our sensors are attached to the stocking’s sole, at the heel, the top of the foot and the ankle, so they can take readings in three dimensions. This is a totally new approach.”

Diabetes patients often suffer from nerve and circulation problems in the feet, which reduce their perception of pain. The nerve pathways that ensure that weight is automatically transferred from one foot to the other during prolonged standing are disrupted, and as a result, diabetics do not notice that their toes, heels, or the balls of their feet are too heavily loaded. The foot receives no relief, and pressure sores, ulcers, and infections may go unnoticed. Serious cases may even lead to amputation.

Related Links:
Fraunhofer Institute for Silicate Research
Fraunhofer Institute for Integrated Circuits