Silver Wrapped in Gold

Medical sensors attached to a patient’s skin offer the strongest and clearest signals for checking muscle activity which is vital for studying muscle fatigue and recovery from injuries. These signals are also used to diagnose and treat neuromuscular diseases such as multiple sclerosis and muscular dystrophy.

However, sensors on the skin can be uncomfortable, especially for prolonged periods, and doctors are always seeking alternatives.

One idea is to place sensors on clothing, and researchers from the University of Utah and Gyeongsang National University in South Korea have developed a bioelectrical sensor that is silk-screened onto fabric. This not only gives doctors access to a patient’s health during exams, but also can be accessed while the patient is outside a hospital or medical facility with information sent over the phone network or the internet.

“The signal we measure is a voltage over a time,” said study author Huanan Zhang, in a prepared statement. “Every time your finger moves, the potential of the body, of the muscle, changes. So, we are able to detect that difference in potential.”

During initial tests, researchers imbedded silver paste onto clothing because of silver’s excellent electrical conductivity. However, some patients complained of minor skin irritations when the paste was left on for a prolonged period of time. The workaround was to encapsulate the silver in gold nanoparticles as gold is inert when exposed to bodily fluids like sweat.

The amounts of gold and silver are small enough to keep the price of the sensor low while silver’s high conductivity assures continuous and solid signal generation. Performance was checked on fingers and the bicep, showing how they move and change during various exercises.

“[Our] work not only designs a wearable device, which has the convenience factor, but it also has great performance and is biocompatible,” Zhang concluded.