KAIST researchers develop new sweat-resistant wearable technology

A research team, led by Professor Jae-Woong Jung from the KAIST School of Electrical Engineering and Professor Jung Kim from the KAIST Department of Mechanical Engineering, has developed a stretchable and adhesive microneedle sensor that can electrically sense physiological signals at a high level without being affected by the state of the user’s skin.

For wearable robots to recognise the intentions behind human movement, primarily for their use in rehabilitation treatment, they require a wearable electrophysiological sensor that gives precise EMG measurements.

The researchers said that existing sensors often show deteriorating signal quality over time and are affected by the user’s skin conditions. A sensor’s higher mechanical hardness can also cause noise since the contact surface is unable to keep up with the deformation of the skin. According to the researchers, these shortcomings limit the reliable, long-term control of wearable robots.

This new technology aims to allow ‘long-term and high-quality’ EMG measurements as it uses a stretchable and adhesive conducting substrate integrated with microneedle arrays that can easily penetrate the stratum corneum without causing discomfort.

The stretchable and adhesive sensor integrates microneedles into a soft silicon polymer substrate. The hard microneedles penetrate through the stratum corneum, which has high electrical resistance.

As a result, the researchers said the sensor can effectively lower contact resistance with the skin and obtain high-quality electrophysiological signals regardless of contamination, and the soft and adhesive conducting substrate can adapt to the skin’s surface that stretches with the wearer’s movement, providing a comfortable fit and minimising noise.

To test the usability of the sensor patch, researchers conducted a motion assistance experiment using a wearable robot. They attached the microneedle patch on a user’s leg, where it could sense the electrical signals generated by the muscle. The sensor accurately sent the detected intention to a wearable robot, which allowed the robot to help the wearer lift a heavy object more easily.

In a statement, Professor Jae-Woong Jung said, “The developed stretchable and adhesive microneedle sensor can stability detect EMG signals without being affected by the state of a user’s skin. Through this, we will be able to control wearable robots with higher precision and stability, which will help the rehabilitation of patients who use robots.”

The research was supported by the Bio-signal Sensor Integrated Technology Development Project by the National Research Foundation of Korea, the Electronic Medicinal Technology Development Project, and the Step 4 BK21 Project.

The research paper, published in Science Advances, can be read in full here.