New sweat-resistant wearable robot sensor
A team of researchers from the KAIST School of Electrical Engineering have developed new electromyography (EMG) sensor technology that enables the long-term stable control of wearable robots and is not affected by the wearer’s sweat and dead skin. Wearable robots are devices used across a range of rehabilitation treatments for the elderly and patients recovering from stroke or trauma. The stretchable and adhesive microneedle sensor, developed by Professor Jae-Woong Jung and Professor Jung Kim from KAIST, 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 for their use in rehabilitation treatment, they require a wearable electrophysiological sensor that gives precise EMG measurements. However, existing sensors can show deteriorating signal quality over time and are affected by the user’s skin conditions. The sensor’s higher mechanical hardness also causes noise since the contact surface is unable to keep up with the deformation of the skin. These shortcomings limit the reliable, long-term control of wearable robots.
The new sensor technology is expected 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 sensor could also stably control wearable robots over a long period of time regardless of the wearer’s changing skin conditions and without the need for a preparation step that removes sweat and dead skin cells from the surface of the skin.
The sensor was developed by integrating microneedles into a soft silicon polymer substrate. The hard microneedles penetrate through the stratum corneum, which has high electrical resistance. As a result, the sensor can lower contact resistance with the skin and obtain electrophysiological signals regardless of contamination. The soft and adhesive conducting substrate can also adapt to the skin’s surface that stretches with the wearer’s movement, providing a comfortable fit and reducing noise caused by movement.
To verify the usability of the new patch, the 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 then sent the detected intention to a wearable robot, allowing the robot to help the wearer lift a heavy object more easily.
The research findings have been published in the journal Science Advances.
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