Researchers from the Institute of Industrial Science at The University of Tokyo and collaborating institutions have developed ultrathin, stretchable on-skin electrodes that are nearly invisible when worn on the face, according to a July 15 article in Science Advances. These new sensors aim to address issues with current wearable health devices, which can be awkward and draw attention, potentially influencing the biological signals they are meant to measure.
The newly developed electrodes consist of an elastic film approximately 200 nanometers thick combined with transparent conductive nanowires. This design closely matches both the appearance and texture of natural skin, minimizing reflections and eliminating the glossy look often associated with wearable electronics. As a result, these sensors remain undetectable by both sight and touch during use.
"In our experiments, neither wearers nor outside observers could reliably detect the electrodes by sight or touch," said lead author Yijun Liu. "The devices remain comfortable and breathable during use and work across a wide range of skin tones and features."
The research team successfully used these electrodes to record electrooculography signals from eye movements, electromyography signals from facial muscles, and electroencephalography signals from brain activity. For several types of biosignals, signal quality was better than that obtained using conventional gel electrodes due to lower skin impedance.
"By making wearable electronics that are both fully functional and effectively invisible, we are moving one step closer to a future in which health monitoring and human–machine interaction are seamlessly integrated into everyday life," said Matsuhisa.
Potential applications for this technology include subtle monitoring of emotional state or cognitive function as well as new methods for controlling devices or virtual-reality systems using eye movements or facial expressions. The researchers believe such invisible sensors could help technology adapt more naturally to people.
