A research group comprised of researchers from the University of Tokyo, Keio University, Seoul National University, VTT Technical Research Centre of Finland, Shibaura Institute of Technology, Minami Kyoto Hospital, and Taisho University has successfully developed a "stealth skin electrode" that is invisible when attached to the face and cannot be detected by touch.
Wearable devices enable the continuous measurement of various biometric information. A great deal of information can be obtained from the face, but conventional facial electrodes are easily visible to others, causing visual discomfort and psychological burden on the wearer, making natural use in daily life difficult.
The research group developed a "stealth skin electrode" that is undetectable by sight or touch. The electrode consists of an optical adjustment layer made of an ultrathin, stretchable electronic material and a transparent, conductive silver nanowire electrode layer. By using an ultrathin film approximately 200 nanometers thick containing titanium oxide nanoparticles, they achieved light reflection and tactile sensation similar to that of skin.
When stealth skin electrodes were attached to the face, neither the wearer nor any observers could visually or tactilely perceive the electrodes. Furthermore, no changes were observed in brainwave responses or psychological state when the wearer viewed photographs of themselves with the stealth skin electrodes attached.
Furthermore, using stealth skin electrodes, measurements of electrooculography (EOG) derived from eye movements and blinking, electromyography (EMG) derived from chewing and jaw movements, and alpha waves in electroencephalography (EEG) that appear when the eyes are closed were possible with almost no change in appearance, whereas with conventional gel electrodes, attaching many electrodes to the face would be very noticeable.
The electrodes developed in this study can measure eye movements, facial muscles, and brain waves in a natural state, and are expected to have applications in understanding psychological and cognitive states, as well as in new ways of operating smartphones and AR/VR devices.
Publication information: [Science Advances] Reduction of appearance artifacts in wearable on-skin electronics
