Highly transparent, intrinsically stretchable, photo-patternable, and vacuum-deposited electrodes for wearable sensors and displays†

The development of stretchable and transparent electrodes is essential for next-generation wearable displays, human-machine interfaces, and on-skin bioelectronic devices; however, conventional approaches are limited by low fabrication compatibility with conventional semiconducting manufacturing processes, unstable electrical conductivity under stretching, and limited non-uniform areal transparency. Here, we report a novel device fabrication strategy for developing a highly transparent, intrinsically stretchable, photo-patternable, and vacuum-deposited (T-iSPV) electrode. The strain-insensitive performance of the T-iSPV is inherent in the in situ formation of a conducting bilayer consisting of a crack-based Au nanomembrane and Au-elastomer nanocomposite during direct thermal deposition of Au onto an elastic substrate. In addition, a photo-patterning process and optimal thickness/design and evaporation rate of the Au bilayer delicately balance the stretchability, electrical conductivity, and transparency of the T-iSPV. To demonstrate its versatility, the T-iSPV is applied as a conformal bioelectronic interfacing electrode for monitoring electrocardiogram (ECG), electromyogram (EMG), and electrooculogram (EOG) signals. Furthermore, the T-iSPV electrochemically activates the stretchable active layers composed of poly-3-hexylthiophene (P3HT) in a styrene-ethylene-butylene-styrene (SEBS) polymer matrix to effectively modulate electrochromic displays. These findings underscore the potential of the T-iSPV for enabling the evolution of next-generation conformal bioelectronic and optoelectronic systems.