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Transparent microelectrodes have received much attention from the biomedical community due to their unique advantages in concurrent crosstalk‐free electrical and optical interrogation of cell/tissue activity. Despite recent progress in constructing transparent microelectrodes, a major challenge is to simultaneously achieve desirable mechanical stretchability, optical transparency, electrochemical performance, and chemical stability for high‐fidelity, conformal, and stable interfacing with soft tissue/organ systems. To address this challenge, we have designed microelectrode arrays (MEAs) with gold‐coated silver nanowires (Au–Ag NWs) by combining technical advances in materials, fabrication, and mechanics. The Au coating improves both the chemical stability and electrochemical impedance of the Au–Ag NW microelectrodes with only slight changes in optical properties. The MEAs exhibit a high optical transparency >80% at 550 nm, a low normalized 1 kHz electrochemical impedance of 1.2–7.5 Ω cm², stable chemical and electromechanical performance after exposure to oxygen plasma for 5 min, and cyclic stretching for 600 cycles at 20% strain, superior to other transparent microelectrode alternatives. The MEAs easily conform to curvilinear heart surfaces for colocalized electrophysiological and optical mapping of cardiac function. This work demonstrates that stretchable transparent metal nanowire MEAs are promising candidates for diverse biomedical science and engineering applications, particularly under mechanically dynamic conditions.

Exploring remote destinations on Earth and in space such as the Antarctic and Mars is of great significance to science and technology. Ultraviolet (UV) irradiation at those locations is usually strong due to the depletion or absence of ozone, which is often accompanied by strong visible light interference and harsh environments with extreme temperatures. Those exploration missions extensively utilize flexible and foldable membranes and shells to meet the extreme requirements on structural size and weight. Ultra‐flexible UV photodetectors (PDs) capable of surviving harsh environments with additional ability to integrate on flexible and foldable structures for in situ visible‐blind UV sensing are critical to the protection of human explorers and engineering materials. However, the development of such UV PDs remains challenging. Here, this work introduces wired and wireless optoelectronic devices based on visible‐blind, ultra‐flexible, sub‐micron nanocomposites of zinc oxide nanoparticles and single‐walled carbon nanotubes. In‐depth studies demonstrate their operation at cold and hot temperatures and low air pressure. Those PDs can employ flexible near‐field communication circuits for wireless, battery‐free data acquisition. Their ultra‐flexibility allows folding into a sharp crease and conformal integration to flexible and origami structures, bringing further opportunities for UV detection in demanding missions on Earth and in space.