Material-independent nanowire-transfer method based on mechanical interlocking for high performance flexible devices

This paper reports a novel transfer method to fabricate ultralong, fully aligned nanowires, made of diverse materials on a flexible substrate. For the uniform transfer of nanowires made from a wide range of materials, a facile and robust mechanics-based nano-transfer method has been developed. A selectively dry-removable amorphous carbon nano-sacrificial layer between a vacuum-deposited nanowire and the underlying master mold is newly introduced, and it facilitates the robust and reliable mechanical transfer of dense and aligned nanowires onto a flexible substrate. Using the developed method, we first fabricated ultralong and fully aligned metal/metal-oxide (gold, platinum, and copper-oxide) nanowires on a large-area flexible substrate (2.5 × 2 cm²). We also fabricated a unique nanowire-heater-embedded gas-sensor using the transferred gold and copper-oxide nanowires, respectively. The developed heater-embedded device exhibited a 33-fold enhancement in sensitivity, responding to 10 ppm NO2 using a 0.6 V heater bias.