Flexible Nanowire Cluster as a Wearable Colorimetric Humidity Sensor

Wearable plasmonic devices combine the advantages of high flexibility, ultrathinness, light weight, and excellent integration with the optical benefits mediated by plasmon‐enhanced electric fields. However, two obstacles severely hinder further developments and applications of a wearable plasmonic device. One is the lack of efficient approach to obtaining devices with robust antimotion‐interference property, i.e., the devices can work independently on the morphology changes of their working structures caused by arbitrary wearing conditions. The other issue is to seek a facile and high‐throughput fabrication method to satisfy the financial requirement of industrialization. In order to overcome these two challenges, a functional flexible film of nanowire cluster is developed, which can be easily fabricated by taking the advantages of both conventional electrochemical and sputtering methods. Such flexible plasmonic films can be made into wearable devices that work independently on shape changes induced by various wearing conditions (such as bending, twisting and stretching). Furthermore, due to plasmonic advantages of color controlling and high sensitivity to environment changes, the flexible film of nanowire cluster can be used to fabricate wearable items (such as bracelet, clothes, bag, or even commercial markers), with the ability of wireless visualization for humidity sensing. A flexible nanowire clusteris fabricated by a conventional sputtering technique with the help of disordered alumina template. Such a nanowire cluster can be made into a wearable sensor, working independently on any arbitrary morphological shapes. With advantages of easy fabrication, high sensitivity, and robust antimotion‐interference merits, the flexible nanowire cluster will greatly help to push the wearable plasmonic device into real industry world.