One‐Step Pyrolysis and ZnO Nanostructure Functionalization of Flexible Textiles for Multimodal Sensing of Pressure, Temperature and Sunlight

Abstract

ABSTRACT Wearables with multimodal sensing capabilities can capture rich, synchronized physiological and environmental data, but remain difficult to fabricate and continue to face challenges with signal crosstalk. Here, we show how laser irradiation of textiles treated with zinc sulfate can produce dense and even distributions of ZnO nanostructures on carbonized cellulose fibers composed of laser‐induced graphene (LIG). Owing to charge carrier generation by ZnO nanostructures, the resistance change of LIG to temperature and sunlight was amplified by ∼ 3.5× and ∼3.2×, respectively. However, ZnO nanostructures had little effect on the pressure sensitivity of LIG, which was accomplished primarily through compaction of the carbonized fiber network. The response and recovery times obtained from ZnO/LIG were also comparable to or better than LIG sensors reported previously. By stacking 2 sensors and decoupling instantaneous pressure signals from slower temperature signals, simultaneous multimodal sensing was demonstrated with ±10% accuracy. The flexible textile sensors were also applied to the uneven contours of a human hand and displayed rapid and repeatable responses across a variety of activities. These findings establish laser irradiation of ZnSO 4 ‐treated textiles as an initial proof‐of‐concept toward developing wearable multimodal sensors with little crosstalk, while further evaluation of wearability‐related characteristics is required.