Ultralight, flexible and conductive silver nanowire/nanofibrillated cellulose aerogel for multifunctional strain sensor

Abstract

Wearable strain sensors have drawn growing interest in the field of intelligent electronic devices because of their inherent advantages including miniaturization and portability. For practical applications, strain sensors with lightness, flexibility, and high sensitivity are urgently desired. Herein, the interconnected silver nanowires (AgNWs) are assembled into the nanofibrillated cellulose (NFC) aerogel through unidirectional freeze-drying yielding an ultralight and conductive AgNWs/NFC aerogel (SNA) with ordered pore orientation. After thermal welding, the SNA possesses unique electron transfer channels, which can efficiently eliminate the interfacial electrical resistance at the AgNWs junctions and bring an impressive conductivity enhancement for the composite aerogel. Benefiting from the synergy of the desired microstructure and superior conductivity of as-prepared aerogel, the derived sensor shows desirable sensitivity (3.86 kPa−1), fast response time (180 ms), ultralow density (less than 13.58 mg/cm3) and detection limit of 0.5% strain, and exceptional stability and durability (over 10,000 cycles). Significantly, the integrated conductive network in SNA simultaneously offers real-time monitoring of subtle deformations and electrophysiological signals, which enables the designs of wearable device, acoustic sensor, and vehicles’ speed and loading detector. The presented strategy opens up a new possibility for designing and manufacturing next-generation multifunctional strain sensor to bring the technology much closer to commercialization.