Silver Nanowire Composite Acrylate Humidity Sensors with Ultrafast Response and Low Hysteresis

Abstract In this study, the polyelectrolyte PDH was prepared by copolymerizing [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC) with hydroxyethyl methacrylate (HEMA), and silver nanowires (AgNWs) were incorporated to construct a PDH/Ag composite humidity-sensitive film. A systematic comparison of the linear response, humidity hysteresis, dynamic response speed, and long-term stability between PDH and PDH/Ag devices was conducted, and the sensing mechanism was analyzed using complex impedance spectroscopy. The test results show that the composite-modified PDH/Ag sensor achieved a linear correlation coefficient as high as 0.996, with humidity hysteresis reduced from 3.15% RH to 1.39% RH and a response time shortened to less than 1 s; after 20 consecutive days of testing at 30% RH, 60% RH, and 90% RH, the PDH/Ag sensor exhibited virtually no baseline drift, demonstrating significantly improved long-term stability. Complex impedance spectroscopy confirmed that at low humidity (11% RH), both types of devices exhibited only intrinsic polymer conductivity; as humidity increased to the medium- and high-humidity ranges, Warburg ion diffusion behavior gradually emerged and continued to intensify. The interwoven silver nanowire network constructs continuous water vapor diffusion channels, enhances ion transport, and restrains polymer swelling and aging, simultaneously addressing the multiple performance shortcomings of pure polyelectrolyte humidity-sensitive materials. This work provides a feasible modification strategy for the structural design of high-performance, long-life polyelectrolyte-based humidity-sensitive membranes.