Smart Wood Dual-Action Off/On Versatile Switches Based on Highly Sensitive Electrical and Electromagnetic Mechanosensing Performances

Smart electromagnetic (EM) functional materials that can arbitrarily utilize EM energy and reduce EM pollution are attractive for future EM devices in an information society; however, studies on precise EM interference (EMI) shielding and sensing are rare. In this work, dual-action electrical and EM-responsive mechanoreceptors are prepared from electrically conductive polypyrrole (PPy) nanoparticle (NP)-infiltrated anisotropic wood (PW) aerogels. The prepared PW aerogels are composed of curved stacked layers of aligned cellulose nanofibers, and can be reversibly condensed and reconstructed for conductive network control during cyclic compression. These PW aerogels can withstand up to 74% compressive strain in a tangential direction and exhibit pressing-enhanced electrical conductivity and polarization loss. The piezoresistive gauge factor (GF) and linearity of the PW aerogels can be adjusted by varying the PPy deposition time, leading to varying GF values in the range of 1.87-4.62. During mechanosensing based on EMI shielding effectiveness (SE), rapid off/on switching between the EM wave transmission and shielding is achieved when the SE varies above and below the effective EMI shielding area (>20 dB) through continuous compression. Such dual-action electrical/EM off/on wood aerogel switches provide opportunities for the development of advanced smart devices from biomass resources.