Multifunctional strain sensor with adjustable conductive network for wearable applications

Wearable sensors based on nanomaterials have recently elicited keen research interest and potential for a new range of flexible devices. This paper presents a simple method for the preparation of laser-induced porous graphene (LIG) and discusses its application in monitoring human vital signs. LIG formed on a polyimide (PI)/polydimethylsiloxane (PDMS) composite material exhibits inherent high stretchability (over 30%), eliminating the need for transfer processes used in LIG prepared by laser scribing on PI films. LIG/CuSO4 composite materials, with different concentrations of Cu particles, show tunable mechanical and electronic properties based on laser-induced graphene. The fabricated LIG demonstrates good cyclic stability and a nearly linear resistance response to tensile strain, making it suitable for wearable electronic devices, the maximum strain value and linear response to applied strain from 3% to 79%. The sensor exhibits a fast response time and high sensitivity, enabling real-time detection of human pulse, joint motion, and complex dynamics. The multifunctionality advantages of LIG flexible sensor offer potential applications in next-generation wearable electronics.