In-situ fabricated LIG electrodes enabling robust capacitive pressure sensors for human motion detection

The emergence of laser-induced graphene (LIG) technology enables low-cost, rapid and patterned fabrication of graphene. However, conventional LIG-based electrodes suffer from inherent limitations: direct-writing on PI films cannot satisfy flexible sensing demands due to substrate limitations, while elastomer transfer damages LIG's 3D porous structure, causing drastic sheet resistance drift and impaired pressure sensor performance. Herein, a novel in-situ fabrication process for LIG electrodes is proposed. Compared with the elastomer transfer method, the LIG electrodes prepared via this in-situ process exhibit a mere 8.17% increase in sheet resistance after fabrication, far outperforming the 67.65% rise from the transfer process; under 0–90° bending and 0–20% stretching, their sheet resistance varies by only 1.40% and − 0.99%, respectively, whereas transferred electrodes undergo dramatic increases of 697.66% and 1195.10%. The capacitive pressure sensor based on the in-situ fabricated LIG electrodes exhibits excellent long-term stability (0.8% capacitance variation after 6000 loading cycles), fast response (20.33 ms response/16.95 ms recovery time) and ultra-low limit of detection (13.55 Pa limit of detection). When it is attached to human skin, this sensor enables accurate detection of fine technical movements in badminton and swimming, which demonstrates its great application potential in human motion detection. The proposed in-situ fabricated LIG electrodes possess superior structural stability, electrical conductivity and flexibility, thus providing a critical technical foundation for the design and engineering implementation of high-performance flexible pressure sensors with long-term stability.