Laser-fabricated reconfigurable PT-symmetric sensors for wireless health monitoring of CFRP structures.

Carbon-fiber-reinforced polymer (CFRP) composite are widely used in hydrogen-energy and aerospace systems for their high specific strength, high specific modulus, and corrosion resistance, making structural health monitoring (SHM) indispensable. In hydrogen storage tanks, in particular, early micro-deformation and pressure drift are precursors to gas leakage and catastrophic failure. Yet most existing methods are wired or contact-based, imposing cabling and maintenance burdens and fitting poorly with embedded CFRP structures. High-precision, wireless solution therefore are urgently required. To address this gap, we laser-modify CFRP to monolithically pattern electrodes and embedded parallel-plate capacitors, constituting inductor-capacitor resonant units when coupled with an inductor. Moreover, we implement a reconfigurable wireless sensor using parity-time-symmetric circuit design. By tuning the reader's initial state and operating involving exact phase to exploit frequency splitting, the system improves sensing sensitivity within the target operating range while extending interrogation distance. Experiments on CFRP specimen and a hydrogen storage tank validate non-contact and in situ remote real-time monitoring, achieving a 15 mm read range with sensitivity of 22.92 MHz/% strain, a gauge coefficient of 10.8, operating strain range (0-0.9375%). The integration of laser-fabricated CFRP-electrode with circuit-level reconfigurability points to precise, durable SHM in CFRP structures and broad applicability across hydrogen-energy infrastructure, aerospace composites, and other safety-critical systems.