Wrinkle-engineered multi-walled carbon nanotubes/laser-induced graphene heterostructured films for ultra-sensitive strain sensing†

Abstract

Flexible strain sensors are considered indispensable for applications in health monitoring and wearable electronics; however, the simultaneous realization of a wide strain range and high sensitivity remains a considerable challenge. In response to this, a flexible wrinkled multi-walled carbon nanotubes/laser-induced graphene (MWCNTs/LIG) strain sensor is fabricated on a polyurethane (PU) substrate through the integration of laser-induced graphitization and mechanical pre-stretching. The introduction of the wrinkled architecture results in a substantial enhancement in sensing performance, with a gauge factor (GF) reaching 1874, a broad strain-operating range, excellent cyclic durability over 1100 loading–unloading cycles, and fast response and recovery times of 28 ms and 25 ms, respectively. Reliable detection of subtle physiological signals is demonstrated, including applications in real-time pulse monitoring—encompassing waveform profiling and arterial stiffness assessment—joint motion tracking, and voice recognition. The feasibility of signal transmission is further validated via Morse code communication. These findings highlight the potential of the proposed sensor for deployment in smart healthcare systems, wearable electronics, human–machine interfaces, and intelligent information transmission platforms.