Sensitivity and strain range are two mutually exclusive features of strain sensors, where a significant improvement in flexibility is usually accompanied by a reduction in sensitivity. The skin of a human fingertip, due to its undulating fingerprint pattern, can easily detect environmental signals and enhances sensitivity without losing elasticity. Inspired by this characteristic, laser-induced graphene (LIG) with a fingerprint structure is prepared in one step on a polyimide (PI) film and transferred into an Ecoflex substrate to assemble resistive strain sensors. Experimentally, the fingerprint-inspired strain sensor exhibits a superfast response time (∼70 ms), balanced sensitivity and strain range (a gauge factor of 191.55 in the 42–50% strain range), and good reliability (>1500 cycles). Self-organized microcracks, initiated in weak mechanical areas, cause prominent resistance changes during reconnection/disconnection but irreversibly fail after excessive stretching. The robust function of fingerprint-inspired sensors is further demonstrated by real-time monitoring of tiny pulses, large body movements, gestures, and voice recognition.

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Graphene plasmons, owing to their diverse applications including electro-optical modulation, optical sensing, spectral photometry and tunable lighting at the nanoscale, have recently attracted much attention. One key challenge in advancing this field is to precisely control the propagation of graphene plasmons. Here, we propose an on-chip integrated platform to engineer the wave front of the graphene plasmons through a metasurface with a refractive index of zero. We demonstrate that a well-designed graphene/photonic-crystal metasurface can possess conical plasmonic dispersion at the Brillouin zone center with a triply degenerate state at the Dirac frequency, giving rise to the zero-effective-index of graphene plasmons. Plane-wave-emission and focusing effects of the graphene plasmons are achieved by tailoring such a zero-index metasurface. In addition to the tunable Dirac point frequency enabled by the electrical tuning of the graphene Fermi level, our highly integrated system also provides stable performance even when defects exist. This actively controllable on-chip platform can potentially be useful for integrated photonic circuits and devices.