Strain sensors that can work sustainably and continuously without any external power supply are highly desirable for future wearable and implantable devices. Herein, a self‐powered stretchable strain sensor based on the integration of mechanoluminescent phosphors with an elastomer optical fiber is proposed and developed. This mechanoluminescent optical fiber is capable of emitting light just driven by external strain, without the need of an external light source or electric power. The strain‐induced emitted light can be collected and guided along the mechanoluminescent optical fiber. The sensor exhibits linear strain response up to 50% and high‐accuracy strain measurement (±1%). Moreover, this optical fiber strain sensor displays consistent signals over 10 000 stretch–release motion cycles, which demonstrates the good durability of the sensor. Due to the excellent light confinement of the elastomer optical fiber, this strain sensor is demonstrated in both bright‐ and dark‐field measurements, wearable gloves, and an implantable sensing device, thereby demonstrating potential as a promising technology for future self‐powered optical sensor systems.

A stretchable fluorescent optical fiber provides a flexible platform for wearable functional devices due to its stretchability and immunity to electromagnetic interference. However, for wearable applications, stretchable fiber sensors suffer from severe body movement-induced strain interference. Here, we report a stretchable optical sensor with strain-decoupling ability. The stretchable core-clad structured optical fiber is prepared with fluorescent nanoparticles and silicone-based elastomers that enable both efficient excitation light delivery and fluorescence collection. The excitation light loss and fluorescence intensity exhibit a linear response to the sensing variables and strain change, which have been utilized as the sensing parameters to decouple the strain from the sensing variables. Our strain-decoupled scheme is widely applicable to other stretchable fluorescent optical fiber sensors that are simultaneously subject to strain. In the experiment described here, the temperature-sensitive fluorescent nanoparticle-doped stretchable fluorescent optical fiber exhibits stable temperature-sensing in the range −10 to 60 °C, with an uncertainty as low as ±0.23 °C and a relative sensitivity of 1.3% °C–1, even when it is subjected to large strain up to 40%. We demonstrate sensor-integrated wearable masks and gloves, which can simultaneously measure physiological thermal changes and the movement of the wrist joint. Our sensor shows great promise as a technology for wearable health monitoring.

Soft actuators, an emerging field in robotics, have great potential for wide‐ranging applications in biology, medicine, engineering, and oceanography. Photoactuators that are stimulated by light to produce reversible mechanical deformation have attracted significant interest in recent years owing to their advantages of high resolution, fast switching, flexible controllability, and electromagnetic interference immunity. Conventional photoactuators rely on free‐space illumination, which limits the control in light‐obstructed surroundings. A low loss optical fiber waveguide‐based soft photoactuator composed of photothermally responsive material hinges and high‐transparency elastomer fiber arms is proposed. When light travels in the elastomer fiber arms, the hinges exhibit a very large shape change so that the arms bend by themselves, with a maximum repeatable bending angle of approximately 145°. The angle is determined by the injected optical power. A fiber photoactuator with dual hinges is designed that is capable of reversible complex deformation. Moreover, in a narrow silicone tube, the fiber photoactuator can still be stimulated with considerable deformation by the light injected along the fiber. A fiber photoactuator‐constructed microhook is demonstrated for grabbing object in water.

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AbstractPhotonic topological insulators (PTIs) bring markedly new opportunities to photonic devices with low dissipation and directional transmission of signal over a wide wavelength range due to the broadband topological protection. However, the maximum gap/mid-gap ratio of PTIs is below 10% and hardly further improved duo to the lack of new bandwidth enhancement mechanism. In this paper, a PTI with the gap/mid-gap ratio of 16.25% is proposed. The designed PTI has a honeycomb lattice structure with triangular air holes, and such a wide bandwidth is obtained by optimizing the refractive-index profile of the primitive cell for increasing the energy proportion in the geometric perturbation region. The PTI shows a large topological nontrivial gap (the gap/mid-gap ratio 33.4%) with the bandwidth approaching its theoretical limit. The edge states propagate smoothly around sharp bends within 1430–1683 nm. Due to topological protection, the bandwidth only decreases 1.38% to 1450–1683 nm under 1%-random-bias disorders. The proposed PTI has a potential application in future high-capacity and nonlinear topological photonic devices.

The ability to locate and quantify large strains will significantly improve the real‐world application scenario of flexible and stretchable strain sensors. However, current methods for implementing stretchable distributed strain sensing still face challenges such as complicated demodulation, multisensor crosstalk, and high power consumption. Herein, a self‐powered and stretchable optical fiber strain sensor is reported with distributed sensing capability based on mechanoluminescent optical fiber, where mechanoluminescent phosphors with different emission color light are discretely integrated onto the outer cladding of the elastomer optical fiber. Based on the wavelength coding technique and time‐domain filtering comparison method, the capability of strain magnitude quantification (10–60%) and strain location identification together in a single stretchable optical fiber is successfully realized, even at multiple positions simultaneously in the strain‐applied situation. Moreover, this stretchable optical fiber strain sensor shows insensitivity to bending, compression, and temperature disturbances and outstanding durability (>8000 cycles). Due to the excellent light confinement of the elastomer optical fiber, demonstrations such as bright‐field measurement, saline water operation, and wearable glove application exhibit its potential as a promising technology for future self‐powered distributed optical sensing systems.