Flexible Wearable Optical Sensor Based on Optical Microfiber Bragg Grating

Wearable sensing devices, which can find tremendous applications in healthcare and automation, are attracting great attention in recent years. Herein, we report a flexible wearable optical sensor (FWOS) which consists of the microfiber Bragg grating ( ${\mu }$ FBG) as the core sensing node and a ductile PDMS film as the sensor encapsulation. Due to the strain amplification effect of the microfiber, the sensitivity of FWOS to pressure, bending angle and temperature is significantly enhanced to 0.03 nm/kPa, 0.19 nm/ $^{\circ }$ and 0.04 nm/ $^{\circ }$ C, respectively. Furthermore, thanks to the better flexibility of the microfiber structure, the FWOS device could be achieved for real-time monitoring of wrist pulses, finger knuckle bending, and human body temperature. The proposed FWOS creates new ideas for the development of future wearable optical devices, which is critical for the advancement of next-generation robotics, and healthcare monitoring.