An Ultra-Sensitive Multi-Functional Optical Micro/Nanofiber Based on Stretchable Encapsulation

Abstract

Stretchable optical fiber sensors (SOFSs), which are promising and ultra-sensitive next-generation sensors, have achieved prominent success in applications including health monitoring, robotics, and biological–electronic interfaces. Here, we report an ultra-sensitive multi-functional optical micro/nanofiber embedded with a flexible polydimethylsiloxane (PDMS) membrane, which is compatible with wearable optical sensors. Based on the effect of a strong evanescent field, the as-fabricated SOFS is highly sensitive to strain, achieving high sensitivity with a peak gauge factor of 450. In addition, considering the large negative thermo-optic coefficient of PDMS, temperature measurements in the range of 30 to 60 °C were realized, resulting in a 0.02 dBm/°C response. In addition, wide-range detection of humidity was demonstrated by a peak sensitivity of 0.5 dB/% RH, with less than 10% variation at each humidity stage. The robust sensing performance, together with the flexibility, enables the real-time monitoring of pulse, body temperature, and respiration. This as-fabricated SOFS provides significant potential for the practical application of wearable healthcare sensors.

Micro-/Nano-Fiber Sensors and Optical Integration Devices

“…Xiang et al proposed stretchable optical fiber sensors (SPFSs) by encapsulating the dual-cone microfiber in the polydimethylsiloxane (PDMS) membrane [ 3 ]. This sensor can be attached to the human skin as a wearable healthcare device to measure the strain, temperature, and humidity caused by pulse, body temperature, and respiration.…”

A Fabry-Perot Sensor With Cascaded Polymer Films Based on Vernier Effect for Simultaneous Measurement of Relative Humidity and Temperature

“…Relative humidity (RH) and temperature are the two most important environmental parameters in many applications, such as monitoring the living conditions of manned spacecrafts, controlling specific chemical reactions, and managing certain hazardous article warehouse. Compared with electronic hygrometers, optical fiber humidity sensors have the advantages of electromagnetic interference resistance, high sensitivity, quick response and so on [1][2][3]. Several kinds of fiber RH sensors have been reported, such as those based on tapered fiber [4,5], Mach-Zehnder interferometers [6][7][8], Fabry-Perot interferometers (FPI) [9,10], optical fiber Bragg gratings [11,12], and microfiber knot resonators [13].…”

Human Pulse and Respiration Monitoring: Reconfigurable and Scalable Balloon‐Shaped Fiber Wearables

“…In flexible wearable systems, micro-nano fiber based probes are mainly used to monitor different physiological activities. [9,10,27,28] But, the fragile and mechanically unstable nature of these fiber materials limits their stretchability and mechanical stability as a wearable system. However, by fabricating the micro-nano fibers using a relatively complex fabrication method, wavy and S-shaped structures have been developed to largely address these problems.…”