Robust, Ultrathin, and Highly Sensitive Reduced Graphene Oxide/Silk Fibroin Wearable Sensors Responded to Temperature and Humidity for Physiological Detection

Abstract

Skin temperature and skin humidity are used for monitoring physiological processes, such as respiration. Despite advances in wearable temperature and humidity sensors, the fabrication of a durable and sensitive sensor for practical uses continues to pose a challenge. Here, we developed a durable, sensitive, and wearable temperature and humidity sensor. A reduced graphene oxide (rGO)/silk fibroin (SF) sensor was fabricated by employing a layer-by-layer technique and thermal reduction treatment. Compared with rGO, the elastic bending modulus of rGO/SF could be increased by up to 232%. Furthermore, an evaluation of the performance of an rGO/SF sensor showed that it had outstanding robustness: it could withstand repeatedly applied temperature and humidity loads and repeated bending. The developed rGO/SF sensor is promising for practical applications in healthcare and biomedical monitoring.

Silk-based wearable devices for health monitoring and medical treatment

“… 80 SF/rGO film fibroin Cho et al. 81 SF/CNC/RTP hydrogel fibroin Wang et al. 82 SF/PNIPAM/PC hydrogel fibroin Zheng et al.…”

“… 79 Respiration SF/rGO film fibroin Cho et al. 81 Respiration SF/rGO film fibroin Jiang et al. 98 Respiration SF/CNT textile fibroin Ma et al.…”

“…Reproduced with permission, from Cho et al. 81 Copyright 2023, American Chemical Society. (E) The SF/CNC/RTP gel showed a tough elastic interlocked network, taking advantage of thermochromism, the sensor became colorless from light blue as temperature rose within 30°C–40°C.…”

“…The reduced graphene oxide (rGO) is a biocompatible derivative of GO with high electrical conductivity, making it an ideal candidate for sensing applications. 118 Using a layer-by-layer dip-coating fabrication method and thermal reduction treatment, a self-assembled SF/rGO film with a nacre-like structure was developed 81 ( Figure 3 D). A strong hierarchical interaction between SF and rGO contributed to the excellent mechanical properties of the film sensor.…”

“… 79 Since hydrophilic rGO is rich in oxygen-containing functional groups, humidity also interacted with the rGO flakes within the aforementioned SF/rGO sensor and another SF/rGO composites-based respiration sensor, 98 causing changes in their network structure and resulting in alterations of electrical conductance. Consequently, the rate of respiration was accurately detected, 81 Ma et al. developed hybrid fibers by combining regenerated SF with CNTs, which exhibited both conductivity and humidity-sensing ability.…”