Highly Sensitive Temperature Detection Based on a Frost- and Dehydration-Resistive Ion-Doped Hydrogel-MXene Composite

Abstract

Wearable temperature sensors with high sensitivity and stability hold great potential for human health monitoring. However, hydrogels, which are commonly used for wearable devices, often show poor thermal and electrical conductivity and are susceptible to dehydration and freezing. Herein, we developed a frost- and dehydration-resistive temperature sensor based on Fe2+/Ti2CT x /κ-carrageenan (CA)-polyacrylamide (PAM) hydrogel. The Fe2+ ions within the hydrogel existed in two forms: as free ions and bonded ions. The free Fe2+ ions could complex with water molecules, resulting in the improved resistance to dehydration and freezing, as well as enhanced ionic conductivity in the hydrogel. On the other hand, the remaining Fe2+ ions acted as linkers to form coordination bonds with the sulfate groups of CA chains, resulting in the greatly enhanced mechanical strength of the hydrogel. In addition, the Ti2CT x nanosheet-based fillers formed a well-defined porous laminar structure, which reduced the phonon scattering and improved the phonon adsorption within the hydrogel. The Fe2+/Ti2CT x /CA-PAM hydrogel sensor exhibited excellent temperature sensing performance including a good linearity (R 2 = 0.998) within a broad working range (−10 to 60 °C), high resolution (0.1 °C), and good repeatability. Furthermore, the sensor was integrated into a wireless system for continuous monitoring of body temperature, demonstrating its potential in healthcare monitoring, electronic skins, and intelligent robots.

Multifunctional Conductive Double-Network Hydrogel Sensors for Multiscale Motion Detection and Temperature Monitoring

“…This is attributed to the improved migration rate of ions, resulting in increased conductivity and reduced relative resistance changes . In Figure c, the hydrogel sensor shows a high TCR of 1.685 % °C –1 in the range of 0–30 °C ( R 2 = 0.9917), which surpasses most previously reported temperature sensors constructed with hydrogel (Figure d). ,,− The calculated TCR is 0.688 % °C –1 in the range of 30–100 °C ( R 2 = 0.9942). The decrease in TCR is due to the dependence of conductivity on temperature following the Vogel–Tamman–Fulcher (VTF) equation .…”

MXene-Based Chemo-Sensors and Other Sensing Devices

“…Compared to most other fire detection and warning sensor systems (based on nanoparticles, graphene oxide and metal oxides), the developed sensor demonstrated a greater reproducibility of fire detection and the benefit of the absence of a need for external power to function. The sensor’s potential in healthcare monitoring, electronic skins, and intelligent robotics was also demonstrated by its integration into a wireless system for body temperature monitoring [ 102 ]. By dip-coating Ti 3 C 2 T x MXene material on a polyester fiber substrate and depositing silver nanoparticles, Hailian Liu et al were able to create a high-performance wearable sensor.…”

Recent advances in wearable iontronic sensors for healthcare applications

“…(L) Response properties of CA/PAAm-based temperature sensor with MXene at various temperature change rate. Reprinted with permission from (A) Zhu et al (2020) , (B) Wen et al (2021) , (C) Zhu et al (2020) , (D) Di Giacomo et al (2017) , (E) Wang et al (2023c) , (F) Yamada and Toshiyoshi (2020) , (G) Gui et al (2017) , (H) Yamada and Toshiyoshi (2020) , (I,J) Chen et al (2022b) , (K) An et al (2020) , (L) Wang et al (2023c) .…”

“… Di Giacomo et al (2017) devised such a sensor using pectin, ionic crosslinked via Ca 2+ ions, operating under 0.1 V between 10°C–55°C. Similarly, Wang et al (2023c) designed a ITS by integrating k-carrageenan ionic crosslinked with Fe 2+ ions into PAAm. This device showed a 1.07% shift in conductivity for each 1°C change between -10°C – 60°C ( Figure 11E ).…”

“…In healthcare monitoring, a response rate of temperature sensor is essential for rapidly diagnosing temperature fluctuations. Ionic gels have lower thermal conductivity due to low thermal conductive polymers and solvents ( Wang et al, 2023c ). To improve it, researchers have incorporated additives like carbon nanotubes or MXene, known for their high thermal conductivity ( Kumanek and Janas, 2019 ; Yi et al, 2022 ).…”