Hu Zhirui, Li Jie, Wei Xiaotong, Wang Chen, Cao Yang, Gao Zhiqiang, Han Jing, Li Yingchun
School of Materials Science and Engineering, North University of China, Taiyuan 030051, P. R. China.
School of Mechatronic Engineering, North University of China, Taiyuan 030051, P. R. China.
ACS Appl Mater Interfaces. 2022 Oct 12;14(40):45853-45868. doi: 10.1021/acsami.2c13074. Epub 2022 Sep 28.
Conductive hydrogels have attracted attention because of their wide application in wearable devices. However, it is still a challenge to achieve conductive hydrogels with high sensitivity and wide frequency band response for smart wearable strain sensors. Here, we report a composite hydrogel with piezoresistive and piezoelectric sensing for flexible strain sensors. The composite hydrogel consists of cross-linked chitosan quaternary ammonium salt (CHACC) as the hydrogel matrix, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) as the conductive filler, and poly(vinylidene fluoride--trifluoroethylene) (PVDF-TrFE) as the piezoelectric filler. A one-pot thermoforming and solution exchange method was used to synthesize the CHACC/PEDOT: PSS/PVDF-TrFE hydrogel. The hydrogel-based strain sensor exhibits very high sensitivity (GF: 19.3), fast response (response time: 63.2 ms), and wide frequency range (response frequency: 5-25 Hz), while maintaining excellent mechanical properties (elongation at break up to 293%). It can be concluded that enhanced strain-sensing properties of the hydrogel are contributed to both greater change in the relative resistance under stress and wider response to dynamic and static stimulus by adding PVDF-TrFE. This has a broad application in monitoring human motion, detecting subtle movements, and identifying object contours and a hydrogel-based array sensor. This work provides an insight into the design of composite hydrogels based on piezoelectric and piezoresistive sensing with applications for wearable sensors.
导电水凝胶因其在可穿戴设备中的广泛应用而备受关注。然而，对于智能可穿戴应变传感器而言，实现具有高灵敏度和宽频带响应的导电水凝胶仍然是一项挑战。在此，我们报道了一种用于柔性应变传感器的具有压阻和压电传感功能的复合水凝胶。该复合水凝胶由交联壳聚糖季铵盐（CHACC）作为水凝胶基质、聚（3,4-乙撑二氧噻吩）：聚（苯乙烯磺酸盐）（PEDOT：PSS）作为导电填料以及聚（偏二氟乙烯-三氟乙烯）（PVDF-TrFE）作为压电填料组成。采用一锅热成型和溶液交换法合成了CHACC/PEDOT：PSS/PVDF-TrFE水凝胶。基于该水凝胶的应变传感器表现出非常高的灵敏度（GF：19.3）、快速响应（响应时间：63.2毫秒）和宽频率范围（响应频率：5 - 25赫兹），同时保持优异的机械性能（断裂伸长率高达293%）。可以得出结论，通过添加PVDF-TrFE，水凝胶增强的应变传感性能既归因于应力下相对电阻的更大变化，也归因于对动态和静态刺激更广泛的响应。这在监测人体运动、检测细微动作以及识别物体轮廓和基于水凝胶的阵列传感器方面具有广泛应用。这项工作为基于压电和压阻传感的复合水凝胶设计提供了见解，可应用于可穿戴传感器。
