Sun Zhenhao, Yin Yunjiang, Liu Baoguo, Xue Tao, Zou Qiang
School of Microelectronics, Tianjin University, Tianjin 300072, China.
Center of Analysis and Testing Facilities, Tianjin University, Tianjin 300072, China.
Sensors (Basel). 2024 May 19;24(10):3232. doi: 10.3390/s24103232.
In recent years, hydrogel-based wearable flexible electronic devices have attracted much attention. However, hydrogel-based sensors are affected by structural fatigue, material aging, and water absorption and swelling, making stability and accuracy a major challenge. In this study, we present a DN-SPEZ dual-network hydrogel prepared using polyvinyl alcohol (PVA), sodium alginate (SA), ethylene glycol (EG), and ZnSO and propose a self-calibration compensation strategy. The strategy utilizes a metal salt solution to adjust the carrier concentration of the hydrogel to mitigate the resistance drift phenomenon to improve the stability and accuracy of hydrogel sensors in amphibious scenarios, such as land and water. The ExpGrow model was used to characterize the trend of the ∆ dynamic response curves of the hydrogels in the stress tests, and the average deviation of the fitted curves ϵ¯ was calculated to quantify the stability differences of different groups. The results showed that the stability of the uncompensated group was much lower than that of the compensated group utilizing LiCl, NaCl, KCl, MgCl, and AlCl solutions (ϵ¯ in the uncompensated group in air was 276.158, 1.888, 2.971, 30.586, and 13.561 times higher than that of the compensated group in LiCl, NaCl, KCl, MgCl, and AlCl, respectively; ϵ¯ in the uncompensated group in seawater was 10.287 times, 1.008 times, 1.161 times, 4.986 times, 1.281 times, respectively, higher than that of the compensated group in LiCl, NaCl, KCl, MgCl and AlCl). In addition, for the ranking of the compensation effect of different compensation solutions, the concentration of the compensation solution and the ionic radius and charge of the cation were found to be important factors in determining the compensation effect. Detection of events in amphibious environments such as swallowing, robotic arm grasping, Morse code, and finger-wrist bending was also performed in this study. This work provides a viable method for stability and accuracy enhancement of dual-network hydrogel sensors with strain and pressure sensing capabilities and offers solutions for sensor applications in both airborne and underwater amphibious environments.
近年来，基于水凝胶的可穿戴柔性电子设备备受关注。然而，基于水凝胶的传感器受到结构疲劳、材料老化以及吸水溶胀的影响，使得稳定性和准确性成为一大挑战。在本研究中，我们展示了一种使用聚乙烯醇（PVA）、海藻酸钠（SA）、乙二醇（EG）和硫酸锌制备的DN - SPEZ双网络水凝胶，并提出了一种自校准补偿策略。该策略利用金属盐溶液调节水凝胶的载流子浓度，以减轻电阻漂移现象，从而提高水凝胶传感器在陆地和水等两栖场景中的稳定性和准确性。使用ExpGrow模型表征水凝胶在应力测试中∆动态响应曲线的趋势，并计算拟合曲线的平均偏差ϵ¯以量化不同组的稳定性差异。结果表明，未补偿组的稳定性远低于使用LiCl、NaCl、KCl、MgCl和AlCl溶液的补偿组（空气中未补偿组的ϵ¯分别是LiCl、NaCl、KCl、MgCl和AlCl补偿组的276.158、1.888、2.971、30.586和13.561倍；海水中未补偿组的ϵ¯分别是LiCl、NaCl、KCl、MgCl和AlCl补偿组的10.287倍、1.008倍、1.161倍、4.986倍和1.281倍）。此外，对于不同补偿溶液的补偿效果排名，发现补偿溶液的浓度以及阳离子的离子半径和电荷是决定补偿效果的重要因素。本研究还进行了在吞咽、机械臂抓取、摩尔斯电码以及手指 - 手腕弯曲等两栖环境中的事件检测。这项工作为增强具有应变和压力传感能力的双网络水凝胶传感器的稳定性和准确性提供了一种可行方法，并为机载和水下两栖环境中的传感器应用提供了解决方案。
