Liu Chuanjie, Liu Zhihong
School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
School of Digital Media, Shenzhen Polytechnic University, Shenzhen 518055, China.
Gels. 2025 Jul 23;11(8):570. doi: 10.3390/gels11080570.
As a bridge for human-machine interaction, the performance improvement of sensors relies on the in-depth understanding of ion transport mechanisms. This study focuses on the surface effect of resistive gel sensors and designs a polyacrylic acid/ferric ion hydrogel (PAA/Fe) gas flow sensor. Prepared by one-pot polymerization, PAA/Fe forms a three-dimensional network through the entanglement of crosslinked and uncrosslinked PAA chains, where the coordination between Fe and carboxyl groups endows the material with excellent mechanical properties (tensile strength of 80 kPa and elongation at break of 1100%). Experiments show that when a gas flow acts on the hydrogel surface, changes in surface humidity alter the density of the network structure, thereby regulating ion migration rates: the network loosens to promote ion transport during water absorption, while it tightens to hinder transport during water loss. This mechanism enables the sensor to exhibit significant resistance responses (ΔR/R up to 0.55) to gentle breezes (0-13 m/s), with a response time of approximately 166 ms and a sensitivity 40 times higher than that of bulk deformation. The surface ion transport model proposed in this study provides a new strategy for ultrasensitive gas flow sensing, showing potential application values in intelligent robotics, electronic skin, and other fields.
作为人机交互的桥梁，传感器性能的提升依赖于对离子传输机制的深入理解。本研究聚焦于电阻式凝胶传感器的表面效应，设计了一种聚丙烯酸/铁离子水凝胶（PAA/Fe）气流传感器。PAA/Fe通过一锅法聚合制备，通过交联和未交联的PAA链的缠结形成三维网络，其中Fe与羧基之间的配位赋予材料优异的力学性能（拉伸强度为80 kPa，断裂伸长率为1100%）。实验表明，当气流作用于水凝胶表面时，表面湿度的变化会改变网络结构的密度，从而调节离子迁移速率：吸水时网络松弛以促进离子传输，失水时网络收紧以阻碍传输。这种机制使传感器对微风（0 - 13 m/s）表现出显著的电阻响应（ΔR/R高达0.55），响应时间约为166 ms，灵敏度比体积变形高40倍。本研究提出的表面离子传输模型为超灵敏气流传感提供了一种新策略，在智能机器人、电子皮肤等领域显示出潜在的应用价值。
