单宁酸/MXene增强水凝胶的制备及其传感性能

Preparation of tannic acid/MXene-enhanced hydrogels and their sensing properties

  • 摘要: 水凝胶可用作可穿戴传感器来检测人体运动。然而,现有的水凝胶传感器普遍存在力学性能较差、耐久性不足、低温易冻结等问题,极大地影响了其在可穿戴设备领域的应用。因此,本文在水凝胶中引入MXene作为导电填料,并浸泡于单宁酸/水/甘油二元溶剂中制备得到有机水凝胶AMT。单宁酸分子上的苯三酚和儿茶酚基团以氢键、π-π相互作用、疏水相互作用等方式与聚合物形成物理交联,从而增强水凝胶的力学性能。结果表明,水凝胶的力学性能随着浸泡单宁酸浓度的升高而增强,当单宁酸浸泡浓度为200 mg/mL时水凝胶的拉伸应变达到658.2%,应力为172.2 kPa。二元溶剂的存在使得水凝胶即使在炎热(60℃)和寒冷环境(−20°C)中也能保持良好的稳定性。此外,基于该水凝胶的可穿戴应变传感器对运动及光照均表现出良好的灵敏度,能够实时监测人体喉咙、脉搏、手指、手腕、手臂等不同部位的运动信号,且该传感器能在光照下通过光热转换间接实现对光照的监测。本研究有望扩展水凝胶传感器在户外光照传感领域的应用。

     

    Abstract: Hydrogels can be used as wearable sensors to detect human motion. However, extant hydrogel sensors generally suffer from poor mechanical properties, insufficient durability, and simple chilling at low temperatures, which significantly influence their applications in the field of wearable devices. Therefore, in this paper, MXene was introduced as a conductive infill in hydrogels and immersed in a tannic acid/water/glycerol binary solvent to obtain the organo-hydrogel AMT. Benzenetriol and catechol groups on the tannic acid molecule formed physical cross-links with the polymer by means of hydrogen bonding, π-π interactions, hydrophobic interactions, etc., which enhanced the mechanical properties of the hydrogel. The results showed that the mechanical properties of the hydrogel were enhanced with the increase of the soaked tannin concentration, and the tensile strain of the hydrogel reached 658.2% with a tension of 172.2 kPa when the tannin-soaked concentration was 200 mg/mL.The presence of the binary solvent allowed the hydrogel to maintain a decent stability even in heated (60℃) and frigid environments (−20℃). In addition, the wearable strain sensor based on this hydrogel shows good sensitivity to both motion and light, and is able to monitor the motion signals of different parts of the human body, such as throat, pulse,fingers, wrists, and arms, in real time, and the sensor is able to indirectly realize the monitoring of light through photothermal conversion under light. This study is expected to extend the application of hydrogel sensors in outdoor light sensing.

     

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