Study on the Modification of Polymers for Human-gentle Sensors and Actuators

聚合物凝胶因其独特的材料形态而作为“智能材料”受到人们的关注。它们也在各个领域得到了研究。通过将聚乙烯醇（PVA）水溶液冷冻并缓慢解冻而合成的水凝胶具有高含水量、高拉伸强度、伸长率等优异的机械性能以及由弹性引起的良好的形状恢复性。所用PVA的聚合度为2500，皂化度为99.5mol%。将7.5g PVA溶于80 g水中得到的溶液在-50 ℃下冷冻3小时，然后用10小时升温至室温，再重复一次冻融过程，合成水凝胶。水凝胶具有约90重量%的水含量。其拉伸强度为0.6MPa，断裂伸长率为130%。在外力作用下变形的水凝胶在解除外力作用后，其形状在短时间内恢复。利用这些特性，制作了应变式传感器和气压式传感器进行了试验。可以将其应用于使用含有电解质溶液的水凝胶的应变传感器和气压传感器。此外，具有含PAA的铂丝电极的PVA水凝胶棒可以通过施加DC而弯曲。该棒能够通过这种弯曲行为作为柔性致动器应用于夹持器的手指。

Polymer gels have attracted attention as the 'intelligent material'because of their peculiar material forms. They aslo have been studied in every field. The hydrogel synthesized by freezing a polyvinyl alcohol (PVA) aqueous solution and thawing it slowly has high water content, excellent mechanical properties of high tensile strength, elongation, and good shape recovery by the elasticity. Used PVA had the degree of polymerization of 2500 andthe degree of saponification of 99.5 mol%. When the solution obtained by the way that 7.5g of the PVA was dissolved in80g of water, was frozen at-50-C for 3 hours and then warmed it up to room temperature taking 10 hours, and in addition, this freezing-thawing process was repeated once again, a hydrogel was synthesized. The hydrogel had the water content of about 90wt%. The tensile strength of it was 0.6MPa and the elongation at break was 130%. The shape ofthe hydrogel which was deformed by the external force recovered in a short time when it was released from the force. This recovery had good persistence and repeatability.Applying these properties, the strain sensor and the gas pressure sensor were made for trial. it can be applied to the strain sensor and the gas pressure sensor using the hydrogel containing an electrolyte solution. Furthermore, the PVA hydrogel rod with platinum wire electrodes containing PAA can bend by applying DC.This rod is able to be applied to fingers of the gripper as a flexible acturator by this bending behavior.