Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education, National Demonstration Center for Experimental Mechanical Engineering Education, School of Mechanical Engineering, Shandong University, Jinan, Shandong 250061, China.
Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China.
Adv Colloid Interface Sci. 2022 Oct;308:102749. doi: 10.1016/j.cis.2022.102749. Epub 2022 Aug 9.
Living bodies are made of numerous bio-sensors and actuators for perceiving external stimuli and making movement. Hydrogels have been considered as ideal candidates for manufacturing bio-sensors and actuators because of their excellent biocompatibility, similar mechanical and electrical properties to that of living organs. The key point of manufacturing hydrogel sensors/actuators is that the materials should not only possess excellent mechanical and electrical properties but also form effective interfacial connections with various substrates. Traditional hydrogel normally shows high electrical resistance (~ MΩ•cm) with limited mechanical strength (<1 MPa), and it is prone to fatigue fracture during continuous loading-unloading cycles. Just like iron should be toughened and hardened into steel, manufacturing and post-treatment processes are necessary for modifying hydrogels. Besides, advanced design and manufacturing strategies can build effective interfaces between sensors/actuators and other substrates, thus enhancing the desired mechanical and electrical performances. Although various literatures have reviewed the manufacture or modification of hydrogels, the summary regarding the post-treatment strategies and the creation of effective electrical and mechanically sustainable interfaces are still lacking. This paper aims at providing an overview of the following topics: (i) the manufacturing and post-engineering treatment of hydrogel sensors and actuators; (ii) the processes of creating sensor(actuator)-substrate interfaces; (iii) the development and innovation of hydrogel manufacturing and interface creation. In the first section, the manufacturing processes and the principles for post-engineering treatments are discussed, and some typical examples are also presented. In the second section, the studies of interfaces between hydrogels and various substrates are reviewed. Lastly, we summarize the current manufacturing processes of hydrogels, and provide potential perspectives for hydrogel manufacturing and post-treatment methods.
活体由众多生物传感器和执行器组成，用于感知外部刺激并做出运动。水凝胶因其出色的生物相容性、与活体器官相似的机械和电气特性，被认为是制造生物传感器和执行器的理想候选材料。制造水凝胶传感器/执行器的关键在于，材料不仅应具有出色的机械和电气性能，而且还应与各种基底形成有效的界面连接。传统水凝胶通常具有较高的电阻（~MΩ•cm）和有限的机械强度（<1 MPa），并且在连续加载-卸载循环过程中容易疲劳断裂。就像铁应该被强化和硬化成钢一样，制造和后处理过程对于改性水凝胶是必要的。此外，先进的设计和制造策略可以在传感器/执行器和其他基底之间建立有效的接口，从而增强所需的机械和电气性能。尽管各种文献已经综述了水凝胶的制造或改性，但关于后处理策略和有效电-机械可持续接口的创建的综述仍然缺乏。本文旨在概述以下主题：（i）水凝胶传感器和执行器的制造和后工程处理；（ii）创建传感器（执行器）-基底接口的过程；（iii）水凝胶制造和接口创建的发展和创新。在第一节中，讨论了制造工艺和后工程处理的原理，并介绍了一些典型实例。在第二节中，综述了水凝胶与各种基底之间的界面研究。最后，我们总结了水凝胶的当前制造工艺，并为水凝胶制造和后处理方法提供了潜在的展望。
