【作者】 李翔宇；

【导师】 郑兆柱；

【作者基本信息】 苏州大学 ， 纺织工程（专业学位）， 2022， 硕士

【摘要】 近几年,柔性可穿戴设备因其特殊的性能和巨大的应用前景而引起了广泛的关注。导电水凝胶因其具有类似组织的顺应性、韧性、可拉伸性、导电性、刺激响应性和应变敏感性等多种性能,成为柔性可穿戴设备传感器最优选择。导电水凝胶制备通常是通过将导电材料(例如碳纳米管,离子盐和导电聚合物)分散在具有良好弹性的柔性基材(如聚二甲基硅氧烷(PDMS)、聚丙烯酰胺(PAM))中进行加工制备。然而,这类化学合成基材聚合中间产物成分、残留不确定、聚合物和降解产物体内毒性不确定、生物降解产物不确定等不足,限制了其在生物医学领域的应用。新一代导电水凝胶旨在使用生物友好型聚合物来克服这些限制,从而赋予导电水凝胶生物相容性和生物降解性。丝素蛋白(Silk)是天然高分子纤维蛋白,具有良好的机械性能、生物相容性、可生物降解性,能够加工制备成多种形态的基质,如生物膜、海绵、凝胶等,同时,将导电材料包埋其中形成导电水凝胶。但已报道丝素蛋白水凝胶弹性及弹性稳定性差。课题组创新性提出以1,4-丁二醇二缩水甘油醚(BDDE)为交联剂,制备了一种柔性、持久耐用性等综合性能优越的水凝胶。本课题在此基础上包载各种导电机制的导电材料,实现传感性与生物相容性有机结合,具体研究分为以下几个部分:第一,在课题组高弹性、高稳定性Silk/BDDE水凝胶基础上,本论文调控丝素蛋白、溴化锂浓度等参数,获得一种Silk/BDDE/Li+导电水凝胶。该凝胶具有高电导率(3.95±0.21 S/m)、优良的回弹性、可拉伸性和可靠的应变电响应性,在柔性应变传感器领域具有广阔的应用前景。第二,为解决高浓度溴化锂具有较强的毒性问题,本论文制备了以生物相容性更高的碳纳米管(CNTs)为导电材料的Silk/BDDE/CNTs导电水凝胶。CNTs的引入,不仅仅赋予水凝胶良好的导电性还明显提高了水凝胶的机械性能(压缩模量提升约50%)。该导电水凝胶经过复杂液体环境前后电响应与弛豫时间分别变化了 10.7%与10.6%明显优于HRP交联的Silk/HRP/CNTs导电水凝胶(分别变化了 344.2%与404.6%)。在30～60%形变量区间具有较高的灵敏度(GF=1.4～1.8),可用于实时监测人体活动,同时,为了最终应用于体内信号传感,进行了模拟实验检测猪肺的扩张/收缩和猪肘关节腔的压力。第三,为进一步提高丝素蛋白导电水凝胶在微小形变下的灵敏度,本论文使用导电聚合物聚吡咯(PPy)代替CNTs,作为导电物质。PPy在高浓度溴化锂中发生聚合反应与丝素蛋白形成Silk/BDDE/CNTs双网络导电水凝胶。该导电水凝胶具有良好的导电性(0.57-1.39 S/m),在0～20%形变量区间具有较高的灵敏度(GF=1.62～2.41),并且能够在不同压缩、拉伸频率以及不同应变的情况下保证电信号的稳定输出。利用仿生学图案化绒叶肖竹芋,加工得到表面微锥结构的导电高分子丝素蛋白水凝胶,其具有良好的柔韧性,可进行适当的拉伸和弯折。该导电水凝胶与金电极组装后制备得到应变传感器,能够探测手指弯曲等一系列微小应变的人体指标。在本论文中,以Silk/BDDE水凝胶为基质材料平台,从导电物质设计角度出发,制备了一系列柔性、持久耐用性等综合性能的水凝胶基应变传感器。对未来可穿戴智能材料的设计具有重要的借鉴意义。更多还原

【Abstract】 In recent years,flexible wearable electronic products have attracted extensive attention due to their special properties and huge application prospects.Conductive hydrogels are the best choice for flexible wearable device sensors due to their tissue-like properties such as compliance,toughness,stretchability,electrical conductivity,stimuli responsiveness,and strain sensitivity.Conductive hydrogels are usually prepared by dispersing conductive materials(such as carbon nanotubes,ionic salts,and conductive polymers)on flexible substrates with good elasticity(such as polydimethylsiloxane(PDMS),polyacrylamide(PAM))for processing and preparation.However,such chemical synthesis substrates suffer from uncertain polymerization residues,uncertain in vivo toxicity,and uncertain biodegradation products,which limit their application in the biomedical field.A new generation of conductive hydrogels aims to overcome these limitations using bio-friendly polymers,which confering biocompatibility and biodegradability to conductive hydrogels.Silk fibroin(Silk)is a protein extracted from natural silk with good mechanical properties,biocompatibility,biodegradability and easy processing.It can be processed into various forms of substrates,such as hydrogels,nanofibers,biofilms,sponges,etc.,and at the same time,the conductive materials can be embedded in them to form conductive hydrogels.However,silk fibroin hydrogels have been reported to have poor elasticity and elastic stability.The research group innovatively proposed to use 1,4-butanediol diglycidyl ether(BDDE)as a cross-linking agent to prepare a column with flexibility,stretchability,durability,fast response,cycle stability,etc.A comprehensive performance hydrogel-based strain sensor.To realize the organic combination of sensing and biocompatibility,the specific research is divided into the following parts:First,based on the high elasticity and high stability of the Silk/BDDE hydrogel of the research group,this work modulates parameters such as silk fibroin and lithium bromide concentration to obtain a Silk/BDDE/Li+ion conductive hydrogel.The gel has high electrical conductivity(3.95±0.21 S/m),excellent resilience,stretchability,and reliable electrical responsiveness to strain,and has broad application prospects in the field of flexible strain sensors.Second,high concentrations of lithium bromide have strong toxicity.In this work,a Silk/BDDE/CNTs conductive hydrogel was prepared using carbon nanotubes(CNTs)with higher biocompatibility as conductive materials.The introduction of CNTs not only endows the hydrogel with good electrical conductivity,but also significantly improves the mechanical properties of the hydrogel(the compressive modulus is increased by about 50%).The electrical response and relaxation time of the conductive hydrogel changed by 10.7%and 10.6%,respectively,before and after the complex liquid environment,which was significantly better than that of the HRP-crosslinked Silk/HRP/CNTs conductive hydrogel(changed by 344.2%and 404.6%,respectively).It has high sensitivity in the 30～60%deformation range(GF=1.4～1.8),which can be used for real-time and repeated monitoring of human activities,including subtle human activities such as finger,pulse and knee movements and speech.For the ultimate application in in vivo signal sensing,simulation experiments were performed to detect the expansion/contraction of pig lungs and the pressure of pig elbow joint cavity.Third,in order to further improve the sensitivity of silk Fibroin conductive hydrogels under small deformation,the conductive polymer poly-pyrrole(PPy)was used in this work instead of CNTs as the conductive material.PPy polymerized with silk fibroin in high concentration of lithium bromide to form a Silk/BDDE/CNTs double network conductive hydrogel.The conductive hydrogel has good conductivity(0.57-1.39 S/m),high sensitivity in the range of 0-20%deformation(GF=1.62-2.41),and can be used at different compression and tension frequencies.And the stable output of the electrical signal is guaranteed under different strain conditions.The conductive polymer silk fibroin hydrogel with micro-cone structure on the surface is obtained by biomimetic patterning of arrowroot,which has good flexibility and can be properly stretched and bent.The conductive hydrogel is assembled with gold electrodes to obtain a strain sensor capable of detecting a series of tiny strains such as finger bending.In this work,a series of comprehensive properties such as flexibility,stretchability,durability,fast response,and cycle stability were prepared from the perspective of conducting material design using Silk/BDDE hydrogel as the matrix material platform.These hydrogel sensors are of great significance to the design of wearable devices.更多还原