室温下羧甲基纤维素导电水凝胶的快速制备及在柔性应变传感器的应用

导电水凝胶由于具有足够的灵活性、耐用性和功能多样化的独特特性,在柔性应变传感器领域具有巨大的发展前景。然而,制备水凝胶的聚合过程大多耗时、耗能且会使用有毒的交联剂,严重阻碍了其在这一新兴领域的实际应用。文中通过木质素磺酸钠/Fe³⁺组成的新型动态氧化还原体系,以羧甲基纤维素钠(CMC)和丙烯酸(AA)为基本原料,在室温快速制备了具有良好力学性能(拉伸强度435 kPa、断裂伸长率1043%)、较高离子电导率(2.23 S/m)、良好传感灵敏度(GF=2.76)及电自修复能力的CMC/PAA/Fe³⁺导电水凝胶。基于该凝胶所制备的应变传感器可以通过稳定且可重复的电信号检测人体大幅度或细微的运动,展现出了其在个人健康监测、人体运动检测和人机交互中的潜在应用价值。在室温快速制备水凝胶的方法为构建用于各种传感应用的导电水凝胶提供了新的思路。     

高灵敏度,超宽响应范围,环境耐受性高的多模式离子凝胶基传感器（英文）

近年来,离子类皮肤传感器因其高性能和良好的兼容性等优点而备受关注.然而,开发一种多功能、稳定、高灵敏度和耐用的离子类皮肤传感器仍面临挑战.本文通过简单的紫外引发聚合制备了具有良好耐用性、环境(抗冻、耐真空)稳定性、离子导电性、自愈性、高粘附性和拉伸性的复合离子凝胶.该离子凝胶可以组装为应变、压力和温度传感器,用于检测外部环境的变化.无论是作为应变传感器还是压力传感器,离子凝胶基传感器都具有高灵敏度(GF=14.7)、宽响应范围(1%-1600%)、快速响应时同(95.8 ms)、优异的稳定性和可重复性(1000次).因此,它不仅可以追踪关节运动,还可以监测细微的表情变化(皱眉).该离子凝胶还可以组装成敲击传感器和高精度书写板传感器,用于信息传递.此外,该传感器对温度变化具有较高的灵敏度,温度感知范围在0-120℃之间,且检测阈值较低(0.1℃).因此,基于离子凝胶的传感器有望应用于多功能电子和传感设备.     

阳离子纤维素纳米纤维分散液态金属制备高灵敏度和自修复导电水凝胶用于应变传感器（英文）

作为一种多功能软填料,液态金属(LM)乳液为制备基于导电水凝胶的多功能应变传感器带来了新机遇.然而,界面张力和密度巨大的LM难以以稳定乳液的形式存在.本文中,我们展示了一种利用阳离子纤维素纳米纤维(CCNFs)包覆LM液滴来稳定LM乳液的策略.通过将CCNF稳定的LM乳液与丙烯酸(AA)混合并引发其原位聚合,以及在聚丙烯酸(PAA)、LM液滴和CCNF之间形成可逆的氢键、离子配位键和静电交联,制备了一种导电水凝胶CCNF-LM-PAA.得益于PAA与CCNF之间形成的可逆氢键、离子配位键和静电结合作用,CCNF-LMPAA水凝胶具有良好的导电性(1.54 S m^-1)、较高的拉伸强度和断裂伸长率、粘附性和快速自愈合能力.CCNF-LM-PAA水凝胶作为应变传感材料,具有超高应变灵敏度(应变系数高达16.2)、低应变检测极限(<1%)、短响应/恢复时间(107/91 ms)和良好的耐用性(300次循环).这些性能使得基于CCNF-LM-PAA水凝胶的应变传感器能够作为可穿戴电子器件用于监测各种人体活动.因此,利用CCNF稳定LM乳液引入静电结合作用,为提高基于...     

聚天冬氨酸/聚(丙烯酰胺-丙烯酸)/Fe^(3+)离子水凝胶应变传感器的制备及在人体运动监测中的应用EI北大核心CSCD

将聚天冬氨酸(PASP)引入聚(丙烯酰胺-丙烯酸)(P(AA-AM))中,制备了PASP/P(AA-AM)水凝胶基质,将该基质浸泡于FeCl_(3)·6H_(2)O水溶液,得到了高强度、超拉伸,灵敏度较好的新型双离子交联PASP/P(AA-AM)/FeCl_(3)(PAAF)水凝胶。Fe^(3+)的引入不仅提高了PAAF水凝胶力学性能,同时也赋予了优秀的传感性能。所得的水凝胶传感器表现出优异的拉伸性能(1125%)、良好的力学强度(802.97 kPa),出色的快速自恢复性能(几乎完全恢复),良好的抗疲劳性和较好的灵敏度(GF=3.04),可以监测不同的人体运动(例如手指、肘部和膝关节),在小应变和大应变下都具有较好的稳定性,有望应用于可穿戴柔性传感器领域,监测人体运动。     

细菌视紫红质在生物传感器中的应用进展

生物传感器是生物敏感材料、理化换能器与电信号放大装置等多学科交叉的综合集成技术装置.典型的生物传感器以特异性感知的生物活性材料作为敏感元件,结合基于微电子器件的物理化学换能器和调理电路,实现生物敏感信息的电信号转换及放大.换能器的灵敏度、抗干扰能力等因素直接影响生物传感器的性能.从嗜盐菌中提取的细菌视紫红质是一种具有良好光敏特性的生物材料,可直接将光信号转化成电信号,从而实现将敏感元件和换能器合二为一的功能,已广泛应用于多种生物传感器中.细菌视紫红质的感光灵敏度和稳定性适用于开发具有颜色灵敏度的光传感器,最早的应用方向是人工视网膜;其光敏感和换能一体化特性可实现使用单个传感元件进行光学运动检测的功能,应用可扩展到运动传感领域.除了在视觉传感领域的应用,细菌视紫红质在病原体检测、水体pH检测、细胞膜电位检测等领域均表现出良好的灵敏性、稳定性和特异性.其不仅在生物传感领域具有应用价值,而且为半导体传感方法的研究提供了新途径.本文在简述细菌视紫红质的质子泵和光电响应特性等基本功能的基础上,阐述了细菌视紫红质构建生物传感器的应用进展,分析了不同传感器的特点,以期为细菌视紫红质的机理及其应用研究提供参考.     

基于光子晶体光纤模间干涉仪的反射式光纤pH值传感器研究

本文将光子晶体光纤模间干涉仪与pH敏感水凝胶相结合来实现pH值的测量。首先,设计了光子晶体光纤模间干涉仪传感结构并对其传感原理进行了理论分析。然后,利用Rsoft软件仿真分析了该结构的传感特性。最后,制备了反射式的pH值传感探头,并搭建实验系统对pH值进行测量,实验结果表明该传感器可测量的pH值范围为1～14,最高灵敏度为3.10nm/pH,具有灵敏度高、结构紧凑、适于远距离传输等优点,可广泛应用于pH测量之中。     

MXene在压力传感中的研究进展

近年来,压力传感器在智能可穿戴纺织品、健康监测、电子皮肤等领域得到了广泛应用。二维纳米材料MXene的出现,为压力传感带来了全新的突破。Ti3C2Tx是压力传感领域研究最多的MXene,具有良好的机械性能、高导电性、优异的亲水性以及广泛的可修饰性,是理想的压力传感材料。因此,近些年研究者们对MXene在压力传感器中的设计和应用进行了大量探索和研究。本文总结了MXene的制备技术和抗氧化方法。同时介绍了基于MXene的微结构设计,包括气凝胶/多孔结构材料、水凝胶、柔性衬底和薄膜。该类设计有利于提高压力传感器的响应范围、灵敏度和柔韧性,促进了压力传感器的快速发展。此外,进一步探讨了MXene压力传感器的工作机制,包括压阻式、电容式、压电式、摩擦电式、电池式和纳米流体式等。MXene以其优异的特性而在各种机制的传感器中得到了广泛应用。最后,对MXene材料的合成、性质以及其在压力传感方面的机遇和挑战进行了展望。     

用于多模式人体体征信号采集人机界面的可回收水凝胶（英文）

离子导电水凝胶由于其在生物相容性、导电性和灵活性方面的独特优势,已成为可穿戴式人体运动检测传感器的最有希望的替代品之一.然而,目前的水凝胶电子器件仍然面临着不可重复使用性和单一信号检测功能的限制.在此,我们通过模拟生物体的网络结构和离子传导机制,制备了基于聚乙烯醇、海藻酸纤维和胶原蛋白的离子导电水凝胶,用于人体运动和电生理信号的双模式信号采集.通过海藻酸纤维和胶原蛋白的协同调节,水凝胶表现出类似皮肤的机械性能,具有低模量、高韧性和抗疲劳性,从而可以最大限度地提高水凝胶可穿戴传感器的穿着舒适度和运动检测能力.此外,具有与生物体相似离子传输行为的水凝胶导体可以用作表皮电极,收集包含重要人体生理信息的表皮电位.通过对可穿戴设备的合理设计和组装,水凝胶不仅可以连续、准确地识别全身运动信号,还可以采集肌电图、心电图等不同电生理信号.值得注意的是,这种基于非共价交联结构的水凝胶是完全可回收的,可以任意重组为新的电子器件,同时保持原有功能,提高水凝胶的可重复使用性,减少电子浪费.     

一种抗冻、可拉伸有机水凝胶的制备及 在柔性应变传感器中的应用

针对导电水凝胶柔性应变传感器在低温环境容易被冻结而发生失效的问题,通过溶剂置换策略制备了一种抗冻、可拉伸的聚多巴胺还原氧化石墨烯/海藻酸钠/聚丙烯酰胺（PDA-rGO/SA/PAM）有机水凝胶。实验结果表明：制得的有机水凝胶具有优异的抗冻性能、良好的机械性能以及灵敏的传感性能。此外,组装的有机水凝胶柔性应变传感器可以检测多种人体运动形式,例如手指弯曲、手腕弯曲、面部微表情等,对未来可穿戴柔性电子产品的发展起到了一定的推动作用。     

分子间相互作用调控丝素蛋白/聚丙烯酰胺水凝胶的网络形貌和β片结晶，赋予水凝胶优异的黏附、应变和传感性能（英文）

丝素蛋白(SF)作为一种特殊的天然聚合物,具有优异的生物相容性、生物降解性和双亲性,是制备柔性传感器的良好候选者.然而,丝素蛋白的高结晶度和结晶不可控性使获得这种出色的仿生水凝胶传感器具有挑战性.纯SF水凝胶是脆性的,没有黏性.在此,我们通过引入聚丙烯酰胺(PAM)到SF水凝胶中来解决这一问题.由于SF/PAM水凝胶具有较强的分子间相互作用,其网络形貌由欧几里得孔改变为非欧几里得孔.同时,其β片结晶很容易被抑制到纳米尺度.这些演变不仅使SF/PAM水凝胶具有优异的机械性能,而且具有出色的黏附性能.与纯PAM水凝胶相比,SF8/PAM水凝胶的拉伸强度、拉伸破坏应变、抗压强度(80%应变下)和黏附性能(在猪皮上)分别提高了133.1%、120.9%、610.8%和104.8%.此外,SF的双亲性可以使碳纳米管(CNTs)在水凝胶中分散良好.制备的CNT0.3/SF8/PAM水凝胶继承并进一步改善了上述性能.除此之外,它还表现出优异的自黏附传感性能,最大灵敏度因子高达10.13,工作应变范围超过1000%,大应变下稳定循环拉伸达500次以上.同时,六种人类活动的精确检测也得到了验证.本工作为...     

Fatigue Resistant Aerogel/Hydrogel Nanostructured Hybrid for Highly Sensitive and Ultrabroad Pressure Sensing

Achieving high sensitivity over a broad pressure range remains a great challenge in designing piezoresistive pressure sensors due to the irreconcilable requirements in structural deformability against extremely high pressures and piezoresistive sensitivity to very low pressures. This work proposes a hybrid aerogel/hydrogel sensor by integrating a nanotube structured polypyrrole aerogel with a polyacrylamide (PAAm) hydrogel. The aerogel is composed of durable twined polypyrrole nanotubes fabricated through a sacrificial templating approach. Its electromechanical performance can be regulated by controlling the thickness of the tube shell. A thicker shell enhances the charge mobility between tube walls and thus expedites current responses, making it highly sensitive in detecting low pressure. Moreover, a nucleotide-doped PAAm hydrogel with a reversible noncovalent interaction network is harnessed as the flexible substrate to assemble the aerogel/hydrogel hybrid sensor and overcome sensing saturation under extreme pressures. This highly stretchable and self-healable hybrid polymer sensor exhibits linear response with high sensitivity (S_min > 1.1 kPa^?1), ultrabroad sensing range (0.12–≈400 kPa), and stable sensing performance over 10 000 cycles at the pressure of 150 kPa, making it an ideal sensing device to monitor pressures from human physiological signals to significant stress exerted by vehicles.     

Microcapsule biosensors using competitive binding resonance energy transfer assays based on apoenzymes

This paper reports the first demonstration of a fluorescence resonance energy transfer based glucose sensor, wherein a competitive binding (CB) assay is encapsulated into polyelectrolyte microcapsules. The work supports the concept that microcapsules are superior to hydrogel systems or other matrixes for competitive-binding-based system, as they provide free movement of the sensing elements within the capsule interior while constant total sensing assay concentration is maintained. The transduction approach employed in these preliminary experiments is also a novel CB system based on a model apoenzyme, apo-glucose oxidase (AG), which is highly specific to beta-d-glucose, as the model target-binding protein. The glucose sensitivity of the fluorescein isothiocyanate (FITC)-dextran and tetramethylrhodamine isothiocyanate-AG encapsulated in microcapsules showed 5 times greater specificity for beta-D-glucose over other sugars, with sensitivity (change in intensity ratio) in the range of 2-6%/mM. It was observed that the sensitivity and range of the response can be tailored by controlling the assay concentration using different FITC-dextran molecular weight and total capsule concentration. The findings support the concepts of using microcapsules to encapsulate CB assays for reversible and stable sensors and the use of apoenzymes as specific molecular recognition elements in CB assays. Further, characterization results for microcapsule glucose sensors demonstrate their suitability for monitoring physiological glucose levels.     

Electrohydrodynamic (EHD) inkjet printing flexible pressure sensors with a multilayer structure and periodically patterned Ag nanoparticles

Flexible pressure sensors are widely employed for accurate pressure sensing on geometrically complex surfaces. As sensing materials, silver nanoparticles (AgNPs) have high electrical conductivity but relatively poor sensitivity as a trade-off. In this work, electrohydrodynamic (EHD) inkjet printing was utilized to directly write patterns of AgNPs tracks with periodic geometries on the flex-substrate surface. The patterns in which the as-printed AgNPs tracks, with a width of several tens of micrometres, exhibited a piezoresistive effect. This work confirmed that introducing multilayered structures into the flexible pressure sensors with AgNPs patterns was a practical path to improve the sensing sensitivity, with the assistance of soft packaging material of Polydimethylsiloxane (PDMS). The sensitivity was improved more than tenfold after fourfold overlapping of the as-printed single-layer sensor. Experimental tests, formula calculations, and numerical simulations of the sensors were conducted. It was concluded that the as-printed single-layer sensor with the AgNPs pattern of concave regular hexagonal structure (CRHTS) had better sensing performance than that of grid-type structure (GTS) or wave-type structure (WTS). For the two-layered CRHTS sensor, the dynamic and quasi-static sensing response characteristics, response recovery duration, cyclic stability, and ability to discriminate different strain frequencies were further measured and analysed. The working principle of the flex sensors was discussed based on the Percolation Theory and the Tunneling Effect. Some application demonstrations of the sensors were also exhibited. The structural design and EHD inkjet printing fabrication path facilitate the development of more versatile flex sensors.

     

High Sensitivity,Wearable, Piezoresistive Pressure Sensors Based on Irregular Microhump Structures and Its Applications in Body Motion Sensing

A pressure sensor based on irregular microhump patterns has been proposed and developed. The devices show high sensitivity and broad operating pressure regime while comparing with regular micropattern devices. Finite element analysis (FEA) is utilized to confirm the sensing mechanism and predict the performance of the pressure sensor based on the microhump structures. Silicon carbide sandpaper is employed as the mold to develop polydimethylsiloxane (PDMS) microhump patterns with various sizes. The active layer of the piezoresistive pressure sensor is developed by spin coating PEDOT:PSS on top of the patterned PDMS. The devices show an averaged sensitivity as high as 851 kPa^?1, broad operating pressure range (20 kPa), low operating power (100 nW), and fast response speed (6.7 kHz). Owing to their flexible properties, the devices are applied to human body motion sensing and radial artery pulse. These flexible high sensitivity devices show great potential in the next generation of smart sensors for robotics, real‐time health monitoring, and biomedical applications.     

基于Na3Zr2Si2PO12固体电解质的非平衡态SO2传感器

基于Na₃Zr₂Si₂PO₁₂(NASICON)固体电解质, 分别以Na₂SO₄-BaSO₄混合盐和NaRe(SO₄)₂复盐为敏感电极材料制备了片式SO₂非平衡态气体传感器。结果表明, 该类型传感器的输出电动势与SO₂气体浓度的对数呈良好的线性关系, 在低温260℃具有最佳性能, 灵敏度分别达到了160 mV/decade和136 mV/decade。传感器在不同浓度的SO₂气体中的交流阻抗谱测试结果显示, 气体在敏感电极的三相界面处电化学反应的活性随着气体浓度的增大而增强, 结合敏感电极结构, 对该类敏感电极的机理进行了分析。由于NASICON具有良好的低温钠离子导电性, 可以大幅降低传感器的工作温度; 由于Na₂SO₄-BaSO₄混合盐和NaRe(SO₄)₂敏感材料具有更好的化学稳定性, 制备的传感器具有良好的可重复性和稳定性。基于非平衡态设计的传感器, 具有结构简单和成本低的优点。以上特性为该传感器在SO₂气体在环境监测方面的应用提供了可能。     

导电水凝胶在柔性可穿戴传感器的应用研究进展

目的 概述导电水凝胶在柔性可穿戴传感器方面的研究情况,挖掘其作为传感器件的应用潜能。方法 查阅大量相关的文献,对导电水凝胶在柔性可穿戴传感领域的最新进展进行归纳与总结。按水凝胶网络分类的4种导电水凝胶,总结归纳其设计、合成、结构和潜在应用。讨论导电水凝胶的导电性、力学性能、黏附性、防冻性能、自愈性能和各式响应性等功能性能的影响因素,总结自黏性、防冻性、自修复和其他多种优秀性能的柔性可穿戴传感器。结论 导电水凝胶是一种具有多功能的独特刺激响应性的功能材料,在柔性可穿戴传感领域进行深入探究具有重大意义。     

(Ba(x)La(1-x)(2))In(2)O(5+x) (0.4 < or = x < or = 0.6) electrolyte-supported mixed-potential CO sensors

The dense (Ba(x)La(1-x)(2))In(2)O(5+x) electrolytes with different compositions (x = 0.4, 0.5, 0.6) were synthesized by Pechini method. The obtained sintered (Ba(x)La(1-x)(2))In(2)O(5+x) electrolytes showed a high relative density of approximately 98%, and the major phase of three electrolyte compositions was indexed as a cubic phase. The CO sensing properties of as-fabricated planar-type (Ba(x)La(1-x)(2))In(2)O(5+x)-based sensors coupled with ITO and Pt as the sensing electrode and reference electrode, respectively, were investigated. The effects of factors such as gas flow rate, chemical compositions, and density of the electrolytes on the sensing performance were investigated. The sensors showed good sensitivity to different concentrations of CO from approximately 100 to approximately 500 ppm and excellent selectivity over low concentrations of methane (<500 ppm). Linear relationships between emf of the sensors and CO gas concentrations from approximately 100 to approximately 400 ppm were observed. However, the sensors indicated more sluggish response compared with the sensors coupled with a corresponding porous electrolyte. The probable reason has been discussed. The long-term stability of the sensor for the detection of CO was also investigated, which indicated a reasonably stable sensor signal after an initial decline during the incubation period.     

Self-healing and wearable conductive hydrogels with dynamic physically crosslinked structure

Traditional hydrogels are easily frozen or evaporated under colder or hotter temperatures, resulting in their performance degradation. In this paper, polyacrylic acid, sodium alginate, carbon nanotubes, water, and glycerol are used to synthesize self-healing, wearable, freezing resistance, and dry resistance conductive hydrogels with interpenetrating crosslinking network structure. The dynamic cross-linking network structure of the hydrogel can rapidly recover and restructure after damage. In addition, the conductive hydrogels exhibit excellent adhesion to various materials (including PTFE, iron, glass, plastic, and skin). Conductive hydrogel has excellent strain-electric sensing properties, and has high sensitivity, significant stability and repeatability. The conductive hydrogel can be used to test the movement of fingers and knee joints by strain sensing, and has excellent, sensitive, and stable resistance response. Therefore, the conductive hydrogel can be used as a wearable strain sensor for real-time detection of human joint movement. The hydrogel has better environmental adaptability and broad application prospects.

     

The effect of carbon nanotube dispersion on CO gas sensing characteristics of polyaniline gas sensor

Polyaniline is one of the most promising conducting polymers for gas sensing applications due to its relatively high stability and n or p type doping capability. However, the conventionally doped polyaniline still exhibits relatively high resistivity, which causes difficulty in gas sensing measurement. In this work, the effect of carbon nanotube (CNT) dispersion on CO gas sensing characteristics of polyaniline gas sensor is studied. The carbon nanotube was synthesized by Chemical Vapor Deposition (CVD) using acetylene and argon gases at 600 degrees C. The Maleic acid doped Emeradine based polyaniline was synthesized by chemical polymerization of aniline. CNT was then added and dispersed in the solution by ultrasonication and deposited on to interdigitated AI electrode by solvent casting. The sensors were tested for CO sensing at room temperature with CO concentrations in the range of 100-1000 ppm. It was found that the gas sensing characteristics of polyaniline based gas sensor were considerably improved with the inclusion of CNT in polyaniline. The sensitivity was increased and response/recovery times were reduced by more than the factor of 2. The results, therefore, suggest that the inclusion of CNT in MA-doped polyaniline is a promising method for achieving a conductive polymer gas sensor with good sensitivity, fast response, low-concentration detection and room-operating-temperature capability.