Flexible and stretchable photodetectors and gas sensors for wearable healthcare based on solution-processable metal chalcogenides

Wearable smart sensors are considered to be the new generation of personal portable devices for health monitoring.By attaching to the skin surface,these sensors are closely related to body signals(such as heart rate,blood oxygen saturation,breath markers,etc.)and ambient signals(such as ultraviolet radiation,inflammable and explosive,toxic and harmful gases),thus providing new opportunities for human activity monitoring and personal telemedicine care.Here we focus on photodetectors and gas sensors built from metal chalcogenide,which have made great progress in recent years.Firstly,we present an overview of healthcare applications based on photodetectors and gas sensors,and discuss the requirement associated with these applications in detail.We then discuss advantages and properties of solution-processable metal chalcogenides,followed by some recent achievements in health monitoring with photodetectors and gas sensors based on metal chalcogenides.Last we present further research directions and challenges to develop an integrated wearable platform for monitoring human activity and personal healthcare.

A nano-metallic-particles-based CMOS image sensor for DNA detection

In this paper we report on a study of the CMOS image sensor detection of DNA based on self-assembled nano- metallic particles, which are selectively deposited on the surface of the passive image sensor. The nano-metallic particles effectively block the optical radiation in the visible spectrum of ordinary light source. When such a technical method is applied to DNA detection, the requirement for a special UV light source in the most popular fluorescence is eliminated. The DNA detection methodology is tested on a CMOS sensor chip fabricated using a standard 0.5 gm CMOS process. It is demonstrated that the approach is highly selective to detecting even a signal-base mismatched DNA target with an extremely-low-concentration DNA sample down to 10 pM under an ordinary light source.

An Optical Sensor Based on Polyvinyl Benzyl Malonate Cross-Linked with Divinyl Benzene Dispersed in a Hydrogel Membrane for Detection of Some Heavy Metals

In previous work we have developed a dicarboxylate functionalized polymer that demonstrated chemical sensing. It showed good response to pH changes as well as to varying concentrations of copper and calcium ions. Our recent in-vest- tigations showed interesting results upon testing the functionalized sensing polymer on heavy metals. This sensor is composed of microspheres of polyvinyl benzyl malonate lightly-cross-linked with divinyl benzene dispersed in a hydrogel membrane. The response of the optical sensor is based on the interaction between the metal cations with the deprotonated functional group. The polymer, thus, undergoes shrinking as a result of neutralization of adjacent negative charges on the back-bone of the polymer. This causes significant changes in the optical properties of the sensing element. The optical changes were measured as absorbance vs. wavelength as the sensing membrane is exposed to solutions of varying concentrations of heavy metal ions. The sensor showed significant increase in absorbance up to a concentration of 5 × 10-3 M to the following metal ions: Ni2+, Zn2+, and Cd2+. Furthermore, the studied capacity of the derivatized microspheres showed close values to Ni2+, Zn2+, Cd2+ (1.20, 1.09, 1.08 mmol/g respectively). These kinds of properly functionalized polymers appear to be suitable, versatile sensing elements for the detection of low concentrations of heavy metal ions. In addition, all of the tested heavy metals showed a similar value of the equilibrium formation constant, (log Kf1 is 2.63). In contrast, the sensor showed no significant response to varying concentrations of K+ and Mg2+ metal ions.

Metal–Organic Framework-Based Sensors for Environmental Contaminant Sensing

Increasing demand for timely and accurate environmental pollution monitoring and control requires new sensing techniques with outstanding performance, i.e.,high sensitivity, high selectivity, and reliability. Metal–organic frameworks(MOFs), also known as porous coordination polymers, are a fascinating class of highly ordered crystalline coordination polymers formed by the coordination of metal ions/clusters and organic bridging linkers/ligands. Owing to their unique structures and properties,i.e., high surface area, tailorable pore size, high density of active sites, and high catalytic activity, various MOF-based sensing platforms have been reported for environmental contaminant detection including anions, heavy metal ions,organic compounds, and gases. In this review, recent progress in MOF-based environmental sensors is introduced with a focus on optical, electrochemical, and field-effect transistor sensors. The sensors have shown unique and promising performance in water and gas contaminant sensing. Moreover, by incorporation with other functional materials, MOF-based composites can greatly improve the sensor performance. The current limitations and future directions of MOF-based sensors are also discussed.

A New Fluorescent Sensor for Transition Metal Ions in Aqueous Solution

A new fluorescent sensor consisted of fluorenyl and dioxotetraaza unit, dimethyl-6-(9-fluorenyl)-1,4,8,11-tetraazaundencane-5,7-dione (L), was synthesize fluorescent sensor for transition metal ions in aqueous solution.

A Heavy Metal Analysis Device Based on Light-addressable Potentiometric Sensor

<正>A full automatic device to detect heavy metal Hg,Fe,Cr elements based on thin-film sensitive materials prepared on surface of light-addressable potentiometric sensors (LAPS) by means of pulsed laser deposition PLD) technique is developed. High-purity chemical compound AgI:Ag_2S:HgI synthesized were used as target of PLD,thin film sensitive to Hg~ (2+) ion was prepared on the surface of LAPS.All-solide-state chalcogenide glass ion-selective electrodes ISE) ,Fe-ISE and Cr-ISE,were also used as targets of PLD,and thin-film sensors on different LAPS sensitive to Fe~ (3+) and Cr~ (6+) ions were prepared.The heavy metal analysis device with characteristics of collect sample in-site,real-time determination,communication and multifunction software were designed.Hardware design of the device mainly includes control and measurement aspects.The detected limits of Hg,Fe,Cr ions are 3.44×10~ (-7) mol/L,6.31×10~ (-6) mol/L and 2.09×10~ (-7) mol/L,respectively.

X-ray detection based on complementary metal-oxide-semiconductor sensors

Complementary metal-oxide-semiconductor(CMOS) sensors can convert X-rays into detectable signals; therefore, they are powerful tools in X-ray detection applications. Herein, we explore the physics behind X-ray detection performed using CMOS sensors. X-ray measurements were obtained using a simulated positioner based on a CMOS sensor, while the X-ray energy was modified by changing the voltage, current, and radiation time. A monitoring control unit collected video data of the detected X-rays. The video images were framed and filtered to detect the effective pixel points(radiation spots).The histograms of the images prove there is a linear relationship between the pixel points and X-ray energy. The relationships between the image pixel points, voltage, and current were quantified, and the resultant correlations were observed to obey some physical laws.

A Novel Uniplanar Multi-Electrode Capacitive Sensor for In-Situ Weathering Damage Detection of Nonmetallic Materials

A uniplanar capacitive sensor with 5-electrodes on one plane substrate and a large reflector electrode,was designed to get the corresponding capacitance information for weathering damage detection of non-metallic materials exposed to a service environment.A 2-D finite-element method was employed to simulate the electric potential distribution and capacitance measurements for the sensor.2 marble slabs,one was healthy and the other was notched,were experimentally detected.Both the simulation and the preliminary experimental results show that the measured capacitances decrease after weathering damage occurs in nonmetallic material.The reflector can enlarge the sensitive depth.The weathering assessment of nonmetallic materials can be done by processing the measured capacitances.The proposed approach can effectively detect the weathering damage of nonmetallic material and can be practically used for in-situ weathering damage evaluation.

金属有机框架荧光传感器在食品中抗生素类兽药残留检测的研究进展

金属-有机框架材料(metal-organic frameworks,MOFs),是一类由金属离子或者是次级构筑单元与有机配体通过配位键自组装形成的材料,是近年快速发展的一种新型功能性检测材料。MOFs具有比表面积大、孔道尺寸可调和结构可控等优势,在构建高选择性和高灵敏度的发光传感器领域有着广阔的应用前景。该文对发光MOFs的不同荧光发光机理进行阐明和详细分类,总结了发光MOFs作为荧光传感器在抗生素类兽药残留检测中的应用实例,最后就目前存在的问题提出建议,并对未来的发展前景进行了展望。

氨基化石墨烯电化学传感器在重金属离子检测中的运用分析

本研究旨在探讨氨基化石墨烯电化学传感器在重金属离子检测中的应用,特别是针对Cd^(2+)和Pb^(2+)的检测。研究内容主要包括氨基化石墨烯(NH_(2)-rGO)、壳聚糖(CS)和聚谷氨酸(Glu)复合材料修饰电极的制备,以及其在电化学检测中的性能评估。通过对不同修饰电极的表征与性能分析,本研究揭示了NH_(2)-rGO/CS/Glu复合材料修饰电极在提高检测灵敏度和选择性方面的显著效果。研究结果表明,相比于裸电极和单一材料修饰电极,NH_(2)-rGO/CS/Glu修饰电极对Cd^(2+)和Pb^(2+)展现出了更高的灵敏度和优异的选择性。此项研究为开发新型高效电化学传感器提供了有价值的参考,对于环境监测和重金属污染控制具有重要意义。

基于高温压力传感器的耐高温金属体系

从制约高温压力传感器发展的耐高温金属体系研究出发,采用钨/氮化钽/铂(W/TaN/Pt)作为金属布线的电传导层,开发出适用于500 ℃高温环境下稳定工作的金属薄膜,实现电信号稳定传输,有效避免相邻金属层之间相互扩散或合金导致的电性能失效。对500 ℃高温前后的压力传感器进行带电测试,并对非线性、迟滞性、灵敏度、重复性等8项指标做了测试对比,高温压力传感器性能稳定,各性能指标均满足使用要求,证明该金属体系的可行性。

基于5-氨基烟酸的锰金属有机框架的合成、结构及荧光传感性质

室温下,通过溶液法将5-氨基烟酸(5-Hana)与MnCl_(2)反应,成功合成了一例新的三维Mn(II)金属有机框架[Mn_(2)(5-ana)_(4)(H_(2)O)]n(命名为Mn-MOF)。通过X射线单晶衍射、X射线粉末衍射、元素分析、红外光谱、热重分析、紫外-可见光谱和荧光光谱法对配合物的结构和性质进行表征。结构分析表明,配合物属单斜晶系,具有双节点(2,8)-c配位网络结构,其中[Mn_(2)(CO_(2))_(2)(H_(2)O)]二聚单元作为8-连接节点,5-ana-配体作为2-连接节点。分子范德瓦耳斯表面静电势(ESP)分析表明,5-ana-配体的第一反应位点在羧基氧原子附近,ESP最小值为-143.37 kcal·mol^(-1),第二和第三反应位点分别位于吡啶环和氨基氮原子附近。Mn-MOF常温下具有良好的热稳定性。荧光光谱测试显示配合物在256 nm光激发下的最大发射波长为402 nm。更重要的是,Mn-MOF可以通过荧光猝灭实现对Fe^(3+)的选择性识别,且猝灭效率达到98.71%,可作为潜在的荧光探针分析水溶液中的Fe^(3+)。

金属氧化物半导体MEMS气体传感器研究进展

随着物联网的快速发展,各领域对气体监测的需求越来越大,基于先进微机电系统(Micro-electro-mechanical systems, MEMS)技术的金属氧化物半导体(Metal oxide semiconductor, MOS)气体传感器在过去几十年里取得了很大发展。MEMS微热板的多样化设计、MOSs纳米结构的多样化以及机器学习算法的出现为MEMS的传感性能以及智能传感系统的构建提供了很大助力。本文从MEMS气体传感器的分类、制备和应用以及传感器阵列的构建等方面综述了金属氧化物半导体MEMS气体传感器的最新研究进展,并对MEMS基气体传感器的发展前景进行了总结和展望。

MOFs基微流控电化学芯片对多种重金属离子的实时在线检测

将具有丰富微孔的ZIF-8金属有机框架和电化学技术对金属离子的富集作用与微流控器件对溶液流动的可控性相结合,构建了一种新型传感器,实现了高通量、实时和快速检测环境中的多种金属离子污染物.研制的ZIF-8-Nafion/ITO基微流控电化学传感器对Cd^(2+),Pb^(2+)及Hg^(2+)离子在0.1~100μmol/L的浓度范围内具有良好的线性关系,检出限分别为0.055,0.0025及0.0016μmol/L(S/N=3).该微流控芯片对于样品的需求量少,可降低对能源的消耗;同时由聚二甲基硅氧烷拓印的微流控器件还有望实现柔性电极的功能,对便携式电化学柔性器件在生物和环境样品的集成化和自动化检测具有重要意义.

金属Sc修饰Ti_(2)CO_(2)吸附气体分子的第一性原理研究

基于第一性原理计算研究了Ti_(2)CO_(2)和金属Sc修饰的Ti_(2)CO_(2)的几何结构和电子性质,分析了不同有害气体(CO,NH_(3),NO,SO_(2),CH_(4),H_(2)S)在这两种材料表面的吸附过程,讨论了金属修饰对Ti_(2)CO_(2)二维过渡金属碳化物(MXene)电子性能和气体吸附性能的影响.计算结果表明,Sc原子位于空心位C原子上方的结构具有较大的结合能,但小于固体Sc的内聚能实验值(3.90 e V),Sc原子可以有效避免成簇.表面Sc金属为气体吸附提供了活性位点.通过分析不同气体的最佳吸附点位、吸附能等参数,分析金属Sc修饰的Ti_(2)CO_(2)对这些气体的吸附效果.其中对SO_(2)的吸附效果更好,吸附能从–0.314 eV提升到–2.043 eV,其他气体的吸附效果均有改善.通过电荷转移、态密度和功函数等参数解释了其吸附能增加的原因.由于在表面引入了新的原子,增大了材料的载流子密度和载流子迁移率,从而提高了材料表面的电荷转移,为金属Sc修饰的Ti_(2)CO_(2)材料的气敏性能提供理论参考.

纤维素-金属氧化物在传感器中的应用研究进展

纤维素-金属氧化物作为一种复合材料同时具有有机半导体的柔性与无机半导体良好的电子传输能力。这种复合材料在传感器领域有着巨大的潜力与研究价值。本文综述了以ZnO、SnO_(2)和TiO_(2)为主的纤维素-金属氧化物复合材料在紫外、气体和生物等传感器研究中的应用,总结了纤维素-金属氧化物复合材料中纤维素的作用、金属氧化物的状态和形貌、纤维素与金属氧化物的连接方式、不同类型传感器的传感机理以及不同传感器的结构、性能和优缺点。希望通过对纤维素-金属氧化物在传感器中研究进展的总结与展望为相关研究以及行业发展提供一定的帮助。

基于液态金属的纤维复合材料应用研究进展

液态金属(LM)是一种兼具导电性与流动性的功能材料,因其优异的电导率以及形变能力而获得广泛关注。纤维材料作为常见的柔性基底,因其良好的可拉伸性、透气性以及可编织等特点,已在众多领域展现出广阔的应用潜力。为了解决电子元器件柔性差,难以满足可穿戴、智能化要求,从基体和导电材料出发,利用纤维材料的可拉伸变形、柔性等优势与LM的高导电、室温流动性等特点,制备的LM基纤维复合材料已广泛用于人体运动监测、储能等领域。该文从化学稳定性、电性能及热性能方面总结了液态金属基纤维性能调控策略;重点阐述了LM基纤维复合材料在柔性传感、电磁屏蔽、能量收集与存储方面的研究进展;最后,对其性能改善及当前研究中存在的问题提出了建议,并对未来发展方向进行了展望。

基于取向纤维基底和图案化双相金属层的高灵敏应变传感器

为了提高液态金属基应变传感器的灵敏度,研究了一种高灵敏度、可拉伸的应变传感器,该传感器由取向的静电纺热塑性聚氨酯纤维基底和图案化双相金属传感层构成。以液态金属Galinstan为“岛”,固体金属银为“海”,构建了图案化双相金属传感层。银“海”可阻止连续的液态金属导电路径的形成,基于银导电区域的裂纹扩展机制,传感器的灵敏度显著提高。此外,纤维取向(水平或垂直)削弱了在受力时纤维的重新排列,增强了传感层的变形。结果表明,对于单一液态金属层或Ag层组成的传感器,基底纤维垂直取向与随机排列比较,灵敏度分别提高1.09倍和33.19倍。最终制成的基于垂直取向纤维基底和图案化双相金属层的应变传感器具有超高的灵敏度(灵敏度系数高达952.20)和宽传感范围(高达59.33%)。这种设计有望在可穿戴设备中显示良好的应用潜力。

柔性液态金属剪切力传感器

使用柔性微管液态金属传感器作为应力测量元件,设计制作了一种剪切力传感器.剪切力传感器由弹性聚二甲基硅氧烷(Polydimethylsiloxane, PDMS)杆件、支撑垫片和柔性微管传感器组成.探讨了剪切力传感器的工作原理以及测量元件的传感机制.弹性PDMS杆件受到剪切力作用后变形,使用剪切力传感器对杆件的剪切角进行测量,并将测量结果与灰度重心法测得的参考值进行对比,系统分析了装配间隙δ、微管布置距离L对测量精度的影响.结果表明:当以弹性PDMS杆件为变形体时,剪切力传感器可在0.004 7~0.038 rad的转角范围内进行有效测量;测量误差随着装配间隙δ的增大而增大,随着微管布置距离L增大而减小.所设计剪切力传感器具有灵敏度高、抗干扰能力强等优点,为剪切力的测量提供了一种新的工具.

用于低浓度氢气检测的超灵敏TiO_(2)传感材料高通量筛选方法研究

基于组合材料学思想,利用材料并行合成平台快速制备了121种具有不同组分的稀贵金属元素表面修饰的TiO_(2)气敏材料膜,开发MOS气敏材料的快速筛选方法,采用XRD、FESEM、EDS等对材料膜进行了微结构表征,并通过高通量筛选平台对所有样品进行了气敏性能分析。筛选结果表明,对于TiO_(2)棒分别修饰0.5%(如无特殊说明,均为摩尔分数)Eu、0.1%Gd、0.1%V、0.1%Rb、0.5%Pt、0.4%Pd的样品,它们在350℃下对1000×10^(-6)H_(2)的气敏响应值可分别达到334、192、1074、1120、62778、39643。其中具有超灵敏响应的TiO_(2)-0.5%Pt样品在350℃时的浓度检测限可低至2×10^(-6)(0.002‰),而TiO_(2)-0.4%Pd在50℃对1000×10^(-6)H_(2)的响应值为15,可见材料具有良好的选择性和长期稳定性,在未来氢能储运安全监测、电池失效前期预警等低浓度氢气检测场合具有广阔的应用前景。