温度不敏感的柔性氧化石墨烯湿度传感器研究

本文设计并制作了一种氧化石墨烯(GO)柔性湿度传感器,通过阻抗分析测试法,分别比较了温度对其电阻和电容湿敏特性的影响,并研究了其动态响应特性。结果表明,电阻工作模式的GO柔性湿度传感器湿敏特性受温度影响较大,而电容工作模式则几乎对温度不敏感。当湿度为50%时,传感器的响应时间和恢复时间分别约为1.7s和8.4s。同时,验证了该传感器可实现穿戴式人体呼吸频率的监测。     

基于激光直写的柔性天线传感器研究

激光直写是一种高效、可规模化制备柔性电子器件的技术。本文采用激光直写技术在具有良好介电性能的聚酰亚胺薄膜上制备了一种可用于应变传感和湿度传感的柔性环形天线传感器。利用激光碳化聚酰亚胺获得的材料表面呈现多孔及堆叠片层碳结构,当施加于天线上的应变和环境湿度改变时,天线的谐振频率会发生规律变化,进而实现应变和湿度感知。制备的环形天线传感器的应变响应灵敏度为?8.943 kHz/με,湿度响应灵敏度为?6.45 MHz/RH%。采用激光直写技术制备的天线传感器可以广泛应用于结构健康监测等领域。     

基于无机卤化物钙钛矿湿度传感器的呼吸率监测系统

呼吸率检测中存在主观因素强、信号提取复杂、设备不易获取和有线连接不方便测试者移动等问题.人体呼吸周期为3 s～6 s,呼吸气流是呼吸动作的最直接反应,与周围空气存在湿度差.本文采用研制的新型无机卤化物钙钛矿湿度传感器测量呼吸率,克服了市面上湿度传感器响应和恢复时间长(10 s以上)的问题.系统使用Zigbee无线通信传...     

基于c‒MWCNTs/GO体系的湿敏型智能包装研究

目的 优选羧基化多壁碳纳米管(c–MWCNTs)与氧化石墨烯(GO)作为敏感材料制备湿度传感器,对其湿敏特性进行研究,探索一种能够快速精确监测包装内湿度变化的传感器。方法 通过丝网印刷工艺印制传感器电极基底,在电极表面涂布c–MWCNTs/GO湿敏溶液,混合湿敏溶液中c–MWCNTs的质量分数分别为20%和67%,烘干后得到电阻型湿度传感器,测定其灵敏度、动态响应、响应恢复时间、吸湿滞后性、重复性等湿敏特性。结果 选用长度为0.5~2 μm的c–MWCNTs制备的湿度传感器灵敏度、线性度优于10~30 μm的。质量分数分别为20%和67%的c–MWCNTs的湿敏溶液制备而得的传感器均对不同湿度敏感,而当c–MWCNTs质量分数为67%时灵敏度更高,线性度更好,在低湿(相对湿度为33%)时响应和恢复时间分别为7 s和3.9 s,高湿(相对湿度为85%)时分别为20 s和15 s,最大吸湿滞后值为17%。结论 将c–MWCNTs与GO掺杂用于制备湿度传感器,可以检测的相对湿度范围为11%~98%,且c–MWCNTs质量分数为67%时传感器具有较高的灵敏度、良好的线性度、良好的重复性、快速的响应恢复能力和较小的吸湿滞后,在未来包装湿度监控应用方面具有广阔前景。     

石墨烯湿敏性能研究进展

湿度传感器与大气监测、工业生产和生物医疗等领域息息相关。随着科技的不断发展,人们对高性能湿度传感器的需求不断增加,这为湿度传感器行业的发展带来了前所未有的机遇和挑战,其中高性能湿敏材料的开发尤为关键。在诸多湿度传感器中,金属氧化物或金属氧化物/聚合物复合材料湿度传感器因其敏感元件选择的多样性、易于后加工处理和响应特性高等特点而受到广泛关注。与聚合物湿度传感器相比,陶瓷材料的合成过程更简便,响应也通常更为迅速,且聚合物的成本更低。近些年,新型纳米材料被广泛应用于湿度传感器领域,逐渐成为湿敏材料的主要发展方向及研究热点。零维和一维纳米碳质材料,如富勒烯、碳纳米管作为湿敏活性层制备的传感器通常具有大比表面积、可室温下工作、易于实现微型化、稳定性好等诸多优点,但它们的零维或一维结构与现有的平面电子器件加工工艺不相匹配。石墨烯是由sp2杂化的碳原子紧密排列构成的二维蜂巢晶格结构的单层石墨,其独特的二维结构适用于现有的平面电子器件加工工艺。石墨烯材料作为湿敏活性层受到研究者们的广泛关注是因为它具备诸多优异特性:(1)石墨烯的所有原子都在表面,具有超大的比表面积,原则上,石墨烯传感器的动态检测范围可以从单个分子到很高的浓度水平;(2)利用石墨烯的电学特性和力学特性可以很好地进行传感信号的转换;(3)金属、聚合物或其他修饰剂功能化的石墨烯能与特定分子发生相互作用,大大增强传感器的选择性;(4)石墨烯单晶可以制作四探针装置,从而能够避免接触电阻的影响,并大大提高灵敏度;(5)与其他纳米碳材料如碳纳米管相比,石墨烯和氧化石墨烯制备成本更低。本文综述了石墨烯湿敏性能及其应用的研究进展,着重讨论了本征石墨烯、氧化石墨烯和改性石墨烯的湿敏特性。文章最后分析了石墨烯基湿度传感器未来的发展方向和面临的挑战。     

基于石英晶体微天平的聚醚酰亚胺湿度传感器

研制了基于石英晶体微天平方法的聚醚酰亚胺湿度传感器,研究了它对相对湿度的响应特性和灵敏度以及这种湿度传感器在高湿度对比下的循环特性和长期老化性能。结果表明:在较宽的湿度范围内,这种湿度传感器表现出良好的湿敏特性。当相对湿度从11%变化至95%时,频率变化达2000Hz。高湿度差对比下的响应时间和恢复时间分别为30和20s。在循环测试和长时间老化测试中,也表现出优良的重复性和稳定性。     

涂敷ZnO纳米线的石英晶体微天平的湿度敏感特性

采用石英晶体微天平传感器电极上旋涂纳米氧化锌薄膜,构造湿度传感敏感元件,实现对湿度检测.介绍了检测系统的组成,纳米氧化锌的制备.通过DAQ数据采集卡和Labview软件实现数据的实时采集.实验结果表明旋涂纳米氧化锌薄膜的传感器频率随测试的相对湿度变化明显,用纳米氧化锌作为敏感元件检测湿度具有很高的灵敏度和重复性.     

湿度传感器的应用

正0引言湿度是用来表征空气中含水量的一个物理量。随着社会的进步,湿度的检测和控制愈来愈重要。湿度传感器是将水蒸气的量转换成可以测量的量的器件,它已被广泛地应用在药物储存、动物养殖、温室大棚、工业生产等领域[1-3]。研究人员已根据不同工作原理制备了相应的湿度传感器,但理想的湿度传感器应该具有高灵敏度、长期稳定性、响应时间短、价格低及能在较大湿度和温度范围内工作的特点。本文对当前湿度传感领域的最新研究进展进行综述,首先介绍湿度传感器的相关知识,之后介绍目前国内外湿度传感器的应用发展,并对未来湿度传感器的发展趋势进行了展望。     

高分子电阻型湿敏材料的老化机理

本文以聚苯乙烯磺酸钠为湿敏材料制备了高分子电阻型湿度传感器,研究了其在高温高湿环境下,施加交流电激励后的老化行为。考察了通电电压、通电时间等对传感器响应特性的影响,并对其老化机理进行了探讨。提出通电老化后,湿敏材料在不同湿度下的电阻变化决定于高温高湿环境造成的溶解效应和施加电压后引起的通道效应和离子破坏效应。研究表明,在较高湿度环境下(87~93%RH),施加800mv的电压可加速湿敏材料的老化过程,使湿度传感器响应信号较快达到稳定,从而有望改善湿度传感器的稳定性。     

电极结构对高分子电阻型湿度传感器性能的影响

本文以聚苯乙烯磺酸钠为湿敏材料,制备了以金叉指电极为基底的高分子电阻型湿度传感器。研究了电极基片材料和叉指电极构型对传感器湿敏响应特性的影响。研究表明,采用多孔结构的基片材料可降低传感器电阻,增强湿敏膜与基片的结合能力从而提高传感器的稳定性;叉指电极构型对传感器的电阻大小有一定影响,增加电极中心线间距离使传感器的稳定性提高。     

Formation of Uniform Water Microdroplets on Wrinkled Graphene for Ultrafast Humidity Sensing

Portable humidity sensors with ultrafast responses fabricated in wearable devices have promising application prospects in disease diagnostics, health status monitoring, and personal healthcare data collecting. However, prolonged exposures to high‐humidity environments usually cause device degradation or failure due to excessive water adsorbed on the sensor surface. In the present work, a graphene film based humidity sensor with a hydrophobic surface and uniformly distributed ring‐like wrinkles is designed and fabricated that exhibits excellent performance in breath sensing. The wrinkled morphology of the graphene sensor is able to effectively prevent the aggregation of water microdroplets and thus maximize the evaporation rate. The as‐fabricated sensor responds to and recovers from humidity in 12.5 ms, the fastest response of humidity sensors reported so far, yet in a very stable manner. The sensor is fabricated into a mask and successfully applied to monitoring sudden changes in respiratory rate and depth, such as breathing disorder or arrest, as well as subtle changes in humidity level caused by talking, cough and skin evaporation. The sensor can potentially enable long‐term daily monitoring of breath and skin evaporation with its ultrafast response and high sensitivity, as well as excellent stability in high‐humidity environments.     

Flexible Smart Noncontact Control Systems with Ultrasensitive Humidity Sensors

The development of noncontact humidity sensors with high sensitivity, rapid response, and a facile fabrication process is urgently desired for advanced noncontact human–machine interaction (HMI) applications. Here, a flexible and transparent humidity sensor based on MoO₃ nanosheets is developed with a low‐cost and easily manufactured process. The designed humidity sensor exhibits ultrahigh sensitivity, fast response, great stability, and high selectivity, exceeding the state‐of‐the‐art humidity sensors. Furthermore, a wearable moisture analysis system is assembled for real‐time monitoring of ambient humidity and human breathing states. Benefiting from the sensitive and rapid response to fingertip humidity, the sensors are successfully applied to both a smart noncontact multistage switch and a novel flexible transparent noncontact screen for smart mobile devices, demonstrating the potential of the MoO₃ nanosheets‐based humidity sensors in future HMI systems.     

A novel integrated acoustic gas and temperature sensor

Acoustic temperature sensors have the advantages of a high-resolution frequency output and ease of integration with other acoustic sensors but require hermetic packaging to prevent sensor contamination. Surface-skimming bulk-wave (SSBW) devices have been found to be much less sensitive to surface contamination than other acoustic devices, and although their temperature response has been studied extensively, they have not been studied specifically as temperature sensors. Surface acoustic wave (SAW) based chemical sensors requiring temperature measurement or control are susceptible to temperature measurement error because the temperature cannot be measured in the same location as the chemical sensor. The objectives of this work were to examine the temperature characteristics and performance of a SSBW temperature sensor when integrated with a SAW condensation and humidity sensor in a novel design. The SSBW temperature sensor had over an order of magnitude less sensitivity to condensation and water uptake in certain polyimide films than an integrated SAW gas sensor indicating that this design is practical for sensing films in the delay path where film thickness is carefully considered.     

露点温度传感器发展趋势综述

介绍了目前露点温度传感器领域的研究现状,阐述了光学式、谐振式、电学式、热学式、重量式、化学式露点温度传感器的原理及构造,指出光学式露点温度传感器测量精度极高,其中冷镜式露点仪可作为湿度计量标准;谐振式露点温度传感器具有体积小、成本低、响应时间短、灵敏度高、可靠性好的特点;电学式露点温度传感器灵敏度高、功耗小,便于实现小型化、集成化;重量法是准确度最高的湿度绝对测量方法;化学法常用来测量低湿环境下的有机混合气体。探讨了露点温度传感器在环境监测、工业制造、医疗诊断等领域的应用情况,指出未来露点温度传感器将会向高精度、高稳定性、高响应的方向发展,且应用范围将进一步拓展,以满足极端环境下的测量需求。     

A Remote Query Pressure Sensor Based on Magnetic Higher Order Harmonic Fields

The design and fabrication of a wireless, passive pressure sensor based on the change in magnetic higher order harmonic fields is described. The sensor was made of an airtight pressure chamber with two opposite membranes: a rigid membrane attached to a magnetically soft ferromagnetic strip (sensing element) and a flexible membrane attached to a permanent magnetic strip (biasing element). The flexible membrane of the chamber deflected with changing pressure, thus varying the separation distance between the sensing and biasing elements. The change in separation distance in turn altered the biasing field experienced by the sensing element, varying the pattern of its magnetic higher order harmonic fields allowing remote pressure monitoring through a magnetic coil. In this work, different materials were used to fabricate the flexible membranes for sensors of different dynamic ranges. Experimental results showed the shifts in magnetic higher order harmonic fields were linear for all sensors, but with different sensitivity depending on the elasticity of the flexible membrane. The novelty of this sensor is its wireless, passive nature, which is ideal for applications where wire connections are prohibited. In addition, the simple sensor design reduces cost, allowing disposable use. Potential applications of such a sensor technology include long-term structural monitoring (concrete, asphalt) and in vivo pressure monitoring inside the human body.      

3D Printed Stretchable Tactile Sensors

The development of methods for the 3D printing of multifunctional devices could impact areas ranging from wearable electronics and energy harvesting devices to smart prosthetics and human–machine interfaces. Recently, the development of stretchable electronic devices has accelerated, concomitant with advances in functional materials and fabrication processes. In particular, novel strategies have been developed to enable the intimate biointegration of wearable electronic devices with human skin in ways that bypass the mechanical and thermal restrictions of traditional microfabrication technologies. Here, a multimaterial, multiscale, and multifunctional 3D printing approach is employed to fabricate 3D tactile sensors under ambient conditions conformally onto freeform surfaces. The customized sensor is demonstrated with the capabilities of detecting and differentiating human movements, including pulse monitoring and finger motions. The custom 3D printing of functional materials and devices opens new routes for the biointegration of various sensors in wearable electronics systems, and toward advanced bionic skin applications.     

Patternable production of SrTi03 nanoparticles using 1-W laser directly on flexible humidity sensor platform based on ITO/SrTiO3/CNT

Perovskite oxides like SrTiO3 at the nanoscale are of interest for emerging applications,including high-k dielectrics and sensors.However,their synthesis requires long calcination at the elevated temperature,which is a barrier of their application to flexible electronics.Here,an effective laser-assisted sol-gel method to patternably produce SrTiO3 nanoparticles (-100 nm) in selective areas on polyimide substrates (coated with ITO) is introduced.Importantly,the violet-laser power is just 1 W but sufficient to crystallize the material in a short period (a few seconds).Furthermore,developing a flexible device platform using carbon nanotubes (CNT) and SrTiO3 nanoparticles for detection of humidity changes at room temperature is proposed.The sensor platform has both capacitive and resistive sensing abilities.The resistive mode with a lower power usage (about 0.2 μW) is suitable for long monitoring of humidity in the range of 2％ RH and above.The capacitive mode with higher sensitivity,faster response/recovery time (1-3 min),and lower detection limit (0.5％ RH) can be used for calibration purposes.The performance of the flexible sensor is still maintained after 5000 bending cycles at 1.5-cm radius.Altogether,our synthesis method and the flexible sensor show chances for mass-producing perovskite oxides at low cost for wearable electronics.