Microfluidic temperature sensor based on temperature-dependent dielectric property of liquid

We propose a low-cost compact microfluidic temperature sensor by virtue of the temperature-dependent permittivity of liquid.The sensor is composed of a coplanar waveguide(CPW)transmission line loaded with three resonators and a microfluidic plate with three channels.The resonant frequency of each resonator relies on the temperature-dependent dielectric property of liquid in corresponding channel,which therefore can be used to extract the temperature.The proposed sensor features a compact size and low cost since it requires only micro fluid volume instead of additional electronic components to produce significant frequency shift with changing temperature.Moreover,it exhibits decent accuracy and stability in a temperature sensing range from 30℃ to 95℃.A theoretical analysis of the sensor is provided,followed by the detailed characterization method,and a prototype is designed,manufactured,and measured to verify the theoretical analysis.

Highly sensitive optical fiber temperature sensor based on resonance in sidewall of liquid-filled silica capillary tube

A highly sensitive optical fiber temperature sensor based on a section of liquid-filled silica capillary tube(SCT)between single mode fibers is proposed. Two micro-holes are drilled on two sides of SCT directly by using femtosecond laser micromachining, and liquid polymer is filled into the SCT through the micro-holes without any air bubbles and then sealed by using ultra-violet(UV) cure adhesive. The sidewall of the SCT forms a Fabry–Perot resonator, and loss peaks are achieved in the transmission spectrum of the SCT at the resonant wavelength. The resonance condition can be influenced by the refractive index variation of the liquid polymer filled in SCT, which is sensitive to temperature due to its high thermooptical coefficient(-2.98 × 10^-4℃^-1). The experimental result shows that the temperature sensitivity of the proposed fiber structure reaches 5.09 nm/℃ with a perfect linearity of 99.8%. In addition, it exhibits good repeatability and reliability in temperature sensing application.

New Measuring Method for Colorless Liquid Level Based on CLC100 Level Sensor and Powercast Wireless Sensor Kit

In this paper, a new wireless measuring method for colorless liquid level measurement was presented, based on latest CLC100 liquid level sensor and Powercast wireless sensor development kit. The wireless system is divided into two parts, level measurement and data transmission part as well as data receiving and display part. First part included the capacitive liquid level sensor CLC100 and the wireless senor board. CLC100 sensor was used for liquid level measurement. Wireless sensor kit from Powercast Corporation included one wireless sensor board, which was used for signal transmission. A built-in PIC microcontroller was embedded in the transmission module, for the purpose of processing and data transmitting. Due to CLC100 sensor’s output voltage exceeding the sensor board’s input limitation, a voltage convertor was designed to connect the sensor and the wireless sensor board. The final results were voltages corresponding to the liquid level, and were processed by an independent PIC development board, and then sent to PC’s hyper terminal via serial-port by this PIC microcontroller. Experiments showed that this wireless sensor node prototype worked well.

Quantitative research of the liquid film characteristics in upward vertical gas, oil and water flows

The study of liquid film characteristics in multiphase flow is a very important research topic, however,the characteristics of the liquid film around Taylor bubble structure in gas, oil and water three-phase flow are not clear. In the present study, a novel liquid film sensor is applied to measure the distributed signals of the liquid film in three-phase flow. Based on the liquid film signals, the liquid film characteristics including the structural characteristics and the nonlinear dynamics characteristics in three-phase flows are investigated for the first time. The structural characteristics including the proportion, the appearance frequency and the thickness of the liquid film are obtained and the influences of the liquid and gas superficial velocities and the oil content on them are investigated. To investigate the nonlinear dynamics characteristics of the liquid film with the changing flow conditions, the entropy analysis is introduced to successfully uncover and quantify the dynamic complexity of the liquid film behavior.

An Unexpected Frequency Response of A Piezoelectric Quartz Crystal Sensor to the Density and Viscosity of the Liquid

An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (?f ) show a wave-shape response to liquid density (ρ) and viscosity (η) in fine structure, if the longitudinal wave effect was not eliminated. This result is different from the well-known linear relationship between of ?f and (ρη)1/2. An oscillating frequency-temperature curve of the sensor was observed and explained.

Design and Fabrication of a Bio-inspired Acceleration Sensor Using Liquid Mass Blocks

A linear acceleration sensor,which is inspired by the human balance organ,is designed and prepared. It uses a liquid mass-block and a symmetrical-electrodes metal-core polyvinylidene fluoride fiber(SMPF)as the sensor element. The output signal of the sensor has an exponential relationship with the excitation amplitude of the impacting vibration. It is capable of detecting the amplitude and the correct frequency for sinusoidal excitations using an exponential correlation. The experiments indicate that both the output signal of the sensor and the resonance frequency increase substantially with increasing diameter of the metal core. The first-order resonance frequencies of the sensors with 40,60,and 80 μm diameter metal wires are below 10 Hz,which is near the range of human body motion frequencies.

An ionic liquid supported CeO_2 nanoparticles-carbon nanotubes composite-enhanced electrochemical DNA-based sensor for the detection of Pb^(2+)

An electrochemical sensor incorporating a signal enhancement for the determination of lead （II） ions （Pb2＋） was designed on the basis of the thrombin-binding aptamer （TBA） as a molecular recog- nition element and ionic liquid supported cerium oxide （CeO2） nanoparticles-carbon nanotubes compo- site modification. The composite comprises nanoparticles CeO2, multi-waU carbon nanotubes （MWNTs） and hydrophobic room temperature ionic liquid （RTIL） 1-ethyl-3-methylimidazolium tetrafluoroborate （EMIMBF4）. The electrochemical sensors were fabricated by immersing the CeOa-MWNTs-EMIMBF4 modified glassy carbon electrode （GCE） into the solution of TBA probe. In the presence of Pb2＋, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb2＋ and TBA. The TBA-bound Pb2＋ can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb2＋. The reduction peak current is linearly related to the concentration of Pb2＋ from 1.0 ＊ 10-8 M to 1.0 ＊ 105 M with a detection limit of 5 ＊ 109 M. This work demonstrates that the CeOz-MWNTs-EMIMBF4 nanocomposite modified GCE provides a promising platform for immobi- lizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.

Refractive Index and Temperature Sensor Using HC-1550 Infiltrating by Different Liquid Crystal

Photonic crystal fiber (PCF) is employed as a refractive index sensor (RIS) for solving a lot of problems in biological, physicochemical, medical, engineering fields and many environmental challenges, where it is used in many industries of food, medicines, chemical materials and material diagnosis. The kind of the PCFs was HC-1550 with three wavelengths of laser source were used;638 nm, 850 nm, and 1550 nm that are useful for recording the intended transmitted signal intensity. Therefore, the measured RI was in the range (1.469 - 1.455 RIU) at the temperature range (36 - 70)°C for the EBBA and it was (1.621 - 1.612 RIU) at the temperature range (22 - 42)°C for the MBBA. The results showed that the highest RI sensitivity was 96.335 dBm/RIU for the HC-1550 infiltrated with MBBA using the laser of wavelength 638 nm, Also, the highest temperature sensitivity was 0.2505 dBm/°C for empty HC-1550 using the laser of wavelength 1550 nm.

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.

基于单片机的造纸用液位自动化控制系统研究

为切实应对以往造纸用液位控制系统依赖于自动控制机理构建控制电路所造成的液位控制精确度低与自动化程度低等问题,由嵌入式技术重焕液位控制系统活力着手,针对造纸碱回收蒸发工段黑液液位控制需求,基于52单片机和超声波传感器搭建了液位自动化控制系统。系统测试结果表明,以单片机与传感器相结合的液位控制系统精准度高、自动化程度高,且安全稳定性更高,不仅可充分适应当前追求无人化、高效化的造纸工业生产体系,还可普遍推广应用于其他工业领域。

基于离散马尔可夫模型的液位感测系统分析

阐述一种新的测量原理及测量电容结构,其利用模型计算传统式电容液位测量方法中测量介质介电常数数据,分析定期标定的原因。新系统根据液位变化、介电常数、电容量关系,实现高精度测量。

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。

液体微小流量测量技术研究进展

随着流体力学与生命科学、材料科学、医疗健康、能源环境和先进制造等多学科领域的交叉融合,微量液体与微流控技术逐渐在这些领域取得了广泛的应用.与此同时,液体微小流量(每分钟几微升、几纳升,甚至更低)的测量需求逐渐凸显出来.随着特征尺度的减小,原有的液体流量测量技术已经无法满足测量准确度的要求,因此,需要流量测量技术的进一步发展来满足微小流量测量和传感器微尺度集成的需求.文章介绍了液体微小流量的应用背景和面临的主要问题,首先,根据测量过程中是否引入外界能量(例如电能、热能等),将现有的和正在开发的液体微小流量测量技术分为有源流量测量技术和无源流量测量技术;其次,分别对其包含的具体测量技术展开论述,主要包括质量流量测量技术(科里奥利和微谐振器)、热式流量测量技术(热损失型、热分布型和热脉冲型)、光流控流量测量技术(光致褪色)、压力转换流量测量技术(压差式、悬臂式和柔性膜形变)、粒子测速技术、重力测量技术和弯月面追踪技术等,并讨论了上述测量技术的传感测量原理、测量性能指标和优缺点;最后,结合液体微小流量测量技术的发展和先进测量体系的建设,总结了液体微小流量测量的应用前景和有待解决的挑战.

准确检测液位的光纤Bragg光栅弹性膜片传感器

为了准确测量液位,研制了一种耦合光纤布喇格光栅和弹性膜片的液位传感器。该传感器由两个光纤光栅(FBG_1和FBG_2)、弹性膜片、弹性橡胶密封垫片、空心管(导气管)和光纤光栅固定装置组成。光纤光栅固定装置材料为聚甲基丙烯酸甲酯。FBG_1和FBG_2固定在弹性膜片表面。FBG_1用于监测液位高度和温度。将FBG_2封装在不锈钢毛细管中进行温度检测,消除液相温度变化对液位测量的负面影响。为了提高传感器检测液位的线性度,实验研究了弹性膜片厚度对液位测量结果的影响,并在此基础上研究了液位变化率和外部振动对液位测量精度的影响。结果表明,当弹性膜片厚度为2 mm时,传感器检测液位的线性范围为0~380 cm,灵敏度为(19.65±6.3)pm/cm。该传感器可在0~100 cm/min液位变化速率和0~5.27 mm/s外部振动强度范围内准确监测液位,最大检测误差为7.2%。

Innovating ionic liquids as repairable electronics for liquid robots

When I read the paper of“Crystal-Confined Freestanding Ionic Liquids for Reconfigurable and Repairable Electronics”that was published on Nature Communications(Nat.Commun.2019,10,547),I felt excited as it led to a new application of ionic liquids in addition to the enormous studies on chemical synthesis,catalysis,gas adsorption,processing biomass,and electrochemistry.This paper intended to mimic the liquid robot which was a classic character in the famous movie of Terminator 2:Judgment Day.The authors successfully exploited an approach to overcome the leakage problem of ionic liquids in the absence of encapsulation layers.It seems that ionic liquids would be one of the promising materials for green electronics with less production of electronic waste.In these regards,I would be delighted to write a highlight for this innovative work and hopefully it may raise more interests in the areas of ionic liquids.

超音速旋流分离器湿气出口段液膜测量

超音速旋流分离技术作为一种新型的多相流分离技术,在天然气脱水脱烃领域有较好的应用前景。超音速分离器内液膜特性与分离性能息息相关,本文以其湿气出口段液膜特征为研究对象,开发了一套FPC电导式液膜厚度测量系统,设计了标定装置获取传感器实际输出特性。搭建实验管段展开气液两相分离实验,研究了入口含液量与背压比对液膜特征的影响。实验显示液膜厚度低于500μm时传感器灵敏度较高,拟合曲线误差在±5%以内。时域上统计学分析表明液膜厚度呈双峰分布,基层厚度约为70μm。频域上小波包分解后第2、第3频段与其他频段能量分布变化趋势有明显差异,据此对原始信号依次进行重构、局部均值分解、求近似熵和聚类,结果表明含液量增大,液膜波动加剧,近似熵可聚类为三类,对应三种流形。采用互相关算法分析液膜扰动波速度,含液量增大其流向分量与周向分量均呈指数增长趋势,流向分量及其RMSE范围分别为84.7~339.0mm/s、1.15~4.51mm/s,周向分量及其RMSE范围分别为54.8~186.4mm/s、1.20~3.38mm/s。

蚕丝基柔性压力传感器的制备及其性能研究

蚕丝具有优异的生物相容性、可降解性和易加工性等,是应用于柔性电子领域的理想柔性基底材料。本文通过气液界面聚合法,在蚕丝织物、平板丝和静电纺丝素膜三种蚕丝材料表面实现聚苯胺的原位生长,成功制备出以聚苯胺为活性导电介质的柔性基材,并将其组装成柔性压阻式压力传感器,这为开发高性能、安全可靠和轻质便携的可穿戴电子产品提供新的方法和途径。结果表明:三种蚕丝基柔性压力传感器中,蚕丝织物聚苯胺传感器具有最大的压力检测范围(16.27~504.79 kPa),拉伸变形可达20%,灵敏度仅为0.00129 kPa^(-1);静电纺丝素膜聚苯胺传感器灵敏度最高(0.01376 kPa^(-1)),但拉伸变形能力差,仅可拉伸2.3%;平板丝聚苯胺传感器压力检测灵敏度略高于蚕丝织物聚苯胺传感器,达到0.00134 kPa^(-1),线性检测范围为9.8~87.6 kPa。本文研究开发的蚕丝基柔性压力传感器在运动检测领域具有较好的应用前景。

基于微波原理的高精度液位传感器

本文提出并演示了一种基于微波谐振原理的带有电阻消能结构的高精度液位传感器,在0~50 mm的量程范围内,分辨率可达微米级。微波谐振原理传感器第一反射点是传感器自带的固定点,第二反射点为液面,即为可变点,两反射点之间形成谐振腔结构。当液面的高度发生变化时,第二反射点发生移动,会导致两个反射点之间的距离发生变化,因此改变谐振腔长,通过测量谐振腔长的大小即可确定液位的变化量。同时,所加入的电阻在提高量程范围的基础上,还大幅提升了频谱质量和测量精度。实验结果表明,该液位传感器在0~50 mm的量程范围内具有1μm数量级的分辨率和-1.927 2 mm/mm(谐振波长变化/液位)的灵敏度。该新型微波液位传感器具有机械鲁棒性强、易于制造、成本低和高分辨率等优点,有望应用于水利水电的量水堰监测等领域。

用于薄液膜厚度测量的面阵列电导传感器的设计与验证

液膜厚度是研究降液膜展开及发展演化所需的重要参数,目前市面上主流的膜厚探头主要是基于点探测原理、无法满足液膜展开的面厚度测量需求,本研究基于降液膜厚度的范围,自主设计了基于柔性印刷电路板的电导法同轴圆环面阵列传感器。成功制造的传感器在42 mm×57 mm面积上有3×4个同轴圆环探测单元,探头间距为15 mm,实现了0.3 mm~3 mm范围内的液膜厚度测量,测量电阻换算厚度的误差在10%以内,能满足薄液膜的面厚度测量需求。

用于应变传感器的自愈合抗冻离子水凝胶

近年来,导电水凝胶在电子驱动器、医疗监测传感器及可穿戴设备等领域的应用备受关注。然而,多数凝胶机械强度低、寿命短、抗冻性能差,从而导致低温下无法使用。为了解决该问题,以聚乙烯醇、离子液体1-丁基-3-甲基咪唑四氟硼酸盐和植酸为原料,在水与二甲基亚砜(DMSO)二元溶液中借助多重氢键及离子基团间的静电作用实现了超分子自组装,制备出一种可用于应变传感的自愈合、耐低温多功能离子水凝胶。研究发现在凝胶中引入DMSO,凝胶表现出优异的抗冻能力;同时,调节DMSO的含量可优化凝胶的强度和韧性,当DMSO体积分数为40%时,最大拉伸强度和断裂伸长率分别可达4.43 MPa和869.1%。该离子水凝胶在低温应变传感器、智能可穿戴响应元件等领域展现出较好的应用潜力。