星地两用光学表面污染检测装置

针对光通信终端的光学表面污染,研制了10 MHz镀铝石英晶体微天平(QCM),用于实时检测真空试验中的污染量以保证光通信的可靠性。该装置通过引入参考晶体消除环境因素的影响,并降低对其控温精度的要求,其理论质量灵敏度可达10-9g/cm2。经过绝对标定实验后,其实际质量灵敏度为10-8g/cm2,满足应用需求,且成本低,实用性好,可用于星上或地面污染检测。文中依据不同的污染源工作温度,分别在32℃高温恒温段,32℃~-27℃降温段,低温保持段及-2℃~32℃升温段进行了污染沉积量的检测。结果表明:在试验初期的高温恒温段,污染源与敏感表面温差高于0℃,15.75h内单位面积污染沉积量为1.68×10-4g/cm2;在低温保持段,温差一直低于-22℃,23.37h内单位面积污染解吸附量为1.08×10-4g/cm2;真空试验的总污染沉积量为2.7×10-5 g/cm2。得到的结果证实了该QCM用于污染量检测的有效性。文中还初步分析了真空试验下的污染沉积过程,为光学表面污染的预估与防护提供了依据。     

QCM生物传感器检测二噁英类物质

介绍一种运用石英晶体微天平(QCM)检测二噁英的方法。由于芳香烃受体能够与二噁英发生结合,先将芳香烃受体通过单分子自组装膜固定在石英晶片表面,运用竞争抑制法,引进一种二噁英类似物作为竞争物,让竞争物与牛血清蛋白形成偶联物,不同浓度的二噁英跟特定滚度的竞争物-牛血清蛋白偶联物混合,将混合液通入反应池,使竞争物与二噁英竞争芳香烃受体的结合位点。通过石英晶体微天平频率的变化来达到检测二噁英的目的。检测花图是0.01～100ng/mL。整个检测方法与气-质联用相比,具有快速、简单、成本低的种点。     

DESIGN OF AN AUTOMATED FEEDBACK CONTROL COOLING SYSTEM FOR SWIR LINEAR IMAGE SENSOR APPLICATION

Our novel automated feedback temperature controlled cooling system consists of a temperature measurement circuit, a TE cooler, a thermistor, a microcontroller, and a digital-to-analog converter and PWM algorithms. The measurement accuracy of this temperature controlled TE system was better than 0.1°C and can be used for maintaining an instrument's isothermal applications. The experimental results of SWIR linear image shows that the temperature can be stably maintained at ?20°C, the dark output current can be reduced almost 80 mV (Integration time: 100 ms) and the SNR of pixel can be improved from 48 dB to 83 dB as well.     

直接甲醇燃料电池测试用温度控制系统

为了精确控制燃料电池阳极燃料的温度,搭建了直接甲醇燃料电池(DMFC)测试用温度控制系统。针对温度控制对象为定速流动的特点,设计了用于加热流动液体的特殊结构,即将不锈钢软管以双层跑道的布局紧密贴合于三层黄铜板之间,以延长液体在加热块中的流动时间,保证出口流动液体温度的精确控制。计算了不同内径的不锈钢软管最小管长和控制系统的最小加热功率。采用半导体制冷片为流体加热/制冷元件,设计制作了其功率驱动和换向电路。采用基于PID闭环控制的VC++程序设计方法实现了温度自动控制。实验结果表明:温度控制系统的平均升/降温速度为14℃/min,稳态温度控制示值误差±2℃,能够满足DMFC恒定温度条件下实时测试的要求。     

Design and construction of a new temperature-controlled chamber for light and confocal microscopy under monitored conditions: biological application for plant samples

A new light microscope–temperature‐controlled chamber (LM–TCC) has been constructed. The special feature of the light microscope–temperature‐controlled chamber is the Peltier‐element temperature control of a specimen holder for biological samples, with a volume capacity of 1 mL. This system has marked advantages when compared to other approaches for temperature‐controlled microscopy. It works in a temperature range of −10°C to +95°C with an accuracy of ±0.1°C in the stationary phase. The light microscope–temperature‐controlled chamber allows rapid temperature shift rates. A maximum heating rate of 12.9°C min⁻¹ and a maximum cooling rate of 6.0°C min⁻¹ are achieved with minimized overshoots (≤1.9°C). This machinery operates at low cost and external coolants are not required. Especially with samples absorbing irradiation strongly, temperature control during microscopy is necessary to avoid overheating of samples. For example, leaf segments of Ficaria verna exposed to 4500 μmol photons m⁻² s⁻¹ in a standard microscopic preparation show a temperature increase (δT) of 18.0°C, whereas in the light microscope–temperature‐controlled chamber this is reduced to 4°C. The kinetics of microscope‐light induced δT are described and infrared thermography demonstrates the dissipation of the temperature. Chloroplasts of the cold adapted plant Ranunculus glacialis show the tendency to form stroma‐filled protrusions in relation to the exposure temperature. The relative number of chloroplasts with protrusions is reduced at 5°C when compared to 25°C. This effect is reversible. The new light microscope–temperature‐controlled chamber will be useful in a wide range of biological applications where a rapid change of temperature during microscopic observations is necessary or has to be avoided allowing a simulation of ecologically relevant temperature scenarios.     

Admittance Analysis of the Resonant Frequency Shift of the Quartz Crystal Microbalance in a Newtonian Liquid

Abstract

The effect of the immersion angle on the resonant frequency shift of the quartz crystal microbalance (QCM) was investigated in a Newtonian liquid. The resonant frequency shift of the QCM was inquired by two types of approaches. One was the shift of the frequency at the minimal impedance and the other was that at the maximal conductance in the admittance analysis. This examination revealed that both frequency shifts were dependent on the immersion angle. However, it became clear that the values of frequency shift at the minimal impedance were larger than those at the maximal conductance.     

用于aPTT测量的Parylene-C增强型石英晶体微天平耗散检测系统

房颤、血栓等患者抗凝药物日常口服等场景迫切需要凝血参数快速检测,本文设计和制作了一种Parylene-C增强型石英晶体微天平(QCM)传感器及其耗散因子检测系统用于凝血测量。首先使用Parylene-C有效增加石英晶体微天平传感器的峰峰值和有效使用次数,基于传感器耗散因子对血液凝固过程血液粘弹性变化敏感,设计电导谱分析法的压电传感器耗散因子快速测量系统,对血浆部分凝血活酶时间(aPTT)进行测量。并用SYSMEX CS 5100光学凝血仪、Lambda 950分光光度计验证系统测量结果。实验表明,Parylene-C增强型QCM传感器信号峰峰值增加8±1%,传感器aPTT实验有效重复使用次数为30次,系统30℃温差最大耗散偏移2.09×10-6。aPTT耗散曲线与光学法(lambda950)吸光度曲线变化趋势一致。与SYSMEX CS 5100临床结果线性拟合决定系数R2为0.99。同样本10次重复实验结果变异系数为1.48%。Parylene-C增强型QCM传感器与耗散分析法的联合应用具备多场景下凝血参数快速检测的能力,系统温度稳定性好,具有满足即时检测应用的潜力。     

Temperature dependency of the fill factor in PV modules between 6 and 40 °C

The definition of the fill factor (FF) and a more accurate formula were used to study the temperature dependency of FF. To investigate FF changes as a function of the temperature in the photovoltaic (PV) modules, we used an equivalent circuit diagram that considers series and parallel resistances. Using a measurement setup that allows precise temperature control of the PV modules, the parameters V_oc, I_sc, V_m, I_m were measured between 6 and 40 °C. Using the theoretical model, a formula for the FF temperature gradient, ∂FF/∂t, could be found. The experimental results show that FF decreases with increasing temperature, and fitting the obtained data points results in a straight line. The FF has a negative temperature coefficient. Specifically, the obtained “defined value” for ∂FF/∂t is −0.00093 1/°C, while the theoretical value is −0.0015 1/°C.

     

塑料微流控芯片热压成形温度控制装置

采用聚合物如塑料等制作微流控芯片是拓展芯片应用,实现芯片产业化的关键。温度是塑料微流控芯片热压成形过程中的重要工艺参数。本文采用半导体热电致冷堆,设计了适合塑料芯片制作的温度控制装置;分析了升降温过程中所需的加热／制冷功率,并对升降温特性进行了研究;设计了半导体热电致冷堆供电电源装置。对温度控制装置的升／降温及温度控制精度进行了实验,并给出了实验结果。     

基于ARM的PCR仪温度控制系统研究

本文设计一种基因扩增仪的温度控制系统,它以ARM芯片为核心,由液晶屏、键盘、驱动电路等模块组成,并以PWM技术、PID控制算法实现温度的控制,使系统可较好地完成基因扩增仪的热循环过程。经测试结果显示该控制系统能够很好地满足基因扩增仪对升降温速度以及精度的要求,真正地实现了低成本、高精确度、快升降温速度。该系统作为基因扩增的专用设备在生命科学、医学研究等研究领域具有良好的应用前景。     

Thermoluminescence apparatus using PT100 resistors as the heating and sensing elements

A novel apparatus for obtaining thermoluminescence glow curves is described. Two standard PT100 precision resistors, which have a well-known dependence of resistance on temperature, are connected back to back to provide a sensing and heating element. The resulting hot finger has very low thermal mass, is nonreactive, and is inexpensive. With dry nitrogen gas-flow cooling, an operational range of -50 to 450 degrees C is achievable. A tailored control circuit which is easily calibrated drives the heating element, and temperature ramps are implemented in software. The simple design permits the use of modularly interchangeable hot fingers for rapid measurement of many samples.     

Comparison of thermal fatigue behaviour of ASTM A 213 grade T-92 base and weld tubes

Super-heater tubes are subjected to alternate heating and cooling in power plants causing them to crack and eventually fail. This phenomenon is referred to as “thermal fatigue.” In this paper, a laboratory simulation for reproducing the thermal fatigue phenomenon is developed to determine the number of cycles necessary before failure occurs in super-heater tubes. The temperature and strain distributions along the specimen were computed theoretically using ANSYS software for the applied temperature condition. The thermal fatigue test was conducted for both base and shielded metal arc (SMA) welded tubes separately and both passed in the non-destructive tests. These tubes were subjected to thermal cycles from 800°C (accelerated temperature) to room temperature. Oxy-acetylene heating setup was utilized as a heating source, and a water bath was utilized for quenching purposes. The tests were carried out until open cracks were identified. Surface cracks were identified in the base and weld tubes after 90 and 60 cycles respectively. This study reveals that heating and cooling cause thermal fatigue, initiate cracks in the tubes.     

Evaluation of mechanical characteristics of the plate-type polymer hyperfine pit pattern by the nanoindentation process

It’s important to measure quantitative properties about the thermal-nano behavior of polymers in order to produce high quality components using the nanoimprint lithography process. Nanoscale indentation can be used to make the cells for molecular electronics, drug delivery, slots for integration into nanodevices and defects for tailoring both the structure and properties. In this study, the formability of polymethylmetacrylate (PMMA) and polycarbonate (PC) were characterized. Thermo-mechanical properties during formation at a high temperature. Polymers become softer at elevated temperature due to heating. In this case it is particularly important to study the high temperature-induced mechanical properties of the polymer. Nanoindentation was used to measure the thermo-mechanical properties of both PMMA and PC. The polymer was heated with the heating stage on a NanoXP. For a CSM (Continuous Stiffness Method) mode test, the heating temperature was 110°C, 120°C, 130°C, 140°C and 150°C for the PMMA, and 140°C, 150°C, 160°C, 170°C and 180°C for the PC. The maximum indentation depth for this test was 2000 nm. For the basic mode test, the heating temperature was 90°C and 110°C for the PMMA, and 140°C and 160°C for the PC. The maximum loads for this test were 10 mN, 20 mN and 40 mN. An indented pattern was also observed by using AFM. The pile-up phenomenon was mitigated due to the indentation at elevated temperature but the sink-in phenomenon occurred in this instance. When patterning at a high temperature, one should consider the variation in the indentation profile and depth after unloading when designing a structure. It was thought that the mechanical properties decrease when the working temperature increases because PMMA and PC are thermoplastics which soften or melt by heating. Further research in this area is required about the molecular weight and molecular movement at elevated temperature when the free volume of molecules increases.     

Design and Implementation of a Three-Dimensional Temperature Measurement System for Indoor Object Monitoring

Abstract

In this paper, we report the design of a system equipped with a multielement thermopile for monitoring the temperature of indoor objects. We evaluate the performance of our measurement system, which comprises two microcontrollers, an analog-to-digital converter, two stepping motors, and four microswitches. We use an RS-232 or a wireless RS-232 interface that transmits temperature values and uses colors to indicate the temperature range on a PC screen. The system is inexpensive and can be used for three-dimensional temperature measurements. The effective detection range of this system is from ?20°C to 120°C or 180°C; the measurement error is within ±1°C. Experimental results demonstrate the effectiveness of the system for monitoring temperatures of remote indoor objects. Hence, it is possible to identify a hot spot in electrical heating equipment, a smoldering source hidden in upholstery, or the activities of a person in a room.     

A MEMS‐based heating holder for the direct imaging of simultaneous in‐situ heating and biasing experiments in scanning/transmission electron microscopes

The introduction of scanning/transmission electron microscopes (S/TEM) with sub‐Angstrom resolution as well as fast and sensitive detection solutions support direct observation of dynamic phenomena in‐situ at the atomic scale. Thereby, in‐situ specimen holders play a crucial role: accurate control of the applied in‐situ stimulus on the nanostructure combined with the overall system stability to assure atomic resolution are paramount for a successful in‐situ S/TEM experiment. For those reasons, MEMS‐based TEM sample holders are becoming one of the preferred choices, also enabling a high precision in measurements of the in‐situ parameter for more reproducible data. A newly developed MEMS‐based microheater is presented in combination with the new NanoEx?‐i/v TEM sample holder. The concept is built on a four‐point probe temperature measurement approach allowing active, accurate local temperature control as well as calorimetry. In this paper, it is shown that it provides high temperature stability up to 1,300°C with a peak temperature of 1,500°C (also working accurately in gaseous environments), high temperature measurement accuracy (<4%) and uniform temperature distribution over the heated specimen area (<1%), enabling not only in‐situ S/TEM imaging experiments, but also elemental mapping at elevated temperatures using energy‐dispersive X‐ray spectroscopy (EDS). Moreover, it has the unique capability to enable simultaneous heating and biasing experiments. Microsc. Res. Tech. 79:239–250, 2016. © 2016 Wiley Periodicals, Inc.     

Effects of tool–workpiece interface temperature on weld quality and quality improvements through temperature control in friction stir welding

A real-time wireless temperature measurement system has been developed and successfully implemented for closed-loop control of tool shoulder–workpiece interface temperature. The system employs two thermocouples in through holes and measures the shoulder and pin interface temperatures with an angular resolution as small as 10°. Both temperatures correlate with weld quality (mechanical testing and weld cross sections), e.g., all welds in 4.76-mm-thick 6061-T6 with an average shoulder interface temperature below 520 °C and an average pin interface temperature below 460 °C fail in the weld zone instead of the heat-affected zone, have unacceptable tensile strengths and in some cases voids. Similarly, welds with shoulder temperatures above the solidus temperature result in a degradation of the weld quality. It was found that a shoulder interface temperature of 533 °C results in the highest weld quality; hence, this temperature should be used as the setpoint temperature in the control system with a constant travel speed of 400 mm/min. The temperature measurement strategy was shown to be able to indicate welds with insufficient shoulder–workpiece contact, thus potentially identifying and preventing welds with detrimental weld quality due to lack of penetration. It was shown that backing plates of different thermal diffusivity change the heat flow out of the weld zone, hence weld temperature, and caused a measurable impact on the weld strength. By changing other process parameters, e.g., through a temperature control system, weld quality can be maintained in the presence of such changing thermal boundary conditions.     

EBSD coupled to SEM in situ annealing for assessing recrystallization and grain growth mechanisms in pure tantalum

An in situ annealing stage has been developed in‐house and integrated in the chamber of a Scanning Electron Microscope equipped with an Electron BackScattered Diffraction system. Based on the Joule effect, this device can reach the temperature of 1200°C at heating rates up to 100°C/s, avoiding microstructural evolutions during heating. A high‐purity tantalum deformed sample has been annealed at variable temperature in the range 750°C–1030°C, and classical mechanisms of microstructural evolutions such as recrystallization and grain coarsening phenomena have been observed. Quantitative measurements of grain growth rates provide an estimate of the mean grain boundary mobility, which is consistent with the value estimated from physical parameters reported for that material. In situ annealing therefore appears to be suited for complementing bulk measurements at relatively high temperatures, in the context of recrystallization and grain growth in such a single‐phase material.     

基于多壁碳纳米管的QCM甲醛传感器的研究

采用化学还原沉积法制备了经贵金属钯(Pd)修饰的多壁碳纳米管(MWCNTs),Pd均匀地分布在多壁碳纳米管上,Pd/MWCNTs的平均粒径为4 nm.以Pd/MWCNTs作为敏感材料将其均匀地涂覆在石英微振天平(QCM)表面制成QCM甲醛传感器.测试系统安装了2个QCM:参比QCM(洁净的晶振)和敏感QCM(涂覆了 Pd/MWCNTs的晶振),传感器的响应为通入待测气体前后这2个QCM间频率差的变化值.在室温条件下,该气体传感器对甲醛气体具有较明显的响应,线性范围为1.3～65 mg/m3,检出限可达0.026 mg/m3.对13 mg/m3甲醛气体的响应为262.4 Hz,响应时间约为120s,恢复时间约110 s.该传感器具有可重复性、较好的使用寿命和一定选择性.     

Extreme nanomechanics: vacuum nanoindentation and nanotribology to 950 °C

Elevated temperature mechanical and tribological properties can be more relevant for practical wear situations than corresponding measurements at room temperature. However, high temperature nanomechanics and nanotribology is highly challenging experimentally. To overcome these challenges the NanoTest*** has been developed with active heating of the indenter and sample with resistive heaters, horizontal loading, patented thermal control method and stage design. By separately actively heating*** and controlling the temperatures of indenter and sample their temperatures can be precisely matched so that there is no heat flow and minimal/no thermal drift during the high temperature indentation,*** and measurements can be performed as reliably as at room temperature. Above 500 °C it is beneficial to use a cubic Boron Nitride indenter with gas purging to limit oxidation of samples. To achieve higher temperatures without indenter or sample oxidation an ultra-low drift high temperature vacuum nanomechanics/tribology system capable of testing to*** much higher temperatures has been recently developed (NanoTest Xtreme). The influence of time-dependent deformation on elevated temperature nanomechanical behaviour is discussed, using published results in Argon on glass-ceramic solid oxide fuel cell seal materials and previously unpublished nanoindentation measurements on single crystal silicon and polycrystalline tungsten using the NanoTest Xtreme in vacuum at temperatures up to 950 °C. Studies of the elevated temperature nano-/micro-tribological*** behaviour of wear-resistant*** nitride-based and MAX-phase coatings are also briefly reviewed.     

生物传感器阻抗信号测量系统设计与实现

针对生物传感器抗体、抗原特异性结合引起电极两端阻抗值的变化,设计一种可在20Hz-10MHz范围频率内对生物传感器阻抗信号进行测量的系统。文中给出阻抗测量原理,电路的设计与方法,并对该系统进行初步测试,结果表明,该系统可在宽频范围内测量阻抗参数。