基于交直流分离的反射式血氧饱和度测量系统的设计

肝储备功能是评价肝脏正常生理活动的重要依据,动脉血氧饱和度是肝储备功能测量的重要中间变量,针对长时间连续无创血氧饱和度测量的要求,提出基于交直流分离的反射式血氧测量系统的设计方案。通过测量手指、耳尖等皮肤薄弱部位的反射式光电容积脉搏波,利用交直流信号分离处理技术,基于动脉血氧饱和度经验测量公式,实现长时间无创动脉血氧饱和度测量。交直流分离技术的使用能够有效的降低系统干扰和噪声的影响,优化血氧饱和度测量结果;经临床医疗对比实验检测,证明系统误差符合实际测量要求。     

Remote flood monitoring system based on plastic optical fibres and wireless motes

This paper summarises an effort in the development of a remote flood monitoring system based on plastic optical fibre (POF) sensors and a wireless mote network. The wireless mote, comprising of a network of MICA2DOT™ units, was used as a platform to monitor and record the signal from the POF sensors and transmit this information to a base station wirelessly. A prototype of the integrated wireless POF sensor unit has been constructed, rendering it possible to deploy the autonomous unit remotely at multiple monitoring points as required. A flood monitoring simulation was carried out in a 24 m × 10 m × 0.9 m wave basin where four of these wireless optical fibre mote sensors were used to detect the rising water level in the basin. The novelty of the work lies in the successful integration of the wireless platform to a POF-based liquid level sensor and the subsequent demonstration of the prototype of the system for the purposes of flood monitoring applications.The sensing principle of the POF sensor developed here is well-known and is based on the loss of total internal reflection of the optical signal as the sensor probe comes in contact with the liquid. Compared to optical fibre-based sensors reported previously in the literature, the probe profile used in this study differs in terms of its simplicity in design, while exhibiting an excellent signal intensity loss ratio without the need for additional attachments to the probe such as optical prisms. The tests carried out showed that the POF sensor is capable of detecting a variety of fluids. Exhibiting good signal stability, the sensor also detects the liquid level reliably when the liquid rises or falls to the predetermined level. The responsiveness of the optical fibre sensor was evaluated by simulating different rates at which the liquid rises by immersing the sensor tip into the liquid and vice-versa at various speeds ranging from 1 mm/min to 500 mm/min.     

PC sound card-based simple instrument for the potentiometric sensors

Development of a simple and low-cost instrument using a PC sound card for the potentiometric sensors has been reported in this work. It consists of a scanning-DC type data acquisition system which will allow us to acquire an AC signal data corresponding to the scanning-DC signal. Therefore in physical or chemical device characterization it can be used to acquire any DC dependent parameter such as the dielectric constant, capacitance, photocurrent of semiconductor heterostructure, electrochemical parameters, etc. Speaker port of the sound card has been used here to deliver an AC (0 –1 V) that is converted to a corresponding DC voltage externally by a hardware composed of a half-wave precision rectifier (HWPR), a low-pass filter and a level-shifter. The DC voltage can be scanned from +2 to −2 V in any desired steps. The PC sound card Microphone input has been used to collect the AC signal corresponding to the DC voltage steps. For outputting the DC an AC voltage having a frequency of 4000 Hz is sent to the PC sound card Speaker port. The sampling rate for the output voltage is fixed at 8000 sample/s. For collecting the data the configurable sampling rate (>Nyquist rate) depending on the frequency of the input signal has been used. As a test case it has been applied to obtain the AC photocurrent response of a Si₃N₄/SiO₂/Si heterostructure. The experimental results show a good promise for the novel very simple instrument to be used in the potentiometric sensing as well as an important tool for the characterization of physical and chemical devices.     

超磁致伸缩薄膜/光纤的制备及其磁探测性能

采用磁控溅射工艺在光纤表面制备了厚度均匀的TbDyFe超磁致伸缩薄膜。利用马赫 曾德尔干涉仪对TbDyFe超磁致伸缩薄膜/光纤传感器的磁探测性能进行了实验测试。结果表明:在调制频率f=1kHz附近,传感器对磁场具有最大的信号响应;在恒定直流磁场及调制磁场强度小于1kA/m的条件下,输出信号大小随调制磁场强度线性增加;在35～50kA/m的直流磁场范围内,传感器(对应1m长传感臂)可探测的最小磁场变化Hmin=8.6×10-2A/m,若采用分辨力为10-6rad的干涉仪并增加镀膜光纤的长度和薄膜厚度,则可进一步提高传感器的磁探测灵敏度。     

A low-power scan driver employing IZO TFTs including an AC–DC type output module

This paper presents a low-power and simple scan driver with a new output module called as AC–DC type output module. 46 stages of the scan driver are fabricated by integrating In–Zn–O Thin-film transistors (IZO TFTs) with back channel etch (BCE) structure on the glass substrate. Under 100 hours’ test, it is shown that the voltage fluctuation of the output signal can be well suppressed by the proposed AC–DC type output module up to the whole 46 stages. The power consumption can be obviously reduced by using the AC–DC type output module compared with the conventional AC–AC type output module. It is measured that the power consumption of one stage for the proposed scan driver with AC–DC type output module at the clock frequency of 16.7 kHz is 170 μW, as well as 393 μW for the proposed scan driver with the conventional AC–AC type output module. It is shown from the simulation results that there is a good tradeoff between the power consumption and the rising time for the proposed AC–DC type output module compared with AC–AC type output module and DC–DC type output module.     

基于反射式血管容积波的心理压力测量

由于计算机对人认知与情感方面的利用将有助于未来智能生活的实现,同时研究发现,血液容积脉搏波（photo-plethysmography,简称PPG)信号包含的心脏收缩与血管壁本身压力的效果将有助于对人体心理压力及情感测量的分析,因此介绍了通过利用反射式血氧传感器得到PPG波形,并采用压力血氧反应指数（stress-induced vascular responses index,简称sVRI)模型来分析人体目前的压力值,验证反射式传感器对于人体心理压力测量方面的适用性.实验中不仅比较了传统透射式传感器与反射式传感器在双波长（红光与红外光)正常情况与压力情况下PPG波形的差异,同时也引入了新的波长——绿光,即利用绿光反射式传感器,通过sVRI模型来分析人体的压力值.通过比较与讨论,证明了反射式血氧传感器的适用性.最后,将实验结果与sVRI模型相结合应用于实验鼠标模型中,将反射式传感器所携带的生理信息应用于日常生活中,其佩戴更加舒适以及佩戴位置范围更广的优点适合脉搏检测的高性能医疗保健设备及可穿戴智能设备.     

Highly sensitive micromachined capacitive pressure sensor with reduced hysteresis and low parasitic capacitance

This paper describes the design and fabrication of a capacitive pressure sensor that has a large capacitance signal and a high sensitivity of 76 pF/bar in touch mode operation. Due to the large signal, problems with parasitic capacitances are avoided and hence it is possible to integrate the sensor with a discrete components electronics circuit for signal conditioning. Using an AC bridge electronics circuit a resolution of 8 mV/mbar is achieved. The large signal is obtained due to a novel membrane structure utilizing closely packed hexagonal elements. The sensor is fabricated in a process based on fusion bonding to create vacuum cavities. The exposed part of the sensor is perfectly flat such that it can be coated with corrosion resistant thin films. Hysteresis is an inherent problem in touch mode capacitive pressure sensors and a technique to significantly reduce it is presented.     

High performance red and green phosphorescent emitters suitable for the BT.2020 color gamut

In this work, we investigated the potential for phosphorescent emitters to achieve the BT.2020 color standard in displays, where the CIE coordinates for red and green are (0.709, 0.292) and (0.170, 0.797), respectively. Optical simulations were performed for both green and red top emission organic light emitting devices (OLEDs). For the green emitter, it is possible to reach (0.170, 0.785) using a spectrum with a peak wavelength (λ_max) at 526 nm and a full width at half maximum (FWHM) less than 30 nm. For the red emitter, in order to achieve (0.708, 0.292) while maintaining a high current efficiency (CE), it is important to decrease the FWHM instead of red-shifting the spectrum. Following the guidance of these simulation results, we designed and synthesized novel deep green (DGD) and deep red phosphorescent (DRD-II) emitters. The photoluminescent (PL) spectrum of DGD shows an FWHM of 30 nm and a λ_max of 523 nm. A top-emission green OLED built using DGD reached a CE of 171 cd/A at an operating voltage of 3.3 V and a lifetime of 95% of initial brightness (LT₉₅) > 1300 h at 10 mA/cm² with a CIE (x, y) = (0.170, 0.777). This is, to our knowledge, the best device performance ever reported for a green phosphorescent OLED at this CIE y. The PL spectrum of DRD-II has a λ_max of 630 nm with an FWHM of 30 nm. A top-emission red OLED built with DRD-II achieved a CE of 59 cd/A, an operating voltage of 3.2 V and an LT₉₅ over 20,000 h at a drive current of 10 mA/cm² with a CIE (x, y) = (0.708, 0.292). We also studied the angular dependence of the above devices and found they were comparable to devices with commercial emitters for the Digital Cinema Initiative P3 (DCI-P3) standard that had a wider FWHM. Combining these green and red emitters with a commercial blue OLED at (0.131, 0.046), we are able to cover 97% of the BT.2020 color gamut. The results using DGD and DRD-II suggest that they have great potential to satisfy BT.2020 in an organic phosphorescent system.     

The effect of transmittance and luminous efficiency with the application of cathode mesh mask in transparent organic light‐emitting devices

With the development of organic light‐emitting devices (OLEDs), the transparent OLED is also restricted by its efficiency and stability. Thus, in order to improve the transmittance and luminous efficiency of transparent OLED, the cathode mesh mask combined with Al:Ag alloy is adopted to prepare the cathode of transparent OLED, which would enhanced the luminance, efficiency, and transmittance of the device. With the same driving voltage, the device has the highest brightness, when the cathode thickness is 85 nm. At the voltage of 13 and 14 V, the luminance, for bottom‐emission and top‐emission, is 9501 cd/m² and 1840 cd/m², respectively. The entire transmittance of the device has achieved about 78% at a 480 nm wavelength.     

基于打印聚合物薄膜技术的NH_3传感器

研究了一种新型的采用打印技术的NH3传感器,探讨了打印"墨水"材料聚苯胺和聚吡咯的制备和"墨水"掺酸比例对NH3传感器敏感度的影响。为了提高传感器灵敏度,分别对传感器的直流和交流阻抗特性进行了研究。结果发现在1.5 kHz左右交流阻抗的测试条件下,传感器灵敏度要较直流阻抗测试高近1个数量级。此外还通过构建1个交流阻抗拟合模型对传感器交流阻抗变化过程作了解释。研究的采用打印技术基于聚合物的NH3传感器具有成本低,可以制作在柔性衬底上和适合大规模生产等特点,在食品加工、养殖业和医疗等领域具有广泛的应用前景。     

基于OTDR的光路监测终端设计

针对目前光纤通信网络规模的不断扩大以及人们对光通信网可靠性的需求,该文研制了一种基于OTDR的光路监测终端。该装置由数据处理模块、光路监测模块、电源模块、人机交互模块等组成。数据处理模块由STM32F407芯片及其子系统组成;光路监测模块由OPM模块以及OTDR模块组成,OPM模块对光路性能参数进行监控,包括功率、波长等,用于发现光路故障,OTDR模块可检测到故障点与监测终端的距离;电源模块由开关电源模块与降压芯片组成,能将220 V交流电转换为5 V/3.3 V直流电,为CPU以及各模块提供电源;人机交互模块采用了0.96寸OLED和GPRS模块组成。软件基于轮询的方式,将监测模块采集的数据进行故障分析,定位故障点,将位置信息以短信方式发送给维护人员,并在OLED上显示光路故障告警信息。     

Intrinsic Power Management Strategy based improvement of power stability in a single-phase AC–DC converter system

Nowadays the size of the use of electronic devices like laptops, cell phone chargers, electric vehicles and UPS is rapidly increasing. So AC–DC converters need to incorporate the power factor correction along with voltage regulation. There are many AC–DC converter control methods available, but these methods do not perform well. Therefore In this paper, a smooth transformation on switching will be characterized by a high power factor in a single phase AC–DC converter by the use of intrinsic power management strategy. The proposed AC–DC converter's circuit topology is obtained by integrating a boost and buck converter. The Boost Converter's switching frequency does power factor correction to get less current harmonics at the input line. In this single phase AC–DC converter, the buck-boost converter is an important component that increases system power quality based on advanced PWM technique. So in this work, the Intrinsic Power Management Strategy (IPMS) is proposed to enhance the control over the DC–DC converter performance during unstable or transient operation. Rather than making a quick Pulse Width Modulation (PWM) signal, the computerized signal processor just creates a moderate changing DC signal to decide the PWM ramp function. The power factor correction model has been created and simulated by utilizing MATLAB programming. The simulation model demonstrates that the power factor is improved and the converter has regulated DC output voltage. To validate this simulation, a 1000 W prototype converter has been developed to feed a DC motor and the analysis of the results are presented.     

Optical flow approximation based motion object extraction for MPEG-2 video stream

This paper presents a compressed-domain motion object extraction algorithm based on optical flow approximation for MPEG-2 video stream. The discrete cosine transform (DCT) coefficients of P and B frames are estimated to reconstruct DC + 2AC image using their motion vectors and the DCT coefficients in I frames, which can be directly extracted from MPEG-2 compressed domain. Initial optical flow is estimated with Black’s optical flow estimation framework, in which DC image is substituted by DC + 2AC image to provide more intensity information. A high confidence measure is exploited to generate dense and accurate motion vector field by removing noisy and false motion vectors. Global motion estimation and iterative rejection are further utilized to separate foreground and background motion vectors. Region growing with automatic seed selection is performed to extract accurate object boundary by motion consistency model. The object boundary is further refined by partially decoding the boundary blocks to improve the accuracy. Experimental results on several test sequences demonstrate that the proposed approach can achieve compressed-domain video object extraction for MPEG-2 video stream in CIF format with real-time performance.     

Novel U-shape gold nanoparticles-modified optical fiber for localized plasmon resonance chemical sensing

A novel fiber-optic localized plasma resonance (FO-LPR) sensor composed of a U-shape optical fiber was proposed and demonstrated in this study. The U-shape optical fiber was fabricated by a femtosecond laser micromachining system. The dimensions of the U-shape zone were 100 μm in depth measured from the surface of the polymer jacket layer, 80 μm in width in the jacket layer, 60 μm in width in the cladding layer. The total length is 5 mm. After laser annealing treatment, the average surface roughness was 205.8 nm as determined by Atom Force Microscope (AFM). The exposed surface of the U-shape fiber was modified with self-assembled gold nanoparticles to produce the FO-LPR sensor. The response of the sensor shows that the signal increases linearly with increasing refractive index. The sensor resolution of the sensor was determined to be 1.06 × 10⁻³ RIU.     

Fabrication of a metal protector for a fiber sensor using through-mask electrochemical micromachining with pulse DC power

The purpose of this study is to fabricate a stainless steel protector for a weak fiber sensor after first stripping the polymer outer-layer off the fiber. In addition to protecting the fiber sensor, the stainless steel protector is required to connect the detection target and the sensor which requires drilling holes in the protector. We accomplished this by electrochemical micromachining the stainless steel protector using pulse DC, using 1 kV/m, 6.62% weight concentration of NaCl electrolyte solution, 500 rpm anode rotating rate, a 5 MHz pulse frequency, a 50% duty factor, and 6 min of machining time with a ring cathode gave the best results, producing an average hole-radius of 231.36 μm.     

飞机襟翼收放角度检查系统设计

介绍了我军某国产战斗机襟翼角度控制原理、真有效值测量器件AD737的结构原理及利用AD737检查襟翼收放角度的方案;该系统利用低频正弦信号发生器ICL8038产生供飞机上襟翼收放角度测量用的传感器2902所需的交流信号,用真有效值测量芯片AD737测量传感器2902的交流输出后送入AD板中进行转换,再送入计算机中进行处理;经使用表明,利用AD737测量线位移传感器2902的真有效值输出的方法检查飞机襟翼收放角度,简单方便,准确可靠,满足了该型飞机的保障要求。     

Ink‐jet‐printable phosphorescent organic light‐emitting‐diode devices

Abstract— A novel method for the fabrication of ink‐jet‐printed organic light‐emitting‐diode devices is discussed. Unlike previously reported solution‐processed OLED devices, the emissive layer of OLED devices reported here does not contain polymeric materials. The emission of the ink‐jet‐printed P²OLED (IJ‐P²OLED) device is demonstrated for the first time. It shows good color and uniform emission although it uses small‐molecule solution. Ink‐jet‐printed green P²OLED devices possess a high luminous efficiency of 22 cd/A at 2000 cd/m² and is based on phosphorescent emission. The latest solution‐processed phosphorescent OLED performance by spin‐coating is disclosed. The red P²OLED exhibits a projected LT50 of >53,000 hours with a luminous efficiency of 9 cd/A at 500 cd/m². The green P²OLED shows a projected LT50 of >52,000 hours with a luminous efficiency of 35 cd/A at 1000 cd/m². Also discussed is a newly developed sky‐blue P²OLED with a projected LT50 of >3000 hour and a luminous efficiency of 18 cd/A at 500 cd/m².     

Contact CMOS imaging of gaseous oxygen sensor array

We describe a compact luminescent gaseous oxygen (O₂) sensor microsystem based on the direct integration of sensor elements with a polymeric optical filter and placed on a low power complementary metal-oxide semiconductor (CMOS) imager integrated circuit (IC). The sensor operates on the measurement of excited-state emission intensity of O₂-sensitive luminophore molecules tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)₃]²⁺) encapsulated within sol-gel derived xerogel thin films. The polymeric optical filter is made with polydimethylsiloxane (PDMS) that is mixed with a dye (Sudan-II). The PDMS membrane surface is molded to incorporate arrays of trapezoidal microstructures that serve to focus the optical sensor signals on to the imager pixels. The molded PDMS membrane is then attached with the PDMS color filter. The xerogel sensor arrays are contact printed on top of the PDMS trapezoidal lens-like microstructures. The CMOS imager uses a 32 × 32 (1024 elements) array of active pixel sensors and each pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. Correlated double sampling circuit, pixel address, digital control and signal integration circuits are also implemented on-chip. The CMOS imager data is read out as a serial coded signal. The CMOS imager consumes a static power of 320 μW and an average dynamic power of 625 μW when operating at 100 Hz sampling frequency and 1.8 V DC. This CMOS sensor system provides a useful platform for the development of miniaturized optical chemical gas sensors.     

A survey on wireless sensor network infrastructure for agriculture

The hybrid wireless sensor network is a promising application of wireless sensor networking techniques. The main difference between a hybrid WSN and a terrestrial wireless sensor network is the wireless underground sensor network, which communicates in the soil. In this paper, a hybrid wireless sensor network architecture is introduced. The framework to deploy and operate a hybrid WSN is developed. Experiments were conducted using a soil that was 50% sand, 35% silt, and 15% clay; it had a bulk density of 1.5 g/cm³ and a specific density of 2.6 cm^? 3. The experiment was conducted for several soil moistures (5, 10, 15, 20 and 25%) and three signal frequencies (433, 868 and 915 MHz). The results show that the radio signal path loss is smallest for low frequency signals and low moisture soils. Furthermore, the node deployment depth affected signal attenuation for the 433 MHz signal. The best node deployment depth for effective transmission in a wireless underground sensor network was determined.     

OLED‐based pico‐projection system

Abstract— Two pico‐projection systems, a monochrome green and a full‐color system, based on high‐efficiency OLED microdisplays (VGA; pixel size, 12 μm) are presented. Both optical systems are described by a numerical aperture of about 0.3, a magnification of 15x, and a working distance of 300–360 mm. The frequency limit of both systems is 42 cycles/mm at an image contrast of about 60%. The monochrome projection system with a volume smaller than 10 cm³ consists of one green OLED and a projection lens with five elements. The measured luminance in the image plane is about 0.061 lm. The image has a diagonal of 150 mm with a working distance of about 300 mm and has a considerable image contrast of 396:1. The second system combines three high‐brightness OLEDs, red, green, and blue colored, together with a projection lens and an image‐combining element, and an X‐Cube to achieve full‐color projection. The estimated luminance value for the three‐panel projection unit with an OLED luminance of 10,000 cd/m² for each display will be about Φcalculated = 0.147 lm. In this paper, the system concepts, the optical designs, and the realized prototypes of the monochrome and full‐color projection system are presented.