Acoustically generated flows in microchannel flexural plate wave sensors: Effects of compressibility

Acoustically generated flowfields in flexural plate wave sensors filled with a Newtonian liquid (water) are considered. A computational model based on compressible flow is developed for the sensor with a moving wall for pumping and mixing applications in microchannels. For the compressible flow formulation, an isothermal equation of state for water is employed. The velocity and pressure profiles for different parameters including flexural wall frequency, channel height, amplitude of the wave and wave length are investigated for four microchannel height/length geometries. It is found that the flowfield becomes pseudo-steady after sufficient number of flexural cycles. Both instantaneous and time averaged results show that an evanescent wave is generated in the microchannel. The predicted flows generated by the FPWs are compared with results available in the literature. The proposed device can be exploited to integrate micropumps with complex microfluidic chips improving the portability of micro-total-analysis systems.     

Modeling flexural plate wave devices

A lumped-parameter model is derived for flexural plate wave (FPW) devices which are rectangular plates or diaphragms with structural layers, a piezoelectric layer, and with interdigitated conducting combs for driving and sensing. This configuration is often used in micromechanical chemical sensors. The model is based an a closed-form solution of a resonating beam; however, the results are applicable to plates supported on four edges. The model gives a voltage or charge output from the sense combs as a function of voltage applied to the drive combs. The analysis predicts the response of the multiple plate modes to axial tensions and to comb finger dimensions and position relative to the diaphragm eigenfunctions. These models are much more detailed than those described in the literature on acoustic chemical sensors and are difficult to obtain by finite-element solutions. Frequency responses of FPW devices constructed from silicon with deposited aluminum nitride as the piezoelectric compared well with analytic results. The effects of boundary conditions on the plate's lateral edges are discussed in both the analysis and testing     

Fluid damping in resonant flexural plate wave device

Fluid damping models are developed for resonant (standing wave) flexural plate wave (FPW) devices, which are rectangular plates or diaphragms with structural layers, a piezoelectric layer, and interdigitated conducting combs for driving and sensing. This configuration is often used in micromechanical chemical, biological, or nonvolatile residue sensors. Where much of the previous work on fluid effects in FPW devices focused on delay lines, this effort investigates resonant devices both analytically and experimentally. The fluid model is based on closed-form solution of a wide beam vibrating into a semi-infinite fluid volume and is mated directly into the beam equation. While the fluid's pressure versus wave motion solution has been reported previously, the application to the resonant FPW is mathematically rigorous and leads to a greater understanding of the FPW damping regimes. Frequency responses of FPW devices constructed from silicon with deposited piezoelectric aluminum nitride and operating in water and alcohol compared well with analytic results with some discrepancies noted.     

姿态传感器在坐底式ADCP波阵列中的应用

ADCP波潮仪利用ADCP波阵列技术测量方向谱.由于宽带ADCP具有独特的空间测点阵列,所以不仅具备了传统阵列测量方向谱的高精度,同时由于ADCP是一个单体设备,像浮标一样有很好的操控性.ADCP内部的姿态传感器实时测量出ADCP的姿态偏角(航向、俯仰、横滚),当ADCP存在较大倾斜时,必须要进行基于姿态传感器测量值的...     

基于集成气体传感器阵列的电子鼻系统

介绍一种基于集成气体传感器阵列的电子鼻系统硬件实现方法。描述了系统的一般组成,重点介绍了所采用的集成气体传感器及其信号拾取方法。该系统可实现对检测气体的自动数据采集、微机传送,具有高的灵敏性和可靠性。另外,对采用的集成气体传感器系列,该电子鼻系统具有一定的通用性。利用该系统对五种葡萄酒进行了检测,结果表明:该电子鼻系统可有效地用于葡萄酒的定性识别,识别准确率达到100%。     

Meter-scale large-area capacitive pressure sensors with fabric with stripe electrodes of conductive polymer-coated fibers

We developed meter-scale large-area capacitive fabric pressure sensors for floor sensors to monitor human position. In the fabric pressure sensor, two fabrics with stripe electrodes of conductive polymer-coated fibers woven into them were stacked vertically, and the capacitance changes between the top and bottom stripe electrodes were measured when pressure was applied. By using the die-coating of a conductive polymer and weaving the resultant fibers with meter-scale automatic looming machines, the 1 m × 1 m area with stripe electrodes at a 20 cm pitch was constructed. The pressure sensitivity, which depends on the number of the sensor fibers forming the stripe electrodes, was characterized and optimized to increase output capacitance change. The stripe electrodes with five sensor fibers were found to exhibit a capacitance change of 1.37 pF when pushed with the average foot pressure (i.e., 2.6 N/cm²), which is large enough to detect with conventional capacitance measurement circuits. Finally, pressure sensing with our woven pressure sensor fabric is demonstrated. Our meter-scale pressure sensor fabric technology will be used for bed and floor sensors for monitoring old people in nursing homes and hospitals.     

Activity recognition with hand-worn magnetic sensors

Activity recognition is a key technology for realizing ambient assisted living applications such as care of the elderly and home automation. This paper proposes a new activity recognition method that employs hand-worn magnetic sensors to recognize a broad range of activities ranging from simple activities that involve hand movements such as walking and running to the use of portable electrical devices such as cell phones and cameras. We sense magnetic fields emitted by electrical devices and the earth with hand-worn sensors, and recognize what a user is doing or which electrical device the user is employing. We frequently use a large number of different electrical devices in our daily lives, and so we can estimate high-level daily activities by recognizing their use. Our approach permits us to recognize a range extending from low-level simple activities to high-level activities that relate to the hands without the need to attach any sensors to the electrical devices.     

Designing an integrated driver assistance system using image sensors

Road accidents cause a great loss to human lives and assets. Most of the accidents occur due to human errors, such as bad awareness, distraction, drowsiness, low training, and fatigue. Advanced driver assistance system (ADAS) can reduce the human errors by keeping an eye on the driving environment and warning a driver to the upcoming danger. However, these systems come only with modern luxury cars because of their high cost and complexity due to several sensors employed. Therefore, camera-based ADAS are becoming an option due to their lower cost, higher availability, numerous applications and ability to combine with other systems. Targeting at designing a camera-based ADAS, we have conducted an ethnographic study of drivers to know what information about the driving environment would be useful in preventing accidents. It turned out that information on speed, distance, relative position, direction, and size and type of the nearby objects would be useful and enough for implementing most of the ADAS functions. Several camera-based techniques are available for capturing the required information. We propose a novel design of an integrated camera-based ADAS that puts technologies??such as five ordinary CMOS image sensors, a digital image processor, and a thin display??into a smart system to offer a dozen advanced driver assistance functions. A basic prototype is also implemented using MATLAB. Our design and the prototype testify that all the required technologies are now available for implementing a full-fledged camera-based ADAS.     

A method for evaluating data-preprocessing techniques for odourclassification with an array of gas sensors

The performance of a pattern recognition system is dependent on, among other things, an appropriate data-preprocessing technique, In this paper, we describe a method to evaluate the performance of a variety of these techniques for the problem of odour classification using an array of gas sensors, also referred to as an electronic nose. Four experimental odour databases with different complexities are used to score the data-preprocessing techniques. The performance measure used is the cross-validation estimate of the classification rate of a K nearest neighbor voting rule operating on Fisher's linear discriminant projection subspace.     

NEMS diaphragm sensors integrated with triple-nano-ring resonator

Two types of circular diaphragm, made by Si and Si/SiO₂, integrated with hexagonal photonic crystal (PhC) lattice with triple-nano-ring (TNR) resonator created at the centre are proposed as nano-scale force and pressure sensor. The optimized channel drop effect of the TNR resonator brings a strong forward drop resonant peak in both the cases and with Q-factor of 1602 and 1737, respectively. The resonant wavelength peak experience red shifts upon the applied load on the circular diaphragm along the normal direction, in terms of a 2nd-order polynomial relationship. The devices can detect a wide range of applied load. Si diaphragm based micro force sensor gives minimum detectable force of 0.847 μN in the region of applied force from 10 to 20 μN. Si/SiO₂ diaphragm based pressure sensor gives minimum detectable pressure of 4.17 MPa in the region of applied pressure from 20 to 40 MPa. From the derived wavelength shift versus a given centre displacement of the diaphragm, Si diaphragm based sensor shows higher sensitivity than Si/SiO₂ diaphragm sensor.     

Development of a micro biochip integrated traveling wave micropumps and surface plasmon resonance imaging sensors

Since most of miniaturized surface plasmon resonance (SPR) sensing systems need commercially available peristaltic or syringe pumps, it is difficult to reduce the system size, biosample volume, and the production cost. In this paper, a compact biochip for clinical diagnosis is presented. The proposed biochip is integrated traveling wave micropumps and SPR imaging sensors on one chip. The micropump is composed of flexible microchannel and piezoelectric bimorph actuator array, and achieved the maximum flow rate 336 μl/min. The SPR imaging biosensor can quantitatively measure biosamples with multi microchannels, i.e. one biosample and two reference flows to obtain an analytical curve. The SPR imaging measurements with bovine serum albumin solutions were carried out using the prototype of the proposed diagnostic system composed of a pair of the micropump and the sensor. Since the clear SPR signal curve was observed, it was confirmed that the proposed system can be applicable to the clinical diagnosis.     

Detecting faulty sensors in an array using symmetrical structure and cultural algorithm hybridized with differential evolution

The detection of fully and partially defective sensors in a linear array composed of N sensors is addressed. First, the symmetrical structure of a linear array is proposed. Second, a hybrid technique based on the cultural algorithm with differential evolution is developed. The symmetrical structure has two advantages: (1) Instead of finding all damaged patterns, only (N–1)/2 patterns are needed; (2) We are required to scan the region from 0° to 90° instead of from 0° to 180°. Obviously, the computational complexity can be reduced. Monte Carlo simulations were carried out to validate the performance of the proposed scheme, compared with existing methods in terms of computational time and mean square error.     

A real-time vision system using an integrated memory array processor prototype

This paper describes a real-time vision system (RVS) architecture and performance and its use of an integrated memory array processor (IMAP) prototype. This prototype integrates eight 8-bit processors and a 144-kbit SRAM on a single chip. The RVS was developed with 64 IMAP prototypes connected in series in a 512 processor-system configuration. A host workstation can access the memory on the IMAP prototypes directly through a random access port. Images are inputted and outputted at high speed through serial access ports. The RVS performance is shown in real-time road-image processing and in a neural network simulation, as well as in low-level image processing algorithms, such as filtering, histograms, discrete cosine transform (DCT), and rotation. The RVS image processing is shown to be much faster than the video rate.     

3D-printed microfluidic manipulation device integrated with magnetic array

This paper reported a transparent, high-precision 3D-printed microfluidic device integrated with magnet array for magnetic manipulation. A reserved groove in the device can well constrain the Halbach array or conventional alternating array. Numerical simulations and experimental data indicate that the magnetic flux density ranges from 30 to 400 mT and its gradient is about 0.2–0.4 T/m in the manipulation channel. The magnetic field parameters of Halbach array in the same location are better than the other array. Diamagnetic polystyrene beads experience a repulsive force and move away from the magnetic field source under the effect of negative magnetophoresis. It is undeniable that as the flow rate increases, the ability of Halbach array to screen particle sizes decreases. Even so, it has a good particle size discrimination at a volumetric flow rate of 1.08 mL/h, which is much larger than that of a conventional PDMS device with a single magnet. The observed particle trajectories also confirm these statements. The deflection angle is related to the magnetic field, flow rate, and particle size. This 3D-printed device integrated with Halbach array offers excellent magnetic manipulation performance.     

An integrated chemical sensor with multiple ion and gas sensors

An integrated chemical sensor with multiple ion and gas sensors, composed of four ISFETs (pH, Na⁺, K⁺ and Cl⁻) and two gas sensors (P_O2 and P_CO2) on a 4 mm × 4 mm chip, is realized using semiconductor processing. The ISFETs are based on an Si₃N₄-gate ISFET, and use polymeric membrane except for the pH ISFET. The P_O2 sensor is a miniaturized Clark-type sensor, consisting of a Pt cathode and Ag/AgCl anode patterned by the lift-off process. The P_CO2 sensor is a miniaturized Severinghaus-type sensor using a pH ISFET. All of the ISFETs show sensitivities over 50 mV/decade, and a linear range between 1 × 10⁻⁴ and 5 × 10⁻¹ mol/l. The sensitivities of the P_O2 and P_CO2 sensors are 0.35 nA/mmHg and 42 mV/decade, respectively, and their response times are 30 s and 1 min, respectively. The integrated chemical sensor with multiple ion and gas sensors could be used for clinical analysis.     

面阵CCD图像传感器不均匀性的校正

针对面阵CCD不均匀性特性 ,对降低CCD不均匀性的不同方法进行了探讨 ,结合某参数测试系统的研制 ,对使用基于参考光源的多点因子加权法的校正进行了讨论 ,为使用面阵CCD进行高精度测量提供实用的降低噪声措施和校正步骤。     

Rapid differentiation between E. coli and Salmonella Typhimurium using metal oxide sensors integrated with pattern recognition

A rapid method to differentiate between E coli and Salmonella Typhimurium was developed. E. coli and S. Typhimurium were separately grown in super broth and incubated at 37 °C. Super broth without inoculation of E. coli or S. Typhimurium was used as control. Numbers of E. coli and S. Typhimurium were followed using a colony counting method. Identification of the volatile metabolites produced by E. coli and S. Typhimurium was determined using solid-phase microextraction coupled with gas chromatography/mass spectrometry. An electronic nose with 12 non-specific metal oxide sensors was used to monitor the volatile profiles produced by E. coli and S. Typhimurium. Principal component analysis (PCA) and back-propagation neural network (BPNN) were used as pattern recognition tools. PCA was used for data exploration and dimensional reduction. PCA could visualize class separation between sample subgroups. The BPNN was shown to be capable of predicting the number of E. coli and S. Typhimurium. Good prediction was possible as measured by a regression coefficient (R² = 0.96) between true and predicted data. Using metal oxide sensors and pattern recognition techniques, it was possible to discriminate between samples containing E. coli from those containing S. Typhimurium.     

Three-axis pneumatic tactile display with integrated capacitive sensors for feedback control

In this paper, we propose a three-axis pneumatic tactile display that is precisely controlled by using integrated capacitive displacement sensors. The proposed tactile display consists of a core body with a 3 × 3 balloon array on its top surface, four lateral balloons made of latex rubber, and inner and outer frames that include capacitive displacement sensors based on a flexible printed circuit board. The 3 × 3 balloon array on the core body is designed to apply normal haptic stimulation to a human fingertip. In addition, the lateral motions of the core body and each frame produce haptic stimulation in a tangential direction. Precise control of lateral motion was achieved by feedback control using the capacitive displacement sensors. The size of the fabricated tactile display was 26 × 26 × 18 mm³. We experimentally performed manipulation of the proposed device with a custom control system, thereby demonstrating accurate control of displacement.