In this work, we synthesize a series of compounds with electron donor (D) and acceptor (A) units. They show general solvent effect in aprotic solvents, suggesting a charge transfer (CT) process. While in protic solven...
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In this work, we synthesize a series of compounds with electron donor (D) and acceptor (A) units. They show general solvent effect in aprotic solvents, suggesting a charge transfer (CT) process. While in protic solvents including water, ethanol and methanol, the spectra exert no polarity-dependence but a remarkable hypochromatic shift together with the fading of CT band. Dynamic analysis implies that intermolecular hydrogen bond will be formed between carboxylic acid and protic solvent, boosting another deactivation pathway that jumps off a bigger energy gap, in other words, favoring the locally excited (LE) state emission. The CT-LE transition involves variations in both absorption and emission spectra, and further poses competition with other mechanisms including activated/restricted intramolecular rotation (IR/RIR). Inspired by the cross-reactivity, we turn our attention to the development of sensor array, in order to identify white wine varieties. The differential spectral responses are recorded, generating multiple factors including absorption wavelength (lambda(ab)), emission wavelength (lambda(em)), absorbance (Abs.) and emission intensity (Int.). These factors are processed with principal component analysis (PCA), creating a three-dimensional fingerprint data base for white wines. The data points in the coordinate system are clustered into 10 different groups, demonstrating a clear differentiation of all the white wines. More importantly, as our final test for whether the sensor array can identify the counterfeits, an adulterated liquor sample, which is provided by police officers, is fingerprinted on the three-dimensional diagram. Its canonical factors fall into an area distinct from the adulterated wine, indicating a clear identification. (C) 2017 Elsevier B.V. All rights reserved.
In this paper, an electronic tongue (ET) based on a quartz-crystal microbalance (QCM) sensor array was designed and the methods for sensor data analysis were described. In this regard, as chemical sensors, QCM crystal...
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In this paper, an electronic tongue (ET) based on a quartz-crystal microbalance (QCM) sensor array was designed and the methods for sensor data analysis were described. In this regard, as chemical sensors, QCM crystals coated with three different phthalocyanines were employed to discriminate toxic chemicals in liquid media. For sensors' preparation, an automatic coating instrument was developed based on the airbrush technique. The oscillator circuits used in the coating instrument and measurement setup were optimized to minimize the noise and mutual interference of the other oscillator circuits in the sensor array. The designed measurement system, which was responsible for collecting and storing data, communicating with a computer, consisted of a field-programmable gate-array-based control unit. The measurement system collected training data from the sensor array, and then computer application using MATLAB used an artificial neural network to find the composition of toxic chemicals in the sample water. The measurement system was tested for three different toxic chemicals, and the average success rate in predicting them was 4.08%. The desired chemicals can be detectable by preparing the necessary sensor array with the proposed ET.
Magnetic field imaging (MFI) is widely used in electromagnetic nondestructive evaluation (ENDE). This paper presents a high-density, large-scale tunneling magnetoresistance (TMR) sensor array for MFI applied in ENDE. ...
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Magnetic field imaging (MFI) is widely used in electromagnetic nondestructive evaluation (ENDE). This paper presents a high-density, large-scale tunneling magnetoresistance (TMR) sensor array for MFI applied in ENDE. The TMR array consists of 180 sensing elements with the distance of 0.5 mm between any pair of TMR sensors adjacent to each other, which enables to acquire an image with high spatial resolution. With a total length of 90 mm, the TMR array is capable of imaging a rectangular area as wide as 90 mm in a single scan resulting in a fast inspection speed for the evaluation of structure with a large surface area. The proposed TMR sensor array has high sensitivity to the magnetic field in a wide frequency range. Therefore, it can be used for the detection of deeply embedded defects in multilayer riveted structures with excitation currents at ultralow frequencies. Experimental results show that machined notches under fasteners head at a distance of 8 mm from the top surface of a multilayer riveted aluminum structure can be detected with a proper fusion of the magnetic field images at 100 and 1000 Hz. Furthermore, surface notch with dimension 300 mu m x 300 mu m x 400 mu m on an aluminum sample can be detected from the obtained magnetic field image with excitation current frequency 20 kHz.
A brand-new colorimetric sensor array was developed based on cross-reactive mechanism to discriminate 9 kinds of aldehydes and 16 volatile organic lung cancer biomarker candidates in low concentration. Sixteen out of ...
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A brand-new colorimetric sensor array was developed based on cross-reactive mechanism to discriminate 9 kinds of aldehydes and 16 volatile organic lung cancer biomarker candidates in low concentration. Sixteen out of twenty-seven dyes were selected to mix with 2,4-dinitrophenylhydrazine (DNPH) in optimized concentration to serve as specific sensing elements, and polyethylene glycol-1000 was chosen from four kinds polyethylene glycols to act as stabilizer. Resultant sensor array shows improved response (about tenfold higher) to aldehydes than former study, and exhibited very good selectivity in low concentration ranging from 40 ppb to 10 ppm with the presence of interfering counterparts. Data analysis was performed by both hierarchical cluster analysis (HCA) and discriminant analysis (DA), which demonstrates the excellent discrimination ability of the sensor to structurally similar aldehydes related to lung cancer. Besides, formaldehyde-spiked air samples were analyzed with developed sensor array, suggesting promising utilization potentiality to monitor such toxic gas. Theoretical detection limit was down to 8.2 ppb with a liner range from 10 ppb to 150 ppm. The sensor array can be further developed for early diagnosis of lung cancer as well as monitoring of domestic and industrial formaldehyde pollution. (C) 2014 Elsevier B.V. All rights reserved.
Touchscreen panels (TSPs), as human-machine interfaces, have been ubiquitously adopted in our daily life, especially in consumer electronics and numerous industrial applications. However, the lack of sensing the force...
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Touchscreen panels (TSPs), as human-machine interfaces, have been ubiquitously adopted in our daily life, especially in consumer electronics and numerous industrial applications. However, the lack of sensing the force information in conventional TSPs draws compromises in gesture strategies and user experiences, leading to complex gestures, multi-level menus, waiting and so on. This paper investigated a piezoresistive tactile sensor array, which sensed the force amplitude of a touch event with the location information using four tactile cells. The development of the sensor array prototype has been discussed, including the design, fabrication, packaging, and tests. Each sensor in the array was tested, demonstrating the sensitivity of 0.31 mV/mN.V in the normal direction. The responses of the sensor array to a 30-mN normal force at various locations along two diagonal lines have been tested, gathering high agreements with numerical solutions. The approach for quantifying the force and location information using a lookup table based on the least square method has been discussed by the probe tests with a 50-mN force in the normal direction on the sensor array. The sensor array showed the capability to achieve the location resolution of 2 mm with tested forces ranging from 0.01 to 0.25 N. The prototype of concept shed light on reducing the number of tactile cells for touchscreen applications. Further numerical analysis indicates the sensor array has the scalability for potential applications, in which a larger area of detection is needed without increasing the number of tactile cells.
The selection of appropriate sensing array nanomaterials and the pattern recognition of sensing signals are two challenges for the development of sensitive, selective, and cost-effective sensor array systems. To tackl...
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The selection of appropriate sensing array nanomaterials and the pattern recognition of sensing signals are two challenges for the development of sensitive, selective, and cost-effective sensor array systems. To tackle both challenges, the work described in this paper focuses on the development of a new hybrid method which couples multi-module method with artificial neural networks (ANNs) for the optimization-optimized multi-module ANN classifier (OMAC) to enhance the correct detection rate for multiple volatile organic compounds (VOCs). In this OMAC method, each module is dedicated to a group of VOCs with specific inputs. Each sensor element's selectivity is quantitatively evaluated to assist the selection of sensing array materials, which also facilitates the selection of inputs to each dedicated neural network module. This OMAC method is shown to be useful for achieving a high overall recognition rate for a selected set of vapor analytes. The results are discussed, along with the implications to the better design of ANN pattern classifiers in chemical sensor applications. (c) 2005 Elsevier B.V. All rights reserved.
Magnetic tracking technology is emerging to provide an occlusion-free tracking scheme for the estimation of full pose of various instruments. This brings substantial benefits for intra-corporeal applications, such as ...
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Magnetic tracking technology is emerging to provide an occlusion-free tracking scheme for the estimation of full pose of various instruments. This brings substantial benefits for intra-corporeal applications, such as tracking of flexible robots or wireless endoscopic devices, and thus is helpful for further computer-assisted diagnosis, interventions, and surgeries. Towards efficient magnetic tracking, we propose a magnetic localization and orientation system in this paper. By modeling the cylindrical magnet, the magnetic models have been compared and analyzed. Moreover, we present a sensor layout strategy based on grid method and its optimization method for better performance. Based on the magnetic model and the layout optimization results, we have built a sensor array for magnetic positioning. Extensive simulations and experiments have shown the feasibility of the proposed system with the average positional and orientational errors of 1.4mm and 3.4 degrees, respectively.
Flow-through electronic tongue based on miniaturized solid-state potentiometric sensors has been developed. A simple technique, i.e. membrane solution casting on the surface of the planar An transducers was applied fo...
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Flow-through electronic tongue based on miniaturized solid-state potentiometric sensors has been developed. A simple technique, i.e. membrane solution casting on the surface of the planar An transducers was applied for the preparation of classical ion-selective and partially selective microelectrodes, introduced in the flow-through sensor array. The performance of the designed electronic tongue was tested in the qualitative analysis of various brands of beer. Samples of the same brand of beer but with different manufacture dates, originating from different manufacture lots, have been applied in the studies. The combination of PLS and ANN techniques allowed the discrimination between different brands of beer with 83% of correct classifications. (c) 2005 Elsevier B.V. All rights reserved.
Specific types of gas sensors are normally produced by adding different dopants to a common substrate. The advancement of technology has made the fabrication of many dopants and consequently various sensors possible. ...
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Specific types of gas sensors are normally produced by adding different dopants to a common substrate. The advancement of technology has made the fabrication of many dopants and consequently various sensors possible. As a result, in each family of gas sensors, one can find tens of different sensors which are only slightly different in the spectrum of response to various volatile compounds. The wide variety of available gas sensors creates a selection problem for any specific application. sensor selection/reduction becomes even more important when cost and technology limitations are issues of concern. Accordingly, a methodology by which one can tailor a sensor array to a specific need is highly desirable. In this paper, a novel method is introduced to address this task using data from an electronic nose that uses polymer gas sensors, This method has been delineated based on the geometry of eigenvectors in Karhunen-Loeve expansion. The methodology is general and therefore suitable for many other feature selection problems.
Magnetic sensor array is usually designed for object detection and localization, where sensor coordinate is required to be consistent. Misalignment angles between coordinates should be calculated and calibrated. A new...
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Magnetic sensor array is usually designed for object detection and localization, where sensor coordinate is required to be consistent. Misalignment angles between coordinates should be calculated and calibrated. A new calibration method is proposed in order to calibrate the misalignment error between host frame and sensors. Host platform frame and perpendicular platform are used to obtain misalignment angles of sensor array. Experiment results show that it can estimate all angles of magnetic sensors and suppress misalignment error. Misalignment rms error is a reduction from 1109.7 to 27.6 nT, which means 2.48% indeed, thus improving the remote sensing accuracy of array which is unified to host frame coordinate.
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