This paper reports a wearable piezoelectric pressure MEMS sensorarray for multi-site conformal sensing of pulse waves. Thinned bulk lead zirconate titanate (PZT) piezoceramic films with high performance are embedded ...
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(纸本)9798350357929
This paper reports a wearable piezoelectric pressure MEMS sensorarray for multi-site conformal sensing of pulse waves. Thinned bulk lead zirconate titanate (PZT) piezoceramic films with high performance are embedded into soft materials, allowing optimal deformability and conformality. Specifically, a spin-on polymeric adhesive is adopted to transfer uniform PZT film during bonding and releasing processes. As a result, the device of single element exhibits high sensitivity with 47.45 mV/N. Furthermore, it can capture a weak pulse with the spatial and temporal distribution without cross talk among channels, which has great potential applications in the diagnosis of cardiovascular disease.
Stiffened structure-induced gain-phase errors degrade the performance of the high-resolution two-dimensional multiple signal classification (2D-MUSIC) algorithm, which makes it impossible to ensure the high accuracy o...
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Stiffened structure-induced gain-phase errors degrade the performance of the high-resolution two-dimensional multiple signal classification (2D-MUSIC) algorithm, which makes it impossible to ensure the high accuracy of impact localization results. To eliminate the localization bias caused by these errors, a calibrated 2D-MUSIC-based impact localization method is first introduced. Firstly, time-frequency characteristics of the non-stationary impact signals are evaluated by experiment to obtain a clear first wave packet or a wave packet that purely corresponds to a single mode through continuous wavelet transform (CWT). Then, the uniform linear array covariance matrix with gain-phase errors is calibrated to be constructed as a Toeplitz structural matrix. By reconstructing covariance matrix R, 2D-MUSIC-based impact localization is calibrated for stiffened curved composite structures. Experimental research on the stiffened curved composite panel is carried out, and these impact localization results demonstrate the validity and effectiveness of the calibrated 2D-MUSIC-based method.
Multipoint detection of the structural deformation of a pulsating 3D heart model was conducted using a flexible piezoelectric sensor array with a poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] thin film sea...
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Multipoint detection of the structural deformation of a pulsating 3D heart model was conducted using a flexible piezoelectric sensor array with a poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] thin film sealed with biocompatible parylene C. The piezoelectric signals detected from the sensorarray attached to the 3D heart model were correlated with an electrocardiogram signal. These piezoelectric signals can be converted into the compressive stress applied to the flexible sensors by the pulsating motion of the 3D heart model. The experimental results mean that the contraction force, generated by the heart muscle (i.e., myocardium), can be directly evaluated. The different output voltages depending on the location were obtained from each sensor, indicating the possibility of a real-time detection of the irregular motion of the heart and the early detection of ischemic heart disease, which leads to the loss of local contractile force in myocardial tissue.
Impedance-based structural health monitoring (ISHM) using piezoelectric materials has been extensively developed to provide a structure health indicator. In practice, due to the environmental disturbances, the receive...
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Impedance-based structural health monitoring (ISHM) using piezoelectric materials has been extensively developed to provide a structure health indicator. In practice, due to the environmental disturbances, the received signal in different surrounding conditions may be different from intact structure received signal. In the past, any difference was assumed being caused by damage even changes such as temperature effects on the received signal. In ISHM, the received signal is different from the intact structure received signal;however, there is not necessarily damage in the system. So, the validity of ISHM depends on the identification of environmental disturbances in order to extract the real results from disturbed results. In this article, a new method using sensorarray and statistical metric analysis has been proposed to identify signal changes derived from damage and/or environmental change. Using this method, it is expected that the environmental variations affect similarly on output signals of different row sensors, whereas changes caused by damage will not be similar for all row and column sensors. This expectation is a general fact because there would be no sensible difference in the environmental variations from one side to other sides of the structure. To identify environmental disturbance from damage detection, an analysis is developed using statistical metrics. Experimental results show that this method is reliable to identify damage.
The applicability of the new parameters of piezoelectric quartz microweighing and principal component and discriminant analysis with the use of latent structure regression to the treatment of the output data of an arr...
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The applicability of the new parameters of piezoelectric quartz microweighing and principal component and discriminant analysis with the use of latent structure regression to the treatment of the output data of an array of piezoelectricsensors in the identification of individual highly volatile compounds in model three-component gas mixtures is discussed. The parameters proposed and the methods of chemometrics were used in the treatment of the multidimensional data of an electronic nose for detecting individual aromaforming compounds and evaluating changes in the aroma of food systems with functional additives.
P-tert-butylcalix[n]arenes (n = 4, 6, 8, abbreviated as CA[4], CA[6], CA[8], respectively) were immobilized on the An surface of the piezoelectric quartz crystal by the reaction between CA[n] and the acid chloride ter...
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P-tert-butylcalix[n]arenes (n = 4, 6, 8, abbreviated as CA[4], CA[6], CA[8], respectively) were immobilized on the An surface of the piezoelectric quartz crystal by the reaction between CA[n] and the acid chloride terminated mercaptoacetic acid (MAA) self assembled monolayers to form MAA/CA[n] bilayers. The sensing films were not only immobilized easily and reproducibly, but also used to improve the reversibility of the sensor signal. The response characteristics show the response of CA to organic amine attributes to specific interaction between CA[n] (host) and organic amines (guest). The frequency shifts of n-butylamine and iso-butylamine are much larger than tert-butylamine and diethylamine because of shape-selection and hydrogen bonding. Compared to CA[6] and CA[4], CA[8] has highest sensitivity to organic amine due to having more flexibility to accommodate guest molecules. A sensorarray with three-layer back-propagation neural network was applied to detect the binary mixture of n-butylamine in the range of 7.14-142 mul l(-1) and iso-butylamine in the range of 7.14-57 mul l(-1). The optimum values of learning rate (0.15) and momentum term (0.8) were determined by experiment. The best epoch of training was 1098. The root mean square error of prediction was 1.69 (mul l(-1)) for n-butylamine, and 1.42 (mul l(-1)) for iso-butylamine. (C) 2002 Elsevier Science B.V. All rights reserved.
A piezoelectric chemical sensorarray was developed using four quartz crystals. Gas chromatographic stationary phases were used as sensing materials and the array was connected to an artificial neural network (ANN). T...
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A piezoelectric chemical sensorarray was developed using four quartz crystals. Gas chromatographic stationary phases were used as sensing materials and the array was connected to an artificial neural network (ANN). The application of the ANN method proved to be particularly advantageous if the measured property (mass, concentration, etc.) should not be connected exactly to the signal of the transducers of the piezoelectricsensor. The optimum structure of neural network was determined by a trial and error method. Different structures were tried with several neurons in the hidden layer and the total error was calculated. The optimum values of primary weight factors, learning rate (eta = 0.15), momentum term (mu = 0.9), and the sigmoid parameter (beta = 1) were determined. Finally, three hidden neurons and 900 training cycles were applied. After the teaching process the network was used for identification of taught analytes (acetone, benzene, chloroform, pentane). Mixtures of organic compounds were also analysed and the ANN method proved to be a reliable way of differentiating the sensing materials and identifying the volatile compounds. (C) 1997 Elsevier Science B.V.
A piezoelectric sensor array was developed using four quartz crystals. For sensing materials gas chromatographic stationary phases were used. Factor analysis was performed and the weight of the factors was applied to ...
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A piezoelectric sensor array was developed using four quartz crystals. For sensing materials gas chromatographic stationary phases were used. Factor analysis was performed and the weight of the factors was applied to characterise the selectivity of the sensing materials. The identification of some organic vapours was carried out by the sensorarray. Principal component analysis was used and the signals were transformed into feature space. It was found that the transformed values of chloroform, acetone and cyclohexane were well separated. The data for the aromatic hydrocarbons were situated near the pixels of methanol and pentane. Organic materials can be identified in a mixture if the calculated factors are different. Interference has been found between benzene and toluene due to their similar factors. The selectivity of the chemical sensorarray can be greatly improved using more sensing elements in one array and sensing compounds with very different chemical features. (C) 1998 Elsevier Science B.V.
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