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In recent years, significant developments have occurred in the field of optically pumped magnetometers (OPMs), which are widely used in biomagnetic measurements. In this study, we propose a temperature optimization model for a single-beam miniaturized atomic magnetometer. Based on this model, we find that there is an optimal operating temperature for each individual vapor cell, under which the OPM achieves optimal performance. We construct a single-beam zero-field modulation OPM to prove this model. The sensitivity of the magnetometer reaches 18 fT/Hz1/2 (close to the theoretical sensitivity) when we adjust the temperature of the vapor cell through our model, and a detection bandwidth of more than 160 Hz is achieved. It is also discovered that the system bandwidth is reduced when the temperature is increased, whereas the sensitivity of the system does not show notable variation during this process. Our model enables a quick definition of the best working temperature for each individual magnetometer, ensuring the best performance at the lowest operating temperature. This model is especially advantageous for miniaturized OPMs and can also be further applied to arrayed integration for biomagnetic measurement in the future work. [ABSTRACT FROM AUTHOR]

This article presents investigation of 3-D electrical capacitance tomography (ECT) sensors with different excitation strategies, including dual-electrode excitation in the same plane, in adjacent plane, in planes separated by one plane or two planes, and in the adjacent position or opposite position in the same or different planes. The results show that a 3-D ECT sensor with dual-electrode excitation in the opposite position provides higher mean capacitance and lower standard deviation than in the adjacent position. Dual-electrode excitation in different planes can increase the capacitance signal and decrease the dynamic range of capacitance measurements, and thus, decrease random errors and improve the quality of 3-D reconstructed images. A 3-D ECT sensor with dual-electrode excitation in planes separated by one plane and opposite position can provide small measurement uncertainty and high image quality. [ABSTRACT FROM AUTHOR]

A conventional electrical capacitance tomography (ECT) sensor consists of multiple rectangular electrodes in a single plane. To generate 3-D images, some researchers use an ECT sensor with multiplane rectangular electrodes and in-line arrangement of different electrode planes and measure the capacitance between the electrode pairs not only within the same plane but also between different planes. Because those electrode pairs in different planes are far away from each other, the measured capacitance signals between them are weak and, hence, are easily affected by noise, resulting in the obvious disturbance on the measured signals and, hence, low image quality. To address those problems, the 3-D ECT sensors with different arrangements and different shapes of electrodes are studied to investigate the effect of different arrangements and different shapes of electrodes on the measured capacitance signals and the image quality. Four 3-D ECT sensors are made with different arrangements or shapes of electrodes: rectangular electrodes are in line arrangement, whereas diamond, circular, and hexagon electrodes are staggered arrangement. The performance of the four 3-D ECT sensors is compared. The results show that 3-D ECT sensors with staggered electrodes can decrease the disturbance on the measured signals and improve the image quality of static models compared with that with conventional rectangular electrodes. Among the three 3-D ECT sensors with staggered electrodes, the 3-D ECT sensor with hexagonal electrodes has superior performance to the other two 3-D ECT sensors with diamond and circular electrodes. It was used to measure moving objects and a fluidized bed. [ABSTRACT FROM AUTHOR]

Image reconstruction plays a key role in the application of electrical capacitance tomography (ECT). Although many different algorithms have been developed in the past, it is often difficult to obtain satisfactory images in all imaging regions by the use of a single algorithm due to the soft-field nature of ECT. This motivated us to develop a novel ECT image reconstruction strategy, in which a high-quality image can be obtained by combining the images reconstructed by two different algorithms via a graph cut method. By doing so, it is possible to retain the advantage of each algorithm for specified imaging regions and improve the quality of the whole image. This strategy was verified both numerically and experimentally for two widely used ECT reconstruction algorithms, i.e., linear backprojection and Tikhonov regularization. The results for stationary objects as well as gas–solid fluidized beds demonstrated that this graph-cut-based combination strategy presents a promising approach for ECT image reconstruction. [ABSTRACT FROM AUTHOR]