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Different types of phantoms, i.e., physical phantom (left), and static mesh phantom (middle), proposed dynamic mesh phantom (right).
Source publication
Phantoms are used to evaluate, calibrate, and compare the performance of electrical impedance tomography (EIT) systems. This paper presents a dynamic thorax-like mesh phantom, which mimics the changes in electrical conductivity distribution within a human thorax at different time frames. Furthermore, element merging and contour smoothing, electrode...
Contexts in source publication
Context 1
... the performance of EIT systems [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17] is a very challenging task in vivo environment. As shown in Figure 1, improving the phantom design is essential for evaluating and calibrating the EIT system in vitro environment [18], [19]. ...
Context 2
... SPICE simulations are used to verify 100 different mesh phantom and identify the suitable DR value. As shown in Figure 10, when the DR decreases, the perturbation becomes more apparent in the reconstructed image along with the increase in ICC. The EIT image with a DR of 0.1 achieves the best ICC of 0.631, where the ICC value for the original mesh is 0.691. ...
Context 3
... of Discretization Location: Upon determining the DR of 0.1, we applied DCS techniques to different parts of the lung region. Figure 11 illustrates 3 distinct discretization locations in the top, middle, and bottom of the right lung, respectively. The ICC of these reconstructed images is 0.642, 0.631, and 0.680, respectively. ...
Context 4
... validate the accuracy of the fabricated PCB, we have tested it with our 16-electrode EIT system [11] and reconstructed the image using the measured result, and compared it with the SPICE simulation. Figure 12 presents the reconstructed image with an ICC of 0.9098. : (a) 0.7, (b) 0.5, (c) 0.3, (d) 0.1, (e) 0.05. ...
Citations
Electrical Impedance Tomography (EIT) systems have shown great promise in many fields such as real-time wearable healthcare imaging, but their fixed number of electrodes and placement locations limit the system's flexibility and adaptability for further advancement. In this paper, we propose a flexible and reconfigurable EIT system (Flexi-EIT) based on digital active electrode (DAE) architecture to address these limitations. By integrating a reconfigurable number of up to 32 replaceable DAEs into the flexible printed circuit (FPC) based wearable electrode belt, we can enable rapid, reliable, and easy placement while maintaining high device flexibility and reliability. We also explore hardware-software co-optimization image reconstruction solutions to balance the size and accuracy of the model, the power consumption, and the real-time latency. Each DAE is designed using commercial chips and fabricated on a printed circuit board (PCB) measuring 13.1 mm × 24.4 mm and weighing 2 grams. In current excitation mode, it can provide programmable sinusoidal current signal output with frequencies up to 100 kHz and amplitudes up to 1 mA
$_{p-p}$
that meets IEC 60601-1 standard. In voltage acquisition mode, it can pre-amplify, filter, and digitize the external response voltage signal, improving the robustness of the system while avoiding the need for subsequent analog signal processing circuits. Measured results on a mesh phantom demonstrate that the Flexi-EIT system can be easily configured with different numbers of DAEs and scan patterns to provide EIT measurement frames at 38 fps and real-time EIT images with at least 5 fps, showing the potential to be deployed in a variety of application scenarios and providing the optimal balance of system performance and hardware resource usage solutions.
This brief describes a high power efficiency, high linearity current driver for wearable electrical impedance tomography (EIT). It is extremely important to improve the power efficiency of the current driver circuit for wearable EIT applications because it consumes the majority of the power. As such, we propose a multi-stage shifting current mirror (S-CM) current-steering current driver circuit with customized dynamic element matching (DEM) techniques to suppress harmonic distortion (HD) to the greatest extent. Furthermore, the placement of switches in the current mirror circuit is optimized to reduce glitches during the switching phases. Operating between 14 MHz to 56 MHz, the power consumptions for the current mirror and the digital control logic are 21.6-141.6
$\mu $
W and 64.8-438
$\mu $
W, respectively. The proposed circuit has demonstrated an excellent energy efficiency of 0.3
$\mu $
W/kHz while maintaining a total harmonic distortion (HD) of <–43 dB (0.7%).
