A Wireless, Low-Power, and Miniaturized EIT System for Remote and Long-Term Monitoring of Lung Ventilation in the Isolation Ward of ICU

Abstract

Individualized lung-protective ventilation strategy is essential for patients with COVID-19. In this study, a wireless, low-power and miniaturized electrical impedance tomography (EIT) system was developed for remote and long-term monitoring of lung ventilation for patients with COVID-19 in the isolation ward of ICU. A new strategy of combining filtering and improved voltage-controlled current was employed to design the current source for a simplified system structure, and a new differential receiver circuit consisting of a buffer amplification and a differential amplification was proposed to design the voltage measurement unit for high precision. Moreover, a Bluetooth interface was adopted for wireless data transmission, and components characterized by low power consumption were selected to minimize the system power consumption. The proposed EIT system occupies a total size of 6.5*4.5*0.6 cm 3 and can work stably within 25 m from the wireless terminal installed with host EIT software. The system has a signal-to-noise of 70 dB at 50 kHz, stability of 0.1% relative change, and power consumption of 114 mW, as tested with a resistor phantom. Further, a comparison between the proposed system and a commercial ICU EIT device was conducted on nine healthy volunteers for ventilation monitoring. The correlation between lung volume and relative impedance changes was higher than 0.9 for both EIT systems (p<0.001). The analysis of the corresponding EIT images revealed that both systems delivered comparable images in terms of linearity, repeatability and regional ventilation distribution. The test and experimental results suggested that the proposed system could conveniently provide reliable data acquisition for remote and long-term lung ventilation monitoring.

Assessment of Low Back Pain in Helicopter Pilots Using Electrical Bio-Impedance Technique: A Feasibility Study

“…Second, for convenient use, it is best to integrate the impedance system into a chip or a circuit board to further reduce its size to embed it into the measurement module. Third, a small excitation current should be explored (1 mA was used in the present study) whether it could also obtain reliable measurements to evaluate LBP, so that a battery of small size can be used as power supply to further minimize the impedance system ( Yang et al, 2021 ).…”

The influence of reference electrode in electrical impedance tomography

“…Reducing the size and the number of cables is essential. Some EIT devices digitalize the voltage signals directly at the electrodes so that the cable connecting the subject and the monitor is minimized, whereas the other devices might use wireless connection to avoid any connection cables [13]. Nevertheless, for EIT systems that equips with reference electrode, it is important to ensure the proper contact and functionality of the reference electrode.…”

Design Automation of a Dynamic Thorax-Like Mesh Phantom for Evaluating the Performance of Electrical Impedance Tomography System

“…The implementation of the mesh phantoms [17], [30]- [39] requires a meticulous handcrafting design of the PCB layout. Thus, we propose the following PCB design automation for the mesh phantom: (i) contour construction of the mesh phantom, (ii) placement and routing of resistors, and (iii) implementation of dynamic mesh phantom.…”

“…The phantoms are generally classified into (i) physical phantoms [15], [21]- [29], and (ii) mesh phantoms [17], [30]- [39]. (i) Physical phantoms are implemented using a container filled with a conductive medium, usually saline water [15], [23], [24], [26], [27], [29].…”