A Low-Cost Portable Wireless Multi-frequency Electrical Impedance Tomography System

Abstract

Electrical impedance tomography (EIT) is an approach to reconstruct electrical resistivity images of the body noninvasively. Here we present a novel wireless high-speed frequency division multiplexing and flexible switching-based EIT system with increased temporal resolution using raspberry pi. Proposed multi-frequency electrical impedance system has good performance, portable, energy and cost-efficient. Current is injected to all the electrodes simultaneously having different frequencies which increase the speed for capturing the fast change in impedances. Proposed system can reconstruct real-time 2D images for continuously monitoring applications where impedance changes rapidly. It can capture 70\xa0frames/sec, and its power consumption is 10\xa0mW. The system is designed for a bandwidth of 1\xa0kHz–1\xa0MHz, which covers most of the medical impedance investigations. Performance of the system was measured at 25 KHz by calculating parameter of blur radius (PBR) and percentage of position error (PPE). Average PBR and PPE obtained were 0.985 and 7.24%, respectively. SNR, linearity and stability were calculated after proper calibration by applying a small current of $$500\\,\\upmu \\hbox {A}$$500μA. SNR of the system is more than 70\xa0dB. Amplitude and phase measurement repeatability were 0.7% and $$1^{\\circ }$$1∘, respectively. CMRR of both wired and wireless systems were measured to find the effect of noise on the wireless system. Result shows that the proposed WMFEIT system has comparable performance with the reference systems and has good scope to be used for clinical imaging applications.