A modular open-source platform for electrical impedance tomography applications

Electrical impedance Tomography (EIT) is a developing medical imaging technology with several benefits over current screening modalities. EIT can produce real time images for a lower cost and with fewer health risks than most common screening techniques. However, EIT is still the subject of research due to a lack of spatial resolution. This work demonstrates an EIT device capable of injecting current into a test subject and measuring the induced boundary voltages from electrodes. The device was designed to be flexible, allowing for different avenues of research to be pursued. Commercial devices do not allow changes to imaging protocols and so are not suitable for most research. The device is split into four different PCBs that can be altered easily. This design allows additional channels or rings of electrodes to be added to the device. The bandwidth of the voltage acquisition board is between 1 kHz and 2 MHz. This bandwidth limits the frequency components of signals that the device can detect. The Current stimulation board can generate arbitrary signals with frequency components up to 2 MHz. The modular circuit design and large bandwidth of the device allow for easy changes to imaging protocols. However, this flexibility means the device is not optimized for a single use case. The device can accurately detect targets in a saline tank when used with the open-source reconstruction software, GREIT. It has a mean Signal to Noise Ratio (SNR) of 85.4 dB and a mean homogenous reconstruction accuracy of 85.5 %. Overall, this study demonstrates the functionality and theory of an Open-Source EIT device that can be used to assist research.