Development of data acquisition devices for electrical impedance tomography of composite materials

This contribution presents a simple and low-cost possibility to build a stand-alone data acquisition device to collect boundary voltage responses for electrical impedance tomography (EIT) evaluation. EIT reconstructs the spatial conductivity distribution of a region using boundary voltage responses to a current passing through the space. To accommodate EIT’s application as a structural health monitoring technique, a hardware device for injecting current and acquiring data is developed. The hardware consists of three main devices: a current source that can generate a direct current in range of mA, a multi-channel voltmeter with desired precision, and a microcontroller that communicates between the device and the computer. In this study a Howland current source and a 16-channel CMOS-switch, both are controlled by an ArduinoTM microcontroller, are developed to regulate the current and voltage connections. A MATLAB GUI is developed to adjust current input, monitor the voltage measurement, and perform EIT reconstruction with embedded EIT algorithm EIDORS. With the aid of the GUI, one can perform quasi real-time EIT evaluation of a 16-electrode spatial area within 9 s. A paper folding test is performed to validate the functionality of the system, indicating that the performance of the device is adequate for structural health monitoring purposes.