Impedance Tomographic Sensor for Monitoring Bioprinted Cell Cultures

One of the most promising and fascinating topics in tissue engineering is 4D bioprinting. In this technique, human cells are embedded inside hydrogels that can be printed in different structures. The printed parts are then cultivated to generate tissue, which can be used for biological modelling and regenerative medicine. However, it still lacks proper monitoring methods for 3D cultures. In this article, we propose an electrical impedance tomography (EIT) circuit to be applied in cell culture assessment and long-term monitoring. The circuit consists of a fully differential Howland source, a measurement circuit based on variable-gain amplifier (VGA), a 16-electrode sensor array, and a digital unit for data processing and host communication. The circuit was able to track the position of multiple biological phantoms, and to detect the presence and location of a biological material inside a bioprinted hydrogel scaffold. This is an important step towards real-time long-term cell monitoring in bioprinting.