Calibrated frequency-difference electrical impedance tomography for 3D tissue culture monitoring

Electrical impedance tomography (EIT) has the potential to be an alternative technique to microscopy for many biological applications. It is a novel approach to monitor cell viability, proliferation or drug response with high temporal resolution in a label-free, non-toxic and non-destructive way. To limit measurement errors, only time-difference EIT is currently used for biological imaging. Still, the need for constant background reference limits its uses in long-term imaging. A novel equivalent circuit model was developed to analyse the errors in frequency-difference EIT (FDEIT) measurements. Based on the circuit model, the calibrated FDEIT (CFDEIT) method has been derived to compensate the measurement errors. Simulation results show that the voltage variations introduced by the leakage current are correctly modelled by the equivalent circuit. Significant improvements in the image quality are observed in both simulation and experimental results after the application of CFDEIT. It indicates that our study improves the accuracy of FDEIT and makes it feasible for 3D tissue culture monitoring.