A Modified Differentiator Circuit for Extracting Cole-Impedance Model Parameters Using Meta-heuristic Optimization Algorithms

A differentiator-based set up is proposed as an alternative solution to measure bio-impedance. The method is modifying the differentiator circuit, replacing the capacitor with the Cole-impedance model representing the biological (fruit) sample. The proposed differentiator gain response (with the embedded fruit) is experimentally recorded. The experimental data’s post-processing is performed using meta-heuristic optimization techniques to extract the Cole-impedance model unknown parameters by solving a group of nonlinear equations. Three meta-heuristic optimization algorithms are used: the moth-flame, the flower pollination and the cuckoo search optimizations. The impedance generated with the extracted parameters is compared with the impedance measured by the Biologic spectroscopy SP150 for the samples of four types of fruits (Apple, Kiwi, Eggplants and Tomato). Experimental results are in the frequency range of 100 Hz–100 kHz for apples, kiwis and tomatoes, while the frequency range for eggplant tissues is 100 Hz–90 kHz.