Toward Portable Bio-impedance devices

Bio-impedance measurement has been used as an indicator for specific physical and chemical changes in food products, fruits and vegetables, cancer detection and other applications. In this paper, a portable wireless bio-impedance measurement embedded system, based on the AD5933 chip, is introduced. The system is calibrated using a parallel RC network and the industry standard electrochemical station BioLogic SP-150. The module can be used in many impedance measuring applications. © 2019 IEEE.

Modeling woody plant tissue using different fractional-order circuits

This chapter presents results on the most suitable bio-impedance circuits for modeling woody plants. The modified double-shell, the modified triple Cole-Cole, and the traditional wood circuit models are compared for fitting experimentally measured data. Consequently, a modified circuit model is proposed. This model gives the best results for all interelectrode spacing distances when compared to the other circuits. All impedance data have been measured using the research-grade SP150 electrochemical station in the frequency range 0.1 Hz to 200 kHz. The fitting is done using the Zfit of the impedance analyzer SP150. © 2022 Elsevier Inc. All rights reserved.

Fractional-order oscillators based on a single Op-Amp

This chapter introduces a family of fractional-order oscillators based on a single operational amplifier (Op-Amp) with two fractional-order capacitors. Twelve different fractional-order oscillator circuits are investigated where the state matrix, oscillation frequency, and oscillation condition for each circuit are presented. The phase difference between the two oscillatory outputs is deduced in terms of the fractional-order parameters. The fractional-order parameter enhances the oscillator performance by providing an extra degree-of-freedom. Also, the resulting circuits provide independent controllability for the phase difference and the oscillation frequency. Numerical simulations using MATLAB® are performed to study the effect of the fractional-order parameters on the circuit response. Moreover, PSpice simulations are performed on different cases using two different fractional-order capacitors. Selected cases are verified experimentally to confirm the theoretical findings. © 2022 Elsevier Inc. All rights reserved.