Sensitivity Analysis for Ultra-Wideband 2-Port Impedance Spectroscopy of a Live Cell

For ultra-wideband (9 kHz-9 GHz) 2-port impedance spectroscopy of a biological cell, sensitivity analysis was carried out for extracting lumped cell characteristics such as membrane resistance (as large as 1 MO) and cytoplasm capacitance (as small as 10 fF) from the scattering parameters. The scattering parameters were measured on a coplanar waveguide with a Jurkat cell trapped by dielectrophoresis either in a series or shunt configuration. The sensitivity analysis validated our previous empirical observation that the insertion loss of a series-trapped cell and the return loss of a shunt-trapped cell were most sensitive to the cell impedance. Additionally, the membrane resistance and cytoplasm capacitance were most sensitive to low- and high-frequency scattering parameters, respectively. In the future, the analysis can be used to optimize the test setup and protocol for fast, compact, and label-free characterization of a cell at the subcelluar level.