An electrical method to measure low-frequency collective and synchronized cell activity using extracellular electrodes

Abstract

An electrical method to measure extracellular bioelectrical activity in vitro is presented. This method exploits the Helmholtz capacitive double-layer established at the electrode surface. Small extracellular voltage variations in the order of μVs induce through the double-layer capacitor a displacement current that is measured. This current is then enhanced by a gain factor proportional to the electrode capacitance. In addition, when measurements are carried out at low frequencies in current mode the electrode contribution to the noise can be minimized. The performance of the electrodes and the method is demonstrated using zebrafish hearts and glioma cell cultures. We propose that this electrical method is an ideal tool to measure in vitro slow and temporally synchronized events that are often involved in long range intracellular signaling

Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations

“…This detection method is referred to as the displacement current method. Details of the model can be found in a study by Medeiros et al ( 10 ). The detected current is given as${\mathit{i}}_{\mathrm{s}}false(\mathrm{italict}false)\cong \frac{\mathrm{italicd}{\mathrm{\nu }}_{\mathrm{S}}}{\mathrm{italicd}\mathrm{italict}}\dot{}{\mathit{C}}_{\mathrm{D}}false(1-{\mathit{e}}^{\frac{-\mathrm{italict}}{\mathrm{\tau }}}false) \text{with} \mathrm{normal\tau }={\mathit{R}}_{\mathrm{C}}{\mathit{R}}_{\mathrm{D}}$…”

“…The experimental setup was optimized for detection below 10 Hz. Details to record the displacement current and noise analysis were published elsewhere ( 10 ). …”

Ultrasensitive System for Electrophysiology of Cancer Cell Populations: A Review

“…6,23 By modifying the surface topology, the impedance of the electrode is reduced, cell attachment improved, leading to improved electrical recordings. 14,15 We teemed our platform bidirectional because it allows electrical recordings of cell populations over time and under different pharmacological compounds. ''The sensor consists of a glass substrate on which circular electrodes of 100 nm Au on top of a 4 nm Cr adhesion layer were evaporated through a shadow mask.…”

“…This circuit has been recently explained in the literature. 14,15,17 In short, the equivalent model takes into account the electrical double layer established at a metal-electrolyte interface. The parallel circuit network is formed by the charge transfer resistance, R D , and the Helmholtz-Gouy-Chapman doublelayer capacitance, C D , in series with the spreading resistance, R C , that accounts for the signal loss into the surrounding electrolyte.…”

“…13 As the electrical activity of non-neuronal cells is minute and difficult to detect, we have derived ultrasensitive electrical transducers to enable electrophysiological recordings. 14,15 In this study, we review our recent advances in sensitive transducers to decode cancer cell-cell communication with emphasis on pH-sensitive rat C6 glioma cells 16,17 and human prostate cancer cell model PC-3. 7…”