Cell membrane electrical noise is an intrinsic property of living cell membranes, caused by ion channel movements generating electrical current on the order of a few femto- to pico-amperes. Measurement of this electrical noise can reveal valuable knowledge of underlying biochemical, physiological and pathological processes as recently explored. A number of sophisticated devices have been proposed in the literature; these include transistors and cantilevers.
In this work we followed a simple approach and we studied how basic electrode arrays using organic semiconducting polymers can be used to probe cell cultures using electrical noise as a probing technique. The aim is to build a very simple platform for drug screening.
We report on microelectrode arrays based on semiconducting polymers such as inkjet printed PEDOT:PSS and electrodeposited doped poly3-methlythiophene. The electrical sensitivity of these polymer based electrodes is compared with conventional metal microelectrodes arrays based in gold and in platinum. As test bed we used rat glioma-derived C6 cell line and Neuro 2A (Mouse neuroblastoma). Glia cells display a form of excitability that is based on variations of the Ca2+ concentration and N2A cells can produce a variety of signals upon stimulation by neurotransmitters. Bursts of quasi-periodic signals generated by the cells with a frequency below 1 Hz were measured and are discussed.
We also report that the electrical-double layer at the interface cell/substrate plays a crucial role on the ability to detect minor electrical changes related with cell activity. The shape of the signals recorded is dependent on the electrode design (width and spacing). The time constant associated with the interface electrode/cell culture medium controls the shape of the signals recorded.
Signal drifts caused by chemical changes in the cell-culture medium, long term stability and reliability of polymer based electrodes is also addressed.
This work is part of an ongoing EU project, “Implantable Organic Nanoelectronics” (I-ONE-FP7) which is aimed to the use of organic electronics in implantable devices for the treatment of the spinal cord injury.