Ultra-low noise PEDOT:PSS electrodes on bacterial cellulose: A sensor to access bioelectrical signals in non-electrogenic cells

This study is focused on the particular advantages of organic-based devices to measure cells that do not generate action potentials, also known as non-electrogenic cells. While there is a vast literature about the application of organic conductors to measure neurons, cardiomyocytes and brain tissues, electrical measurements of non-electrogenic cells are rare. This is because non-electrogenic cells generate weak signals with frequencies below 1 Hz. Designing low noise devices in a millihertz frequency range is extremely challenging due to the intrinsic thermal and 1/f type noise generated by the sensing electrode. Here, we demonstrate that the coating of cellulose nanofibers with conducting PEDOT:PSS ink allows the fabrication of a nanostructured surface that establishes a low electrical double-layer resistance with liquid solutions. The low interfacial resistance combined with the large effective sensing area of PEDOT:PSS electrodes minimizes the thermal noise and lowers the amplitude detection limit of the sensor. The electrode noise decreases with frequency from 548 nV r.m.s at 0.1 Hz to a minimum of 6 nV r.m.s for frequencies higher than 100 Hz. This low noise makes it possible to measure low frequency bioelectrical communication signals, typical of non-electrogenic cells, that have until now been difficult to explore using metallic-based microelectrode arrays. The performance of the PEDOT:PSS-based electrodes is demonstrated by recording signals generated by populations of glioma cells with a signal-to-noise ratio as high as 140.