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

Inácio, P. ; Medeiros, M. C. R. ; Carvalho, T. C ; Félix, R. ; Mestre, A. G. ; Hubbard, P. ; Ferreira, Q. ; Morgado, J. ; Charas, A. ; Ferreira, C. S. R. F. ; Biscarini, F. ; Power, D. ; Gomes, H.L.

Organic Electronics: physics, materials, applications Vol. 85, Nº 85, pp. 105882 - 105882, October, 2020.

ISSN (print): 1566-1199
ISSN (online):

Journal Impact Factor: 3,827 (in 2014)

Digital Object Identifier: 10.1016/j.orgel.2020.105882

Abstract
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.