Laser-scribed graphene (LSG) as new electrode material for impedance-based cellular assays

Impedance-based monitoring of cell-based assays has evolved to a multi-functional tool in fundamental and applied biomedical research. The majority of studies rely on gold-films as the electrode material which serves as growth surface and electrode at a time. Besides all its favorable properties like inertness, biocompatibility and superior electrochemical characteristics, gold-film electrodes in contact to cell culture medium show a capacitance of the electrode/electrolyte interface that may become limiting for the sensitivity of the readout. This study describes the use of laser-scribed graphene (LSG) as an alternative electrode material in impedance-based cell monitoring. LSG electrodes are prepared from commercial polyimide foils by simple CO2-laser-induced carbonization. The resulting electrodes show a 25times larger interface capacitance than standard gold-film electrodes due to their foam-like surface topography. Furthermore, LSG-electrodes are (i) highly compatible with cell attachment, (ii) easy to prepare in customized geometries from mm to cm with tunable surface topography and (iii) accessible by roll-to-roll production lines. We conclude from time- and frequency dependent impedance measurements of cell-covered LSG electrodes in direct comparison to the reference material gold that LSG provides an enormous potential to improve the sensitivity of impedance-based monitoring and electric-field mediated manipulation of adherent cells.