Printed Flexible Microelectrode for Application of Nanosecond Pulsed Electric Fields on Cells

Medical treatment is increasingly benefiting from biomedical microsystems, especially the trending telemedical application. A promising modality for tumor therapy showed the application of nanosecond pulsed electric fields (nsPEF) on cells to achieve nanoporation, cell death, and other cell reactions. A key technology for this method is the generation of pulsed fields in the nanosecond range with high-field strengths in the range of several kilovolts per centimeter. For further biomedical applications, state-of-the-art setups need to decrease in size and improve their capability of integration into microsystems. Due to demanding electronic requirements, i.e., using high voltages and fast pulses, miniaturization and low-cost fabrication of the electrode is first considered. This paper proposes a proof-of-concept for a miniaturized printed flexible electrode that can apply nsPEF on adherent fibroblast cells. The interdigital gold electrode was printed on polyimide with line-width of about 10 µm using an electrohydrodynamic inkjet printer. Furthermore, an electrical circuit was developed to generate both electrical pulses in the nano-second range and voltages up to 180 V. The electrode was integrated into an experimental setup for in-vitro application to human fibroblasts. Field strengths up to 100 kV/cm with 45 ns pulse duration were applied, depending on the degree of cell confluence. The cells show contraction, detachment from the electrode, and lethal reactions after the nsPEF treatment. Furthermore, this printed miniaturized electrode was found to be suitable for subsequent microsystem integration and further cell experiments to optimize pulse parameters for control of cell reaction and behavior.