Lab-on-PCB: Low Cost 3D Microelectrode Array Device for Extracellular Recordings

Lab on a Chip (LOC) technologies are emerging candidates for highly sensitive and real time disease diagnostics and treatments. Yet, the high manufacturing costs of LOC devices has been a downfall. Microelectrode arrays (MEA), as a subclass of LOC technologies, record extracellular field potentials of cells or tissues adhered to the electrodes. The electrical reaction of cells to different pharmacological compounds allows in this way better and real time diagnostics. A current disadvantage is the limited signal-to-noise ratio (SNR) due to (1) the weak coupling between cells and sensing electrodes and (2) the high electrode impedance of current MEAs. In this paper, we present a low cost fabrication process to develop new LOC devices using Printed Circuit Board Technologies (Lab-on-PCB), coupled with 3D microelectrode arrays to improve SNR by optimizing cell-electrode coupling, decreasing the electrode impedance and improving the contact in organotypic cultures. Apart of the fabrication process, the characterization of 3D gold microelectrodes by measuring its impedance and baseline noise under different electrolytes conductivities is presented. Impedance measurements show similar values to state-of-the-art MEAs, e.g, $1\mathbf{K}\Omega$ at high frequencies, as well as a baseline noise in the order of the 10 $\mu\mathbf{V}_{\mathbf{p}\mathbf{p}}$ for a 100 $\mu\mathbf{m}$ diameter microelectrode. Hence, we show that Lab on PCB devices are a valid low cost solution for the new generation of electrophysiological LOC applications.