Monitoring systems that are capable to record neuronal activity in in-vitro cell cultures are prerequisite to the comprehensive investigation of neuronal processes. Low temperature cofired ceramics are a suitable platform for rapid prototyping of biological reactors, entailing a wide assortment of integration-capable sensors. Neuronal spikes capture is fundamental for understanding of the signal propagation within the neuronal network. It requires reliable electrodes, which can be arranged 3-dimensionally in an in vitro cell culture. Thick film gold electrodes have been proven for such applications, however their characteristics especially at small dimensions stray strongly. This work investigates thin films separating small thick film gold electrodes and an electrolyte solution with regard to their influence on the charge transport processes in such systems. PEDOT:PSS layer and TiOxNy deposited on LTCC gold electrodes, including their impedance characteristics are discussed and compared. TiOxNy layers with serial resistance Rs of 32 kΩ and serial capacitance Cs of 4.1 pF measured at 1 kHz are proposed to be the used as sensing elements in 3-dimensional in vitro cell cultures.