Cells are equipped with a host of receptors that can convert chemical signals into electrical ones. Cell-based biosensors take cells as sensing elements for detecting the intracellular/extracellular microenvironment and some special characteristics of cells selves. This paper presents the design of the cell-based biosensor and optimization of the automatic fluidic system that makes it feasible to control the detecting process accurately, and the goal of which is to improve the maneuverability, repeatability and stability of sensor. In this study, excitable neural cells (rat cortical neurons or olfactory cell) are grown on top of the surface of the cell-based biosensor which is based on the principle of light-addressable potentiometric sensor. The optical beam is focused on the stimulated cell and the chip surface potential below the stimulated cell is recorded by the biosensor. Although the results demonstrate that this kind of cell-based biosensor has potential to monitor electrophysiology of living cell noninvasively for long term, the low signal-to-noise ratio so far hampers practical applications.