Also, monitoring of extracellular ion concentration-dependent changes in membrane potential in response to a variety of chemical stimuli has been developed on the basis of a cell-based biosensor. For example, Wang et al. established a non-invasive monitoring system for studying ion channels modulation, which is the most evaluated potential target for therapeutics. They designed an ISFET sensor array to detect the concentration of extracellular ions, such as Na+, K+, and Ca2+, showing that their ISFET biosensors allowed for non-destructive, real-time and long-time analysis of cell coupling. For the use of cells in a biosensor device, it is essential to localize the cells in the active area of the sensor, which can be achieved by dielectrophoresis (DEP). As shown in Figure 7, the sensor consists of integrated DEP electrodes for cell positioning, ISFETs, and reference electrode. Using the developed ISFET device with integrated DEP electrodes as a tool for characterizing bacterial positioning, bacterial metabolism was also detected over a few hours by monitoring pH variation after adding glucose. When glucose was added, uptake and consumption of glucose took place by the bacterial cells. When the oxygen supply was limited, the bacterial cells metabolized glucose thereby dropping the pH. Also Castellarnau et al. showed that the typical performance of pump stop and flow could be achieved by using one ISFET with cells (LS 174T adenocarcinoma colorectal cell line) and the other ISFET without cells. Their cell-based ISFET system is expected to be practically used for bacteriological applications, for example, monitoring of sugar consumption metabolized by various types of bacteria.