An on-chip system to monitor the pH of cell culture media

We presents an ion sensitive field effect transistor to measure the pH of the cell culture media of human mammary adenocarcinoma (SKBR3). We use a drift mitigation technique that cycles the transistor to reset the drift in the system. We use to technique in the system to demonstrate an integrated system to monitor the pH continuously. As a part of the system a pulse width modulation circuit is designed in a 0.5 μm CMOS process which cycles the vertical electric field of the ion sensitive field effect transistor to reset the threshold voltage drift. We demonstrate the viability of a complete integrated system implementing our drift mitigation technique to monitor cultured cells. The integration is important in this application to allow for autonomous operation inside an incubator during cell culture.