Measurement of cell and bacterial activity using array-based ISFET Chemical Current-Conveyor in weak-inversion

The ISFET chemical current conveyor (CCCII+) was first reported by the authors at ISCAS 2008. In this paper a new application of the CCCII+ is presented, namely to provide a direct means of measuring cell and bacterial activity. The measurement system is based on an array of unmodified ISFET CCCII+ sensors each of which when operated in weak inversion gives an output corresponding to the time derivative of hydrogen ions. Combining each of the CCCII+ time derivative outputs in the array using the analog computational versatility of the CCCII+ current output stage provides a signal corresponding to cell and bacterial activity. The design has been fully simulated using Triple-well 0.18-μm CMOS technology and the results presented in this paper show that a viable system for direct measurement of cell and bacterial activity can be obtain, further confirming the utility of the CCCII+ for another biochemical sensing application.