A bulk-driven ISFET-based chemical mixer

In this work the concept of the chemical mixer for comparing the pH of two aqueous solutions is introduced. Ionic concentrations are sensed via a pair of ISFETs, which are then translated into signals with frequencies that correspond to the pH values of the solutions. Using the bulk-driven single balanced topology, the number of transistors is significantly reduced, making it suitable for applications where a low supply voltage and low power consumption are essential. Finally, it is demonstrated that the output frequency of the mixer depends on the ΔpH of the solutions under test.