ISFET based urea:creatinine translinear sensor

Presented is an ion-sensitive field-effect transistor (ISFET) based circuit capable of continuous analogue computation of the urea:creatinine ratio, a marker important for the prediction of pre-renal failure. The designed circuit utilises the weak-inversion of operation to derive sensor currents directly related to the urea and creatinine concentrations, as well as to implement linear division at extremely low power by using a translinear cell.