Patent ID: 8357957

Claim:
A method of detecting an ionic material using a FET-based sensor, the method comprising: flowing a first solution into and out of a sensing chamber and a reference chamber of the FET-based sensor comprising: the sensing chamber including a reference electrode and a plurality of sensing FETs, wherein the sensing chamber is defined by a lower substrate including the plurality of sensing FETs, sidewalls, and an upper substrate which functions as the reference electrode; and the reference chamber including a reference electrode and a plurality of reference FETs, wherein the reference chamber is defined by the lower substrate including the plurality of reference FETs, sidewalls, and the upper substrate which functions as the reference electrode; flowing a second solution to be evaluated for the presence of an ionic material into and out of the sensing chamber while continuously flowing the first solution into and out of the reference chamber; measuring a current in a channel region between a source and a drain of each of the sensing and reference FETs while flowing the first and second solutions through the sensing chamber and the reference chamber, respectively; and correcting the current of the sensing FETs by subtracting the current of the reference FETs from the current of the sensing FETs.