Chemical sensitivity of an ISFET with Ta2O5 membrane in strong acid and alkaline solutions

Abstract A detailed study concerning the chemical sensitivity of an ISFET with a Ta 2 O 5 membrane is presented. The results indicate that in the absence of alkali ions, the Ta 2 O 5 -ISFET has practically an ideal Nernstian pH response in a wide pH range from −7 to 13.7. A deviation from Nernstian response has been observed in electrolyte solutions containing lithium (at pH>7), sodium and potassium (at pH>12) ions. Lithium ions have the most significant effect, giving rise to a change from pH response to pLi response.