Chemically Modified Copper Hybrid Ion Sensor with 7,7,8,8,-Tetracyanoquinodimethane

Abstract
A copper hybrid ion sensor modified with 7,7,8,8,-tetracyanoquinodimethane (TCNQ) is proposed as a preparation method of an ion sensing membrane. The copper coated lead-wire ion selective field-effect transistor (CLISFET) with a copper TCNQ anion radical complex film showed a linear response of about 30 mV per decade change of copper ion activity (almost a theoretical Nernstian slope) in the range from 10-5 M to 10-1 M. Ag+, Hg2+ and S2- interfered with Cu(TCNQ m i n u s d u ) film. However, the selectivity coefficients for other ions were below 10-2.5. The copper CLISFET gave a stable potential response after a slight initial drift during 2.5 hours. The response time of the copper CLISFET was less than 10 seconds from low to high concentrations; in the reverse case, the response time became less than 30 seconds as a result of the memory effect.