ISFET sensor coupled with CMOS read-out circuit microsystem

We report on the development of a prototype microsystem for measurement of pH, i.e. H+ ions concentration, of acqueous electrolytic solution with a resolution higher than 1/20 of pH. The microsystem is composed of an ISFET sensor coupled with a CMOS read-out channel capable to provide a low-impedance analog output and protection against electrostatic discharges. The silicon integrated ISFET sensor chip and the CMOS read-out chip have been fabricated, packaged and successfully tested at IRST-Microsystem Division of Trento (Italy) by using the internal microfabrication facility