PACKAGING TECHNOLOGIES FOR INTEGRATED ELECTROCHEMICAL SENSORS

The packaging of chemically-sensitive electronic devices (CSED) has been considered from the standpoint of a possible industrial technology. The efficiency of the electrical isolation provided by CMOS technology, the use of passivation layers as well as the epoxy encapsulation of input/output connections of a CHEMFET have been investigated with respect to protection of the electronic component from the surrounding liquid. Long-term stability experiments on planar Si3N4- and Al2O3-gate ISFETs have confirmed their good isolating properties in various media. Planar CMOS and three-dimensional needle-type ISFET devices have also been fabricated and classically encapsulated with an epoxy resin. A moulding technique has been developed for the packaging of ISFETs in catheters, leading to sensors that have been tested in clinical in vivo pH measurements. For the miniaturization of both the electrochemical sensor and its reference electrode, a combined reverse-side contracted (RSC) ISFET integrated reference electrode (IRE) is proposed. This structure permits a much simpler packaging technique to be utilized and possesses advantages for many of the medical applications.