Sensor chips including two ISFETs cf. Fig. 1 , were glued on a ceramic support made of fused alumina measur ing 28 mm =6 mm thickness 1.0 mm . The sensor contact pads were electrically bonded by ultrasonic wiring to aluminum conducting paths which were photolithographically patterned on the ceramic support. After wiring, the contact pads and wires were encapsulated with epoxy resin. Details about the construction and operation of the ISFETs can be found in Ref.