Micromachined packaging for chemical microsensors

The critical issues involved in chemical microsensor packaging and encapsulation are reviewed and a hybrid solution is presented. In the design approach, the microsensor is divided into two principal physical parts, an electrode and electronics-containing substrate, and a micromachined membrane package. The fabrication and the resultant performance of each part are independently optimizable. The final microsensor is constructed by first binding the two parts together at the wafer level, followed by die separation, and then lead attachment. The micromachined membrane-holders are then filled with liquid membranes to yield functioning sensors. A calcium-ion sensor fabricated by this method is demonstrated