An ultraminiature solid-state pressure sensor for a cardiovascular catheter

An ultraminiature solid-state capacitive pressure sensor that can be mounted in a 0.5-mm OD catheter suitable for multipoint pressure measurements from within the coronary artery of the heart is described. The transducer consists of a silicon 290×550×1.5-μm³ microdiaphragm surrounded by a 12-μm-thick silicon supporting rim, both defined by the boron etch-stop technique. The transducer process features a batch wafer-to-glass electrostatic seal followed by the silicon etch, which eliminates handling of individual small diaphragm structures until die separation and final packaging. A hybrid interface circuit chip provides a high-level output signal and allows the sensor to be compatible with use on a multisite catheter having only two leads