Ultra slim packaging and assembly method for 360-μm diameter guide wires

In this work, we present an ultra-slim profile packaging and assembly solution of a 360-μm diameter medical guide wire fitted and integrated with silicon based fractional flow reserve (FFR) sensor. The miniaturization of the whole sensorized guide wire assembly without sacrificing its sensing functionality was made possible by the use of polyimide flexible printed circuit board (FPCB) as the substrate material for the silicon platform and by the use of lowest possible wire looping profile to create interconnection between the FFR sensor and the FPCB's bonding pads using the gold wires. In order to reinforce and protect the wire interfaces, as well as to maintain the required biocompatibility of the whole system, a thin layer of Polydimethylsiloxane (PDMS) was used for the encapsulation process. Long signal wires were then attached to the bonding pads of FPCB before finally fitted inside a miniaturized metal housing. This whole system has easily fit and integrated with the 360-μm diameter medical guide wire. In order to verify the packaging feasibility, the electrical short testing of the bonding pads and SEM observations were conducted.