Fiber Interconnect for Intelligent Guidewires
There is an increasing trend to integrate electronic sensors on the tip of catheters and guidewires, because it allows for the measurement of physical quantities like flow, pressure and vessel diameter exactly at the place of interest. Especially the integration of sensors on guide-wires is attractive because the wire is in most cases used anyway to guide other instruments to the point of intervention. Integrating multiple complex electronic sensor systems on the tip of guide-wires, often only 360 µm in diameter, is from a micro-fabrication point of view challenging. Sensors and electronic circuits, often made in different platform technologies, need to be assembled and squeezed into the extremely small volume of the instrument tip.
We will address the transport of measurement data from the distal tip of the instrument to the proximal side. These electrical wires in the guidewire (4 at the most due to space constraints) are unsuitable for the high-speed data communication needed for complex sensor systems, especially for imaging. We will develop a high-speed optical data link using an optical fiber between the distal sensor tip and the proximal connector. An additional advantage is the inherent MRI compatibility of such a system. We have chosen a 360 µm diameter guidewire as the integration platform since a technological solution for these small devices can easily be ported to larger devices such as catheters and laparoscopic instruments.
WP1.4.1: VCSELS integration at the distal guidewire tip (TUD)
Over the past ten years the production technology for Vertical-Cavity Surface-Emitting Lasers (VCSEL) has gone through a tremendous development. VCSELs combine an extremely small size (emitting area ~20 µm diameter) and low current consumption (~mA), making VCSEL lasers the ideal light source for the realization of an optical data link in catheters and guidewires. Fabrication schemes have been proposed to combine the VCSEL with a photo diode allowing for two-way communication. Recently we have proposed a silicon-based Flex-to-Rigid (F2R) platform for the integration f extremely small, partly flexible guidewires with complex sensor assemblies and ASICs (Application Specific Integrated Circuits) for signal processing, conditioning and multiplexing. In this project we will extend our F2R platform with an optical link. Challenges include: alignment of the VCSEL laser to the fiber, assembly of the fiber/sensor combination on the guidewire core, optimal electrical driving schemes and safety.
WP1.4.2: Development of an optical/electrical connector at the proximal side (TUD)
Since instruments like balloons and stents are shifted over the guide wire, its diameter can never exceed 300 um over the total length of the wire. This poses severe design constraints on the connector at the proximal side of the guidewire, which has to establish an optical and electrical link between the patient monitoring system and the guidewire itself. To make the barrier for acceptance of any new system by physicians as low as possible the use and operation of the system has to be as simple and robust as possible. The development of such a robust connector design is therefore an integral part of the project.