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Proceedings Paper

Integration of a capacitive pressure sensing system into the outer catheter wall for coronary artery FFR measurements
Author(s): Frank Stam; Heikki Kuisma; Feng Gao; Jaakko Saarilahti; David Gomes Martins; Anu Kärkkäinen; Brendan Marrinan; Sebastian Pintal
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Paper Abstract

The deadliest disease in the world is coronary artery disease (CAD), which is related to a narrowing (stenosis) of blood vessels due to fatty deposits, plaque, on the arterial walls. The level of stenosis in the coronary arteries can be assessed by Fractional Flow Reserve (FFR) measurements. This involves determining the ratio between the maximum achievable blood flow in a diseased coronary artery and the theoretical maximum flow in a normal coronary artery. The blood flow is represented by a pressure drop, thus a pressure wire or pressure sensor integrated in a catheter can be used to calculate the ratio between the coronary pressure distal to the stenosis and the normal coronary pressure. A 2 Fr (0.67mm) outer diameter catheter was used, which required a high level of microelectronics miniaturisation to fit a pressure sensing system into the outer wall. The catheter has an eccentric guidewire lumen with a diameter of 0.43mm, which implies that the thickest catheter wall section provides less than 210 microns height for flex assembly integration consisting of two dies, a capacitive MEMS pressure sensor and an ASIC. In order to achieve this a very thin circuit flex was used, and the two chips were thinned down to 75 microns and flip chip mounted face down on the flex. Many challenges were involved in obtaining a flex layout that could wrap into a small tube without getting the dies damaged, while still maintaining enough flexibility for the catheter to navigate the arterial system.

Paper Details

Date Published: 30 May 2017
PDF: 10 pages
Proc. SPIE 10247, Bio-MEMS and Medical Microdevices III, 1024703 (30 May 2017); doi: 10.1117/12.2263779
Show Author Affiliations
Frank Stam, Tyndall National Institute (Ireland)
Heikki Kuisma, Murata Electronics Ltd. (Finland)
Feng Gao, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Jaakko Saarilahti, VTT Technical Research Ctr. of Finland Ltd. (Finland)
David Gomes Martins, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Anu Kärkkäinen, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Brendan Marrinan, Creganna Medical (Ireland)
Sebastian Pintal, Creganna Medical (Ireland)


Published in SPIE Proceedings Vol. 10247:
Bio-MEMS and Medical Microdevices III
Sander van den Driesche; Ioanna Giouroudi; Manuel Delgado-Restituto, Editor(s)

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