@inproceedings{f028d6f9a218454c9922efd02b7ce020,
title = "Integration of a capacitive pressure sensing system into the outer catheter wall for coronary artery FFR measurements",
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.",
keywords = "capacitive pressure sensor, catheter integration, chip bumping & coining, die thinning, flexible circuit, flip chip interconnect, fractional Flow Reserve (FFR), solder laser jetting, Fractional Flow Reserve (FFR), OtaNano",
author = "Frank Stam and Heikki Kuisma and Feng Gao and Jaakko Saarilahti and {Gomes Martins}, David and Anu K{\"a}rkk{\"a}inen and Brendan Marrinan and Sebastian Pintal",
year = "2017",
month = jan,
day = "1",
doi = "10.1117/12.2263779",
language = "English",
isbn = "978-1-5106-0995-2",
series = "Proceedings of SPIE",
publisher = "International Society for Optics and Photonics SPIE",
editor = "Ioanna Giouroudi and Ioanna Giouroudi and Manuel Delgado-Restituto and {van den Driesche}, Sander",
booktitle = "Bio-MEMS and Medical Microdevices III",
address = "United States",
note = "Bio-MEMS and Medical Microdevices III Conference 2017 ; Conference date: 09-05-2017 Through 10-05-2017",
}