In the well-known catheterization procedures in medical diagnostics and therapy, navigation using the guide wire is difficult even for experienced internists. For example, in cardiac catheterizations, a guide wire is inserted through the patient’s vascular system to open occlusions of the coronary vessels or to insert other diagnostic tools. In this process, the physician usually moves blindly through the body. Today, orientation is based on knowledge of the anatomical conditions as well as on two-dimensional X-ray images. This means that any collisions in the vessels, damage to the inside of the vessel or puncture of the vessel wall by the catheter are difficult to detect using the conventional method.
A miniaturized force sensor measures the forces at catheter tips that occur between the guide wire (catheter) and blood vessels during insertion. The KASYS mini-chip, only 200 x 220 x 640 µm in size and thus just twice as wide as a hair, is the heart of a haptic assistance system that will simplify catheterizations in medicine in the future and reduce the risk of injury.
This assistance system is currently being developed in a lead role at the TU Darmstadt, Institute for Electromechanical Design. The CiS Research Institute is acting as a partner here and has designed the prototype force sensor KASYS.
The challenge for the Erfurt experts was, among other things, to design a cost-effective and MRI-compatible disposable force sensor that can be attached to the catheter. After several years of intensive R&D work, they succeeded in producing a piezoresistive force element with an asymmetrical base body. Tricky problems were also encountered in the separation, handling and contacting of the extremely small silicon chips with ultra-fine wires (diameter <25µm). New process steps were developed for this. In the future, the assistance system based on the force sensor should simplify catheterization and make it safer.
The German Federal Ministry of Economics and Technology supported the developments as part of the Mi-KAB (MF090076) and KASYS (IW 072104) funding projects.
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