Study on Hydraulically-Driven Active Catheter for Safe Operation (2nd Report, Development of Quantitative Design Method Based on Dimensional Analysis)

Abstract

Our group has been developing an active catheter that can be used safely in human blood vessels. Earlier studies have proposed a hydraulic active catheter with active segments that can be independently driven with water pressure alone. The system can be achieved with a "Band Pass Valve (BPV)," a micro valve with an inner flow path set to open within a specific pressure range for the supply of fluid into a bending soft actuator inside. A prototype BPV was fabricated by hybrid micro stereolithography and tested in experiments to verify its function. During the design of the BPV, the complex interaction between fluid and elastomer made it quite difficult to set the driving pressure range theoretically. This paper proposes a quantitative design method for the BPV based on a dimensional analysis. With this method, dimensionless numbers and design charts can be provided for any kind of micro valve. This method enabled the development of a hydraulic active catheter with a minimal configuration and simplified valve composition. The valve thus designed was fabricated and tested for verification of its driving performance.