Scaling a Hydraulic Motor for Minimally Invasive Medical Devices.

Area of Science:

• Medical device engineering
• Biomedical engineering
• Microfluidics

Background:

• The medical device industry is prioritizing miniaturization for advanced applications.
• There is a need for biocompatible micromotors, especially in the 2 mm actuator range, for mechanical tasks.
• Current micromotor technology limits the development of integrated devices for procedures like cutting and drug delivery.

Purpose of the Study:

• To present a novel hydraulic motor-driven cutting module prototype.
• To explore additive manufacturing techniques for fabricating miniature hydraulic motors.
• To evaluate the performance of a ~4 mm outside diameter (OD) hydraulic motor prototype designed for micro-cutting and drug delivery.

Main Methods:

• Fabrication of four distinct hydraulic motor designs using additive manufacturing.
• Benchtop experimental testing to measure angular velocity at various flow rates.
• Numerical modeling using 3D-transient simulations (ANSYS CFX) to analyze performance characteristics and internal resistance.
• Development of simplified mathematical models to estimate peak torque.

Main Results:

• The prototype motor with a perpendicular fluid inlet achieved high angular velocities: 10,593 RPM at 3.6 mL/s and 42,597 RPM at 10.1 mL/s.
• 3D-transient simulations provided insights into motor performance and internal resistance.
• Mathematical models were used to validate simulation results for peak torque.

Conclusions:

• The developed 4 mm OD hydraulic motor prototype is a significant step towards achieving the target 2 mm OD for micro-actuators.
• This technology demonstrates potential for integration into micro-cutting and drug delivery systems.
• The study validates the feasibility of using additive manufacturing and simulation for developing miniature hydraulic systems.