Prosthesis Fatigue Testing via Electromagnetic Diaphragm Drive
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Solution Overview
Problem
Current prosthetic device fatigue testing systems require significant capital investment, offer limited operating frequencies and measurement capabilities, and are inflexible due to traditional fluid drive technologies that resonate and create standing waves, failing to simulate natural physiological loading conditions effectively.
Innovation Solution
A fatigue testing system that simulates physiological loading conditions using a flexible diaphragm drive member, a central flow conduit, and an optical micrometer system, allowing for controlled pressure, flow, and temperature environments, and enabling testing of various prosthesis sizes and configurations with a flexible and clinically relevant pressure waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional fluid drive technologies (flexible metallic bellows or piston and cylinder) are used, then the system can provide pressure actuation, but the system requires large driving systems, has limited operating frequencies, and creates standing waves that do not simulate natural physiological loading
Solution Approach 1:
The patent replaces traditional mechanical drive systems (piston-cylinder, flexible metallic bellows) with an electromagnetic drive system. The electromagnetic actuator uses magnetic fields to directly drive the diaphragm, eliminating mechanical linkages and reducing the size of the driving system while enabling higher operating frequencies and more natural pressure waveforms that simulate physiological loading conditions.
Solution Approach 2:
The patent changes the operating parameters of the drive system by using electromagnetic actuation instead of mechanical actuation. This allows the system to operate at elevated frequencies and produce more natural pressure waveforms that match physiological conditions, while reducing the overall size of the driving system through efficient electromagnetic field conversion.
2Reliability
If piston and cylinder arrangements with traditional seals are used, then pressure actuation can be provided, but friction severely limits the life of the system in high cycle applications
Solution Approach 1:
The patent replaces the mechanical piston-cylinder seal system with an electromagnetic drive system that actuates a diaphragm. This substitution eliminates mechanical friction between seals and cylinder walls, significantly reducing wear and extending the system life in high cycle applications while maintaining the ability to provide pressure actuation.
Solution Approach 2:
The patent uses a fluid-filled chamber with a diaphragm to transmit electromagnetic force to the prosthesis. The fluid medium (pneumatic or hydraulic) transmits the pressure changes generated by the electromagnetic actuator, eliminating the need for mechanical seals and reducing friction while maintaining effective pressure actuation on the test sample.
3Device complexity
If single drive systems are used, then the system structure is simplified, but standing waves are created along the length of the prosthetic device, which is not a natural pressure waveform
Solution Approach 1:
The patent divides the drive system into multiple independent electromagnetic actuators positioned at different locations along the prosthesis. Each actuator can independently generate pressure waves, and their combined effect creates a more natural pressure waveform that matches physiological conditions, eliminating standing waves while maintaining reasonable system complexity.
Solution Approach 2:
The patent uses multiple electromagnetic actuators that can operate with independent control to dynamically adjust the pressure waveform along the prosthesis. This dynamic control allows the system to simulate natural physiological pressure variations more accurately, eliminating the artificial standing waves created by single drive systems while maintaining test validity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides efficient and flexible fatigue testing at elevated frequencies, accurately simulating physiological conditions, reducing the need for large driving systems and extending test speeds, while ensuring consistent and natural loading of prostheses, thus enhancing the reliability of test results.
Implementation Method 1
A linear motor, which may be electromagnetic, is coupled to a fluid drive member to generate a pressure wave in a working fluid
Implementation Method 2
A working fluid, which may be water, saline, a saline/glycerin solution, a glycerin/water solution, or a blood analog or substitute, is employed within the testing system
Implementation Method 3
An optical micrometer system may be employed to measure the diameter or other dimensions of the prosthesis
Data Source
AI summary
Prostheses are fatigue tested using an apparatus under simulated physiological loading conditions. A fluid housing defines an entrance chamber having fluid outflow ports and an exit chamber having opposing fluid inflow ports and a central flow conduit in communication with the entrance chamber and the exit chamber. A plurality of housing tubes into which prosthesis are deployed may extend between the fluid outflow and inflow ports. Alternatively, tubular prostheses may be connected directly between the inflow and outflow ports. A reciprocating linear drive pump having a flexible diaphragm is provided to cyclically pressurize fluid through a common closed loop within the fluid housing and drive the pressurized fluid through the prosthesis being tested. The test system is capable of rotation independent of the motor drive for accurate diameter measurements of all test samples at elevated frequencies.