Linear-Bearing Implantable Blood Pump for Low-Shear Pulsatile Flow
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Solution Overview
Problem
Existing implantable blood pumps, such as LVADs, are bulky, heavy, require significant energy to operate, cause hemolysis and platelet activation, and struggle to mimic natural heart pulsatility while maintaining physiological pressure gradients, leading to thrombus formation and non-optimal performance.
Innovation Solution
An implantable pump system with an undulating membrane using hydrodynamic or thin-film bearings for actuation, which reduces shear forces and incorporates a magnetic assembly for efficient blood pumping without valves, enabling fast start and stop responses over a wide range of flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional rotary or reciprocating pumps are used, then blood pumping function is achieved, but device size and weight increase
Solution Approach 1:
The patent replaces traditional mechanical rotary or reciprocating pumping mechanisms with an electromagnetic field-based actuation system. Electromagnetic coils generate oscillating magnetic fields that directly actuate the undulating membrane, eliminating the need for heavy mechanical rotors, cranks, or connecting rods while maintaining effective blood pumping function.
Solution Approach 2:
The patent changes the operating parameters from rotational motion to linear oscillation frequency and amplitude. By controlling the frequency and amplitude of the electromagnetic actuation, the system achieves variable blood flow rates without requiring mechanical speed reduction mechanisms, thereby reducing device complexity and weight.
2Ease of operation
If traditional mechanical bearings are used, then actuation is achieved, but hemolysis and platelet activation occur
Solution Approach 1:
The patent replaces traditional mechanical bearings with hydrodynamic or thin-film bearing technology. These alternative bearings use fluid film lubrication principles to eliminate direct mechanical contact between moving parts, thereby reducing shear forces on blood while maintaining smooth actuation of the undulating membrane.
Solution Approach 2:
The patent introduces a fluid film as an intermediary between the actuator and the undulating membrane. This fluid film acts as a mediator that transmits motion while providing a non-contact interface, reducing mechanical shear forces on blood cells and preventing hemolysis and platelet activation.
3Ease of operation
If valves are incorporated, then blood flow control is achieved, but device complexity and thrombus formation risk increase
Solution Approach 1:
The patent removes the valve component entirely from the pump system. Instead of using valves to control blood flow direction, the system relies on the inherent unidirectional flow characteristics of the undulating membrane and the pressure gradient between inlet and outlet, eliminating valve complexity and thrombus formation risk.
Solution Approach 2:
The patent enables the pump system to control blood flow directionally through its own operational mechanics rather than through separate valve components. The undulating membrane's motion pattern and the resulting pressure changes automatically direct blood flow from inlet to outlet, making the system self-regulating without requiring additional flow control devices.
4Productivity
If high shear forces are applied, then blood pumping efficiency is improved, but hemolysis and platelet activation increase
Solution Approach 1:
The patent substitutes high-shear mechanical mixing and pumping actions with low-shear oscillating motion. The undulating membrane creates blood flow through gentle rhythmic expansion and contraction, generating sufficient pumping efficiency while maintaining low shear forces that protect blood cells from damage.
Solution Approach 2:
The patent uses periodic oscillating motion of the undulating membrane to achieve continuous blood pumping. This periodic action creates sustained blood flow through repeated cycles of membrane deformation, maintaining pumping efficiency while avoiding the high transient shear forces associated with abrupt mechanical actuation.
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 achieves improved hydraulic performance with reduced hemolysis and platelet activation, maintaining physiological flow rates and pulsatility, while being lightweight and compact.
Implementation Method 1
The actuator assembly may include a magnetic assembly that selectively generates a magnetic field to cause the linear reciprocating movement
Implementation Method 2
incorporating linear bearings based on hydrodynamic or thin-film bearing technology
Implementation Method 3
The reciprocating movement may cause a pressure in the bearing that offsets the moving assembly from the actuator
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A blood pump (20) incorporating linear bearing (242, 243) technology are provided. The pump (20) includes an actuator assembly, a moving assembly, and a linear hydrodynamic or thin-film bearing positioned within a housing. The moving assembly may include at least one magnet (225) and the actuator assembly may include a magnetic assembly (76) for selectively generating a magnetic field to cause linear reciprocating movement of the moving assembly with respect to the actuator assembly. The linear hydrodynamic or thin- film bearing may include a bearing portion on the moving assembly that is in fluid communication with a bearing portion on the actuator assembly or pump housing. The implantable pump may be suitable for use as a left ventricular assist device (LVAD).