Implantable Blood Pump Control Using Current-Based Position Estimation
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Solution Overview
Problem
Existing LVADs are bulky, difficult to implant, apply significant shear forces to blood, risk hemolysis and thrombus formation, and fail to mimic physiological pulsatility, leading to inefficiencies and potential vessel calcification.
Innovation Solution
An implantable blood pump with an undulating membrane driven by an actuator powered by alternating current, controlled by a controller that adjusts operation based on current signals to achieve synchronized pulsatile flow without position or motion sensors, reducing shear forces and improving hydraulic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LVAD designs are used, then pumping function is provided, but the device becomes bulky and difficult to implant
Solution Approach 1:
The pump is divided into modular components: an implantable pump unit with motor and membrane, a separate controller, and a power source. This segmentation allows the implantable portion to be compact while distributing system functions across multiple elements, reducing overall device complexity and easing implantation.
Solution Approach 2:
The motor is positioned within the pump housing, and the membrane is nested within the pump chamber. The controller can be positioned externally or in a separate implantable compartment. This nesting arrangement maximizes space utilization and minimizes the overall footprint of the implantable device.
2Productivity
If high shear forces are applied to blood for effective pumping, then pumping efficiency improves, but hemolysis and platelet activation increase
Solution Approach 1:
The membrane undergoes periodic undulating motions that create pulsatile flow patterns. This periodic action mimics natural cardiac function, providing effective pumping while maintaining gentle shear stress on blood cells. The alternating motion directions prevent blood stasis and reduce activation of platelets and hemolysis.
Solution Approach 2:
The pump operates by changing the physical state of the membrane from static to dynamically undulating. By controlling the frequency and amplitude of membrane undulation, the system optimizes pumping efficiency while maintaining blood-compatible shear forces. The parameter adjustments allow effective pumping at physiological flow rates without excessive shear stress.
3Stability of the object's composition
If continuous flow is maintained for stable pumping, then pumping stability improves, but pulsatility is lost leading to vessel calcification
Solution Approach 1:
The membrane undulation creates periodic pulsatile flow that mimics natural cardiac output. This periodic action maintains pumping stability through controlled rhythm while restoring physiological pulsatility to the circulatory system, preventing vessel calcification and maintaining vascular health.
Solution Approach 2:
The pump provides continuous pumping action through sustained membrane undulation, ensuring stable blood flow delivery. Simultaneously, the continuous pulsatile pattern prevents blood stasis and maintains vascular elasticity, eliminating the harmful effects of non-pulsatile flow while preserving pumping continuity.
4Measurement precision
If position sensors are added for precise control, then control accuracy improves, but device complexity and size increase
Solution Approach 1:
The controller determines membrane position by measuring electrical characteristics (current, voltage, impedance) of the actuation signals rather than using physical position sensors. The system self-monitors its own operational parameters, eliminating the need for separate sensing components and reducing device complexity while maintaining control accuracy.
Solution Approach 2:
The patent replaces mechanical position sensors with electrical measurement methods. By monitoring the electrical properties of the actuation signals and their interaction with the membrane, the system derives position information without mechanical contact or additional sensing hardware, simplifying the device architecture.
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, lightweight, and responsive blood pumping with reduced hemolysis and thrombus risk, mimicking physiological flow rates and pressures, enhancing patient outcomes.
Implementation Method 1
an actuator having a stationary component and a moving component coupled to the deformable membrane. The actuator is powered by an alternating current that causes the moving component to reciprocate at a predetermined frequency and amplitude relative to the stationary component
Data Source
AI summary
Systems and methods for controlling an implantable pump are provided. For example, the exemplary controller for controlling the implantable pump may only rely on the actuator's current measurement. The controller is robust to pressure and flow changes inside the pump head, and allows fast change of pump's operation point. For example, the controller includes, a two stage, nonlinear position observer module based on a reduced order model of the electromagnetic actuator. The controller includes an algorithm that estimates the position of the moving component of the implantable pump based on the actuator's current measurement and adjusts operation of the pump accordingly. Alternatively, the controller may rely on position measurements and/or velocity estimations.