Blood Pump Flow Estimation via Back EMF Thrust Monitoring
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Solution Overview
Problem
Existing blood pumps lack effective monitoring and control mechanisms to ensure optimal blood flow rates, leading to undesirable suction conditions or insufficient circulatory assistance if flow rates are either excessive or insufficient, which can result in rapid decline in pump efficiency or inadequate patient support.
Innovation Solution
An implantable blood pump system with a control circuit that determines the thrust parameter, specifically back electromotive force (BEMF), to calculate blood flow rates and adjust pump operation accordingly, using a combination of hardware and software modules to power, control, and monitor the pump's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a blood pump operates at high flow rates to provide sufficient circulatory assistance, then the patient receives adequate blood flow support, but the pump may create suction conditions within the ventricle causing ventricle collapse and rapid flow rate decline
Solution Approach 1:
The control circuit continuously monitors the back electromotive force (BEMF) generated in the stator coils, which serves as a feedback signal indicating the thrust on the rotor and corresponding blood flow rate. Based on this feedback, the control circuit adjusts the pump operation to maintain flow within safe limits, preventing both suction conditions and insufficient circulatory assistance
Solution Approach 2:
The patent replaces direct mechanical flow measurement with an electrical measurement approach by monitoring the back electromotive force (BEMF) in the stator coils. The BEMF signal provides information about rotor thrust and blood flow rate without requiring mechanical flow sensors, enabling non-intrusive flow monitoring and control
2Reliability
If a blood pump operates at low flow rates to prevent ventricle collapse, then suction conditions are avoided, but the device fails to provide sufficient circulatory assistance to the patient
Solution Approach 1:
The control circuit uses BEMF monitoring to detect when flow rates are insufficient and adjusts pump operation accordingly, ensuring the pump maintains adequate circulatory assistance while preventing ventricle collapse
Solution Approach 2:
The pump system monitors its own performance through BEMF measurement and autonomously adjusts its operation to maintain optimal flow rates, eliminating the need for external flow measurement devices or manual intervention
3Productivity
If the pump speed is increased to maintain adequate circulatory assistance, then sufficient blood flow is provided, but the pump efficiency rapidly declines due to occlusion or suction conditions
Solution Approach 1:
The control circuit continuously monitors BEMF to detect changes in pump efficiency and flow conditions, adjusting pump speed in real-time to maintain optimal operation and prevent energy loss from occlusion or suction conditions
Solution Approach 2:
The pump system dynamically adjusts its operating parameters based on real-time BEMF measurements, adapting to changing hemodynamic conditions to maintain efficient operation across varying flow requirements
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 effectively monitors and controls blood flow rates, preventing suction conditions and ensuring adequate circulatory assistance by adjusting pump speed based on real-time flow rate determinations, thereby maintaining optimal blood flow and pressure.
Implementation Method 1
The parameter related to thrust may be the back electromotive force generated in a coil or coils of the pump stator
Data Source
AI summary
The flow rate of blood in an implantable blood pump is determined at least in part based on a parameter related to thrust on the rotor of the pump. The parameter may be a parameter related to displacement of the rotor along its axis, such as a function of the back electromotive force generated in one or more coils of the stator. The back electromotive force may be measured during open-phase periods of a particular coil or set of coils, during which no power is applied to the coil or set of coils by the motor drive circuit. The parameter related to thrust may be used in conjunction with the speed of rotation of the rotor, the magnitude of current supplied to the rotor, or both to determine the flow rate. The pump may be controlled responsive to the determined flow rate.