Two-Chamber Blood Pump With Time-Varying Piston Velocity
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Solution Overview
Problem
Existing extracorporeal blood pumps struggle to produce a pulsatile flow while maintaining a user-specified average flow rate, limiting their effectiveness in cardiac perfusion applications.
Innovation Solution
A piston assembly with two pump chambers and three valves, where one piston passively fills and rapidly expels fluid into the second chamber, producing a pulsatile pressure profile, controlled by a system that adjusts piston velocity to achieve a time-varying flow rate, ensuring consistent and pulsatile fluid delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a roller or centrifugal pump is combined with an additional device that periodically compresses the tube, then a pulsatile flow can be introduced, but the device complexity increases and the ability to maintain desired average flow rate while producing pulsatile flow of desired characteristics is limited
Solution Approach 1:
The pump is divided into two separate pump chambers (first pump chamber and second pump chamber) that operate independently but sequentially. Each chamber has its own piston and valves, allowing the system to generate pulsatile flow through the coordinated action of these segmented units without requiring additional compression devices.
Solution Approach 2:
The patent merges the pulsatile flow generation function directly into the pump mechanism itself by using two pump chambers that transfer fluid between them. The first chamber fills passively and rapidly expels fluid into the second chamber, which then expels fluid downstream at high pressure, creating pulsatile flow without external compression devices.
2Use of energy by moving object
If the number of revolutions per minute of a centrifugal pump is varied periodically to achieve pulsatile flow, then pulsatile flow can be produced, but the ability to maintain both desired pulsatile flow characteristics and desired average flow rate is limited
Solution Approach 1:
The pump employs periodic action through the coordinated reciprocating motion of two pistons that transfer fluid between two chambers. The first piston pushes fluid from the first chamber to the second, and the second piston pushes fluid from the second chamber downstream, creating periodic pulsatile flow cycles that maintain both pulsatile characteristics and average flow rate.
Solution Approach 2:
The system ensures continuity of useful action by having the first chamber passively fill and then rapidly expel fluid into the second chamber, which is always ready to receive and subsequently expel the fluid. This continuous transfer mechanism maintains steady average flow rate while producing pulsatile pressure profile downstream.
3Use of energy by moving object
If a peristaltic pump is used to achieve pulsatile flow, then pulsatile flow can be produced, but the ability to produce pulsatile flow of desired characteristics while maintaining desired average flow rate is limited
Solution Approach 1:
The pump chambers serve themselves through passive filling mechanisms. The first pump chamber passively fills from the inlet during the piston retraction phase, eliminating the need for active suction mechanisms. The system uses the pressure differential created by piston movement to automatically draw fluid into the chamber, maintaining both pulsatile flow characteristics and average flow rate.
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 solution effectively mimics the heart's pulsatile flow, providing better cardiac perfusion and maintaining a user-specified average flow rate, enhancing the efficiency of extracorporeal circulation systems.
Implementation Method 1
The first piston pushes fluid from the first chamber to the second
Implementation Method 2
the second piston pushes fluid from the second chamber downstream out of the pump
Implementation Method 3
Three valves are coordinated with the action of the pistons to control fluid flow into and out of the pump chambers by applying and releasing pressure
Data Source
AI summary
A fluid pump for medical applications. The pump includes a flexible cassette containing two pump chambers of differing volume, each chamber having a dedicated piston. The first piston pushes fluid from the first chamber to the second, and the second piston pushes fluid from the second chamber and out of the pump. Three valves are coordinated with the action of the pistons to control fluid flow into and out of the pump chambers by applying and releasing pressure to and from specific points of the flexible cassette. A control system controls the operation of the pistons and valves and directs the pistons to be advanced according to a time-varying velocity profile. The first pump chamber passively fills and then rapidly expels the collected fluid into the second chamber at low pressure. The second chamber, once filled, expels the fluid downstream at high pressure, producing a pulsatile pressure profile.