Sensorless flow and head estimation in the VentrAssist rotary blood pump

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Medical Devices

Background:

• Implantable rotary blood pumps require accurate flow rate and pressure difference monitoring for control.
• Current methods using flow or pressure probes reduce reliability and increase power consumption and cost.
• Sensorless estimation offers a potential solution to these limitations.

Purpose of the Study:

• To evaluate the accuracy of sensorless estimation of flow rate and pressure difference for the VentrAssist centrifugal blood pump.
• To investigate the impact of impeller design and fluid properties on estimation accuracy.
• To compare estimation performance using different blood analogues.

Main Methods:

• Sensorless estimation of flow rate and pressure difference using motor speed and input power.
• Comparison of two impeller designs for the VentrAssist pump.
• Testing across a fluid viscosity range of 1.2 to 4.5 mPas.
• Utilizing aqueous glycerol and red blood cells in Haemaccel as blood analogues.

Main Results:

• Sensorless estimation accuracy is dependent on impeller design, with optimization improving results.
• Fluid viscosity influences estimation accuracy.
• The type of blood analogue (e.g., glycerol vs. red blood cells) also affects estimation accuracy, beyond just viscosity.

Conclusions:

• Sensorless estimation of key blood pump variables is feasible using motor speed and power.
• Impeller design optimization is crucial for enhancing sensorless estimation accuracy.
• The rheological properties of the fluid, not solely viscosity, impact the reliability of sensorless measurements in blood pumps.