Non-occlusive Peristaltic Pumps for Precise Transport of Demanding Media
Peristaltic pumps have been an important pump class for pumping sensitive fluids for many years. Particularly in medical technology, they are frequently used as roller pumps in dialysis machines or in extracorporeal blood circuits for blood pumping. These pumps operate on the positive displacement principle. The main disadvantage of this principle it that, due to the complete occlusion of the tube (complete closure of the tube), the pumped fluid is subject to high mechanical stress. In the case of blood pumps this leads to a damage of the red blood cells (hemolysis), which limits the maximum application time of roller pumps due to the strain of the patient's organism.
The occurring blood damage can be significantly reduced by deliberately avoiding complete tube occlusion. For this purpose, a novel peristaltic pump concept was developed. The non-occlusive peristaltic pump principle uses a circulating eccentric oscillation, which stimulates the pump tube. This results in the propagation of a pulse wave in the tube in addition to the periodic volume displacement with reflux as a result of partial occlusion. At the pump output there is a dynamically acting resistor, which interacts with the pulse wave. Due to the interaction between volume displacement, pulse wave and resistor, the tubing winding forms a resonator, which generates the desired pumping action without complete tube occlusion. With oscillation amplitudes of < 300 µm, flow rates of up to 500 ml/min can be achieved.
Another advantage of the non-occlusive peristaltic pump compared to conventional roller pumps is the controllability of the volume flow. In addition to precisely adjustable continuous flow, dynamically variable (pulsatile) flows can also be generated with the non-occlusive pump principle, for example to imitate the blood flow in the human body.
The developed prototypes of the non-occlusive peristaltic pump are characterized by:
- Flow rate: Q = (1 … 500) ml/min
- Back pressure: p = (0 … 35) kPa
- Inner tube diameter: d = (1 ... 5) mm, depending on the desired flow rate
- Tube material: Silikon, Tygon, Noprene, ...
- Special features:
- No complete occlusion of the tube
- Significantly reduction of blood damage (reduction of hemolysis by 55% in experiments with pig blood)
- Continuous volume flow (85% less pulsation compared to a comparable roller pump)
- Dynamically controllable volume flow, programmable flow pulsation depending on the desired application
- Scalable pump design (depending on desired flow rate and back pressure)
- Application areas: extracorporeal blood circulation, analysis technology, dosing technology, microfluidics, biotechnology, ...