Peristaltic pump

The rotor has a number of "wipers" or "rollers" attached to its external circumference, which compress the flexible tube as they rotate by.

Peristaltic pumps may run continuously, or they may be indexed through partial revolutions to deliver smaller amounts of fluid.

The pump used a leather hose which did not need to self-open when released by the rollers, instead relying on the incoming water having sufficient pressure to fill the open inlet end on each cycle.

It was developed by heart surgeon Dr. Michael DeBakey[4] for blood transfusions[5] while he was a medical student in 1932 and later used by him for cardiopulmonary bypass[6] systems.

A specialized nonocclusive roller pump (US Patent 5222880)[7] using soft flat tubing was developed in 1992 for cardiopulmonary bypass systems.

Some common applications include pumping IV fluids through an infusion device, apheresis, highly reactive chemicals, high-solids slurries, and other materials where isolation of the product from the environment are critical.

Such an ideal peristaltic pump would offer the longest possible tubing lifetime and provide a constant and pulsation-free flow rate.

This requirement eliminates a variety of non-elastomeric polymers that have compatibility with a wide range of chemicals, such as PTFE, polyolefins, PVDF, etc.

The popular elastomers for pump tubing are nitrile (NBR), Hypalon, Viton, silicone, PVC, EPDM, EPDM+polypropylene (as in Santoprene), polyurethane and natural rubber.

have good compatibility with acids, hydrocarbons, and petroleum fuels, but have insufficient fatigue resistance to achieve an effective tube life.

In the case of stiff plastic liners like the polyolefins, with repeated flexing in the peristaltic pump they can develop cracks, rendering the bulk material again vulnerable to chemical attack.

There are many online sites for checking the chemical compatibility of the tubing material with the pumped fluid.

The minimum gap between the roller and the housing determines the maximum squeeze applied on the tubing.

However, a longer tube implies more pinch points between inlet and outlet, increasing the pressure that the pump can generate.

Lower pressure peristaltic pumps typically have dry casings and use rollers along with non-reinforced, extruded tubing.

Traditional pumps require a large volume of liquid external to the microfluidic circuit.

Wu et al. presented in 2008 a pneumatically actuated peristaltic micropump which eliminates the need for large external circulating fluid volumes.

Types of tubing commonly used in peristaltic pumps include: For continuous use, most of the materials perform similarly over short time frames.

[10] This suggests that overlooked low cost materials such as PVC might meet the needs of a short-term, one time use medical applications.