In medical testing and laboratory settings, pumps are needed to move biological samples such as blood, serum, cells, and proteins. However, these same samples can contaminate a pump’s internal components.
While peristaltic pumps are a common solution, they often lose precision and accuracy over time, and the frequent replacement of tubing can become expensive.
Fluid Metering pumps offer a cost-effective and dependable solution here, utilizing a protective barrier media known as contamination-free sample dispensing.
Image Credit: Fluid Metering, Inc.
The contamination problem
When pumps directly contact biological samples, you're risking more than just downtime. Residual fluids can contaminate future samples, proteins stick to internal surfaces, and cleaning often requires time-consuming disassembly.
All of this results in biofouling, cross-contamination, and infection control issues, which can cause operational headaches and regulatory burdens for medical device makers.
How barrier media solves the problem
Contamination-free sample dispensing overcomes these issues with a simple, three-step technique that keeps biological fluids totally segregated from pump internals:
Step 1: Prime with barrier media
The pump is filled with the chosen barrier media, which will protect the pump internals from biological contaminants. Options include:
- Buffer solutions (saline, PBS, or other biocompatible fluids): Provide adequate lubrication, a clean interior environment, and chemical compatibility with biological samples.
- High-purity water: Provides a steady flow and prevents chemical interactions, making it perfect for avoiding air bubbles or working with delicate samples.
Step 2: Create an additional barrier (Air barrier technique only)
With the air barrier approach, a specific volume of air is inhaled into the fluid route, forming a compressible cushion between the priming fluid inside the pump and the biological sample. This phase allows for volume flexibility and easy visual confirmation of barrier integrity.
Step 3: Aspirate and dispense
The biological sample is sucked into the tube. During dispensing, the priming fluid pushes the sample forward (or the air, which then pushes the sample in air-barrier applications), accurately delivering it without ever coming into contact with the pump's internal components.
Choosing the right barrier approach
The selection of barrier technique is based on unique application requirements:
The air technique (prime with buffer/water + aspirate air) works best when:
- Visual validation of barrier integrity is required
- Compressibility is beneficial for volume control
- Flexible barrier location is necessary due to variable sample volumes
- Working with non-air-sensitive samples
High-purity water barriers (primed exclusively with high-purity water) are preferred when:
- Maintaining consistent fluid characteristics is crucial
- Air bubbles may interfere with detection systems
- The samples are air-sensitive or reactive
- Uniform flow characteristics are necessary
- Chemical inertness is key
Buffer solution barriers (prime with buffer only) perform best when:
- Chemical compatibility with samples is crucial
- Maintaining specific pH and ionic strength is crucial
- Samples require specific environmental conditions
- Biological activity should be maintained throughout handling
Why Fluid Metering pumps excel at barrier media protection
Fluid Metering’s pump technology is a natural fit for contamination-free dispensing, no matter what type of barrier media you're using.
Thanks to its positive displacement design, you get precise control over buffer, air, and sample volumes, which helps keep the protective barrier stable and effective with every cycle.
Unlike peristaltic or diaphragm pumps, Fluid Metering’s CeramPump® design sealed piston design works reliably with both liquid and air barriers. In liquid systems, the incompressible priming fluid transmits force smoothly and consistently. And in air-based setups, the pump handles compressible air barriers without unwanted shifting or migration.
The continuous piston motion ensures each sample is delivered cleanly, without leftover volume or retention
Fluid Metering pumps, which use ceramic and PTFE-wetted materials, can accommodate nearly any buffer solution while remaining chemically inert. This adaptability enables system designers to maximize both internal buffer and barrier media selection for their individual application while avoiding material compatibility limitations.
Real-world impact
Medical device manufacturers are implementing contamination-free sample dispensing with Fluid Metering pumps across diverse applications:
- Clinical analyzers handling blood and serum
- Genomics workstations dispensing PCR reagents
- Immunoassay platforms moving antibody solutions
- Cell culture automation systems
- Bioprocessing equipment
- Veterinary diagnostic instruments
In each case, the barrier media (whether air, high-purity water, or specialized buffer) enables precise biological sample handling without the contamination risks, maintenance burdens, or performance degradation associated with direct pump-sample contact.
Beyond contamination control
The contamination-free sample dispensing approach offers clear system-level benefits that directly impact the bottom line. As biological materials never come into contact with the pump internals, service intervals are significantly extended.
Cleaning is also massively simplified, as only the external tubing and dispense tip need to be rinsed. There is no need to disassemble or clean the internal pump components. The same tubing set can then be reused across multiple samples with just a quick rinse, helping to significantly reduce disposable costs.
And with no direct contact between the pump and the sample, regulatory validation becomes a lot less complex.
Most importantly, the pumps retain factory-fresh performance characteristics even after thousands of biological sample dispenses, resulting in a cheaper cost of ownership due to less maintenance labor, fewer replacement parts, and less downtime.
Flexible protection for all applications
Contamination-free sample dispensing really is a game-changer when it comes to how biological fluids are handled.
Instead of accepting contamination as an unavoidable part of the process, this approach uses protective barriers (whether liquid priming media or air) to keep pump mechanisms clean while still delivering the precision required in medical diagnostics.
Whether you're using high-purity water or buffers as liquid barriers, or applying air slug techniques for added flexibility, the barrier method can be tailored to meet the specific needs of each application.
Fluid Metering’s pump technology makes this approach both practical and dependable, supporting a new generation of medical devices that handle sensitive biological materials with confidence and without compromise.
Acknowledgments
Produced from materials originally authored by Stephanie Moreau & Sean Madden from Fluid Metering.
About Fluid Metering, Inc.
Fluid Metering, Inc is a leading manufacturer of precision fluid control solutions, with a legacy of innovation dating back to 1959. As the pioneer of the first valveless rotating and reciprocating piston metering pump, Fluid Metering has continually refined its technology to meet the evolving needs of advanced applications.
Today, the company specializes in the design and production of high-performance dispensing pumps and metering systems, delivering exceptional accuracy, precision, and reliability across a wide range of industries. ISO 9001:2015 certified.
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