Point-of-care testing (POCT) is a rapidly expanding segment of the healthcare industry. This expansion is driven by an increasingly diverse array of advanced medical diagnostic equipment that can be used at or near the point of care, which leads to easier testing and faster clinical decisions. POCT equipment measures a wide range of health indicators, including pathogen detection, electrolyte concentrations, cardiovascular markers, cholesterol, drug levels, urine chemistry, infectious diseases, organ function, and immune response.
Demand for POCT is expanding as the functionality increases and instrument size is reduced. By testing multiple targets at the same time with a single sample, patients can be diagnosed more rapidly, providing better treatment for the patient and faster turn around time for the healthcare system. A smaller POCT instrument allows a system to be placed in more locations, where patients have easier and faster access to care. POCT devices are typically based on proven and precise assays, frequently using the same chemistry from larger in-vitro diagnostic (IVD) systems, but are designed for miniaturized handheld or benchtop units. Often miniaturizing the system or using a disposable cartridge requires much smaller volumes of fluid samples and reagents, while continuing to deliver rapid testing and precise analysis.
POCT manufacturers must balance a number of scientific disciplines to create a POCT device, including mechanical, chemical, and software engineering. The first step in developing a device is understanding the chemistry of the test (for example, molecular diagnostics, immunochemistry, or other assays).
Scaling down both the fluidics and the chemistry for a device is not as simple as just making things smaller. Chemical reactions often behave differently as the volume is decreased. In many cases this has a positive effect on performance—for example, reactions often proceed more rapidly in small volumes, with less reagent consumption.
To make devices easier and faster to use, POCT engineers design into the instrument many of the steps that are normally performed by separate instruments in the lab. These include sample preparation, cell lysis, nucleic acid purification, amplification, and detection—all in a single cartridge. This saves time, reduces sample handling, and minimizes the potential for contamination or error.
Once the chemistry is scaled down, the next challenge is designing a compact, reliable, and cost-effective cartridge to contain the reagents and reactions. Such a small cartridge also requires miniaturized, high-performance components such as pumps and valves to control the liquids through the cartridge, which must be durable, precise in design, and chemically inert. Parker’s best-in-class 8mm X valve and 7mm C7 cartridge valves are examples of miniaturized components that provide the same performance as larger valves but within a very small footprint. This allows POCT OEMs to pack these fluidic components into smaller and smaller devices.
The final POCT design challenge deals with automating the precise movement of samples and reagents within the cartridge to ensure tests are reliably and accurately performed. This requires a deep understanding of fluid mechanics and how pumps, valves, and manifolds can affect the movement of liquids in the cartridge. High-precision flow control is required for the samples and reagents as they make their way through the different reaction chambers within the POCT cartridge. Parker offers a variety of miniature solenoid valves to control the delivery of reagents using either on-off, diverter or proportional control of flow methods. Both pneumatic pumps and valves or liquid pumps and valves can be used to move fluids through the different reactions. Electronic pressure controllers are also available to provide precise pressure control.
The above point of care testing flow diagram features the new Helix pump. Parker’s Helix pump is a compact, high-pressure pump designed to enable the smallest of point-of-care instruments. Helix enables high-pressure operation for faster assay processing in gas driven micro-fluidic circuits and systems, by delivering more than 5.5 LPM flow and pressures up to 100 PSI (6.9 bar). The additional capacity also allows operation around the globe in challenging high-altitude environments and applications where external compressed air is not available.
Parker Precision Fluidics understands the needs of POCT design engineers. We can help design the perfect fluidics systems for your devices, allowing you to focus on what you do best—the chemistry. Because we manufacture both pumps and valves, our engineers are highly experienced in the flow mechanics required for POCT and can provide reliable, complete, and cost-effective solutions. Solutions can be customized to your needs, including complete fluidic subsystems or components that are preassembled and tested for easy assembly into your products.
Our applications engineering team is always available to provide recommendations and customize equipment to customer specifications.
For more information on Parker Precision Fluidics' products and solutions, please visit our website or call 603-595-1500 to speak with an engineer.
This post was contributed by Don McNeil, market development manager, Parker Precision Fluidics.