Point-of-care testing (POCT) is a rapidly expanding segment of the healthcare industry, especially for at-home care and disease management. 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 blood glucose, electrolyte concentrations, cardiovascular markers, cholesterol, drug levels, urine chemistry, infectious diseases, organ function, and immune response.
Another reason POCT is growing in demand is that these instruments are becoming more advanced in terms of functionality, yet at the same time also smaller and more compact—making them easier to use (which improves at-home compliance). POCT equipment runs the same tests that the larger in-vitro diagnostic (IVD) systems do, but is designed as a handheld or bench unit, requiring much smaller volumes of fluid samples and reagents, while also delivering 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 assay).
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.
POCT flow diagram
Miniaturized pumps and valves
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, 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 in 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 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.
Experienced engineering team
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.
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.