Customer Brief: Fluidnet

Fluidnet used CFdesign to help revolutionize the IV therapy market with a fully featured infusion pump that weighs less than two pounds and fits in the palm of a hand. A key to success was the design of a new generation of flow sensor and flow resistor for the administration set used with the IV pump.

CFdesign enabled Fluidnet to form an accurate picture of how a flow sensor and resistor really worked, and what dimensions would affect performance.  That’s something that can’t be done with experience, intuition or even an unlimited number of physical prototypes.

In IV therapy there is a clinical need to deliver fluids at rates from .1 ml/hr to 6,000 ml/hr, an extremely large dynamic range for a mechanical system.  The driving pressure from the pump to move the fluid can vary only by a factor of 3-4X, which doesn't come close to allowing the full range of flow rates.

A Million Dollar Business Case
“If forced to make molds for each of our guesses at the design, we would have had to go through many more rounds of tooling and would have ended up with inferior performance,” stated  Ben Powers, system engineering manager for Fluidnet. “We also would have been way over budget and beyond our schedule – it would have taken years and more than a million dollars in tooling to get the same result.”

Innovation Enabler
One of the unique engineering challenges that made CFdesign so valuable was the very small flow channels – tapering from zero to a .030-inch half circle – required by the design.  At that scale, it is very difficult to intuitively picture what’s going on. CFdesign provided a detailed internal performance picture of flow through these tiny channels, information and insight not obtainable with even the most sophisticated physical test methods.

CFdesign allowed the Fluidnet team to iterate on the design and assess performance changes associated with tolerance shifts.  They then optimized the design to satisfy all requirements.  Results predicted by CFdesign and actual results were almost dead on.

Supplier Communication
In one case, Fluidnet encountered strange behavior with some flow resistors that appeared to be related to a molding error.  They modeled the error in SolidWorks, ran a CFdesign simulation, and were able to replicate the physical results they were seeing.  The visualization of this error proved persuasive in getting the molder to fix the tool.

One and Done
After design refinement was complete, Fluidnet had single-cavity injection molding tools made to test out physical parts.  The detail and geometry required for the application precluded standard SLA or machined prototypes.  This is where the accuracy of CFdesign simulations came into play –only one set of molds needed to be produced since the resultant parts performed as predicted in the simulations.

Fluidnet is currently doing clean-room builds of the disposable administration set that includes the flow sensor and resistor, and finalizing the exterior pump design.  The simplicity, portability, efficiency and convenience of the pump will create a new freedom for care providers and patients.