As often happens in the medical industry, innovative ideas hatched in university research settings spawn innovative companies, which create innovative products. A case in point: HemoSonics. The Charlottesville, VA-based medical device company was started in 2005 by two professors and a post-doctoral research student at the University of Virginia School of Medicine's Bio-Medical Engineering program — Bill Walker, Mike Lawrence, and Francesco Viola, respectively. The trio identified a method for measuring the stiffness of blood clots by using ultrasound imaging technology and created a system built around that technology aimed to improve patient outcomes and reduce costs.
A number of years followed of extensive research and development, which included securing key patents, conducting numerous hospital studies, and consulting with physicians and other clinicians. More recently, HemoSonics has been preparing to bring its Quantra System diagnostic products to market, including prototyping and end-use manufacturing. HemoSonics has worked with Protolabs since 2011, from its early R&D days to more recent, end-use production work on the Quantra System. Complex devices like the Quantra System often require multiple manufacturing methods throughout the design and development process. HemoSonics used 3D printing, CNC machining, and injection molding to develop blood analysis machine.
A Need for Speed and Flexibility
In HemoSonics’ early research and development days, engineers were “iterating through multiple designs under tight deadlines,” says Andy Homyk, senior engineer, who joined the company more than six years ago when it had just five employees. “We were on a tight timeline so we needed a supplier who could machine parts for us quickly, within a couple of days.”
That was in 2012. Since that time, Protolabs has produced hundreds of prototypes and thousands of components for HemoSonics, using 3D printing, CNC machining, and injection molding — for a variety of projects and parts: robotic fixturing, thermal control units, pneumatic manifolds, and more.
“Speed and flexibility — being able to deploy different manufacturing options — and a commitment to customer service, are the main reasons we use Protolabs,” Homyk says.
More recently, HemoSonics needed help with the “skins” or casings that fit around the Quantra System. HemoSonics engineers needed design prototypes about the size of a computer monitor — first using 3D printing and then injection molding — to demonstrate form, fit, and function of the Quantra System to physicians at various hospitals.
The Quantra System is designed as a rapid, easy-to-use diagnostic platform that uses disposable cartridges to conduct a panel of tests. The Quantra Hemostasis Analyzer is designed for use in critical care settings that require results to be generated quickly from an instrument that is easy to operate at the point of care.
A challenge emerged when the project switched from additive manufacturing to injection molding. “These are pretty big parts, so one of the molding challenges, in prototyping, was color matching,” Homyk says.
Molding Materials and Finishing Touches
HemoSonics wanted these casings Pantone color-matched to its marketing department's specifications. One of the ways to do tha, in the injection molding process is to take the plastic resin in the natural color of the specific material chosen and apply around a 3 percent salt-and-pepper mix of colored resins. Final parts are typically very close to the preferred color. But, because of the nature of HemoSonics parts, some swirling and flow marks were showing up on them. The first batch of parts did not look good cosmetically.
To address this, Protolabs, and one of its plastic resin suppliers, and HemoSonics collaborated to precompound the colors. They mixed the plastic with the dye before molding to get pellets with a nice uniform color. This custom, precolored resin produced flawless parts.
Material selection was also carefully considered, given that a requirement of almost any kind of medical device is that it needs to meet certain flammability standards. For the casings, HemoSonics opted for an ABS plastic that met those standards and also offered durability.
Beyond machining, 3D printing, and injection molding, HemoSonics engineers also used some additional finishing options on the injection-molded parts, such as heat staking and pad printing. Heat staking is a process that uses a heated stake to melt metal threaded inserts into plastic parts. This makes it so that screws can be used to attach the Quantra System casing parts to a frame, for example.
Pad printing is a process that uses a stamp called a cliché to apply colored logos or decals to parts. HemoSonics used pad printing to put company logos on the Quantra System case parts.
Those long years of research and development, multiple design iterations and prototypes, numerous hospital studies, scores of visits to physicians and other clinicians, the securing of key patents, and the landing of important certifications in Europe — including the CE Mark, is finally paying off with the recent launch of the Quantra System in Europe and planned U.S. launch soon.
This article was written by Angelo Gentile, Senior Marketing Content Writer for Protolabs, Maple Plain, MN. For more information, visit here.