Microfluidics combines expertise in engineering, physics, chemistry, biochemistry, nanotechnology, and biotechnology to design systems in which extremely small volumes of fluids are processed through tiny channels milled into a device substrate. Applications include the development of inkjet printheads—the most successful commercial application of microfluidics—as well as microbiology testing devices that separate fluids into their component parts.
Understanding the behavior of advanced microfluidic systems requires a great deal of research as materials and electronics behave differently at the micro scale. The BioMicroSystems (BMS) Lab at the University of Cincinnati performs multi-disciplinary research to understand and develop microfluidic systems and sensors for improving public health and safety.
The BMS Lab is a core member of the NSF Industry/University Collaborative Center for Advanced Design & Manufacturing of Integrated Microfluidics (CADMIM), a group of industrial and academic institutions that aim to develop micro and nano scale fluidics for commercial and government applications. The BMS Lab is also a member of the Ohio Center for Microfluidic Innovation (OCMI) at the University of Cincinnati – a center recently funded by the State of Ohio to provide tools needed to take new microfluidic devices from concept, to fabrication, all the way through industry standard characterization and performance specification. Advanced microfluidic devices developed by BMS Lab have been used in a wide range of applications, from separating blood into cellular components to isolation of circulating tumor cells to particulate filtration.
Fig.1 Microfluidic chip and cell separation histogram
Machining microfluidic devices involves milling micron-scale channels to exact dimensions into the substrate material, channels that will only allow specific fluids to pass through and to achieve specified tolerances such as flow rate, surface tension and resistance. As a leader in microfluidics research, the BMS Lab has also become a leader in micro machining technology to continue to advance research into the technology.
To meet its precision micro machining challenges, the BMS lab turned to a high precision five-axis milling station for its most demanding micro machining challenges for microfluidic research. “The two best features of the system are the footprint and the accuracy,” says Jeff Simkins, Microelectronics Engineer at OCMI. “We’re creating micro channels as small as 20 microns wide. Bigger machines are simply too large and too expensive for our environment.” Not only is Jeff able to use platform to mill microfluidic channels and structures in polymers (such as PMMA or PC), but also do so on flexible titanium substrates (400um thick).
Fig2 (a) There is a strong need for simple methods of mid- to large-scale fabrication of microfluidic and sensor systems. (b) Microlution 5100-S five axis micro milling station
The high acceleration and overall performance of the platform enables features, accuracy and quality not possible with other machines. “The system is very rigid and the tool is extremely stable,” says Jeff. “We can change direction and still make extremely accurate corners. The system specs say it achieves accuracy within one micron. I’ve hit within 100 nanometers, verified by a calibrated contour microscope.”
The university’s microfluidic systems are used to research and develop particle separation solutions for advanced blood testing. They are also developing microfluidics on flexible substrates and reel to reel embossing of microchannels. The lab is busy, with commercial and government research projects frequently calling for new designs to be machined. The flexibility of the micro machining platform helps Jeff keep up with the steady flow of projects. “A researcher will say, ‘I’ve got an idea, I want to see if we can do it,” he says. “We can turn a design into a reality very quickly. I can get a drawing on Monday and have the part made that week.”
“The system is a huge asset to our program,” Jeff says. “It is easy to set up and reconfigure. It allows us to be very productive and innovative. We can even make channels of multiple heights on a single workpiece. No other machine has been able to do this.”
The Microlution 5100-S is a high speed, high precision five-axis micro milling platform, featuring micron level accuracy and tolerances. Microlution’s entire product line of precision milling, drilling, cutting and turning solutions are especially designed to machine small features in small parts with extreme accuracy. Each Microlution platform features high stability and rigidity, can be configured as a standalone system for rapid prototyping and R&D, and can scale up to a full production automated micro machining work cell.