If you have ever had any blood work done, you understand the hassle of drawing blood and filling a separate tube for each criterion to be tested, each sample then requiring time-consuming analysis. Imagine, instead, only giving one drop and having your results instantaneously.
Dr. Adam Woolley and Dr. Milton Lee of the Department of Chemistry and Biochemistry along with Dr. Aaron Hawkins of the Department of Electrical and Computer Engineering have been working together for ten years, creating nanofluidic devices that can predict and detect diseases based on the proteins present in blood.
These devices are made from engineering tools typically used to make computer circuits, but the team has adapted them to make fluidic structures through a similar process of thin-film microfabrication.
“This is in the title of the paper,” Woolley said. “It’s called ‘Thin-Film Microfabricated Nanofluidic Arrays for Size-Selective Protein Fractionation’. [The process] basically entails adding or subtracting little, thin layers on a surface, and, using light, you pattern the layers to get to two dimensional and three dimensional patterns which make up the device.”
The device works by filtering the sample through nanochannels—measured in billionths of a meter—that run parallel to each other but differ in height. The array of channels acts like a sieve, allowing the contents of the sample to be analyzed using fluorescence to determine acceptable levels and sizes of the tested protein.
“[In using this device, you] put the fluid sample in the one side, and then it flows through the channels and fills by itself,” Woolley said. “Then you do a simple readout step where you see how much is trapped at an interface versus how much got through to the end, and that gives you an idea of how big the particles are. The size is related to a bunch of useful things, like risk for heart disease or determining if a drug is still useful.”
The design of these devices requires some iteration to fine-tune them for a specific application. Currently, each device takes about a week to make. If testing suggests that the device needs to be a nanometer taller, it takes another week to make the modified device.
The newest discovery in this project is that the amount of salt added to the sample changes the way the particles behave in the device. This discovery offers the potential for tuning the devices after they have been made.
“Now that the device is reliable, what we’re working on is some of these ways to try and make it more user friendly,” Woolley said.