Lab-on-a-chip devices have the promise of delivering advanced diagnostics for all sorts of clinical and life science applications, bringing with them ease of use and potential reduction in costs. One major stumbling block of the technology is the production process of such devices, which requires that each lab-on-a-chip be designed specifically for every unique task. To overcome the problem, Purdue engineers have been working on a programmable lab-on-a-chip system that can become a ubiquitous multi-purpose product for a wide range of uses.
“With conventional technology, you have to design the individual layout of the chip, fabricate it, test it and then redesign it when testing uncovers problems,” Wereley [Steven T. Wereley, associate professor of mechanical engineering at Purdue] said. “You are talking about a lot of time, effort and expense that could be dramatically reduced by having a multipurpose programmable chip.”
For the life scientists who primarily use the technology, the devices are labor-intensive to develop and use.
“Imagine if running a word processing application on your computer required you to go to the lab and design your own microprocessor for that specific application,” Amin [doctoral student Ahmed Amin] said. “Instead, wouldn’t it be better if you could just buy a multipurpose chip and download the software you needed? That’s what we’re going to do — make it easier to use so that the life scientists using the chips can concentrate on their own work instead of chip design.”
Researchers at the Massachusetts Institute of Technology first suggested the idea of applying computer programming concepts to lab-on-a-chip technology in 2004.
“They have focused on programming-language aspects, while we’re taking the idea to realization by focusing on the hardware and the software-hardware interface,” Amin said. “We have developed the software compiler and the runtime system that would automatically understand a program and convert it into signals to control more complex chips.”
The new chip is made out of a rubber-like polymer, called polydimethylsiloxane, instead of the rigid glass or silicon wafers often used. The flexible material is needed because pumps used to direct the flow of fluid operate with moving diaphragms.
Most other chips have the polymer layer sandwiched between two glass layers.
“We chose to build the whole chip out of the PDMS polymer, which makes it easier to fabricate and reduces cost over other alternatives, such as silicon or glass,” Chuang [doctoral student Han-Sheng Chuang] said.
The Purdue-designed chip is able to mix, store, heat and sense what the sample is made of, whereas previous programmable chips have been limited to mixing and storing samples.
The researchers have demonstrated how the chip works using a mock sample and reagent dyed with food coloring.
The programmable chips are likely to be commercially available within five years, said Amin, a student in the School of Electrical and Computer Engineering who developed the programming language and “architecture,” or interface between the hardware and software.
The language enables the “assay protocols” required for specific tasks to be downloaded to the chip.
Purdue has applied for a provisional patent on the technology.
“What we eventually aim to do is create different classes of chips, where each class can run multiple assays from a few related life-science domains,” Amin said.