Advances in Microfluidics

Researchers at Photonics West presented their latest microfluidics techniques, including new chip-based platforms, as well as applications of the technology

Straight channel microfluidic chip. Credit: Microfluidic ChipShop

Microfluidics technology allows researchers to precisely manipulate tiny drops of liquid. This level of control allows for a new class of miniaturized experiments using mere microns of liquid. These experiments span basic biology research to industry-relevant food safety tests. Over several days, researchers at Photonics West presented their latest microfluidics techniques, including new chip-based platforms, as well as applications of the technology.

On Sunday, Paul Gordon of Texas A&M University presented a microfluidics platform for detecting malaria parasites in blood samples. On their platform, a small amount of blood is deposited in a microfluidic channel. Typically, blood samples for malaria diagnosis are placed on a microscope slide, but the thickness of the slides are only compatible with more expensive microscopes. Gordon's group wanted to develop a thinner substrate for their microfluidics platform that could be used with relatively cheaper microscopes. They found that a high-index polycarbonate material worked the best.

Researchers are also developing microfluidics chips, about the size of a microscope slide, that can perform biological assays on their own. These chips consist of tiny chambers and vessels with pneumatic valves to move the liquid around. Holger Becker of Microfluidic ChipShop, based in Germany, presented an all-in-one chip with applications in industrial food production. With just two pneumatic valves, the chip can run a test to detect mycotoxins, which are biological pathogens produced by fungi, in grain dust. This detection occurs via a competitive fluorescence immunoassay that has been miniaturized. Its performance is comparable to a conventional plate-based assay, ELISA. The device is based on a chip platform originally developed for the Bill & Melinda Gates Foundation that is intended to be a universal diagnostic system.

In the same session, Udo Klotzbach of German research institute Fraunhofer IWS presented a chip for researching cell injury. The cell culture fits on the chip, where they used a green laser to kill and injure some cells. They then monitor how the cells regenerate on the chip under different conditions. For example, they can change the pressure and oxygen levels in the microfluidic chambers to simulate the conditions of hypertension or hypoxia in the body. This microfluidic platform could allow for animal-free drug testing, said Klotzbach.

Naoki Shinohara of Osaka University in Japan is working on a study for improving the body's integration of poly-methyl methacrylate (PMMA), a common material used to make artificial bone implants. This material is chemically stable, hard, and lightweight, but once implanted in the body it takes a long time to bind with new and existing bone. Shinohara's group wants to manipulate how cells interact with the implant material to encourage them to attach to the material. Shinohara's group wants to manipulate how cells interact with the implant material to encourage them to attach to the material-controlling the flow of fluids at a very small scale.

Their approach involves using a femtosecond laser to irradiate the PMMA material. The laser creates periodic ridges on the PMMA about 60 nanometers deep and half a micron apart, and they can change this periodicity by changing the wavelength of the laser. The presence of these nanostructures changes how the cells behave. They found that with the nanostructures, the cells adhered to the PMMA 7.7 times more.