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Department of Chemical Engineering and Biotechnology

 
Fluidic chip showing micro and nano features

Researchers from our Laser Analytics group have developed a laser-based manufacturing process that can produce combined nanofluidic and microfluidic devices in a fast and scalable manner.

Nanofluidic chips can allow researchers to observe biological processes at the single-molecule level, but current fabrication methods are slow and very expensive. In this paper, a research team led by Tuomas Knowles and Clemens Kaminski used conventional light-blocking masks and laser technology to craft a light-sensitive material into devices with micron to nano-sized channels.

“Fluidic chip devices are similar to computer chips but instead of having metal wires connecting different areas you have tiny channels – microchannels – the width of a human hair, that are filled with liquid,” says Oliver Vanderpoorten, a PhD student in the group who developed the method. “This allows us to study biological specimen in a very confined space. The liquid that goes through is always laminar and smooth and it makes everything very controllable.”

Microfluidic chips are widely used to study biological samples in small, confined spaces but by making these channels even smaller in nanofluidic devices, researchers can trap and image single molecules without modifying them through labelling or fixing them to a surface. It also allows researchers to use even smaller sample sizes in their experiments, reducing the amount of time spent on making or purifying the biological components.

“Proteins and aggregates like those that cause Alzheimer's disease are nanometer sized and we need new ways to filter these and study these on a single molecule level,” says Vanderpoorten.

Current methods to make nanofluidic devices rely on access to a clean room and use expensive and slow ion beam etching to produce the nanoscale features. In their technique, Vanderpoorten and his colleagues Quentin Peter and Pavan Kumar Challa use conventional UV mask lithography to make their microfluidic features and then use an innovative two-photon writing technique to add the nanoscale channels.

In this way, devices with both micro and nanofluidic properties can be prepared in the same procedure, using quick, cheap and well established techniques.

The researchers used microscopy and single-molecule tracking of dyes to verify the functionality of the final imprinted device, which also demonstrates the integration of nanofluidic channels into existing microfluidics designs.

“Our method is open source and can be adopted by a lot of people who can use their readily available systems to make these devices and do their own nanofluidic science,” says Vanderpoorten. 

“We've developed this technique and now for the rest of my PhD I want to show the four big areas of this field which are nanodroplet generation, diffusional sizing of molecules, electrophoresis, and entropic trapping. Entropic trapping allows us to capture nanoparticles, vesicles or exosomes, in space in solution, without influencing it too much and you can then observe these for longer times.”

 “I hope that with this method we can measure protein aggregates that are involved in Alzheimer's disease, on a chip; that would be my dream. On a single molecule or single aggregate level, we hope to detect label-free proteins in solution in these nanochannels and measure their size, because their size is related to their toxicity.”

Read the full paper, published in Nature journal Microsystems and Nanoengineering: ‘Scalable integration of nano-, and microfluidics with hybrid two-photon lithography’.

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