Nanolens scope combines surface chemistry, computational imaging

Ashley N. Rice, ashley.rice@photonics.com

A new optical microscopy platform uses tiny self-assembling liquid lenses and a simple LED light source to view viruses such as influenza.

The portable, cost-effective platform was developed at the University of California, Los Angeles, Henry Samueli School of Engineering and Applied Science to replace the current gold standard for viewing nanoscale objects - electron microscopy, which uses a beam of electrons to outline the shape and structure of nanoscale objects.

Electron microscopy and other optical imaging-based microscopy techniques are relatively bulky, time-intensive for sample preparation and analysis and have a limited field of view - typically smaller than 0.2 mm² - which can make viewing particles in a sparse population, such as low concentrations of viruses, challenging. Such systems are also not practical in places with limited medical resources.

To overcome these issues, the UCLA team, led by associate professor of electrical engineering and bioengineering Aydogan Ozcan, developed its microscopy platform by using nanoscale lenses that stick to the objects that need to be imaged. This enables users to see single viruses and other objects in a relatively inexpensive way and allows for the processing of a high volume of samples.

Left three columns: lens-free pixel superresolved holographic detection of individual influenza A (H1N1) viruses. For comparison, right column: bright-field oil immersion objective lens images of H1N1 viruses and a single scanning electron microscope image of an H1N1.

Although not as high a resolution as electron microscopy, the system has a much wider field of view - more than 20 mm².

“This work demonstrates a high-throughput and cost-effective technique to detect sub–100-nanometer particles or viruses over very large sample areas,” said Ozcan, who is also a member of the California NanoSystems Institute. “It is enabled by a unique combination of surface chemistry and computational imaging.”

By using a silicon-based sensor array that is also found in cell-phone cameras, lens-free holograms of the nanoparticles are detected. The holograms are then rapidly reconstructed with the help of a personal computer to detect single nanoparticles on a glass substrate.

The new technique has been used to create images of single polystyrene nanoparticles as well as adenoviruses and H1N1 influenza viral particles.

The research was published in Nature Photonics (doi: 10.1038/nphoton.2012.337).