Researchers Are Using DNA To Inspire the Creation of Optical Antennas

Through the effort of the DALI technique, researchers have the ability to create just about any virtual nanoscale shape that they can conceive.

A large group of researchers recently published a report in the latest issue of Science Advances that describes a new technique that allows researchers to create micro metallic nanostructures that take the design cues from DNA structures. This new method could be used and applied to various new developments in micro-engineering.  

By using the DNA origami technique, researchers have the ability to create just about any virtual nanoscale shape that they can conceive. Using the DNA origami technique they are now able to create millions of fully metallic nanostructures. As stated by Adjunct Professor Veikko Linko from Aalto University, "We can build virtually any nanoscale shape using a DNA origami technique, and now we have shown how to use these accurate shapes as "stencils" to create millions of fully metallic nanostructures with 10 nm feature sizes in one go."

Dubbed the DALI Method or the DNA-assisted lithography method would allow for the creation and eventual scaling up of diverse metallic nanostructures with tailored plasmonic features. How does it work? The DALI method has DNA structures deposited on a chip coated with silicon. By doing this, the silicon oxide can be selectively grown only on bare areas of the substrate.

Linko furthers explains this insight in the published report by stating, "By controlling this process, we can create origami-shaped openings on the grown silicon oxide layer, and this layer can be used as a mask for the following lithography steps. Finally, we evaporate metal through these openings and create metallic structures having the same shape and size as the original DNA origami on a transparent substrate, such as sapphire."

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By having the tiny metallic features cover the entirety of the whole transparent substrate this creates a wide range of intriguing optical properties. These extremely small antennas could be used to create optical devices with a range of features including infrared. "Actually, we have demonstrated here a structure that we believe is the world's smallest entirely metallic bowtie-shaped antenna. This extremely small size extends the operating range of optical features from infrared to visible," says Adjunct Professor Jussi Toppari from the University of Jyväskylä. The tools could be applied to enhance Raman spectroscopy or biosensing.  

The DALI method could open the gates to a host of cheap wafer-scale production of surfaces. Interestingly, the DALI method does not rely on costly patterning methods.  Even more so, this new process could help further other studies related metallization.