Focus on autonomous lenses

researchers have made a tiny lens so ‘smart’ it can adapt its focal length from minus infinity to plus infinity without external control.

Incorporating hydrogels that respond to physical, chemical or biological stimuli and actuate lens function, these liquid microlenses could advance lab-on-a-chip technologies, optical imaging, medical diagnostics and bio-optical microfluidic systems.

Hongrui Jiang, a University of Wisconsin-Madison assistant professor of electrical and computer engineering; David Beebe, a professor of biomedical engineering; Liang Dong, a postdoctoral researcher; and Abhishek Agarwal, a doctoral student, describe the technology in the August 3 issue of the journal Nature.

At this size variable focal length lenses aren't new; however, existing microlenses require external control systems to function, said Beebe. ‘The ability to respond in autonomous fashion to the local environment is new and unique,’ he said.

In a lab-on-a-chip environment, for example, a researcher might want to detect a potentially hazardous chemical or biological agent in a tiny fluid sample. Using traditional sensors on microchips is an option for this kind of work — but liquid environments often aren't kind to the electronics, said Jiang.