Insects Inspire
Digital Camera


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Scientists have long been fascinated with the wide-angle field of view of the compound eyes of insects and other arthropods, and now a team of engineers and scientists inspired by these creatures has achieved a long-sought goal of building a digital camera that takes wide-angle photos without the image distortion that often occurs.

The camera is still just a lab demo so a lot more work needs to be done before it can be used for real applications, including improving the camera's resolution capability since it has few pixels. But the team has a good start in making that a reality.

Applications for such a camera could include surveillance devices, endoscopy and detection of unmanned aerial vehicles.

Jianliang Xiao is an assistant professor in the Department of Mechanical Engineering at the University of Colorado-Boulder and co-lead author of a study about the work published in the journal Nature, in May. He says the team had to overcome key challenges such as building high-performance optoelectronics onto curved surfaces, building a microlens array on a hemispherical shape without distorting the optics and integrating the microlens array and photodiode array to perfectly match the optics requirements.

The prototype for the digital camera was inspired by the compound eyes of insects. Image: John A. Rogers, University of Illinois at Urbana-Champaign

 

Xiao says he had been interested for some time in the unique features of insect eyes, particularly because they can provide a wide-angle field of view, high acuity to motion and an infinite depth of field. "These features are not available in our human eyes," he says.

Their compound eyes are made up of many smaller eyes, each with their own lenses, acting together. Similarly, the camera has 180 miniature lenses and associated electronics.

While there had been some research in this area before, no one had been able to produce a fully functional insect-eye-like imaging device. Xiao started working on this project in 2011 as a post-doctoral researcher at the University of Illinois, where his other co-lead authors of the study still work.

Stretchable Electronics

He attributes a lot of the success to the advances that have been made in stretchable electronics that allow the electronics to be placed on a curved surface. Until recently, scientists were limited to flat surfaces because the silicon used for most of the electronics is very brittle. With stretchable electronics and a sheet of microlenses made from a substance similar to that used in contact lenses, the team was able to imitate the compound eyes of insects.

"The development of stretchable electronics technology is indeed the key to this breakthrough, which makes it possible to build high-performance electronics onto complex geometries, such as hemispheres," he says. "On the other hand, the innovation of a stretchable microlens array is also very critical for this success."

The positive outcome also involved coming up with ideas for new materials and fabrication methods but, importantly, still using conventional manufacturing processes. The electronics and lenses are both fabricated and integrated together while flat, which means they can be manufactured using conventional technology. They are later molded into a hemispherical shape using homemade hydraulics equipment, Xiao explains.

"During the geometry transformation, huge strains were introduced into both the electronic and optic subsystems," he says, to make sure both subsystems can sustain large strains without affecting their electronic and optic performances.

The success comes years after working on stretchable electronics to make their electronic performances comparable to their commercial counterparts but in addition allow them to be stretched, twisted and manipulated like a rubber band. The team also developed a stretchable photodiode array based on previous research and an innovative way of creating microlens arrays that can be stretched extensively without distorting the optics, he says. Such work enables a variety of applications that have not been possible with the hard, planar integrated circuits that exist today.

In addition to Xiao's former colleagues at the University of Illinois, the team includes members from Harvard University, Northwestern University, and from universities in China, Korea, and Singapore.

Nancy S. Giges is an independent writer.

The development of stretchable electronics technology is indeed the key to this breakthrough.

Jianliang Xiao, University of Colorado-Boulder

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July 2013

by Nancy S. Giges, ASME.org