A tiny microphone

A transparent device that can fit into a contact lens could help to diagnose macular degeneration and diabetic eye disease.

Scientists at Northwestern University have created a tiny ultrasensitive device capable of determining the speed of blood flow and the oxygen metabolic rate at the back of the eye.

The Micro-ring resonator detector was developed following Professor Hao Zhang’s work on photoacoustic imaging, which combines sound and light waves to create images of biological materials.

Professor Zhang told OT that the technology had many biomedical applications, including photoacoustic imaging of the retina.

He started the work in 2006 after the Feinberg School of Medicine asked him to develop a new diagnostic device that could measure biological activities at the back of the eye.

Associate professor of mechanical engineering, Dr Cheng Sun, explained that ultrasound detection devices at the time were bulky, opaque and insensitive,

“It could only capture part of what was happening in the eye,” he said.

The researchers needed to create a device that was small, soft and could generate a high resolution of hundreds of megahertz.

“The challenge was to fabricate it, have it fit in the size of a contact lens and make it still work,” Dr Sun highlighted.

The device they created is 60 micrometres in diameter and one micron high.

As well as its potential for detecting eye disease, the new technology holds potential in diverse fields from neuroscience to geology.

Work is being done to further improve the device and prepare it for clinical trials.  

Image credit: Etan J. Tal