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Portable device can quickly determine the extent of an eye injury

09 December 2015

An engineer and an ophthalmologist are developing a portable sensor that can quickly and inexpensively determine whether an eye injury is mild or severe.

The sensor can detect differences in vitamin C concentration in fluids that leak from the eye. Higher concentrations indicate a more severe injury (photo: L. Brian Stauffer)

The device, dubbed 'OcuCheck', measures levels of vitamin C in the fluids that coat or leak from the eye. The sensor could speed efforts to determine the extent of eye injuries at accident sites, in rural areas lacking ophthalmology specialists or on the battlefield.

"The sensor takes advantage of the fact that the ocular tear film - the viscous fluid that coats the eyeball - contains low levels of ascorbic acid, which is just vitamin C, while the interior of the eye contains much higher levels," says University of Illinois bioengineering professor Dipanjan Pan, who is creating the device in collaboration with ophthalmologist Dr Leanne Labriola. "So the concept is, if there is severe damage to the eye that penetrates deeply, the ascorbic acid will leak out in high concentration."

At present, those with eye injuries must find their way to a hospital to have their injuries assessed. The process is often complicated, time-consuming and imprecise. The researchers believe that no current techniques for assessing eye injuries involve measurements of ascorbic acid, making this development one-of-a-kind.

The new sensor uses graphene platelets that are layered one nanometre thick on filter paper. Upper layers include a polymer that interacts with the graphene, gold electrodes and ascorbate oxidase, an enzyme that binds to ascorbic acid.

"The idea is that the moment that the ascorbic acid comes in and binds to the ascorbate oxidase, it will pull the polymer out of its interaction with the graphene [changing the sensor's electrical properties]," says Pan.

In tests with clinical samples from 16 patients undergoing eye surgery, the team found that their sensor could - with high sensitivity, accuracy and specificity - detect a range of ascorbic acid concentrations. The sensor's sensitivity to ascorbic acid is retained even in the presence of blood.

The team is now working to commercialise the new sensor.

An article describing this work is published in the journal, Scientific Reports.

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