OcuCheck biosensor (L. Brian Stauffer, University of Illinois – Champaign)
9 December 2015. A medical and engineering team at University of Illinois in Champaign designed a sensor providing a quick, portable test for the severity of eye injuries. The researchers led by bioengineering professor Dipanjan Pan and ophthalmologist Leanne Labriola at Carle Foundation Hospital affiliated with the university described the proof-of-concept device last month in the journal Scientific Reports. Pan and Labriola also started a company to take their invention to market.
The device is designed to help first responders and clinicians quickly determine the extent of eye injuries at accident scenes or in battlefield clinics where standard hospital diagnostic equipment is not available. Currently there are no diagnostic tests approved by Food and Drug Administration in the U.S. for point-of-care assesments of eye injuries.
The biosensor designed by the Illinois team measures levels of ascorbic acid, also known as vitamin C, in the ocular tear film, the fluid coating the eyeball. Ocular tear film normally contains low levels of ascorbic acid, while the interior of the eye has much higher levels. The device is based on the premise that if the eye is damaged, higher concentrations of ascorbic acid will be present in the ocular tear film indicating damage to the eye.
The sensor is built on filter paper with a layer of nanoscale platelets of graphene, a carbon material closely related to graphite like that used in pencils, but consists of only a single layer of atoms arrayed in a hexagonal mesh pattern. The material is very light, strong, chemically stable, and can conduct both heat and electricity, with applications in fields such as electronics, energy, and health care.
The graphene layer is then coated with a polystyrene polymer that interacts with graphene, and ascorbate oxidase, an enzyme that binds to and oxidizes ascorbic acid in the ocular tear fluid sample. The sensor acts by ascorbate oxidase binding to the ascorbic acid and pulling out the polymer, leaving conductive graphene. Gold electrodes between the enzyme and polymer layers transmit the signal to a connected handheld voltage meter.
The researchers tested the device they call OcuCheck with 16 patients undergoing eye surgery who offered samples of aqueous humor fluid, which were also assessed with standard lab equipment. The results show OcuCheck assessments correspond closely to standard lab tests, with greater than 80 percent accuracy, 88 percent sensitivity (returning true positive results), and 71 percent specificity (returning true negative results). Further tests show OcuCheck was able to test eye fluid samples even when those samples were mixed with blood.
Pan and Labriola founded a new company, InnSight Technology, to commercialize the device, for which the university filed a patent application. On 2 December, InnSight Technology received a $150,000 Small Business Innovation Research grant from National Science Foundation to build OcuCheck into a commercial product. The early-stage grant supports further design and development work to prove the device’s technical and commercial feasibility.
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