Smart Contact Lens Detects Diabetes and Glaucoma – IEEE Spectrum

Posted: May 5, 2017 at 11:42 pm

While tech giant Google continues to struggle to make a contact lens for monitoring diabetes,researchers at Ulsan National Institute of Science and Technology (UNIST) in South Korea have offered up at least one part of the puzzle: better wearability. Through the use of a hybrid film made from graphene and silver nanowires, the UNIST researchers have made contact lenses for detecting multiple biomarkers that are clear and flexible.

In research described in the journal Nature Communications, the UNIST researchers used graphene-nanowire hybrid films to serve as conducting, transparent, and stretchable electrodes. While the hybrid film alone does not perform any detection, the electrodes do ensure that the electrodes in the contact lenses dont obscure vision and that theyre flexible enough to make wearingthe lenses comfortable.

In addition to offering better transparency and comfort, the contact lenses developed by the UNIST researchers depart from previous contact lens sensors in that theyreable to detect multiple biomarkers. This contact lens should be able to pick up indictorsfor intraocular pressure, diabetes mellitus, and other health conditions, according to the researchers.

To detect intraocular pressure, a dielectric layer is sandwiched between two hybrid films. In this arrangement, the films now become a capacitor that responds to intraocular pressure. At high intraocular pressure, the thickness of the dielectric layer decreases, resulting in the increased capacitance. High intraocular pressure also increases the inductance of the antenna coil by bi-axial lateral expansion.

For detecting glucose, the top hybrid film layeris exposed to tears and detects glucose. In a selected region of the film, the researchers removed the nanowires so only graphene remained. The surface of graphene was then coated with an enzyme that binds selectively to glucose.Thisbinding changes the resistance of the graphene.

The changes of resistance, inductance and capacitance in these two detection modes can be monitored wirelesslyin real-time.

One of the challenging aspects of the research was the glucose sensor, according to the researchers. In tears, there are many interfering ions and molecules that potentially cause false positive responses, explained Chang Young Lee, an assistant professor at UNIST and co-author of the study, in an email interview with IEEE Spectrum. We need to test the selectivity and long-term reliability of the glucose sensor. The effort includes designing and finding a molecule that selectively binds to glucose, which is another large research area.

Lee envisions this research as a novel platform that will enableintegration of glucose sensor onto a soft contact lens. Measuring the glucose accurately and reliably is another large research area, Lee added. A good glucose sensor developed by another researcher, for example, can easily be integrated onto our platform.

In this novel platform, both the graphene and the silver nanowires contribute indispensible properties. The silver nanowires offer a one-dimensional (1D) conducting material, and by creating a network (mesh) of it, its possible to make a transparent, conducting, and flexible film. However, the film made of silver nanowires alone has limitations, such as high contact resistance at the nanowire-nanowire junctions, low breakdown voltages, poor adhesion to flexible substrates, and oxidation in harsh environments.

This is where the two-dimensional (2D) graphene comes in, with its properties of being highly transparent, conducting and flexible. By creating a hybrid structure of graphene and nanowires, the limitations of the nanowires are overcome. The key is in the hybrid of 1D and 2D structures, added Lee.

IEEE Spectrums nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

Controlling the electrical current for heating graphene allows sound frequencies to be mixed together, amplified, and equalized 5May

Technique opens up potential of tailoring material properties nearly atom-by-atom 2May

Discovery could be the answer to the demands for increasing information storage density as device feature sizes decrease 26Apr

Technique could reduce costs for compound semiconductor circuits and lead to new devices 24Apr

The new molybdenum disulfide microprocessor has 115 transistors 11Apr

A graphene photodetector can pinpoint the position of light that falls far from it 10Apr

Researchers at SLAC are leveraging X-rays to enable the next generation of batteries and photovoltaics 5Apr

Diamondoids are showing promise in applications as divergent as electron guns and quantum computing 31Mar

The electronic skin is touch-sensitive and could be inexpensively manufactured 30Mar

Stanford researchers are getting a lot of mileage from nanomaterials by analyzing market needs 29Mar

The elliptical shape makes the lasing process easier 20Mar

Japanese materials company prototypes a 26.3 percent efficient silicon cell, steps away from the 29 percent theoretical maximum 20Mar

Otherlabs self-fluffing fabric changes its insulation in response to temperature 18Mar

Development is incremental in molecular nanotechnology, but it is coming along slowly 14Mar

New encoding method makes it possible to come close to the theoretical maximum for DNA data storage 2Mar

Replacing high-voltage power source with nanogenerators increases sensitivity to new records 27Feb

First borophene-based heterostructure should guide future work with borophene in nanoelectronic applications 23Feb

Five teams, four rockets, and 380,000 kilometers togo 22Feb

Current can literally blow copper interconnects away, but graphene could keep them intact 17Feb

Biocompatibile inks open up medical devices for inkjet-printed devices 2Feb

Continue reading here:
Smart Contact Lens Detects Diabetes and Glaucoma - IEEE Spectrum

Related Posts