New glucose sensor using sponge-like copper

Credit: University of Wollongong

A team of researchers from the Institute for Superconducting and Electronic Materials (ISEM) of the University of Wollongong has developed a sponge-like copper that makes glucose detection from sweat or tears simpler. This could lead to a less complex and less expensive management of diabetes.

Diabetes is a disease associated with erratic blood-sugar levels due to low levels of the hormone insulin, which is responsible for the conversion of sugar to energy. The disease is caused by a variety of factors: diet, physical activity and genetics. Persons diagnosed with diabetes often need their blood-sugar levels monitored to avoid further complications.

However the current method in monitoring blood-sugar levels uses platinum as sensor. This means the technology is expensive despite support from the government of Australia.

The solution is to replace the precious metal sensor with something that is readily available like copper. The method of glucose detection would be the same: the device would be inserted under the skin and will provide regular readings. Only this time it would come at a much lower price.

Professor Yusuke Yamauchi of ISEM recognizes the exceptional conductivity of platinum as well as gold which is the reason why they are the material of choice for current glucose sensors. “But they are very expensive and we wanted to focus on more abundant and cheaper metals,” he adds.

Yamauchi has been eyeing copper-based glucose sensor even when he is still at Japan’s National Institute of Material Science. Copper is a good conductor and cheaper; the challenge lies in making it porous. It is known to readily oxidize when exposed to air and would lose its desired levels of conductivity.

“Not only are these metals are highly reactive with air, they do not reduce easily in solutions and are difficult to deposit consistently on to substrates,” adds Yamauchi.

Yamauchi and his team’s solution was to create a liquid solution of copper plus polystyrene. This would lead to copper coated polystyrene balls which are then attached to a substrate. Upon exposure to ultraviolet rays, the polystyrene center melts and leaves microscopic holes that are thousand times thinner than human hair. The end result is a sponge-like copper film with a porous structure.

The film easily reacted to glucose without interference from other substances in sweat like acids and sugars. It also reacted quickly to the presence of glucose in small amounts of liquid. This means that the carbon film is both selective and sensitive – qualities of a good sensor.

Professor Yamauchi said that the sensitivity is due to the increase of surface area which in turn is due to the sponge-like porous structure. Besides this, copper is known to be intrinsically reactive towards glucose oxidation. “This makes this copper film a good candidate for the direct detection of glucose to satisfy the requirements of diverse applications, such as diabetes management,” he adds.

Future application of the carbon film would be smartwatch or other wearable integration. The device would provide continuous glucose readings for the user. The data could also be sent to the user’s doctor.

Because the material is now cheaper, glucose detection is now more possible for remote and poor communities. Professor Yamauchi and his team now eyes creating other porous materials from abundant materials with the aim of creating materials with diverse applications at a much cheaper price.

More information can be found at: University of Wollongong.

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