Contact lenses for diabetics
The glucose sensor in contact lenses will feed on tears
ChemPort.Ru based on RSC materials: Glucose-sensing contact lens could run on power of tearsIt is possible that someday patients suffering from diabetes will be able to determine the level of glucose in the blood not through regular painful injections, but with the help of bionic contact lenses.
Researchers have developed a new fuel cell that works at the expense of tear fluid.
The idea that you can use contact lenses to monitor the health of a diabetic is not so new – the development of devices of this kind has been carried out for the last decade. An electric glucose sensor in a contact lens can be in direct contact with tear fluid, can analyze its composition and display the results of this analysis on a display integrated into the lens, such information can be easily read by the lens wearer. However, such a sensor must have a power source, and until recently, the lack of such a power source was the main problem on the way to creating sensors of this kind.
An international team led by Sergey Shleev, who works at the University of Malmo (Sweden), may have solved this difficult task by creating a biofuel energy element that generates energy through the conversion of ascorbate and oxygen present in the tear fluid. The fuel cell uses two organic catalysts that accelerate the anodic oxidation of ascorbate, and the enzyme bilirubin oxidase, which restores oxygen at the cathode. Using human tear samples, researchers have shown that such a fuel cell can use tears to generate energy, while the glucose content in tears does not change (Falk et al., Miniature Biofuel Cell as a Potential Power Source for Glucose-Sensing Contact Lenses // Anal. Chem., June 5, 2013).
It is possible that this fuel cell will eventually be able to provide power to glucose sensors mounted in contact lenses.
The energy output of the new power source is very, very modest – in accordance with the theoretical estimates for this contact lens, based on the concentration of ascorbate ion in the tear fluid, is only 22.1 microwatts. However, the researchers note that such output power will be enough to power a tiny sensor, especially if the area of the electrodes is increased by using both sides of the contact lens.
However, Chris Geddes, director of the Fluorescence Institute in Baltimore, notes that the new technology is unlikely to find a large-scale application for glucose control. Some time ago, Geddes successfully developed fluorescent glucose sensors integrated into contact lenses (Ophthalmic glucose sensing: a novel monosaccharide sensing disposable and colorless contact lens // Analyst, Issue 6, 2004), but when it came to commercialization of the invention, companies showed only limited interest in it. He notes that it is almost impossible to compete in price efficiency with standard blood glucose meters, for which a drop of blood is taken – most patients are currently not ready to buy expensive disposable contact lenses.
Nevertheless, Geddes adds, he admires the idea of an electrochemical power source integrated into a contact lens, and he hopes that over time wearable electronics will be able to occupy a worthy niche in medicine – and not necessarily for monitoring the condition of diabetic patients.
Portal "Eternal youth" http://vechnayamolodost.ru01.07.2013