There is nothing more fascinating to soak in the scenes of life, and that which ingrains those images in our hearts and minds are our eyes. They are the window to the world. The greater the clarity and sharpness, the more the impact.
Those who wear lenses go through the ordeal of storing them in contact solutions, wearing and taking them off with trained fingers to avoid damaging the eyes and lenses.
Smart lenses are similar to traditional ones as they are placed directly on the surface of the eye, but they monitor a wide range of parameters. It can track health metrics, including blood sugar levels, intraocular pressure, and other vital factors.
Some categories of smart lenses can also function like fitness watches recording heart rate, steps and other activities. Smart lenses can offer augmented reality directly in front of the wearer’s eyes.
Although there are innumerable benefits that come with smart lenses, they are expensive and have limited battery life. The lenses run on small batteries that need to be recharged or replaced at regular intervals, making them unfit for wearing for long periods.
However, Nanyang Technological University, Singapore (NTU) scientists have developed a flexible battery whose thickness is equivalent to the cornea that can store electricity, when it is placed in a saline solution.
The battery developed by NTU is produced from biocompatible materials instead of wires or induction coils in rechargeable batteries or wireless charging modules. It is composed of a glucose-based coating reacting with the sodium and chloride ions in the saline solution surrounding it, while the electricity is channeled through the water that serves as the circuit. How will power be generated? Human tears could be a source as it contains sodium and potassium ions in a diluted form.
The experts tested the existing battery system with a simulated tear solution and it showed that the battery’s life could be extended by an additional hour for every 12-hour wearing cycle. The battery can also be charged conventionally. Associate Professor Lee Seok Woo, from NTU’s School of Electrical and Electronic Engineering (EEE), who led the study, recalled that the research was triggered by a simple question: Could contact lens batteries be recharged with our tears?
Drawing a comparison, he said that earlier lens batteries were “not perfect” as one side of the battery electrode was charged and the other was not. “Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction.”
The team conducted an experiment using a simulated human eye as the basal tears – which create a thin film on the eyeballs – reacted with the battery which is about 0.5 mm thin and generated electricity through a process called reduction. The battery could produce a maximum power of 201 microwatts, sufficient for smart lenses.
The findings were published in the scientific journal Nano Energy in June.