NTU Singapore’s Break Through Discovery – Human Tears Lenses

Researchers at Nanyang Technological University (NTU) in Singapore have created an incredibly thin battery that is just a few micrometers in size, has the unique ability to power smart contact lenses. Furthermore, these human tears lenses can gain charge using tears, according to a press release from the university, according to Interesting Engineering. Moreover, the group has developed a metal-free battery under the guidance of Lee Seok Woo, an assistant professor at NTU’s School of Electrical and Electronic Engineering (EEE).

History and Future of Contact Lens

In the past, contact lenses were used to correct vision. However, as technology developed, scientists started focusing on developing smarter iterations that could connect to gadgets like smartphones. Furthermore, they also tried to show information directly in front of the wearer’s eyes. Hence, the incorporation of an internal battery within the human tears lenses gained importance for this kind of capability.

Previously, extremely thin batteries with induction coils and metal wires were used to power augmented reality displays on smart contact lenses. However, the user’s eyes might be at risk from these. To meet this difficulty, the NTU research team created a biocompatible material battery that is covered with a glucose-based compound. The coating successfully creates circuitry to produce electricity by interacting with salt and chloride ions found in the battery’s internal water. Importantly, since tears contain salt and chloride ions as well, the lenses could potentially charge spontaneously while being worn.

The Modern Technology-infused Human Tears Lenses

Lee Seok Woo explained, “This research began with a simple question: Could contact lens batteries be recharged with our tears? Previous techniques for human tears lenses’ batteries failed to deliver perfection. Since often, the batteries’ electrode gained charge while the other did not. Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction.”The glucose and water used in the procedure are safe for the environment and pose no risk to the consumer.

Despite the battery’s extremely small size, which is only a fraction of a millimeter thick, worries about its energy capacity and durability persist. Hence, to overcome this, the researchers used a simulated eye model in their trials. The battery can provide a current of 45 microamperes and a maximum power output of 201 microwatts, which is enough to run the gadget for the majority of the day, according to the results.

Tears are used in an inventive charging technique, which is essential. For every twelve hours of use, putting the battery in a simulated tear solution can add one hour to these human tears lenses’ lifespan. Furthermore, the battery can be kept in a concentrated saline solution with lots of glucose, potassium, and sodium ions when not in use to make charging easier.

The research team verified that the battery can undergo 200 charge-discharge cycles, demonstrating its durability. Moreover, Li Zongkang, a Ph.D. student at NTU involved in the project, noted, “By combining the battery and biofuel cell into a single component, the battery can charge itself without the need for additional space for wired or wireless components. Furthermore, the electrodes placed at the outer side of the human tears contact lenses ensured no obstruction of the eye vision.”

To introduce this revolutionary technology to the market, the team is presently concentrating on boosting the battery’s discharge capacity and working with contact lens manufacturers.

Biography of Assoc Prof Lee Seok Woo

Source: NTU Singapore 

After earning a B.S. in mechanical engineering from Pohang University of Science and Technology (POSTECH) in 2003 as well as a Ph.D. in the same field from Korea Advanced Institute of Science and Technology (KAIST) in 2008, Seok Woo Lee entered the workforce. Furthermore, after working as a research associate and postdoctoral fellow at Stanford University for almost six years, he has been an assistant professor at Nanyang Technological University’s School of Electrical and Electronic Engineering since January 2016. Moreover, he has written 37 journal articles and received more than 2600 citations. Lastly, his area of interest in research is energy storage and conversion electrochemical systems.