NTU Singapore Released Tear-based Smart Contact Lens
Recently, scientists and researchers from Nanyang Technical University, Singapore (NTU Singapore) released a smart contact lens powered by the tear-based battery. The research team mentioned in their article that the new smart contact lens can be charged with biofuel and utilize human tears since tears are electrolyte solutions [1]. That means the smart contact lenses can be charged when put on by the user or immersed in the contact lens box.
How is this possible?
Some people might be curious at first glance: how this could be possible? As we all know, contact lenses are wearable devices designed for vision correction. In most cases, they don’t need to be “charged” at all, and it is hard to imagine how we can charge devices as little as contact lenses. So, how is this possible?
As Yun et al. disclosed in the article, they chose a miniaturized unwired connection to ensure the comfort and safety level of the contact lenses. Although aqueous battery sounds like a good choice, it might be risky to the users since it will release hazardous chemical components if broken [2]. Therefore, the team finally chose to develop a battery-driven by biofuel. That means the apparatus doesn’t require an external power supply and won’t cause potential leakage issues like aqueous batteries. Instead, they can be charged when the biofuel solution is at a specific concentration, i.e., the tears mentioned above.
To achieve this goal, they designed the cathode consisting of CuHCFe (Copper hexacyanoferrate) and GOx (glucose oxidase enzyme), and it can be charged by the enzymatic reaction of Gox with glucose. As for the anode, it was charged by the self-reduction of PPy (Polypyrrole) [1]. After simulating the usage cycle of contact lenses in artificial human tears, this tear-based battery demonstrated excellent capability in charging and discharging, and it may provide voltages up to 1V [1]. In other words, it would be sufficient for daily usage of a regular contact lens user. Therefore, this could be an excellent enzymatic reaction-charged platform.
Yet, would it be safe to be applied in the real scenario? Currently, the answer is positive. The research team has investigated the biocompatibility of the battery by performing cytotoxicity test on cultured Human Bone Osteosarcoma Epithelia cell line. As the result shows, this battery exhibits biocompatibility during charging and discharging for 24 hours [1]. Yet more experiments might be required after being launched to the market.
Why this could be important to us?
However, many people may still have a question: it sounds fancy, but why should we need a smart contact lens like this? To answer this question, we may reflect on the development of AR/VR/XR: various companies are trying to develop lightweight and comfortable AR devices. Meta has introduced Oculus, and Apple had scheduled to launch Apple Vision Pro in 2024. Yet, have you imagined we can do this with contact lenses one day? At that time, the UI will be right before our eyes. You can translate texts with the smart contact lens and see the trending news as well. It may also display your heart rate and health condition like your Apple watch will do, even better. You may feel a broader world since you don’t have to wear an apparatus on your head.
In other words, the advancement of flexible batteries and portable devices will foster the progress of AR/VR/XR. As Joo-Sung Kim, the Chief Executive of LiBEST (a South Korean startup), stated, suitable wearable devices will help to create a world with no space restrictions, as known as the Metaverse [3]. Although it may take some time to integrate all those technologies with the smart contact lenses, it is still inspiring.
Last Word
As we’ve discussed, the smart contact lens equipped with the tear-based battery driven by biofuel is remarkable progress. Although numerous experiments are still needed before they can be put into practical use, we can keep an eye on it for now. In the future, contact lenses might have more meaning than a “vision correction device” in our daily lives.
References:
[1] Yun, J., Li, Z., Miao, X., Li, X., Lee, J. Y., Zhao, W., & Lee, S. W. (2023). A tear-based battery charged by biofuel for smart contact lenses. Nano Energy, 110. https://doi.org/10.1016/j.nanoen.2023.108344
[2] Park, J., Ahn, D. B., Kim, J., Cha, E., Bae, B. S., Lee, S. Y., & Park, J. U. (2019). Printing of wirelessly rechargeable solid-state supercapacitors for soft, smart contact lenses with continuous operations. Science advances, 5(12), eaay0764. https://doi.org/10.1126/sciadv.aay0764
[3] Cureton, D. (2023, August 29). NTU Singapore unveils saline-powered smart contact plans. XR Today. https://www.xrtoday.com/augmented-reality/ntu-singapore-unveils-saline-powered-smart-contact-plans/
