Contact lenses are most often used to correct blurry vision, but sometimes, people wear differently colored ones for fun. And with Halloween just around the corner, people will soon be stocking up on red, black or cat-eye contacts to look extra spooky. Researchers are currently working hard to adapt these little hydrogels into smart devices to treat color blindness, for use in wearable virtual displays, and for drug delivery and noninvasive health monitoring. Below are some recent papers published in ACS journals that report insights into powering smart contacts, as well as new ways they can deliver drugs. Reporters can request free access to these papers by emailing newsroom@acs.org.
Powering smart lenses
“Safe, Durable, and Sustainable Self-Powered Smart Contact Lenses”
ACS Nano
Sept. 7, 2022
Here, researchers showed that the glucose in tears can power smart contact lenses. They sandwiched a microscopic glucose fuel cell between soft hydrogel layers. Combining the fuel cell with color-changing crystal arrays produced a protype sensor that visibly distinguished artificial tears simulating a diabetic condition from controls. The device still needs to be made even smaller, however, before it could be used in smart glucose-sensing contact lenses, say the researchers.
“Flexible and Semi-Transparent Silicon Solar Cells as a Power Supply to Smart Contact Lenses”
ACS Applied Electronic Materials
Aug.1, 2022
In this paper, flexible, semi-transparent solar cells were designed for running the microelectronic and optoelectronic elements in smart contact lenses. Researchers molded the 15 µm-thick silicon-based photovoltaics in arcs, embedding them into dome-shaped lenses. Based on experiments in indoor and outdoor light, the researchers estimated that their 25 and 50% transparent solar cells could generate 49.3 and 26.6 J cm-2 per day, respectively, showing their potential to deliver energy to smart contact lenses.
Delivering drugs
“Printable Metal–Polymer Conductors for Local Drug Delivery”
Nano Letters
Sept. 19, 2022
Medications, such as drops or ointments, that are administered topically can enter the body more easily with localized applications of electricity. As a step toward using this technique to treat eyes and skin, researchers printed liquid metal circuits onto stretchable and bendable pieces of polydimethylsiloxane, simulating contact lenses and skin patches. In animal model tests, electrical pulses were applied to the metal-polymer contact lens, which the researchers found improved the therapeutic effect of eye drops.
“Pressure-Triggered Microfluidic Contact Lens for Ocular Drug Delivery”
ACS Applied Polymer Materials
Sept. 7, 2022
Most eye infections are treated with drops, but blinking and tears quickly rinse them away. So, researchers have developed prototype smart contact lenses that can gradually deliver drugs directly onto the eye. The lenses have arc-shaped microfluidic channels and a micropump that’s activated by eyelid pressure. In blinking simulations, the flexible, transparent lenses released drug-like fluids in a controlled and sustained manner without the need for electronic components.
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