PU Discovery Enables ‘Smart’ Contact Lenses to Monitor Health
A Purdue University researcher believes he’s on the way to creating high-tech contact lenses soldiers could wear for night vision. Another ambition is augmented reality, minus the bulky goggles. It seems far-fetched, but Biomedical Engineering and Mechanical Engineering Assistant Professor Chi Hwan Lee has a health-focused, patent-pending innovation that he believes is a stepping stone to the vision technologies of tomorrow.
Before night vision and augmented reality can exist on contact lenses, the process of adding devices and sensors must first be perfected. Lee has developed and earned a patent on a method that clears a very high hurdle—putting sensors or other technology on a soft contact lens. Lee was inspired by Google Contact Lens, a smart contact lens project that was announced in 2014 to help people with diabetes monitor glucose levels.
But Lee says the Google Contact Lens and other innovations like it had one major stumbling block: the technologies had to be built on plastic-based, custom-made, more rigid contact lenses that have flatter surfaces, “because a hard lens can withstand the fabrication conditions for the devices, like high temperature.” However, hard lenses have limited biocompatibility; simply put, they’re not comfortable to wear for a long period of time.
However, Lee’s discovery allows sensors and other small devices to be built on commercially available soft contact lenses, which is no small feat. Technical challenges abound: commercially available soft contact lenses have curved surfaces and are made of very soft material called hydrogel, which Lee says is 90 percent liquid.
“The soft contact lens is a very, very challenging substrate (surface) on which to fabricate electronics,” says Lee. “We developed the transfer printing process; we fabricate conventional, high-performance sensors on top of conventional substrate. So we don’t develop the sensors; we just use conventional sensors—miniaturized or in-film sensors. Our technology allows us to transfer [these] sensors from the hard substrate to the soft contact lens.”
Lee believes the method to build various sensors and devices on soft contact lenses opens the door to customization.
“Thin-film sensors can contain a range of sensing elements—temperature sensors, pressure sensors or chemical sensors. The sensor can be customized depending on the purpose of the final product,” says Lee. “The current version we have has an array of temperature sensors, such that it can measure the temperature distribution on the surface of the eyes. Any abnormal distribution of the surface temperature on the eye can be a sign of some ocular diseases, such as glaucoma.”
Chemical sensors, he notes, could monitor glucose levels on a continuous basis. Inspired by his father-in-law who has diabetes, Lee says the method would decrease the burden of finger pricks to check glucose levels and have the added benefit of constant monitoring, versus only a snapshot in time.
Because it’s difficult to make every sensor or tiny device transparent, Lee’s method involves placing the items around the periphery of the lens, maintaining the clear center of the contact lens, so the additions don’t obstruct the wearer’s vision.
Lee has worked with the Purdue Office of Technology Commercialization to obtain a patent for the technology and hopes to license it soon. His ultimate goal is to modify the discovery for wearable night vision or augmented reality, both of which are in his “long-term pipeline.”
“I hope this technology will be very beneficial to many people who suffer from [diabetes, glaucoma and other ocular diseases]. That makes me very motivated,” says Lee. “The fact that this technology can help many, many patients throughout the world—including my father-in-law—makes it very exciting.”