imec, a research and innovation hub for nanoelectronics and digital technologies, has announced a hydrogel-based smart contact lens that incorporates a silicon microchip, integrated LED light, and radiofrequency (RF) antenna for wireless energy transfer. Belgium-based imec claims that the new lens paves the way for integrated sensors or drug delivery capabilities, whereby a contact lens could continuously monitor for signs of ocular diseases, and even administer treatments.
Ghent University and SEED Co., a contact lens manufacturer based in Japan, collaborated with imec to develop the device. Designing flexible electronic components and seamlessly integrating them into a soft hydrogel lens were major challenges in creating the new device.
The lens needed to be oxygen-permeable, wrinkle-free, thin, and comfortable to wear, while maintaining electrical functionality. The researchers conducted significant optimization to achieve these properties.
The lens incorporates a blue LED light that is powered by a radiofrequency antenna. The antenna should also allow for any integrated sensors to transmit data to a handheld device for analysis. At present, the device represents a proof-of-concept, and imec hopes to expand its capabilities in the future.
Medgadget asked Prof. Herbert De Smet of Ghent University and imec, some questions about the system.
Conn Hastings, Medgadget: Please give us some background on this type of technology and the current state of the art.
Herbert De Smet: Globally, quite some effort has been spent on realizing so-called ‘smart contact lenses’ — contact lenses that contain electronics to increase the functionality of the lens in many possible ways. Most efforts have focused on hard lenses made of rigid gas permeable material or on soft lenses made of silicone, both of which are materials that are still relatively compatible with standard electronics integration technologies. However, we are one of the only groups in the world that has demonstrated the capability of integrating functional electronics in hydrogel-based soft contact lenses.
Medgadget: What types of ocular diseases could a smart contact lens be useful for monitoring and treating?
Herbert De Smet: Smart contact lenses could offer adaptive optical correction for presbyopia patients. They can also offer a solution for people with iris deficiencies, such as aniridia or coloboma. As reported in our research, we have prepared the technological platform to integrate sensors that continuously or regularly monitor bodily parameters such as the concentration of certain substances in the tear fluid. The sensors can be powered and also read out wirelessly. Our partner, SEED, is presently assessing which parameter would be the most important for a first use case.
Medgadget: Is there potential for this type of device in other diseases where continuous monitoring could be useful, such as diabetes?
Herbert De Smet: Continuous monitoring is an important diagnostic tool for early diagnosis of many diseases. Diabetes may be the best known example, but unfortunately, it is not the easiest use case because the glucose concentration measured in the tear fluid lags too far behind compared to the glucose concentration in the blood. Fortunately, there are other applications where a contact lens is excellently positioned to do the monitoring.
Medgadget: Please give us an overview of the device that imec and collaborators have created, and its current capabilities. How does the wireless energy transfer system work?
Herbert De Smet: The smart contact lens that we have demonstrated is comprised of a wirelessly-powered microsystem embedded in a hydrogel-based contact lens. The lens has a normal lens shape, which resembles a spherical cap. Its total thickness is in the range of 150–200 micrometers. The embedded electronics insert has a total thickness of less than 100 micrometers and is thermoformed to give it a spherical cap shape with the correct radius of curvature so that it fits in the very limited space offered by the lens. The electronics include a ring-shaped antenna for wireless powering and communication, and a small integrated circuit (IC) that harvests electrical energy from the antenna and uses it to drive a blue micro-LED that is also integrated. The energy transfer and communication with the IC (that could also interface with a sensor and transmit numerical data wirelessly) happens via the near field communication (NFC) protocol.
Medgadget: What were the greatest challenges in miniaturizing the electrical components for the lens?
Herbert De Smet: The greatest challenges were the very limited thickness that is allowed, the spherical cap shape that the electronics needs to have before it can be integrated into the lens and the fact that it has to be very flexible even after thermoforming. We achieved this through a combination of material choices and wrinkle-avoiding designs supported by multiphysics simulations. Our industrial partner, SEED, has shown exceptional skills to embed the insert into its very thin hydrogel lenses.
Medgadget: Where do you see this technology going in the future? What are your plans in terms of developing the device further?
Herbert De Smet: In the short term, the integration of a suitable sensor is targeted. For autonomous operation we are also looking at the integration of a micro-battery. In the somewhat longer term, we are looking at integrating actuators for controlled drug release. In parallel, we are constantly improving our barrier layer technologies to protect the embedded electronics from the tear fluid and vice versa.
Link: imec…