An autonomous contact lens to improve human vision

Two teams from IMT Atlantique and Mines Saint-Étienne have developed an autonomous contact lens which is powered by an integrated flexible micro-battery. This invention is a world first that opens new health prospects, whilst also opening the door for scientists to develop other human-machine interfaces.

 

Human augmentation, a field of research that aims to enhance human abilities through technological progress, has always fascinated authors of science fiction. It is a recurring theme in the British TV series Black Mirror and The Six Million Dollar Man. But beyond dystopia and action adventure, it also interests science. The recent findings from teams at IMT Atlantique and Mines Saint Étienne are one of the latest examples of this.

Jean-Louis de Bougrenet is the head of the Optics Department at IMT Atlantique. Thierry Djenizian is the head the Flexible Electronics Department at the Centre Microéléctronique de Provence at Mines Saint Étienne. Together, the two scientists have achieved a world first; they developed the cyborg lens, an autonomous contact lens with a built-in flexible micro-battery.

The origins of the cyborg lens

In the medical division of his department, Jean-Louis de Bougrenet was working on devices to improve people’s vision. Whilst doing this, the researcher and his team used oculometers, instruments used to analyze how eyes behave, measure an individual’s fatigue or stress, and also to see the direction of their gaze. These devices are used in technology such as VR headsets which can use the direction of someone’s gaze or when they blink to make a command.

However, to be truly efficient, the oculometer must be able to do two things. Firstly, it has to be extremely precise. Secondly, to make sure the VR headset does not contain any additional components that weigh the user down, the oculometer has to be as light as possible. These factors made it clear to the scientists that the oculometer had to be placed directly in the user’s eye. “The contact lens very quickly emerged as a way to make human augmentation possible, since it allowed humans to carry a smart device directly on them,” explains the optical researcher. This system is made possible by advances in nanotechnology.

Thierry Djenizian has spent the last four years working on integrating electric components onto flexible and stretchable surfaces. His research led to the patenting of a flexible micro-battery. However, this device wasn’t originally made to be used on a contact lens.

Read on I’MTech: Towards a new generation of lithium batteries?

After becoming interested in Thierry Djenizian’s work in flexible electronics, Jean-Louis de Bougrenet got in touch with his colleague at Mines Saint-Étienne. During his visit to the Centre Microélectronique de Provence à Gardanne (Bouches-du-Rhône), he observed the advances made in flexible micro-batteries. This led to the idea to integrate this little device directly into the cyborg contact lenses developed at IMT Atlantique, which was extremely innovative, since the scientists were awarded a joint patent for their work.

A flexible micro-battery directly placed in a contact lens

The device is a world first, as an energy storage source is directly incorporated into the small ocular device. “Whenever functions are performed locally by an autonomous system, the system must have energy autonomy,” explains Jean-Louis de Bougrenet.  Until now, ‘smart’ contact lenses have been powered by an external energy source such as a magnetic induction system, using a coil placed in the device. The problem with this process is that, if the energy source is cut, the device no longer works, something that is now no longer the case thanks to this new innovation. In the device developed by the two scientists, the lens is instead powered by a micro-battery that can also be paired to an external source to charge it, or in case it needs to use more energy.

Thierry Djenizian’s aim was to apply results he had already obtained from his previous studies to the design and performance constraints of an ocular device.  This meant that he built on his previous work, which was mainly based on innovation and design.

“Normally, flexible batteries are made up of electrodes connected to each other by ductile coils which then carry current.  Our device uses the entire surface area occupied by the coils by carrying microelectrodes directly on these wires,” explains the researcher at Mines Saint-Étienne. In practice, during the manufacture of flexible batteries, electrodes made from several composite materials are placed on an aluminum foil and shaped into vertical ‘micropillars’ using laser ablation with regular spacing. For the lenses, the same technique is used to manufacture the coils that support microelectrodes, giving the battery great flexibility.

 

 

As well as this, the scientists aim to use innovative materials to improve the performance of the device. One example of this is for the electrolyte, which separates the battery’s two electrodes.  The polymers that are currently used will eventually be replaced by other materials with a self-repairing nature. This will offset the strain put on the battery when the device is being charged.

Now, the scientists have succeeded in making a battery that is 0.75cm² and integrated into a scleral contact lens. This lens rests on the ‘white’ of the eye (the sclera) and is both bigger and more stable than a standard contact lens. To make the device, the area of the lens which is in front of the iris is removed and replaced with microelectronic components, including the energy storage device. This method has the distinct advantage of not obstructing the wearer’s field of vision, as light can always enter the eye through the pupil free of any obstacle. The micro-battery has already proved its worth as it can power an LED for several hours. “An LED is a textbook example since it is generally the most energy-intensive microelectronic device,” says Thierry Djenizian.

Already, there are many ways to improve this technology

While the current device is already ground-breaking, the two researchers continue to try to perfect it. The priority for the Flexible Electronics Department at Mines Saint-Étienne is optimizing the system, as well as improving its reliability. “From a technological perspective, we still have a lot of work to do,” states the head of department. “We have the concept, but improving the device is similar to taking a CRT television and turning it into a modern flat screen TV.”

The next step has already been decided. The scientists want to develop miniature antennae in order to charge the battery and make the lens a communicative device, which will allow it to transmit information from the oculometer. Another option that is currently being studied uses an infrared laser to follow the user’s eyes. This laser would be activated by blinking and would show the direction that the user is looking.

Assistance for people with bad eyesight and professional uses

According to Jean-Louis Bougrenet, the innovation will allow them to “take localized engineering to the next level.” The project has a wide range of potential uses, including helping visually impaired people. The scientists have paired up with the Institut de la Vision with the aim of developing a device which can improve the sensory abilities of visually impaired people. As well as this, the cyborg lens could be used in VR headsets as a way of making visual commands.  Discussions have already started with key people in this industry.

In the future, the lenses could have several other applications. In the automotive industry, for example, they could be used to monitor the drivers’ attention or level of fatigue.  However, “at the moment we are only discussing how the lenses could be used professionally, or for people with disabilities. If we make the lenses available to the general public, for example to be used when driving, then we raise issues that go far beyond the technical aspects of the device. This is because it involves people’s consent to wear the device, which is not a trivial matter,” states Jean-Louis de Boygrenet.

Even if the cyborg lens can help humans, there is still some way to go before the device can be seen in an entirely positive light.

This article was written (in French) by Bastien Contreras for I’MTech