20-01-2021 | | By Robin Mitchell
Recently, scientists have developed a new contact lens sensor that differs significantly from other previous designs. What does this sensor allow for, what challenges do electronics face in such applications, and how can it help the medical field?
As discussed several times in other articles, the human body is wet, gooey, and unbelievably complex with an extremely unforgiving environment. To put into perspective how difficult an environment the human body is, it’s objectively easier to design a circuit to operate in space or the deepest ocean.
Unlike most environments, anything that is operated in the human body has to cope with the conditions of the human body and have no impact on the environment around it. In other words, operating in the human body means that a device must have NO impact on bodily functions in any regard.
Designing electronics for use in and on the human eye is no exception. While the eye's surface may not require surgery to gain access, constant tears create a permanently moist environment, and the eyes need to be flexible means that any devices on the eye will be subject to constant deformation. Furthermore, the eye requires blinking whereby a lid of skin effectively washes the whole eye's surface. Thus a device would be under constant mechanical stresses.
Recently, researchers from the US and UK have announced that they have developed a contact lens sensor that integrates various sensors. Unlike previous generations of contact lens sensors that are sandwiched between two protective layers, the new design makes direct contact with tears.
The researchers' ultra-thin design is highly biocompatible, meaning that the human body does not easily reject it. Furthermore, the ability to directly contact bodily fluids allows for direct measurement of sugar and salt content. The new device also allows for deformation, meaning that it can easily adapt to the human eye. Its mechanical strength allows it to operate even when blinking without affecting the blinking motion.
The new sensor system utilizes FET technology that allows it also to record the temperature of the cornea. Furthermore, optical sensors are also integrated to allow the recording of optical information which allows the design to provide a whole range of information about the wearer and the eye's condition.
"This multifunctional contact lens with field-effect transistors can provide diversified signals from eyes, which could be combined with advanced data analysis algorithms to provide personalized and accurate medical analysis for users. This kind of research will also become one of the major research directions at the Ningbo Research Institute." - Professor Sheng Zhang, co-author from Zhejiang University.
The immediate answer to the question “how does this help the medical field” allows medical professionals to track and monitor the eye. The human eye is probably one of the most important organs as the power of sight allows for independent navigation and interaction. While those without sight can function, having sight makes for a large advantage.
Eye-sight loss can come from various causes, whether it be an accident or a disease. Some of these cases take time and can even be preventable via proper medication and diet changes. Thus, the sensors data can track sugar content to look out for diabetes, while temperature fluctuations could indicate cornea diseases.
However, if combined with AI, such a device can provide predictive diagnosis and detect conditions before they show symptoms. This can not only help to prevent the eye-sight loss but eliminate other conditions outright. Furthermore, using a non-invasive sensor to monitor temperature, sugar, and salt reduces the chance of infection of implanted devices and invasive tests.