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Flexible Electronics in medical domain : BioSerenity

Standard Electronics is dominated by mineral components especially silicon. However, the discovery of conductive polymers have offered an alternative to the use of minerals in electronics. The polymers are obtained naturally or synthesized and are composed of natural fibres, rubber, plastic, adhesive, resin, paints and even ink. This material has thus allowed the printing of electronic circuits on flexible substrates, an impossible operation with silicon as it is much more rigid. In this way,  flexible electronics have emerged offering many possibilities.

At the heart of the prototyping space of the Ecole Polytechnique, flexible electronics have their rightful place and combine well with digital and additive manufacturing. The users of X-Fab particularly have the possibility of using the Voltera printer that allows the creation of printed circuit boards with the help of conductive ink. The X-Novation Talks webinar on flexible electronics held on 25 November 2020 hosted different actors of innovation to discuss the performance, sustainability and accessibility of flexible electronics especially in the medical sector with BioSerenity.


Meaning of flexible electronics
Flexible electronics is a technology that allows us to add electronics on soft and flexible support such as textile or polyimide. It is a relatively generic term that regroups many fields : printed electronics, flexible electronics, conformable electronics, stretchable electronics and organic electronics. It is different in nature than conventional electronics as they are more often flat and rigid.


Printed electronics
When talking about printed electronics, it relates to printing electric circuits as done for textile or paper. Such printing is possible due to functional ink : conductive, semi-conductive or insulating as proposed by VFP Ink Technologies in France. This possibility to print makes the use of different types of support and components possible.
It is to be noted that while it is possible to print electronic circuits on soft substrates, printed electronics functions also on rigid support.
Flexible electronics
Flexible electronics is a technology of printed circuit that applies to flexible plastic substrates such as polyimide, PEEK film or polyester. It is possible to use the same components as rigid printed circuits but on flexible, perhaps foldable forms while usage.
Conformable electronics
It is relatively similar to flexible electronics but with limited time. Indeed the used substrate is flexible but only during its manufacturing with thermoformable plastic for example. The final product could therefore have a curved form but be rigid during its use.


Stretchable electronics


This has the advantage of being stretchable and deformable during its use. These circuits are used on elastic substrates such as silicon, textile or polymers (PU, PET). The conductive ink conserves its properties even under pressure.
Organic electronics
Organic electronics consist of using molecules or organic polymer showing electronic properties such as conduction or semi-conduction. For instance, OLED, an organic LED used in curved television or foldable smartphones.
Examples of application
Flexible electronics offer a wide range of products made with the help of various possible choices of usable support : flexible or rigid. Even with no knowledge of flexible electronics, we use it in our daily life. For example, the soft keyboard in the induction plates used for cooking for increasing temperature or the alarm that rings when a passenger doesn't wear his seatbelt use the concept of flexible electronics.
In the future, application of flexible electronics would be made in much more complex ways especially in medical, automobile and sports industry. It is also used in smart textile as printed electronics are stretchable, light and thinner than classic electronics. It will allow the manufacturing of a new type of smart fabric connected with LED or printed circuit on the textile.
Flexible electronics in medical domain
A true revolution in the medical sector, flexible electronics offer a new generation of printed electronics devices on flexible support such as plastic or textile which is more comfortable for patients.
BioSerenity : Flexible electronics for electrophysiologic measures
BioSerenity is a French startup that provides diagnostic and monitoring solutions to patients based on the acquisition and interpretation of electrophysiological examination(EEG, ECG and polysomnography) through artificial intelligence. It is currently developing projects in various areas of therapy : neurology, cardiology, sleep, women's health, urology and psychiatry.
Nicolas Jurado,Director of Innovative Medical Affairs, explains that flexible electronics are a part of their development strategy and it can provide solutions in healthcare system that is constantly evolving. Thanks to flexible electronics, the objective of BioSerenity is to create tools of electrophysiological type that the patient can wear as "second skin" from one hour to thirty days and measure different physiological parameters. The use of flexible electronics and printing ink is thus inevitable for developping such products.
EEG : Today, we conduct around one million tests of electrophysiology in a day in the French territory but there is a strong regional disparity among these tests. BioSerenity is hence developing Neuronaute, a wireless smart cap that will help access a patient's EEG while he wears it in all circumstances.
While using flexible electronics, Neuronaute carries the signal from the scalp via around thirty electrodes to their recording box. Flexibility is an essential criteria because the conduction track must adjust to the morphology of the head. The connected cap must be capable of manipulating, turning and extending without modifying signal quality. Only flexible electronics can respond to such constraints while printing conducting ink on textile.
Watch our webinar on flexible electronics and its prototyping
Second episode of X-Novation Talks on the theme Flexible Electronics is now available on YouTube. Aline Becq, Head of X-Fab conducted the talk with experts of flexible electronics : Nicolas Jurado and Gaëtan Gerber of BioSerenity, Vincent Carniato of VFP Ink Technologies and Yvan Bonnassieux, professor-researcher at Ecole Polytechnique and director of Physics Laboratory for Interface and Thin Films.