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Roberto Vargiolu / Hassan Zahouani

Laboratoire de Tribologie et Dynamique des Systèmes (LTDS) / Ecole Centrale de Lyon

CNRS / ENISE / ENTPE / Université de Lyon / INSTITUT CARNOT - Ingénierie@Lyon

Correspondent : email : / twitter : @roberto.vargiolu


Specialised in 'touch engineering', the Laboratory in Tribology and System Dynamics (LTDS) of École Centrale de Lyon and CNRS have developed an innovative device for an augmented and connected human finger.  By simply fitting their finger with a ring equipped with sensors, customers will be able to assess the softness of their skin and hair for the first time. The data provided by the ring and analysed remotely by an AI algorithm will identify a sensory profile. Ultra-personalised treatments can then be offered by cosmetic brands willing to offer a new sensory experience to their customers. The project was awarded the 'Coup de Coeur du Jury' prize at the 6th edition of 'The cosmetics victories 2021'


What does the innovation consist in? How is it used?

Knowing and understanding touch allows you to get acquainted with your customers' inner feelings. This can therefore become an essential asset in cosmetic marketing. The LTDS (Laboratoire de Tribologie et Dynamique des Systèmes) is a pioneer and the leader in France in developing tools dedicated to touch metrology. They have developed specific savoir-faire and technologies in touch objectification. Their research specialises in skin and hair bioengineering; it focuses on broadening our knowledge of the tactile interaction of human fingers when feeling an object. This innovative in-vivo device is now making it possible to qualify touch.

When we touch the surface of an object with our index finger, the friction of skin on surface makes the mechanoreceptors present in the pad of our finger vibrate. One can imagine these biosensors as small discs, ultra sensitive to vibration and to the deformation of the skin of the finger. If the object is soft, the friction generates small vibrations of just a few hertz. If it is rough, the vibrations have a greater amplitude and their frequency is a few hundred hertz. The vibratory response is then instantly converted into an electrical signal, transmitted via the central nervous system to the brain, for the information to be interpreted in terms of sensory quality of the surface.
Drawing inspiration from the workings of a human finger, LTDS have developed an augmented human finger in the form of a connected object capable of measuring the smoothness of skin, hair or any other surface. Just like a human finger, the device is equipped with vibration sensors. Another sensor measures the pressing force. It comes in the form of a half ring which slides over the tip of the index finger. When touching a surface, the vibrations and pressing force recorded by the device are transformed into a parameter of softness. The information is then sent to a tablet through wifi connection. The results obtained from experiments showed a perfect correlation between the vibrations and the sensory classification previously defined by groups of experts.

principe de l'innovation
Principle of innovation

What is new? How can it influence the development of cosmetics and personal care products?

Today, to assess the tactile sensation of their products, cosmetic manufacturers call on groups of experts. Their mission is to subjectively evaluate the sensory quality perceived on skin or hair. Although this method does give a sensory tendency, it does not make it possible to objectively measure the softness of skin or hair.  To date, there is no device in the cosmetics industry which can measure the softness of skin or hair with an instrumented and connected human finger. By simply fitting their finger with a half-ring, for the first time, customers will be able to assess the softness of their skin and hair before and after applying a product. The data provided by the ring and analysed remotely by an AI algorithm, will identify a sensory profile. Ultra-personalised treatments can then be offered by cosmetic brands willing to offer a new sensory experience to their customers.


Where did the idea come from

The idea emerged from a simple observation: when you touch a surface with your finger, it generates a friction noise. The higher the noise, the less smooth the surface and vice versa. Another solution would have been to simply measure the noise with a microphone, but this is not feasible in a busy sound environment. The solution to this issue was to use a vibration sensor called an accelerometer.  By sticking this sensor to the side of the finger pad, we noticed that the range of frequencies of measured vibrations corresponds to those of the mechanoceptors, ie. 10 and 2000 Hz. Experimental trials with experienced panellists then confirmed the link between the vibrations of the fingertip and the smoothness of a surface.
Although the tests initially consisted in carrying out measurements with a sensor stuck on the pad of the finger, this primary solution quickly moved on to the present solution of a half ring slipped onto the index finger.

principe de fonctionnement
Principle of operation

What were the challenges to overcome? What skills or technologies contributed to its success?

When there is no existing solution, measuring a physical value on living things to qualify softness is a real scientific and technological challenge. For the development of this invention, significant research on the mechanical and tribological behaviour of the finger pad upon touching a surface was required. The results showed that there is a link between the vibration of the fingertip and the sensory perception, and that the pressing force of the finger is proportional to the deformation of the fingertip. A patent was filed on this result in 2021.
Taking these results into account, we then designed a half-ring fitted with miniature sensors, which slips over the finger and whose technological characteristics allow the vibratory response of the finger and its deformation to be faithfully measured while leaving the finger pad free. It is this innovation that contributed to the success of the invention, because for the first time the human finger can be used as an instrument for measuring smoothness.

Closeup on the 'The cosmetics victories 2021' competition

The Touchy Finger project, finalist of the 6th edition in 2021, was selected among 81 projects from 14 different countries (Spain, Italy, Poland, United States, Taiwan, Thailand, Ghana, Hungary, Belgium, Brazil, Ukraine, Denmark, New Caledonia and France). This project was awarded the 'Coup de Coeur du Jury' prize in the final selection, and was praised by Marc-Antoine Jamet, president of Cosmetic Valley and secretary-general of the LVMH group: “I am also happy that a grain of sand in the gears of our regulation system should allow us to reward Doctor Roberto Vargiolu and Professor Hassan Zahouani for their incredible 'Touchy Finger' ”. In search of investors and/or a CEO to create a start-up dedicated to this innovation, this project will benefit, thanks to this competition, from wide visibility in the cosmetic sector. On October 13 and 14, 2021, the project will participate in the international innovation fair 'COSMETIC 360' in the perfume-cosmetic sector.

touchy finger
Touchy Finger

Posted on 27/05/2021

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