Support device for holding a hair sample for measurements

The present invention relates to the field of hair holding, in particular for hair damage evaluation, in particular for the purpose o f determining user specific hair cosmetic products or hair treatment.

The term "cosmetic product" is understood, in particular within the meaning of the present invention, to mean a product as defined in Regulation (EC) No 1223/2009 of the European Parliament and Council of 30 November 2009 relating to cosmetic products.

The number and specificity of cosmetic products, and in particular of hair products, on the market is continuously increasing. Given the diversity of existing hair products, it is preferable to determine the state of the hair quality and to provide the relevant cosmetic product suggestion in terms of hair products used. Hair products include, for example, hair coloration, natural coloration, hair color make-up, hair bleach, hair perm, hair relaxer, hair care products: shampoos, conditioners, hair mask, etc.

In order to determine which hair products to apply according to the individual user, there is a known practice to make use of questionnaires that are answered by users.

In this regard, reference could be made to document US-A1 - 2014/0216492, which describes a method for determining the state of the hair quality and a diagnostic system for prescribing a cosmetic hair product which is personalized according to information obtained by means of a questionnaire. However, the analysis of these questionnaires is particularly laborious and relatively subjective.

Reference could also be made to document WO2018007354, which describes a method for determining a user-specific hair treatment. However, the method described does not give an accurate numerical result of hair damage state.

Furthermore, the accuracy of measurements depends on the support device used for holding a hair sample. Most support devices are generally heavy and do not maintain the hair sample in an efficient manner.

The aim of the invention is to improve, in terms of accuracy and ergonomy, support devices for holding a hair sample for measurements.

The object of the present invention is to provide a support device for holding a hair sample for measurements comprising a holder designed to be mounted on a measuring device having a hair probe surface.

Said device further comprises a clamping unit for fixing the hair sample on the hair probe surface.

The terms “keratin fiber” and “hair” comprises furs, wool, feathers, and especially human hair.

The clamping unit is configured for holding or fixing the hair sample on the hair probe surface with an adequate pressure. The adequate pressure ranges above lkg/mm ² .

The support device is capable of holding every kinds of threated hairs (coloration, bleach, highlight, relaxer, permanent ... )

Advantageously, the holder comprises a body radially surrounding the measuring device.

For example, said body is in radial contact with said measuring device.

For example, said body of the support device may be, in a non limiting way, annular.

For example, the upper surface of said body is aligned with the hair probe surface of the measuring device.

Advantageously, the support device further comprises guiding elements configured to receive the hair sample.

Said guiding elements allow to calibrate the amount of hair sample.

Thanks to said guiding elements, the hair sample to be measured is precisely quantified and located on the measuring device. The guiding elements for example comprise two opened radial slots provided on a surface of the body of the holder, said slots being in the extension of one another.

In an embodiment, the clamping unit comprises a clamping member pivotably mounted on the holder.

For example, the clamping member is mobile compared to the body between an unclamped position, in which the clamping member is away from the hair probe surface and a clamped position in which hair sample is held between the clamping element and said hair probe surface.

In another embodiment, the clamping member of the clamping unit is pivotably mounted directly mounted on the measurement device.

In an embodiment, the holder comprises two parallel mounting flanges extending radially outwards and the clamping member comprises a pivot axle rotatable mounted between said mounting flanges.

The two mounting flanges are identical.

For example, the clamping member comprises a first part and a second part, said parts being asymmetrical compared to the pivot axle.

For example, the first part has a length bigger than the length o f the second parts.

The clamping member may be a flat lever arm.

The first part of the clamping member may be provided with a clamping element extending substantially perpendicularly from the body of the clamping member.

Said clamping element is configured to come in contact with the hair sample inserted in the slots.

Said clamping element may have a conical contact surface.

The clamping member is mobile around the pivot axle between an opened or unclamped position, in which the first end is away from the hair probe surface and a clamped position in which hair sample is held between the clamping element and the hair probe surface.

The asymmetric lever arm or clamping member allows to multiply forces over a short distance for holding the hair sample. The clamping element may be located at a small distance from the roots of the hair sample, for example at 10mm.

The clamping member is made of a material in accordance with the type of measurements. For example, the clamping member is made of plastic material, for example elastomeric material.

Advantageously, the device further comprises a pressure adjustment unit configured to come in axial contact with the clamping member.

Said pressure adjustment unit is configured to pivot the clamping member between the unclamped position to the clamped position.

For example, the pressure adjustment unit comprises a threaded rod having threads cooperating with complementary threads on the holder, a rotary wheel connected to said threaded rod and a pushing rod connected to said rotary wheel and in contact with the clamping member.

The threads of the threaded rod and the holder may be M6 threads.

The threaded rod is designed to enable a pressure adjustment depending on a measurement signal and get the best response for collecting a clean spectrum.

The pushing rod may be in axial contact with the second part of the clamping member.

For example, the end of the pushing rod has a round surface, providing a point contact with the lower surface of said second part.

In an embodiment, the pressure adjustment unit further comprises a spring mounted radially around the pushing rod and axially between the rotary wheel and a surface, for example the lower surface, of the clamping member.

The spring is thus compressed between the rotary wheel and a surface of the clamping member and allows to give a holding pressure on the hair sample. Said holding pressure can thus be adjusted adequately with the pressure adjustment unit. This spring allows the unlocking of the hair sample from the surface probe with a simple pressure on the second part of the clamping member.

When the rotary wheel is turned in a first direction, for example a counter-clockwise direction, for example using a knob, the pressure adjustment unit is translated axially towards the second part of the clamping member which pivots around the pivot axle. The spring is thus compressed between the rotary wheel and a surface of the clamping member and allows to give a holding pressure on the hair sample. Said holding pressure can thus be adjusted adequately with the pressure adjustment unit.

Thanks to the support device, it is possible to provide a maximum pressure on the hair sample with minimum movement on the threads.

According to another aspect, the invention concerns a measurement system such as, for example a portable infrared spectrophotometer, designed to make any type of physical or chemical measurements on any type of hair sample comprising a measurement device and a support device as described above mounted on said measurement device.

The measurement device may also be any type of device designed to make a quantitative measurement of the reflection of a material as a function of a wavelength, using any type of beam, for example visible light, near ultraviolet light, or near infrared light. The measurement device may also be a sensor.

The support device is designed to be mounted on said measurement device and to hold or fix a hair sample in view of making one or a plurality of measurements.

The measurement device may comprise a hollowed body a hair probe surface configured to receive the hair sample.

The measurement device may comprise a base plate which may be configured to be connected for example to a mobile arm. Said hollowed body have, in a non-limiting way, a generally cylindrical shape.

Said hollowed body may have an inner cavity inside which is emitted the infrared light by an emitting module.

For example, the hair probe surface is a flat surface.

said hollowed body may further comprise a through-hole extending from the hair probe surface to the inner cavity of the body and a support as described above mounted on said measurement device.

The measurement device may also be any type of device designed to make a quantitative measurement of the reflection of a material as a function of a wavelength, using any type of beam, for example visible light, near ultraviolet light, or near infrared light. The measurement device may also be a sensor.

The support device is designed to be mounted on said measurement device and to hold or fix a hair sample in view of making one or a plurality of measurements.

For example, the measurement device comprises a hollowed body a hair probe surface configured to receive the hair sample.

The measurement device may comprise a base plate which may be configured to be connected for example to a mobile arm.

Said hollowed body have, in a non-limiting way, a generally cylindrical shape.

Said hollowed body may have an inner cavity inside which is emitted the infrared light by an emitting module (not shown).

For example, the hair probe surface is a flat surface.

said hollowed body may further comprise a through-hole extending from the hair probe surface to the inner cavity of the body.

Further aims, features and advantages of the invention will become apparent from reading the following description, which is given only by way of non-limiting example and with reference to the appended drawings, in which:

[FIG 1 ] is a perspective view of a measurement system having a support device according to an embodiment of the invention; [FIG2] is a cross section view of Figure 1 ;

[FIG 3] is a schematic view of a system for determining hair damage according to an embodiment of the invention comprising the measurement device of Figure 1 ; and

[FIG 4] is a flowchart illustrating the steps of a method for determining hair oxidative damage of the hair sample according to an embodiment of the invention.

A measurement system 10 designed to make any type of physical or chemical measurements on any type of hair sample is illustrated on Figure 1 .

The hair sample may comprise every kind of threated hairs (coloration, bleach, highlight, relaxer, permanent... ).

The measurement system 10 comprises a measurement device 12, such as, for example a portable infrared spectrophotometer, and a support device 20 for holding a hair sample for measurements.

The measurement device 12 may also be any type of device designed to make a quantitative measurement of the reflection of a material as a function of a wavelength, using any type of beam, for example visible light, near ultraviolet light, or near infrared light. The measurement device 12 may also be a sensor.

The support device 20 is designed to be mounted on said measurement device 12 and to hold or fix a hair sample in view o f making one or a plurality of measurements.

The measurement device 12 comprises a hollowed body 14 and a base plate 16 which may be configured to be connected for example to a mobile arm (not show). Said hollowed body 14 have, in a non-limiting way, a generally cylindrical shape. Said hollowed body 14 has an inner cavity 14a inside which is emitted the infrared light by an emitting module (not shown).

Said hollowed body 14 further comprises a hair probe surface

14b, on an end opposite to the base plate 16. The hair probe surface 14b is configured to receive the hair sample. As shown, the hair probe surface 14b is a flat surface. Said hollowed body 14 further comprises a through-hole 14c extending from the hair probe surface 14b to the inner cavity 14a of the body 14.

The support device 20 comprises a holder 22 having a body 24 radially surrounding the body 14 of the measuring device 12 and in radial contact with said body 14. The body 24 of the support device 20 may be, in a non-limiting way, annular. The upper surface 24a of the body 24 is aligned with the hair probe surface 14b of the measuring device 12.

The body 24 of the support device 20 comprises two mounting flanges 26 extending radially outwards form the outer cylindrical surface (not referenced) of said 24. The two mounting flanges 26 are identical and parallel to each other.

The body 24 of the support device 20 further comprises on its upper surface, two opened radial slots 27 or grooves in the extension o f one another. Said slots 27 are configured to receive the hair sample. Said slots 27 allow to calibrate the amount of hair sample.

Thanks to said slots, the hair sample to be measured is precisely quantified and located on the measuring device 12.

The support device 20 further comprises a clamping unit 30 for holding or fixing the hair sample on the hair probe surface 14b with an adequate pressure. The adequate pressure ranges above lkg/mm ² .

As explained further, said pressure exerted by the clamping unit 30 is adjustable until the collected spectrum is clean.

The clamping unit 30 comprises a clamping member 32 having a pivot axle 34 rotatable mounted between the two mounting flanges 26 of the body 24.

The clamping member 32 is a flat arm comprising a first part 32a and a second part 32b. Said parts 32a, 32b are asymmetrical compared to the pivot axle 34. As illustrated, the first part 32a has a length bigger than the length of the second parts 32b.

The first part 32a of the clamping member 32 is provided with a clamping element 33 extending substantially perpendicularly from the body of the clamping member 32. Said clamping element 33 is configured to come in contact with the hair sample inserted in the slots 27. As illustrated and in a non-limiting way, said clamping element 33 has a conical contact surface.

The clamping member 32 is mobile around the pivot axle 34 between an opened or unclamped position, in which the first end 32a is away from the hair probe surface 14b and a clamped position in which hair sample is held between the clamping element 33 and the hair probe surface 14b.

The asymmetric lever arm or clamping member 32 allows to multiply forces over a short distance for holding the hair sample.

The clamping element 33 may be located at a small distance from the roots of the hair sample, for example at 10mm.

The clamping member 32 is made of a material in accordance with the type of measurements. For example, the clamping member 32 is made of plastic material, for example elastomeric material.

The support device 20 further comprises a pressure adjustment unit 36 in axial contact with the second part 32b of the clamping member 32.

The pressure adjustment unit 36 comprises a threaded rod 37 having outer threads 37a cooperating with complementary inner threads 25 on the holder 22.

The threads 37a, 25 may be M6 threads, i.e. having a nominal outer diameter of 6mm. Indeed, M3 or M4 threads are not strong enough. The threaded rod 37 is designed to enable a pressure adjustment depending on a measurement signal and get the best response for collecting a clean spectrum.

The pressure adjustment unit 36 further comprises a rotary wheel

38 connected to said threaded rod 37 and a pushing rod 39 connected to said rotary wheel 38 and in axial contact with the second part 32b of the clamping member 32. As shown on Figure 2, the end of the pushing rod

39 has a round surface, providing a point contact with the lower surface of said second part 32b. The pressure adjustment unit 36 further comprises a helical spring 40 mounted radially around the pushing rod 39 and axially between the rotary wheel 38 and the lower surface of the clamping member 32.

This spring 40 allows the unlocking of the hair sample from the surface probe 14b with a simple pressure on the second part 32b of the clamping member 32.

When the rotary wheel 38 is turned in a first direction, for example a counter-clockwise direction, for example using a knob 41 , the pressure adjustment unit 36 is translated axially towards the second part 32b of the clamping member 32 which pivots around the pivot axle 34. The spring 40 is thus compressed between the rotary wheel 38 and a surface of the clamping member 32 and allows to give a holding pressure on the hair sample. Said holding pressure can thus be adjusted adequately with the pressure adjustment unit 36.

Thanks to the support device 20, it is possible to provide a maximum pressure on the hair sample with minimum movement on the threads.

The support device 20 is capable of holding and fixing every kinds of untreated and threated hairs (coloration, bleach, highlight, relaxer, permanent.) homogeneity and inhomogeneity in appearance and, the fixing approach is adaptable to specific treatments and to hair sample quantity.

Thanks to the support device, it is possible to provide an adequate holding pressure of a hair sample to be measured.

The support device is also particularly ergonomic, easy to use and allowing fast and accurate mechanical lock of hair sample on a probe surface.

The particular shape of the support device allows to make a measurement close to the hair root, which is particularly interesting for in vivo measurements. A system 40 for determining hair damage, and notably oxidative hair damage in view of determining if hair product(s) may be applied on said hair is illustrated on Figure 3.

The hair product may be a cosmetic product, for example, hair coloration, natural coloration, hair color make-up, hair bleach, hair perm, hair relaxer, hair care products : shampoos, conditioners, hair mask, etc, that is intended to be applied, for example, to the hair of the user.

Oxidative hair damage is generally due to UV exposure, or the chemical treatments, such as: hair coloration, hair bleach, hair perm, etc.

The damage process can be caused by a degradation of amino acids, for example cystine, tryptophan, methionine, tyrosine, histidine or lysine. The deterioration of cystine can destroy the mechanical stability of the hair and even lead to a complete and irreversible hair breakage. Generally speaking, the decrease of cystine well correlates to the increase of cysteic acid, thus cysteic acid is the oxidative marker for the hair damage.

The terms “keratin fiber” and “hair” comprises furs, wool, feathers, and especially human hair.

Said system 40 comprises the measurement system 10, an acquisition module 42 for collecting a spectrum under a mid-infrared light, a communication unit 44, an analysis module 46 and a display device 48. The communication unit 44 is capable of transmitting the collected spectrum taken by the acquisition module 42 to the analysis module 46 and to the display device 48. The display device 48 may be, for example, a tablet, a computer or any other display means such as, a mobile phone, a screen.

Mid-infrared spectroscopy allows direct, non-destructive determination of oxidation product content of an amino acid and can be performed directly on keratin fibers located on the user’s head. Mid- Infrared spectroscopy uses infrared radiation to excite the amino acid molecules and generates an infrared spectrum of the energy absorbed by these molecules as a function of the wavenumber in a range of 4000 to 700cm- l .

The analysis module 46 is configured to adjust the spectrum baseline at zero absorbance on the selected wavelengths without interest of the data manipulation. The intensity of the signal at said specific wavelength is fixed at a reference value, thus the IR spectrum is reprocessed to be normalized, which allows to eliminate the variability during acquisition of the spectrum.

The normalized spectrum value is then processed in order to give an automatically converted numerical value of cysteic acid, which corresponds to the oxidative marker for hairs.

The method for converting the normalized spectrum value into a numerical value of cysteic acid is based on the combination of first and second derivatives at mid-infrared range and comprises a correlation equation using known high-performance liquid chromatography (HPLC) method data.

The system 40 is configured to repeat one to ten times, for example six times said measurements and to determine a reliable oxidative damage diagnostic of the hair sample. The analysis module 46 is configured to transmit to the display device 48 the result of the oxidative damage diagnostic of the hair sample, which displays on the display means, if the hair is capable of receiving a hair product, and what kinds of the cosmetic hair products can be applied.

Figure 4 is a flowchart illustrating the main steps of a method 100 for determining hair damage, and notably oxidative hair damage in view of determining if hair product(s) may be applied on said hair using the system 40 illustrated on Figure 3.

The method 100 comprises a first step 101 of collecting a background spectrum under a mid-infrared light. Background spectrum means that no hair sample is hold by a holding device.

The method 100 further comprises a step 102 of fixing a hair sample with adequate pressure on the IR probe surface using a holding device (not shown). For example, at 10cm to 15 cm from the hair scalp of the user.

At a step 103 , mid-infrared light is emitted and the spectrum of the hair sample under said mid-infrared light is collected. Mid-infrared spectroscopy allows direct, non-destructive determination of oxidation product content of an amino acid and can be performed directly on keratin fibers located on the user’s head. Mid-Infrared spectroscopy uses infrared radiation to excite the amino acid molecules and generates an infrared spectrum of the energy absorbed by these molecules as a function of the wavenumber in a range of 4000 to 700cm- l .

At step 104, the hair sample spectrum is adjusted at zero absorbance on the selected wavelengths without interest of the data manipulation. The intensity of the signal at said specific wavelength is fixed at a reference value, thus the IR spectrum is reprocessed to be normalized, which allows to eliminate the variability during acquisition of the spectrum.

At step 105 , the normalized spectrum value is then processed in order to give an automatically converted numerical value of cysteic acid, which corresponds to the oxidative marker for hairs.

The method for converting the normalized spectrum value into a numerical value of cysteic acid is based on the combination of first and second derivatives at mid-infrared range and comprises a correlation equation using known high-performance liquid chromatography (HPLC) method data.

At step 106, said numerical value is compared with a defined threshold value to determine the oxidative damage of the hair sample and to suggest the following cosmetic hair products applied on the head.

Finally, at step 107, the result of the oxidative damage diagnostic of the hair sample is displayed on the display means.

The result displayed may be in the form of“yes” or“no”,“yes” meaning that product(s) may be applied on said hair, at least 1 more time and “no” meaning that the hair is too much damaged and it is preferably not to apply certain product(s) on said hair, but some products still could be recommended.

The result displayed may be shown with colors,“red” when the hair is too much damaged and “green” if the hair is not too much damaged. Other forms of showing the result are possible, but if the value presented in the numeral value of cysteic acid, the comparison step 106 is optional.

The method 100 may be repeat one to ten times, for example six times, said measurements in order to determine a reliable oxidative damage diagnostic of the hair sample.

Said method according allows to easily and accurately determine the level o f oxidation product of an amino acid in the hair sample and obtain a matched hair treatment instruction.