FR2580400A1 - DEVICE FOR THE STUDY OF PROPERTIES, ESPECIALLY OF THE ELASTICITY OF A SURFACE, IN PARTICULAR OF THE SKIN - Google Patents

Abstract

DEVICE D INCLUDES PNEUMATIC MEANS P FOR MOMENTLY ALTERING A ZONE A OF THE SKIN 1 AND MEANS E FOR ESTIMATING THE IMPORTANCE OF THE ALTERATION, THESE MEANS OF ESTIMATION INCLUDING A RADIATION EMITTER 20 TOWARDS THE ZONE A AND A RECEIVER 21 CLEAN TO RECEIVE PART OF THE RADIATION RETURNED BY THE SAID ZONE A. THE PNEUMATIC MEANS P INCLUDE A NOZZLE 2 SUITABLE FOR BLOWING GAS ON ZONE A OF THE SURFACE CONSIDERED, WHILE MAINTAINING MEANS M ARE PROVIDED SUPPORT NOZZLE 2 AT A PREDETERMINED DISTANCE H FROM THE SURFACE.

Description

DEVICE FOR THE STUDY OF PROPERTIES, PARTICULARLY

  THE ELASTICITY OF A SURFACE, PARTICULARLY OF THE SKIN.

  The invention relates to a device for studying

  of properties, in particular of elasticity, of a surface, in particular of the skin. The expression study of the properties of a surface must be understood in a broad manner, that is to say that the properties studied, in particular when it is a question of mechanical properties such as elasticity, may relate to, in particular in the case of human skin, the entire surface, and

underlying tissue.

  The devices targeted by the invention are of the type which include pneumatic means for altering, in particular for temporarily deforming an area of the surface under determined conditions, without material contact other than gas, and means for estimation of the extent of the alteration, in particular of the deformation, of said zone, these estimation means comprising

  a radiation emitter in the direction of the sur-

  face studied and a receiver capable of receiving part of the radiation returned by said zone, this part returned

  depending on the extent of the alteration.

  Such devices allow, for example, to determine the influence of cosmetics on the elasticity and moisture of the skin and thus to judge the effectiveness of these

products.

  A device of the kind defined above is de-

  Crit in DE-A-3 304 503. This device is relatively compact.

  brant and its implementation is not very practical. It also has a relatively high inertia, which is troublesome for the

  speed, sensitivity and precision of measurements.

  The invention aims, above all, to make the dis-

  positive of the kind defined above such that they meet better than hitherto the various requirements of the practice and in particular such that their bulk is reduced and that their

  implementation is simpler and faster. It is desired

  table, moreover, that their inertia is also reduced and that the speed, as well as the precision, of the measurements are improved. According to the invention, a device for studying

  properties, including elasticity, of a surface, in part

  particular of the skin, of the kind defined above, is characterized by the fact that the pneumatic means for altering the surface comprise a nozzle, or the like, capable of blowing a gas over the area of the surface in question and that holding means are designed to support the nozzle at a distance

predetermined area.

  Generally, the alteration of the surface consists of a deformation of this surface and the pressure of the gas jet at the outlet orifice of the nozzle is of the order of 0.1 to 1.0 bar. The pressurized gas can be simply

consisting of compressed air.

  Preferably, the nozzle is arranged so as to blow the gas in a substantially orthogonal direction

to the studied area of the surface.

  Generally, the nozzle comprises a body whose axis is substantially orthogonal to said studied area of the surface, the outlet orifice of the nozzle having its center located on this axis. The nozzle body can be fitted, on the side of the gas outlet, with adjustable support means against the surface

  to study, so that the distance from the exit orifice

  tie the nozzle to said surface can be adjusted at will.

  The nozzle orifice can have a diameter ranging from 1 mm to 5 mm, and preferably equal to 4 mm. This orifice is located at a distance of the order of 2 mm from the surface, when the latter is not deformed, that is to say when the

gas is not blown.

  Advantageously, the means of estimating the im-

  bearing of the alteration comprise, in a manner known in itself, a light radiation emitter and a receiver of the part of the light radiation returned by the area studied, this receiver being suitable for transforming into a quantity

  electric the amount of light received. These means of estimation

  tion therefore form an opto-electronic sensor, in particular of the type described and claimed in FR-A-2 465 213, at

name of the applicant company.

  The means of estimation, the importance of the al-

  teration ---------------- advantageously include a part-

  tie arranged inside the nozzle so that the ray-

  incident, and the radiation reflected from the surface, be

  confused with, or near the axis of the jet blown by the nozzle.

  When the estimation means use a radius-

  In addition, there are preferably optical fibers arranged coaxially with the injection nozzle, inside the latter, and stopping at a certain distance from the opening through which the gas is blown. The distance between the end of the optical fibers and the opening of the nozzle can be of the order of 3 mm to 30 mm. Part of these optical fibers is used for incident light, while the other part

  is used to collect the returned light.

  In a manner known in itself, light

  the light can be collected by a cylindrical optical fiber arranged along the axis of the jet, while the incident light comes from an optical fiber with an annular section surrounding the

previous fiber.

  The nozzle can be supplied with gas from a pressurized gas cylinder, fitted with a regulator, connected to the nozzle by a supply pipe equipped with a solenoid valve. The nozzle supply line is also advantageously equipped with a pressure sensor arranged

downstream of the solenoid valve.

  The means of estimation preferably include

  a digital memory oscilloscope and a recorder.

  A relatively large volume, in particular of the order of 20 cm 3, is formed by the pipe between the regulator and the solenoid valve to serve as a gas reserve during a measurement at

variable pressure.

2580400.

  The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with a particular embodiment described with reference to the attached drawings, but which is in no way limiting. Figure 1 of these drawings is a schematic view

  of an entire installation comprising a device

form to the invention.

  Figure 2 is a view, on a larger scale, in

longitudinal section of the device.

  Figure 3 is a diagram showing the variations

  tions of a quantity in relation to the elasticity of the sur-

  face, as a function of time, when gas is blown through the nozzle. Figure 4 is a diagram, similar to that of Figure 3, but corresponding to a gas cut under

pressure blown by the nozzle.

  FIG. 5 is a diagram illustrating a variation of the pressure, plotted on the ordinate, of the gas blown by the

nozzle, as a function of time.

  FIG. 6 is a diagram, similar to that of FIG. 3, illustrating the variations of the quantity, given in

  ordered, depending on the elasticity of the surface, depending on

  tion of time, when a pressure signal corresponding to

  that of Figure 5 is applied to the nozzle.

  Figure 7, finally, is a diagram representing the variations of the above magnitude, depending on the elasticity

  of the surface, depending on the pressure of the blown gas,

x-axis.

  Referring to the drawings, in particular to Figures 1 and 2, one can see a device D for studying the properties of a surface; in the example envisaged, the device D is more particularly intended for the study of the elasticity of human skin, in particular for the study of the effectiveness of

cosmetic products.

  It is recalled that the elasticity of the tissues decreases with

  age and is further subject to the influence of various parameters

  very such as the subject's state of health or fatigue. Cosmetic products aim, in particular, to increase elasticity

  and the moisture content of the skin. To assess the effectiveness

  cited such cosmetic products, it is therefore desirable to be able to measure the in vivo elasticity of the skin, before and

  after applying cosmetic products.

  The device D comprises pneumatic means P for temporarily altering an area A (FIG. 2) of the skin 1

  under specified conditions. In the example considered, re-

  latif to the study of the elasticity of the skin, the alteration of the

  zone A consists of a deformation of this zone, as shown

  shown schematically in Figure 2.

  The device D further comprises means for testing

  timation E which include a radiation emitter S towards zone A and a receiver R suitable for receiving part of the radiation returned by zone A, this part

  returned depending on the size of the deformation.

  The pneumatic means P comprise a nozzle 2, or

  similar, suitable for blowing a gas, usually air

  award-winning, in zone A. Holding means M are provided

  to support nozzle 2 at a distance h (figure 2) predeter-

  undermined from undistorted surface 3.

  The nozzle 2 is advantageously arranged so as to

  blow the gas in a direction, represented by an arrow

  che F in Figures 1 and 2, substantially orthogonal to the studied area A of the surface. This nozzle 2 may include a body 4, in particular cylindrical, of revolution, the part of which

  end 5, facing the skin 1, has a frustoconical shape

  that narrowing and ending in the opening of

  nozzle outlet 6. This orifice 6 may have a diameter al-

  lant from 1 mm to 5 mm, this diameter preferably being equal to

  4 mm or about 4 mm. The distance h mentioned above, cor-

  corresponds to the distance from orifice 6 to surface 3. This dis-

  tance h is advantageously of the order of 2 mm. The body 4, on the side remote from its outlet orifice 6, is closed by a

  transverse bottom 7; a compressed air inlet pipe 8

  mé opens into the side wall of nozzle 2, in the vicinity

from the bottom 7.

  The support means M can be constituted by a sleeve 9 surrounding the end of the nozzle adjacent to the outlet orifice 6. This sleeve 9 can be slidably mounted on the body 4 of the nozzle 2 with sufficient tightening to allow maintaining the two parts in a relative position that has been chosen and adjusted. According to a variant, the sleeve 9 could be screwed onto the body 4, the adjustment of the axial position of the sleeve 9 relative to the body 4 being effected by

  a rotational movement. The sleeve 9, at its end turns-

  born towards the skin 1, has an enlarged frustoconical base intended to bear on the skin 1. Openings

  (not shown) are ------ provided in the wall of the man-

  chon 9, at the base 10, to allow the air to

  award-winning blown by the nozzle 6 to escape from the interior volume of the sleeve 9, after having struck the zone A. A bottle 11 (FIG. 1) of compressed air serves to

  the supply of the nozzle 2. A regulator device 12 adjustable

  ble is provided on this bottle 11 to allow adjustment

  constant gas pressure, using a pre-

  cision. Preset pressure, for working conditions,

  is preferably less than 1 bar (relative pressure).

  The regulator 12 is connected by a tube 13 to an electric

  solenoid valve 14 making it possible to open or close the passage for compressed air, in response to an electrical signal supplied by an electronic control circuit 15. This control circuit can be used both for automatic triggering and for

  manual activation of the solenoid valve 14; circuit 15 in-

  channel, at the same time, a synchronization signal to an oscil-

loscope 16 with digital memory.

  The solenoid valve 14 is connected, by a tube 17, to a conventional pressure sensor 18, making it possible to control the pressure when the gas is applied to the zone A. This

  pressure sensor 18 is capable of supplying an electrical signal

  than analog, especially linearly proportional

  with pressure. The sensor 18 is connected to the oscilloscope 16 au-

  which it transmits the pressure signal, which thus makes it possible to control the excitation signal as a function of time (AP = f (A t)). The output of the sensor 18 is connected by a conduit 19

to the nozzle 8 of the nozzle 2.

  The means E of estimating the importance of the deformation

  mation include an emitter 20 of light radiation no-

  as much visible light, and a receiver 21 of the part of the light radiation returned by the studied area A. This

  receiver 21 is suitable for transforming into an electrical quantity

  that the amount of light received; this electrical quantity is transmitted by a link 22 to the oscilloscope 16. The

  estimation means E are advantageously formed by a cap-

  opto-electronic sensor of the kind described in

  FR-A-2 465 213. These estimation methods E. work for example-

Dle with unmodulated light.

  The estimation means E comprise a part 23

  arranged inside the nozzle 2 so that the ray-

  incident incident schematically represented by arrows 24 in FIG. 2 either coincident with or close to the axis of the jet blown by the nozzle 2. The part of the radiation returned by surface A to the receiver 21 is schematically represented by an arrow 25 on the Figure 2, also close to the axis of the

jet blown.

  This part 23 comprises optical fibers 26, 27 arranged coaxially with the injection nozzle 2, and stopping at a certain distance j (FIG. 2) from the opening 6. -This distance can be of the order of 3 mmin so that the

  distance 1 from the ends (located in the same transverse plane

  sal) of fibers 26 and 27, at the surface 3, not deformed, or

substantially equal to 5 mm.

  The fiber 26 (or the fiber bundle) conducts the incident light, from the emitter 20 with which it is in optical connection; this fiber 26 has an annular cross section. and is coaxial with the nozzle 2. The fiber 27 conducts, towards the receiver 21, part of the light returned by the zone A; the optical fiber 27 (or the fiber bundle) has a cylindrical section coaxial with the nozzle 2, and is surrounded by the annular section fiber 26. The end of the fiber 27 remote from the orifice 6, is in optical connection with the receiver 21. All of the optical fibers 26, 27

  crosses the bottom 7 of the nozzle 2, sealing means for

  before being planned at this crossing.

  The oscilloscope 16 is connected to a recorder 28.

  The dimensions of the application device

  gas pressure on the skin are low; the diameter and the length

  copeur 4 may be reduced, in particular because the optical fibers 26 and 27 have reduced dimensions and

  do not constitute an obstacle for the passage of air

  premium. The stream of compressed gas can thus be applied in a precise manner to a selected location on the skin 1. The

  conditions for applying the gas jet to the skin are generally

  Lely determined so that a jet is obtained having a pressure, at the orifice 6, of the order of 0.1 to 1.0 bar, so as to thus exert a deformation of the surface of the skin 1 whose diameter G (figure 2) can vary from 0.5 to cm, and the depth u (figure 2) of deformation can vary from 0.5 mm to 2 mm depending on the location and the property of the skin

  chosen, or the individual. It should be noted that the diameter in-

  the inside of the sleeve 9 can be of the order of 5 cm.

  The volume V1 of the tube 13, comprised between the regulator 12 and the solenoid valve 14, is chosen large enough so as to constitute a reservoir; this volume V1 can be of the order of 20 ml. The volume of the tube 17 is equal to V2, while the volume of the tube 19 is equal to V3. The assembly is carried out so that this volume V3

  of the tube t9 is as small as possible, while the volume V1 is much

  stroke greater than the sum V2 + V3.

  In Figure 1, there is shown the device D during app-

  plication (the sleeve 9 has not yet come into contact with the skin 1)

  on the arm B of an individual, this arm resting on a gutter

  re 29 supported by an easel 30.

  That said, we will now describe the operation

  and the implementation of the device according to the invention.

  Three types of measurement are possible, namely: - measurements at constant stabilized gas pressure; - measurements at variable gas pressure (pulse regime); - measurements for the plotting of the pressure / deformation characteristic. We will successively examine these different types

of measures.

  We first consider the measurements

  under a stabilized constant pressure PO of compressed air.

  The selected pressure PO is pre-selected using

  regulator 12, PO being less than 1 bar.

  The opening of the solenoid valve 14 is controlled at time t0 (see FIG. 3). The quantity of light collected by the receiver 21 and transformed into an electric voltage q0, before deformation, is greater than that collected after deformation of the zone A. The minimum electric voltage qm obtained on the receiver 21, occurs at time t0 At (At = approximately 10 ms). The variation of the electric voltage q

  as a function of time t is represented by curve 31.

  The deformation u therefore varies in the opposite direction to the

  electric voltage q; this is the reason why the

  their of u were carried on an axis oriented in opposite direction

in figure 3.

  The deformation of the skin tu = um - u0 corresponds, in FIG. 3, to the drop in electrical voltage

  q = q0 - qm, supplied by the opto-electronic sensor.

  The amplitude parameter q0 - qm thus represents the compression

  bility of the skin under the P0 constraint.

  The time interval t (equal to 10 ms in the case

  in Figure 3) between the time t00 of opening the electro-

  valve 14 and the moment tO0 + A t occurs the minimum qm, constitutes an evaluation of the viscoelastic property of

  the skin and the establishment time of the pressure variation

  sion p. When the solenoid valve 14 is closed, which amounts to cutting off the current of blown gas in zone A, a curve 32, shown in FIG. 4, is obtained, opposite to that

  of FIG. 3. This curve 32 corresponds to the curve of re-

  establishment of the skin surface.

  We will now consider measurements made under variable pressure, corresponding in a way to

a pulse.

  A volume V1 of gas under pressure (compressed air in the example envisaged) is enclosed in the tube 13 under a given pressure P0 between the regulator 12 and the solenoid valve 14, upstream of the pressure sensor 18. The bottle 11 is isolated from the tube 13, for example by closing the pressure reducer 12 when

  the pressure P0 prevails in the tube 13 and therefore in the volume V1.

  At time t - 0, the opening of the controlled test solenoid valve 14, the volume Vi of compressed air expands and passes through

  the tube 17 and the conduit 19 to be blown through the ori-

  fice 6. The air pressure, measured by the sensor 18, during this "pulse" varies, as a function of time, according to the curve 33 represented in FIG. 5. In this figure, the

  time is plotted on the abscissa while the pressure, measured -

  by the sensor 18, is plotted on the ordinate. The pressure passes through a maximum value P max after a time t1, in particular around 10 ms. At the end of a time t2, of the order of four times t1 (i.e. substantially 40 ms in the example considered) the

  (relative) pressure is low, and continues to decrease.

  Deformation of zone A of skin 1, in response

  to the pressure of gas under pressure of FIG. 5, is represented

  felt by the curve 34 of FIG. 6. The time is always plotted on the abscissa while on the ordinate we plotted, as in the case of FIG. 3, the electric voltage at the output of the receiver 21; on another axis oriented in direction

  inverse, the deformation proper was reported

in the u parameter.

  At time 0, the deformation is zero and the electrical voltage qO is maximum. At time t1, corresponding to

  P max (M1 being substantially equal to 10 ms in the example approx.

  sage) the deformation is maximum and is equal to _m.

  The pressure of the blown gas then decreases so that the deformation also decreases. At time t2

  the remaining deformation is small. The curve 34 at the allu-

  re of an asymmetrical V, the point of which is rounded.

  FIG. 7 corresponds to the plot of the characteristic 35 of the deformation u plotted on the ordinate as a function of the pressure P of the blown gas, plotted on the abscissa. Up to one

  pressure P1, of the order of 0.3 bar in the example of realization

  tion and in the application envisaged, the variation of the de-

  pressure-dependent training is substantially linear.

  Curve 35 is established using a succession

  of experiments applying pressures of different values

  annuities. The device of the invention, of small dimensions, can be applied to any part of the skin, and enables measurements to be carried out quickly and precisely, in particular for determining the compressibility, the humidity, viscosity and elasticity of the skin,

  which makes it possible to determine the effects of cosmetic preparations

  ques. The location of the area A studied is determined by the

  positioning of sleeve 9 or guard ring.

  It should be noted that the device of the invention allows

  puts to study an alteration of the skin other than a deformation

  tion. For example, we could study the change in

  their in contact with a specific gas blown through nozzle 2. The

  teration would then consist of this color change.

Claims (16)

  1. Device for studying the properties, in particular of the elasticity, of a surface, in particular of the skin, comprising pneumatic means for altering, in particular for temporarily deforming, an area of the surface under deter- amines, without material contact other than gas, and means of estimation   of the alteration of said area, these means of estimation -----   comprising a radiation emitter in the direction of the area of the surface being studied and a receiver capable of receiving a portion of the radiation returned by said area, this returned portion depending on the extent of the alteration, characterized in that the pneumatic means ( P) to alter the   surface include a nozzle (2), or the like, suitable for blowing   fler a gas on the area (A) of the surface considered and that holding means (M) are provided to support the nozzle   (2) at a predetermined distance (h) from the surface (3).   2. Device according to claim 1 wherein the alteration of the surface consists of a deformation of this surface, characterized in that the pressure of the gas jet at the outlet orifice (6) of the nozzle (2) is of the order of 0.1 to 1.0 bar.   3. Device according to claim 1 or 2, charac-   terrified by the fact that the nozzle (2) is arranged so as to   blow the gas in a direction (F) substantially ortho-   gonal to the studied area (A) of the surface.   4. Device according to any one of the claims.   above, characterized in that the nozzle (2) comprises   takes a body (4) whose axis is substantially orthogonal to said studied area (A), the outlet orifice (6) of the nozzle   having its center located on this axis.   5. Device according to any one of the claims.   tions, characterized in that the means of   holding (M) comprises adjustable support means (9)   be the surface to be studied, so that the distance (h) from the outlet orifice of the nozzle to said surface can be   adjusted at will, these support means can be   killed by a sleeve (9) surrounding the end of the nozzle (2) near the outlet (6).   6. Device according to any one of the claims.   tions above, characterized in that the orifice (6) of the nozzle has a diameter ranging from 1 mm to 5 mm, and equal to preferably 4 mm.   7. Device according to any one of the claims.   previous tions, characterized in that the distance (h)   from the nozzle outlet (6) to the surface (3), when   that it is not deformed, is of the order of 2 mm.   8. Device according to any one of the claims.   above, characterized in that the means for estimating (E) the extent of the alteration comprise, in a manner known per se, a light emitter (20) and a receiver (21) of the part of the light radiation reflected by the studied area (A), this receiver (21)   being suitable for transforming the quantity tity of light reviewed.   9. Device according to claim 8, characterized in that the estimation means (E) comprise a part (23) disposed inside the nozzle (2) so that the incident radiation and the radiation returned by the surface are confused with, or near the axis of the jet blown by the nozzle (2).   10. Device according to claim 8 or 9, charac-   tered by the fact that the estimation means (E) comprise optical fibers (26, 27) arranged coaxially with the nozzle   injection (2), inside the latter, and stops   both at a certain distance (i) from the opening (6) through which   the gas is blown 11. Device according to claim 10, characterized in that the distance (j) between the end of the optical fibers (26, 27) and the opening (6) of the nozzle is of the order from 3 to 30 mm.   12. Device according to claim 10 or 11, charac-   terrified by the fact that it includes a cylindrical optical fiber   (27), arranged along the axis of the jet, to collect the light   returned material, while an optical fiber has annular section   the area (26) surrounding the preceding fiber, is provided for incident light.   13. Device according to any one of the preceding claims, characterized in that the nozzle (2)   is supplied from a cylinder (11) of gas under pressure   sion, provided with a pressure reducer (12) connected to the nozzle (2) by a   supply line (13, 17, 19) fitted with an electric valve (14).   14. Device according to claim 13, characterized in that the nozzle supply line (2) is equipped with a pressure sensor (18) disposed downstream of the solenoid valve (14).   15. Device according to claim 13 or 14, ca-   characterized by the fact that a pipe (13) provided between   the regulator (12) and the solenoid valve (14) have a relative volume   large, especially around 20 cm3, to serve as   reserve during a variable pressure measurement.   16. Device according to any one of the claims.   previous tions, characterized in that the estimation means (E) comprise a memory oscilloscope (16) digital and a recorder (28).