FR3053236A1 - DEVICE FOR MEASURING A MECHANICAL STRESS OR A MOVEMENT. - Google Patents

Abstract

The present invention relates to a measuring device (10) comprising: - a support (1), - a film (2) extending from the support (1), - a sensor (3) integral with the film (2) and arranged to convert a mechanical stress or a movement (4), parallel to the thickness of the film (2) at the sensor (3), into an electrical signal.

Description

Technical area

The present invention relates to a device for measuring (quantitatively by a value or qualitatively by simple detection) a mechanical stress or a movement, typically for measuring a pulse wave.

Such a device allows a user to measure a pulse wave of a patient by pressing the device against a blood vessel of that patient.

The field of the invention is more particularly but not limited to that of medical devices.

State of the art

State-of-the-art devices are known for measuring and characterizing the carotid pulse wave on the basis of the diagnosis of arterial health and for calculating the speed of the pulse wave, a parameter correlated to the degree of arterial stiffness. .

Among them, devices are known, for example, comprising a sensor having the shape of a "pen", the tip of which must be pressed against a blood vessel. However, the sensor itself has several drawbacks:

discomfort for the patient, inaccuracy in its positioning: by holding only the sensor with one hand, the practitioner is uncertain of the correct positioning of the sensor relative to the blood vessel. The practitioner is obliged to regularly use both hands: one to feel the pulse and the other to position the sensor.

The object of the present invention is to solve at least one of these drawbacks.

-2 Statement of the invention

This objective is achieved with a measurement device comprising:

- a support,

- a film extending from the support,

- A sensor integral with the film and arranged to transform a mechanical stress or a movement, parallel to the thickness of the film at the level of the sensor, into an electrical signal.

The film may include means for conveying the electrical signal from the sensor to the exterior of the film.

The sensor is preferably integrated or coated or encapsulated in the film.

The sensor is preferably a piezoelectric sensor.

The film can be a textile or a polymer film, preferably an elastomer film.

The device according to the invention may include electronics arranged to receive the electrical signal and process it. The electronics can be secured to the support and / or the film.

The film can extend over a length of at least 10 mm, preferably over a length of between 40 mm and 80 mm.

The support can be a handle.

The support may comprise a hollow tube comprising a periphery delimited by a wall, the film extending from the wall of the tube or along the wall of the tube. The tube can be

- a ring or a ring or a bracelet.

- A part of a finger pocket or a glove finger, preferably comprising the unclosed end of this finger pocket or this glove finger.

The wall of the tube preferably has an internal perimeter of between 30 mm and 75 mm (for example in the case of a ring) or between 130 mm and 250 mm (for example in the case of a bracelet).

The electronics can be located:

- in a housing integral with the tube, and / or

- in the wall of the tube or along the wall of the tube.

The wall of the tube can be located around an axis of the tube, the film comprising a face oriented towards the axis of the tube and a face oriented opposite the axis of the tube. The film is preferably provided with a protuberance superimposed on the sensor on its face oriented towards the axis of the tube. In general, the film can be provided with a protuberance superimposed on the sensor.

According to yet another aspect of the invention, there is provided a method of using a device according to the invention, characterized in that a user positions one of his fingers above the film so that this finger is is in a position of use for which a part of this finger (preferably the distal phalanx of this finger) is superimposed on the sensor, preferably by exerting a pressure on the film.

In the position of use:

the user can position the part of his finger (preferably the distal phalanx of the finger) above a blood vessel so that the sensor is included between the blood vessel and the finger, and / or

- in the case of a support with tube: the user can position his finger in the position of use by inserting his finger into the tube of the support, and / or

- in the case of a film with protuberance: the protuberance is preferably located between the finger and the sensor.

Description of the figures and embodiments

Other advantages and particularities of the invention will appear on reading the detailed description of implementations and embodiments in no way limiting, and the following appended drawings:

FIG. 1 is a schematic top view of a sensor 3 and of a flexible substrate 71 for an embodiment of the device 10 according to the invention, which is the preferred embodiment of the invention,

FIG. 2 is a schematic top view of the sensor 3 and of the flexible substrate 71 encapsulated in a film 2,

FIG. 3 is a schematic profile view of the sensor 3 and of the flexible substrate 71 encapsulated in the film 2,

FIG. 4 is a schematic front view of the sensor 3 encapsulated in the film 2 and pressed, by a finger 15 of a user, against the skin of a patient 19 above an artery 16,

FIG. 5 is a schematic view of electronics 8 of the device 10,

FIGS. 6 and 7 are views of a first variant of the device 10,

FIGS. 8 and 9 are views of a second variant of the device 10,

FIGS. 10 and 11 are views of a third variant of the device 10,

FIG. 12 is a view of a fourth variant of the device 10, and

FIG. 13 is a view of a fifth variant of the device 10.

These embodiments being in no way limitative, it will be possible in particular to consider variants of the invention comprising only a selection of characteristics described or illustrated subsequently isolated from the other characteristics described or illustrated (even if this selection is isolated within a sentence including these other characteristics), if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one characteristic, preferably functional, without structural details, and / or with only part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention from the state of the art. anterior.

We will first describe, with reference to Figures 1 to 13, a measuring device 10 according to the invention comprising a support 1 (rigid or

-5souple), ensuring the maintenance of the device 10 on a part of the hand or forearm of a user.

The device 10 comprises a film 2 extending from the support 1. This film 2 is a flexible film, deforming under its own weight (which is particularly visible when the device 10 is turned over).

The device 10 comprises a sensor 3 secured to the film 2 and arranged to transform a mechanical stress 4 or a movement 4 into an electrical signal, this stress 4 or this movement 4 being:

- perpendicular to an elongation direction 5 of the film 2 at a contact area 6 between the film 2 and the sensor 3,

more precisely parallel to or carried by an axis 25 perpendicular to an outer face 23 or 24 of the film 2 and passing through the sensor 3, this axis 25 being parallel to the thickness of the film 2, that is to say to the smaller spatial dimension of film 2.

The device 10 is arranged to allow the positioning of the sensor 3 at the end of a finger 15 of the user.

The film 2 comprises means 7, 71, 72 for conveying the electrical signal from the sensor 3 to the outside of the film 2.

The sensor 3 is integrated in the film 2. The sensor 3 is thus packaged in a flexible material of the film 2 in order to allow the user to feel the beating of a blood vessel 16 (typically an artery) above from which the sensor 3 is positioned as illustrated in FIG. 4.

The sensor 3 is a piezoelectric sensor.

Film 2 is a polymer film, more precisely an elastomer film, typically made of PDMS (Polydimethylsiloxane).

The sensor 3 is a very thin piezoelectric sensor (preferably 10 to 50 μm in thickness, typically 28 μm in thickness) encapsulated in the film 2 of flexible elastomeric material. This film 2 is integrated or embedded, integrally or at least at one of its ends, in the support 1. The film 2 extends over a sufficient length (specified below for each of the variants) so that, in a position of use of the device 10, the film 10 extends over the entire length of the finger 15 so that the sensor 3 is positioned at the end of this finger 15.

The sensor 3 therefore comprises a piezoelectric material 31. It is a material 31 generating electrical charges when it is subjected to mechanical stress. Any piezoelectric material may be suitable for this invention. In this exemplary embodiment of device 10, PVDF (Polyvinylidene fluoride) was chosen because it has many advantages which are as follows:

(i) it is a polymer: compared to a piezoelectric ceramic, it is more flexible and can therefore undergo greater mechanical stresses without breaking.

(ii) it presents a satisfactory piezoelectric response.

(iii) This material is available in the form of thin films commercially or easily synthesized in the laboratory.

(iv) The process for manufacturing piezoelectric sensors using this process is simple and inexpensive

The piezoelectric material 31 used for producing the transducer is a PVDF film with a thickness of 28 μm.

The material 31 is surrounded by two electrodes 32, 33.

These electrodes 32, 33 are metallic electrodes.

The electrodes 32, 33 are produced by depositing metallic layers facing each other on the face of the material 31. These metallic layers are used as electrodes 32, 33 to collect the electric charges generated by the piezoelectric material 31 when a constraint applies. These metal layers are deposited directly on the material 31 by sputtering technique through stencils to define the geometry of the electrode. The materials used for these layers are TiW-Au layers typically 50 nm thick: each electrode 32, 33 comprises a layer of titanium Tungsten (TiW) and a layer of gold (AU), the layer of titanium tungsten of the electrode respectively 32 or 33 being in contact with the piezoelectric layer 31 and situated between the material 31 and the gold layer of this same electrode respectively 32 or 33. Any other conductive material (metals, conductive anchor, etc.) and any other deposition techniques compatible with material 31 sensitive to mechanical stresses can be applied.

Each metal layer 32, 33 includes a connection tab respectively 321, 331.

The resumption of contact with the piezoelectric transducer 3 is carried out with a flexible substrate 71 in Kapton which has two conductive (and metallic) tracks 72:

on a first face of the substrate 71, a track 72 is welded to the tab 321 of the electrode 32 by a weld 721 or a point of conductive adhesive,

- On the other face of the substrate 71, the other track 72 is welded to the tab 331 of the electrode 33 by a weld 731 or a point of conductive adhesive; in the top view of FIG. 1, the tab 331 and the solder 731 directly connected to this tab 331 should not be illustrated because they are hidden by the piezoelectric layer 31, but have nevertheless been illustrated “by transparency” in order to be able to be located.

This flexible substrate 71 has a length geometry so as to be able to extend the resumption of contact with the transducer 3 all along the finger 15 to the support 1.

The sensor 3 and the contact recovery means 7, 71, 72 are encapsulated in the film 2 of ultra-flexible polymer (PDMS in this example) according to the following manufacturing process: a first layer of PDMS is molded. The sensor 3 is then positioned on this first layer. Finally the second layer of PDMS is poured onto the sensor 3 to finalize the encapsulation. This ensures electrical insulation and improves the robustness of sensor 3.

The device 10 includes electronics 8 arranged to receive the electrical signal and process it.

The device 10 further comprises connection means 18 arranged to transmit the information, thus processed by the electronics 8, to a digital platform (PC, tablet, computer ...).

The sensor 3 is therefore connected to this electronics 8 which is located nearby and which provides the preconditioning of the signals, the digitization and the communication, via the wired or non-wired link 18, to a tablet 17, a computer, a smartphone. , a digital bracelet or any other digital interface for viewing and / or recording the signal

-8collected. Depending on the digital interface used, a communication protocol adaptation module may be necessary.

At the level of the support 1, two wires 73, 74 welded (by welds 75) to the end of the metal tracks 72 of the substrate 71 in flexible Kapton make it possible to ensure contact with the electronics 8.

The wires 73, 74 for contact resumption with the sensor 3 are welded to dedicated pins of the electronics 8.

The electronics 8 are included in the mechanical support 1 which maintains the sensor 3 at the end of the finger 15.

The electronics 8 allow the amplification then the preprocessing of the signal in an analogical way then the digitization of the signal, and includes:

- analog preprocessing means 81, 82, comprising:

o an amplifier 81, o a low pass filter 82,

means 83 for electrical supply,

- a microcontroller 84,

- an analog / digital converter 85

- an interface 86 (UART-TTL) allowing communication with different types of computer interfaces. Depending on the interface chosen, an appropriate conversion module (for example "UART to USB" for Android ™ or Windows ™ PCs and tablets or "UART to Lightning" for Apple ™ products) is used.

The film 2 is provided with a protuberance 9 superimposed on the sensor 3. The protuberance 9, located above the sensor 3, makes it possible to feel the position of the sensor 3 at the level of the finger 15. The protuberance 9 has a thickness of at least minus 0.2 mm, preferably at least 0.5 mm.

The electronics 8 is preferably integral with the film 2.

The film 2 has a thickness, between the sensor 3 and one of its faces (more exactly between the sensor 3 and its face 24 not carrying the protuberance 9) less than or equal to 5 mm, preferably less than or equal to 2 mm, ideally less than or equal to 1mm.

The device 10 is preferably arranged so that the film 2 (in particular the part of the film 2 in which the sensor 3 is coated) is

-9accessible and can be touched (by a patient) on one of its faces 24 from outside the device 10 in operation.

We will now describe different variants. In each variant, the sensor 3, included in the flexible and thin packaging 2, is arranged to be able to be positioned at the end of the index 15 so that the electronics 8 is located nearby.

We will now describe, with reference to FIGS. 6 and 7, a first variant 11 of the device according to the invention, which will only be described for its specific features compared to the previous description of the device 10.

The support 1 is a rigid support.

The support 1 comprises a hollow tube comprising a periphery delimited by a wall.

This wall is a double wall inside which part of the film 2 is embedded.

The wall of the tube is located around an axis 22 of the tube.

The film 2 extends, over its entire length or over at least part of its length, and from the wall of the tube, parallel to the axis 22 of the tube.

The tube is a ring or ring, which is rigid.

The wall of the tube has an internal perimeter between 30 mm and 75 mm.

The electronics 8 is integral with the tube. The electronics 8 is located in a housing 21 which is integral with the tube.

The mechanical support 1 which contains the miniaturized electronics 8 is therefore here rigid and has the shape of a ring on its lower part allowing the structure to be maintained around the finger 15.

The film 2 comprises a face 23 oriented towards the axis 22 of the tube and a face 24 oriented opposite the axis 22 of the tube.

The film 2 is provided with the protuberance 9 on its face 23 oriented towards the axis 22 of the tube, this protuberance 9 being superimposed on the sensor 3 on the face 23 oriented towards the axis 22 of the tube.

The electronics 8 is fixed to the support 1, more exactly fixed to the tube. · ·,

To secure the adapter 3 in the support or tube or ring 1, the end of the film 2 opposite the sensor 3 is embedded in the double wall of the ring 1. In parallel, the electronics 8 is fixed in its location dedicated in the upper part of the tube 1. PDMS is then poured into this double wall to permanently secure the two flexible (film 2) and rigid (support 1) parts. The assembly is finalized by placing and fixing a cover on the upper part of the finger box 1, that is to say on the housing 21 housing the electronics 8.

The film 2 extends (preferably parallel to the axis 22 of the tube) over at least 10 mm, preferably over a length of between 40 mm and 80 mm.

We will now describe, with reference to FIGS. 8 and 9, a second variant 12 of the device according to the invention, which will be described for its specificities and differences compared to the first variant 11.

The support 1 is a flexible support and comprises a finger pad (typically of textile or polymer, preferably of the same material as the film 2).

The support 1 comprises a hollow tube comprising a periphery delimited by a wall.

The wall of the tube is located around an axis 22 of the tube.

The film 2 extends, along the wall of the tube, parallel to the axis 22 of the tube 22 over its entire length or over at least part of its length.

The tube comprises a part of the finger box, comprising the open end of this finger box.

The wall of the tube has an internal perimeter between 30 mm and 75 mm.

The electronics 8 is located:

- in the wall of the tube or

- along the wall of the tube (preferably inside the tube).

- The film 2 comprises a face 23 oriented towards the axis 22 of the tube and a face 24 oriented opposite the axis 22 of the tube.

The film 2 is provided with the protuberance 9 on its face 23 oriented towards the axis 22 of the tube, this protuberance 9 being superimposed on the sensor 3 on the face 23 oriented towards the axis 22 of the tube.

The film 2 extends (preferably parallel to the axis 22 of the tube) over at least 10 mm, preferably over a length of between 40mm and 80 mm.

In this variant, the sensor 3 and the electronics 8 are therefore included; o in the same packaging: they are located in (or along) the wall of the finger-box 1 which takes the form of finger 15. In this way, the The index finger can easily be inserted into the instrument finger box.

We will now describe, with reference to FIGS. 10 and 11, a third variant 13 of the device according to the invention, which will only be described for its specificities and differences compared to the second variant 12.

In this variant, the electronics 8 is here deported (in whole or in part) in another support (rigid or flexible) which can take the appearance of a bracelet or any other form making it possible to include the electronics 8 and connect to sensor 3.

We will now describe, with reference to FIG. 12, a fourth variant 14 of the device according to the invention, which will only be described for its specificities and differences compared to the second variant

12.

In this variant, the support 1 is a glove.

The tube of the support 1 comprises a part of this glove, comprising the open end of a finger of this glove.

The sensor 3 and the electronics 8 are included in the glove (on the index part). The glove can be made of textile or elastomeric material (preferably in the same elastomer or textile as film 2).

We will now describe, with reference to FIG. 13, a fifth variant 51 of the device according to the invention, which will only be described for its specific features compared to the description of the device 10.

In this variant, the support 1 is a handle.

The rigid support 1.

The electronics 8 is located in the handle 1.

The film 2 extends over at least 10 mm, preferably over a length of between 40 mm and 100 mm.

We will now describe a sixth variant (not illustrated) of the device according to the invention, which will only be described for its specific features and differences compared to the first variant 11.

In this variant, the tube of the support 1 is a larger ring, that is to say a bracelet.

The wall of the tube has an internal perimeter of between 130mm and 250mm.

The film 2 extends (preferably parallel to the axis 22 of the tube) over a length of between 80 mm and 200 mm.

We will now describe, with reference to FIGS. 1 to 13, a method according to the invention for using the device 10.

When mechanical stresses are exerted on the piezoelectric material 31, the charges generated are collected by the electrodes 32, 33 deposited facing each other on the two opposite surfaces of the material 31. In the application described here, the finger 15 of the user applies pressure 20 to the sensor 3 to press it above the patient's skin 19. If the sensor 3 is positioned above an artery 16, the pulsation induced by the passage of blood generates a mechanical stress at the level of the piezoelectric sensor 3. The charges generated vary at the rate of the average deformation signal. So that the measured deformation signal is as faithful as possible to that of the pulsation of the artery 16, the sensor 3 is dimensioned so that it is of dimension close to the diameter of the artery where the measurement is carried out. .

In the configuration described with two electrodes 32, 33 facing each other on two opposite faces, charges can be generated when mechanical stresses are exerted along the axis 25 perpendicular to the plane of the electrodes 32, 33, and / or perpendicular to this axis when the sensor 3 is flexed or extended. In the case of the device 10, the active area of the sensor 3 has a dimension close to the diameter of the artery 16 and less than that of the finger 15 which exerts the force or pressure 20. If the sensor 3 is correctly pressed (via the film 2) against the skin of the patient 19 by the stress 20 applied by the finger 15, it can be considered that the mechanical signal from the artery 16 does little deformation of the sensor 3 out of plane and thus that the generation of charges is essentially induced by the stress mechanical which is exerted along the axis 25 perpendicular to the plane of the electrodes 32, 33.

In a method of using the device 10, the user positions one of his fingers 15 above the film 2 (preferably directly on the film 2) so that this finger 15 is in the position of use for which the distal phalanx of this finger 15 (ie the phalanx furthest from the palm of the hand carrying this finger 15) is superimposed on the sensor 3 by exerting a pressure on the film 2.

In this position of use, the user positions the distal phalanx of the finger 15 above the blood vessel 16 so that the sensor 3 is included between the blood vessel 16 and the finger 15. The film 2 is in direct contact with the skin under which the vessel 16 is located. The finger 15, the sensor 3 and the blood vessel 16 are superimposed in the stacking direction of the two electrodes 32, 33 and of the piezoelectric material 31, that is to say according to axis 25.

The user positions his finger 15 in the position of use:

- in the case of variants of Figures 6 to 12: by pushing the finger into the tube of the support 1;

- in the case of FIG. 13: by taking the handle 1 in the palm of his hand, so that the finger 15 belonging to this hand extends along the film 2.

In the position of use, the protuberance 9 is located between the finger 15 and the sensor 3.

- ¹⁴ ~

The use of the device 10 is very instinctive, and allows for example to monitor the carotid or femoral pulse wave.

Associated with an electrocardiogram module (ECG) for synchronizing the signal from the carotid artery and the femoral artery, the device 10 allows the calculation of the speed of the pulse wave.

Of course, the invention is not limited to the embodiments, variants and examples which have just been described and numerous modifications can be made thereto without departing from the scope of the invention. In particular :

the film 2 can be a textile, and / or

- for sensor 3, any transducer capable of converting a mechanical stress or a movement into a usable electrical signal can be used, for example a piezoelectric transducer, a piezoresistive transducer, a variable capacity transducer, a resistive transducer, an inductive transducer, etc. ...

- the sensor 3 can be manufactured in the film 2 according to the manufacturing process described in the document WO 2014/187 937

- the electronics 8 can be integrated into the film 2.

Of course, the different characteristics, forms, variants and embodiments of the invention can be associated with one another in various combinations insofar as they are not incompatible or mutually exclusive of each other. In particular, all the variants and embodiments described above can be combined with one another.

Claims (20)

1. Measuring device (10) comprising: - a support (1), - a film (2) extending from the support (1), - a sensor (3) integral with the film (2) and arranged to transform a mechanical stress or a movement (4), parallel to the thickness of the film (2) at the sensor (3), into an electrical signal, the film (2) comprising means (71) for conveying the electrical signal from the sensor (3) to the outside of the film (2). 2. Device according to claim 1, characterized in that the sensor (3) is integrated in the film (2). 3. Device according to any one of the preceding claims, characterized in that the sensor (3) is a piezoelectric sensor. 4. Device according to any one of the preceding claims, characterized in that the film (2) is a textile or a polymer film, preferably an elastomer film. 5. Device according to any one of the preceding claims, characterized in that it comprises electronics (8) arranged to receive the electrical signal and process it. 6. Device according to claim 5, characterized in that the electronics (8) is integral with the support (1). 7. Device according to claim 5 or 6, characterized in that the electronics (8) is integral with the film (2). 8. Device according to any one of the preceding claims, characterized in that the film (2) extends over a length of at least -1610 mm, preferably over a length between 40 mm and 80 mm. 9. Measuring device according to any one of the preceding claims, characterized in that the support (1) comprises a hollow tube comprising a periphery delimited by a wall, the film (2) extending from the wall of the tube or along the wall of the tube. 10. Device according to claim 9, characterized in that the tube is a ring or a ring or a bracelet. 11. Device according to claim 9, characterized in that the tube is a part of a finger or a glove finger. 12. Device according to any one of claims 9 to 11, characterized in that the wall of the tube has an internal perimeter between 30 mm and 75 mm or between 130mm and 250 mm. 13. Device according to any one of claims 9 to 12, considered as dependent on any one of claims 5 to 7, characterized in that the electronics (8) is located in a housing (21) integral with the tube. 14. Device according to any one of claims 9 to 12, considered as dependent on any one of claims 5 to 7, characterized in that the electronics (8) is located in the wall of the tube or along the tube wall. 15. Device according to any one of claims 9 to 14, characterized in that the wall of the tube is located around an axis (22) of the tube, the film (2) comprising a face (23) oriented towards the axis (22) of the tube and a face (24) oriented opposite the axis (22) of the tube, the film (2) being provided with a protuberance (9) superimposed on the sensor (3) on its face (23) oriented towards the axis (22) of the tübe. - 1716. Measuring device according to any one of claims 1 to 8, characterized in that the support (1) is a handle. 17. Device according to any one of claims 1 to 14 and 16, characterized in that the film (22) is provided with a protuberance (9) superimposed on the sensor (3). 18. Method of using a device according to any one of the preceding claims, characterized in that a user positions one of his fingers (15) above the film (2) so that this finger (15) is in a position of use for which a part of this finger (15) is superimposed on the sensor (3) by exerting a pressure on the film (2). 19. The method of claim 18, characterized in that, in the position of use, the user positions the part of his finger (15) above a blood vessel (16) so that the sensor (3 ) is between the blood vessel (16) and the finger (15). 20. Method according to claim 18 or 19, characterized in that the device (10) is a device according to any one of claims 9 to 15, and in that the user positions his finger (15) in the position d 'use by inserting the finger (15) into the support tube. 21. Method according to claim 18 or 19, characterized in that the device (10) is a device according to claim 15 or 17, and in that in the position of use the protuberance (9) is located between the finger ( 15) and the sensor (3). 1/4