Ultrasonic capture device with lubricant dispensing on its capture surface

Abstract

Ultrasonic capture device with lubricant dispensing on its capture surface The present description relates to an ultrasonic capture device (100) comprising at least: - an ultrasonic transducer circuit (104); - a contact layer (106) arranged on the ultrasonic transducer circuit and forming a capture surface (102) configured so that at least one element is arranged thereon during a capture by the ultrasonic capture device; - a reservoir (108) configured to store a lubricant and communicating with the capture surface such that the lubricant can be dispensed onto the capture surface. Figure for abstract: Fig. 1

Description

Title of the invention: Ultrasonic capture device with lubricant dispensing on its capture surface Technical field

[0001] The present description relates generally to the field of capture devices based on the capture and measurement of information by ultrasonic transduction, finding for example applications in the fields of biometric identification, medical, non-destructive testing, or even in other general public fields. Prior art

[0002] A biometric identification device is used to verify or determine the identity of a user of the device based on a measurement of at least one biometric characteristic of the user such as a fingerprint, face shape, iris pattern, retina pattern, etc. The different techniques for measuring one or other of these characteristics each have advantages and disadvantages depending on different criteria, including in particular: greater or lesser error rate, ease or not of stealing the template with which the measurements are compared, possibility of detecting an imitation or not, proof or not of life, ease and comfort of use, size of the sensor required, energy consumption required, etc.

[0003] In the case of a biometric identification device by ultrasonic transduction in which the measurement of a biometric characteristic involves contact between the device and the user, it is sometimes advisable to optimize the acoustic coupling between the part of the user's body on which the measurement is intended to be carried out (corresponding for example to one or more fingers of the user) and the capture surface of the device with which this part of the user's body is intended to be in contact. This is particularly the case for identification devices measuring biometric characteristics present under the user's skin, for example devices performing recognition of the microvasculature of the user's finger(s), i.e. performing image capture of the micro-blood vessels of this or these fingers of the user of the device.Optimizing this acoustic coupling generally involves depositing a lubricant such as water-based gel, or hydrogel, on the capture surface of the device. The lubricant can be deposited, directly or via a container such as a vial or bottle, on the capture surface by the user. However, this intervention on the part of the user to deposit the lubricant on the capture surface is a disadvantage. By . For example, this dispensation may be poorly carried out (uncontrolled quantity of lubricant, dispersion of the lubricant outside the capture surface, etc.). In addition, this implies that the user must be in possession of such a lubricant.

[0004] These problems are also found for capture devices other than biometric identification devices, for example in the medical field, non-destructive testing, or even in other consumer fields. Summary of the invention

[0005] There is a need to propose an ultrasonic capture device, or ultrasonic transduction capture device, which does not have at least some of the drawbacks of existing solutions.

[0006] One embodiment overcomes all or part of the drawbacks of known solutions and proposes an ultrasonic capture device comprising at least:

[0007] - an ultrasonic transducer circuit;

[0008] - a contact layer arranged on the ultrasonic transducer circuit and forming a capture surface configured so that at least one element is disposed thereon during capture by the ultrasonic capture device;

[0009] - a reservoir configured to store a lubricant and communicating with the surface capture such that the lubricant can be dispensed onto the capture surface.

[0010] According to a particular embodiment, the contact layer has a thickness greater than or equal to 500 μm, and / or the material of the contact layer has a Young's modulus of between 1 and 200 kPa.

[0011] According to a particular embodiment, the contact layer comprises at least one elastomer of at least one of the following families of materials and their different copolymers: natural or synthetic rubbers (polyisoprenes), silicones, polyurethanes and thermoplastic polyolefins, polybutadiene, polyethers.

[0012] According to a particular embodiment, the reservoir is arranged in the contact layer.

[0013] According to a particular embodiment, walls of the reservoir are formed by the material of the contact layer, and the contact layer has a Young's modulus such that pressure on the capture surface causes compression of the reservoir and ejection of a portion of the lubricant onto the capture surface.

[0014] According to a particular embodiment:

[0015] - the tank is arranged outside the path of transmission of ul- acoustic waves transonic signals intended to be transmitted between the ultrasonic transducer circuit and the capture surface, or

[0016] - at least a portion of the reservoir is arranged in the transmission path ultrasonic acoustic waves intended to be transmitted between the circuit ultrasonic transducer and the capture surface, and the ultrasonic capture device comprises a plurality of capillary channels communicating on one side with said portion of the reservoir and on the other with the capture surface.

[0017] According to a particular embodiment, the reservoir corresponds to porosities formed in the contact layer.

[0018] According to a particular embodiment, the reservoir is arranged outside the contact layer, and the device further comprises an actuator configured to control the extraction of the lubricant from the reservoir towards the capture surface.

[0019] According to a particular embodiment, the actuator comprises a micro-pump communicating on one side with the reservoir and on the other with the capture surface, and / or is configured to apply a mechanical force to the reservoir causing compression of the reservoir and ejection of a portion of the lubricant onto the capture surface.

[0020] According to a particular embodiment, the actuator is configured to control a movement of the lubricant by electrowetting and / or by application of electrical attraction and / or repulsion forces.

[0021] According to a particular embodiment, the actuator is configured to apply a temperature causing a displacement of the lubricant by thermal expansion and / or by phase change of the lubricant.

[0022] According to a particular embodiment, the ultrasonic capture device further comprises at least one sensor configured to detect the presence of the element near or on the capture surface and to control the actuator when the element is detected near or on the capture surface.

[0023] According to a particular embodiment, the device is configured to carry out an acquisition of at least one surface image of the element and an acquisition of volume information of the element, and the device is configured to dispense the lubricant onto the capture surface after the acquisition of the surface image and before the acquisition of the volume information.

[0024] According to a particular embodiment, the device corresponds to a biometric identification device configured to implement biometric identification from a part of a user's body intended to be placed on the capture surface. Brief description of the drawings

[0025] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0026] [Fig.l] schematically represents an ultrasonic capture device according to a first embodiment;

[0027] [Fig.2] schematically represents an ultrasonic capture device according to a second embodiment;

[0028] [Fig.3] schematically represents an ultrasonic capture device according to a third embodiment;

[0029] [Fig.4] schematically represents an ultrasonic capture device according to a fourth embodiment. Description of the embodiments

[0030] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0031] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been shown and are detailed. In particular, different elements (ultrasonic transducer circuit, actuator, detector, etc.) and different steps implemented (acquisition of images, processing of acquired images, determination of minutiae, calculations performed) are not detailed. Those skilled in the art will be able to implement these elements in detail from the functional description given here.

[0032] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0033] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures in a normal position of use.

[0034] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0035] Throughout the document, the term “vasculature” is used interchangeably to designate blood vessels or micro-blood vessels, of the artery and / or vein type, and is used as a synonym for the term “microvasculature”.

[0036] An ultrasonic capture device 100 according to a first embodiment is described below in connection with [Fig.l].

[0037] In the example described, the device 100 is configured to implement an iden biometric identification by performing measurements of biometric characteristics of a part of the body of the user of the device 100. In the various embodiments described, this part of the user's body corresponds to one or more fingers of the user. Alternatively, other parts of the user's body may be used to perform the biometric identification by the device 100. Furthermore, in the various examples described here, the part of the user's body used to perform the biometric identification corresponds to a single finger of the user.

[0038] The device 100 comprises a capture surface 102 on which the finger of the user of the device 100 is intended to be placed during biometric identification.

[0039] The device 100 further comprises an ultrasonic transducer circuit 104 configured to perform transmission and reception of ultrasonic signals during measurements used for the biometric identification of the user of the device 100. According to an exemplary embodiment, the circuit 104 may comprise a plurality of ultrasonic transducers configured to perform the image acquisitions required for the biometric identification. The ultrasonic transducers are for example arranged in a matrix manner or in another manner adapted to the captures to be performed. The number of ultrasonic transducers of the circuit 104 may depend on the dimensions of the capture surface 102, the dimensions of each ultrasonic transducer, the resolution of the measurements intended to be performed by the device 100, etc.The circuit 104 may for example comprise transducers of the CMUT type (“Capacitive Micromachined Ultrasonic Transducer” in English, or capacitive micromachined ultrasonic transducer) or of the PMUT type (“Piezoelectric Micromachined Ultrasonic Transducer” in English, or piezoelectric micromachined ultrasonic transducer) or of another type.

[0040] In the exemplary embodiment described, the device 100 can be configured to perform an acquisition of at least one surface image of the user's finger placed on the capture surface 102 and in contact therewith, that is to say an acquisition of at least one image of a fingerprint of the finger, formed of ridges and valleys present on the surface of the skin of the finger placed on the capture surface 102. In the device 100, the acquisition of a surface image of the user's finger placed on the capture surface 102 and in contact therewith is possible because the ultrasound emitted by a circuit 104 is reflected more significantly against the air present in the valleys of the finger than against the ridges.The difference between the signals received by the circuit 104 which are reflected on the valleys and those which are reflected on the peaks can be used to reconstruct the image of the fingerprint of the user's finger present on the capture surface 102.

[0041] In addition, the device 100 can also be configured to carry out acquisitions of volume or depth information from the finger placed on the capture surface. 102 of the device 100 and in contact with it, and from which it is for example possible to determine, by processing this volume information, global information on the vasculature of the finger, for example a global volume image of the vasculature of this finger, that is to say a capture of images of the blood vessels of the finger of the user of the device 100. According to a particular example, the acquired volume information can correspond to volume, or depth, images of the finger placed on the capture surface 102. The global volume information obtained can be deduced from several volume information captured successively at non-zero depths (dimension parallel to the Z axis visible in [Fig.l] and which is for example substantially perpendicular to the capture surface 102) of the finger present on the capture surface 102.

[0042] Alternatively, it is possible for the device 100 to be configured to perform only one of the two types of acquisition described above.

[0043] The device 100 further comprises a contact layer 106 arranged on the circuit 104 and forming the capture surface 102. In the example of [Fig.l], the contact layer 106 is arranged against the circuit 104. Alternatively, it is possible for one or more other materials to be present between the circuit 104 and the contact layer 106.

[0044] The geometric characteristics of the contact layer 106 and its material(s) may be such that the contact layer 106 is deformable and flexible. These properties of the contact layer 106 may in particular be such that the layer 106 has excellent conformability to the finger, in particular at the submillimeter scale, intended to be positioned on the capture surface 102, even when this finger applies moderate pressure to the capture surface 102 (for example less than approximately 50 gf, i.e. less than approximately 0.5 N). Thus, the layer 106 can deform so as to at least partially match the microtopography of the finger applying pressure to the layer 106.

[0045] Furthermore, the characteristics of the contact layer 106 may be such as to give it good acoustic properties in order to ensure good acoustic coupling (i.e. low attenuation in the transmission of acoustic waves) between the capture surface 102 and the circuit 104. Such acoustic coupling may be obtained by ensuring good acoustic impedance matching either between the circuit 104 and the target (the target corresponding to the user's finger in the example described), or between the circuit 104 and the acoustic impedance value with Za and Zb corresponding respectively to the acoustic impedances of circuit 104 and the target.

[0046] According to an exemplary embodiment, the contact layer 106 may comprise a thickness (dimension parallel to the Z axis) greater than or equal to 500 μm, or even greater than or equal to 2 mm. In addition, the material of the contact layer 106 may have a Young's modulus of between 1 and 200 kPa. The material of the contact layer 106 may also be chosen such that its hardness is between 5 and 60 Shore OO (for example measured in accordance with the ASTM D2240 standard). In the exemplary embodiment described, the material of the contact layer 106 may be an elastomer. In addition, the contact layer 106 may correspond to a stack of several distinct layers of materials.

[0047] The device 100 also comprises a reservoir 108 configured to store a lubricant and communicating with the capture surface 102 such that the lubricant can be dispensed onto the capture surface 102.

[0048] In the exemplary embodiment shown in [Fig.l], the reservoir 108 is arranged in the contact layer 106. In addition, in this example, the reservoir 108 is formed of several distinct parts (two visible in [Fig.l]), each communicating with the capture surface 102 by a channel 110. In the exemplary embodiment shown in [Fig.l], the channels 110 are also made in the contact layer 106. Furthermore, in the first embodiment described, the reservoir 108 (or each of the parts of the reservoir 108) is not arranged opposite, or facing, the circuit 104. In other words, the reservoir 108 is not arranged in the path followed by the acoustic waves sent / received between the circuit 104 and the capture surface 102. According to one example, the dimensions of the sides of the reservoir 108 may be less than 10 mm.

[0049] In the embodiment described in connection with [Fig.l], the walls of the reservoir 108 are formed by the material of the contact layer 106. In other words, the reservoir 108 is, in this first embodiment, formed by one or more empty spaces made in the contact layer 106. In addition, the contact layer 106 and the reservoir 108 are such that pressure from the finger on the capture surface 102 causes compression of the reservoir 108 and a tendency to create a reduction in the volume of the reservoir 108. Thus, when the finger present on the capture surface 102 applies pressure thereto, the compression of the contact layer 106 results in an ejection of a portion of the lubricant present in the reservoir 108 towards the capture surface 102 via the channel(s) 110.Upon contact with the finger, the lubricant dispensed onto the capture surface 102 from the reservoir 108 is distributed and forms an interface improving the acoustic coupling between the finger and the capture surface 102.

[0050] According to a particular example, the lubricant may correspond to a gel including a liquid providing the lubrication function, this liquid corresponding for example to water in the case of a hydrogel. In addition, the quantity of lubricant present in the reservoir 108 may be much greater than that dispensed onto the capture surface 102 when applying pressure from a finger to the capture surface 102, which allows lubricant to be dispensed numerous times onto the capture surface 102 before the reservoir 108 is empty.

[0051] When the channel(s) 110 are not arranged opposite the circuit 104 (as is the case in the example of [Fig. 1]), that is to say when the channel(s) 110 are not located on the transmission path of the ultrasonic acoustic waves between the circuit 104 and the capture surface 102, this or these channel(s) 110 do not impact the transmission of these ultrasounds. In this case, the dimensions of the channel(s) 110 may be large. For example, in such a configuration corresponding to that visible in [Fig. 1], the diameter of a channel 110 may be between 100 μm and 1 mm. On the other hand, if a part of the channel(s) 110 is located in the path traveled by the ultrasonic waves between the circuit 104 and the capture surface 102, the dimensions of this or these channels are chosen such that they are very small, and for example between 5 pm and 50 pm.

[0052] According to a particular embodiment of the device 100, the properties of the capture surface 102 (for example the wetting angle formed with the lubricant, the roughness of the capture surface 102, etc.) may be such that when the finger is removed from the capture surface 102, at least a portion of the lubricant present on the capture surface 102 tends to naturally return, for example due to capillary forces and / or surface tensions exerted on the lubricant, inside the channel(s) 110 to be stored again in the reservoir 108.

[0053] An ultrasonic capture device 100 according to a second embodiment is described below in connection with [Fig.2].

[0054] Unlike the first embodiment, the reservoir 108 of the device 100 according to this second embodiment comprises at least one part which is arranged opposite the circuit 104, that is to say in the path followed by the ultrasonic acoustic waves transmitted between the circuit 104 and the capture surface 102. The communication of the lubricant between the reservoir 108 and the capture surface 102 is ensured by a plurality of capillary channels 110 whose dimensions are very small, for example between 5 μm and 50 μm. As in the first embodiment, the channels 110 are also formed in the contact layer 106, communicating on one side with the reservoir 108 and on the other with the capture surface 102.

[0055] An ultrasonic capture device 100 according to a third embodiment is described below in connection with [Fig.3].

[0056] Unlike the first and second embodiments in which the reservoir 108 corresponds to one or more empty spaces of defined shape made in the contact layer 106, the reservoir 108 is formed by porosities present in the material of the contact layer 106. These porosities are for example obtained by implementing a microstructuring / nanostructuring method of a layer of material, or any other suitable method for forming porosities in a material used to make the contact layer 106. For example, the contact layer 106 may comprise silicone rubber and the porosities forming the reservoir 108 may be made as described for example in the document by Zhao, Jian et al. “Preparation of microporous silicone rubber membrane with tunable pore size via solvent evaporation-induced phase separation.” ACS applied materials & interfaces 5 6 (2013): 2040-6. According to another example, the contact layer 106 may comprise polyurethane and the porosities forming the reservoir 108 may be made as described for example in the document by Zhang Xiaoqian et al., “A porous elastomeric polyurethane monolith synthesized by concentrated emulsion templating and its pressure-sensitive conductive property,” RSC Adv., 2015,5.According to another example, the porosities forming the reservoir 108 can be produced as described for example in the document by Juthani, N., Howell, C., Ledoux, H. et al. Infused polymers for cell sheet release. Sci Rep 6, 26109 (2016). Other materials are conceivable for producing a contact layer 106 comprising porosities forming the reservoir 108, such as for example elastomer.

[0057] In this third embodiment, the lubricant can be stored in the porosities present in the contact layer 106 thanks to at least one of the following physical effects: microporosity, adsorption, mixing, effect of chemical bonds with the material of the contact layer 106.

[0058] In the first, second and third embodiments previously described, the dispensing of the lubricant onto the contact surface 102 is controlled by a pressure applied to the capture surface 102. Other mechanisms can however be envisaged to extract the lubricant from the reservoir 108 towards the capture surface 102: capillarity and wetting, diffusion, thermal expansion, phase change, etc.

[0059] An ultrasonic capture device 100 according to a fourth embodiment is described below in connection with [Fig.4].

[0060] Unlike the embodiments previously described in connection with figures 1 to 3, the reservoir 108 here corresponds to at least one cavity formed outside the contact layer 106. In addition, in this fourth embodiment, the device 100 further comprises an actuator 112 configured to control the extraction of the lubricant from the reservoir 108 to the capture surface 102. The channel 110 allows on one side the passage of the lubricant from the reservoir 108 to the actuator 112, and on the other side the passage of the lubricant from the actuator 112 to the capture surface 102.

[0061] In the embodiment shown in [Fig. 4], the actuator 112 comprises a micro-pump communicating on one side with the reservoir 108 and on the other with the capture surface 102. Such a micro-pump can be magnetically controlled, as described for example in the paper by Pan, Tingrui et al. “A magnetically driven PDMS micropump with bail check-valves.” Journal of Micromechanics and Microengineering 15 (2005): 1021 - 1026, or be realized for example as described in the paper by Liyu Liu et al., “Electrorhological fluid-actuated microfluidic pump,” Applied Physics Letters, August 2006.

[0062] Alternatively, the actuator 112 may correspond to a mechanism other than a micropump and be configured to apply a mechanical force to the reservoir 108, causing a compression of the reservoir 108 and a tendency to create a reduction in the volume of the reservoir 108 in order to bring a portion of the lubricant present in the reservoir 108 onto the capture surface 102.

[0063] According to another variant, the actuator 112 may be configured to control a displacement of the lubricant by electro-wetting and / or by application of electrical attraction and / or repulsion forces. In this case, the lubricant may correspond to a liquid system containing at least one electrically conductive compound, for example an aqueous salt solution. In particular, in the case of a displacement of the lubricant by electro-wetting, the lubricant may be one of at least two mixed immiscible liquids. In this case, depending on the value of a potential difference applied to the mixture of liquids containing the lubricant, the contact angle between the immiscible liquids changes, generating forces creating the desired displacement.

[0064] According to another variant, the lubricant may comprise a material exhibiting a certain thermal expansion from a given temperature, or else comprise a phase change material. In this case, the actuator 112 may be configured to apply a temperature generating a displacement of the lubricant by thermal expansion and / or by phase change (for example melting, condensation, etc.) of the lubricant.

[0065] In this fourth embodiment, regardless of the physical principle used by the actuator 112 to dispense the lubricant from the reservoir 108 to the capture surface 102, the dispensing carried out corresponds to an active dispensing carried out by the actuator 112 and not to a passive dispensing carried out by the user's finger as in the first, second and third embodiments. The piloting, or control, of the actuator 112 can be carried out for example by a microcontroller, not shown in [Fig.4].

[0066] In this fourth embodiment, the control of the actuator 112 can be triggered by carrying out a prior detection in order to know if a finger is placed on the capture surface 102 or in the vicinity thereof. According to a first example, this detection can be carried out by an emission / reception of ultrasonic signals by the circuit 104 (only a part of the detectors of the circuit 104 can be used to carry out this detection). According to a second example corresponding to the confi configuration visible in [Fig.4], this detection can be carried out by a sensor 114 configured to detect the presence of the user's finger near the capture surface 102 and to control the actuator 112 when the user's finger is detected near the capture surface 102. By way of example, the sensor 114 can be configured to carry out force, contact or proximity detection of the user's finger. For example, the sensor 114 can correspond to electrical detection electrodes. According to other examples, the sensor 114 can be configured to carry out detection of capacitive coupling between the finger and the sensor 114, or a pressure measurement in the reservoir 108, measurement of the pressure of the finger pressing on the capture surface 102, a measurement of thermal properties of the capture surface 102, etc.

[0067] In this fourth embodiment, the reservoir 108, the channel 110 and any other elements linked to the circulation of the lubricant can be produced by implementing the techniques used in the field of microfluidics, such as for example soft lithography, embossing, lamination, 3D printing, etc. The materials used by these techniques are for example PDMS (Polydimethylsiloxane) and silicones, polyurethane elastomers, etc.

[0068] In the various embodiments, the contact layer 106 may comprise at least one elastomer of at least one of the following families of materials and their various copolymers: natural or synthetic rubbers (polyisoprenes), silicones, thermoplastic polyurethanes and polyolefins, polybutadiene, polyethers.

[0069] In all embodiments, the amount of lubricant dispensed may depend on the size of the capture surface 102, and may be of the order of one or a few picograms. This amount of lubricant is controlled either passively as a function of the pressure applied by the user's finger as in the case of the first, second and third embodiments, or actively by the actuator 114 in the case of the fourth embodiment.

[0070] When the device 100 is configured to measure biometric characteristics present on the surface of the user's skin, for example a fingerprint capture of the user's finger, and other biometric characteristics present under the user's skin, for example a capture of the vasculature of the user's finger, the device 100 can be configured to dispense the lubricant only when the device 100 is capturing the volume information of the user's finger and not during the capture of the surface image(s) for which it is preferable not to replace the air present in the hollows of the fingerprint with lubricant.

[0071] In such a configuration, the dispensing of the lubricant onto the capture surface 102 during the capture of the volume information from the user's finger allows that the entire contact surface between the capture surface 102 and the finger is well acoustically coupled, without the presence of air or any interface defect introducing significant differences in speed or acoustic impedance, or strong attenuation. In the case of passive dispensing of the lubricant, as in the first, second and third embodiments, it is possible to trigger the capture of the surface image(s) before the user's finger applies sufficient pressure to the capture surface 102 to trigger the dispensing of the lubricant onto the capture surface 102. In the case of active dispensing of the lubricant, as in the fourth embodiment, this dispensing of the lubricant onto the capture surface 102 only during the capture of the volume information can be controlled by means of the actuator 112 which does not control the dispensing of the lubricant during the capture of the surface image(s).

[0072] The device 100 comprises other elements which are not described in detail in the present description, such as for example a control circuit intended to control the circuit 104, a data processing circuit, etc.

[0073] The device 100 can implement additional functions to those previously described, such as for example a contribution to the detection of living things from the captured information.

[0074] In all embodiments, the device 100 allows automatic dispensing of lubricant onto the capture surface 102, without user intervention related solely to this dispensing of lubricant. Furthermore, the device 100 allows dispensing of a controlled quantity of lubricant onto the capture surface 102. Finally, the device 100 avoids the user having to be in possession of lubricant.

[0075] In the various embodiments described above, the ultrasound capture device 100 corresponds to a biometric identification device. Alternatively, these various embodiments may apply to a device 100 performing an ultrasound capture not corresponding to a biometric identification, such as for example a capture performed for medical purposes or to perform a non-destructive test, for example, of an object. In this case, the element intended to be arranged on the capture surface of the device may correspond to something other than a part of the body of the user of the device 100, for example a surface to be checked by ultrasound measurement.

[0076] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0077] Finally, the practical implementation of the embodiments and variants described is within the reach of the person skilled in the art from the functional indications given below. above.

Claims

Claims

1. An ultrasonic capture device (100) comprising at least: - an ultrasonic transducer circuit (104); - a contact layer (106) disposed on the ultrasonic transducer circuit (104) and forming a capture surface (102) configured so that at least one element is disposed thereon during capture by the ultrasonic capture device (100); - a reservoir (108) configured to store a lubricant and communicating with the capture surface (102) such that the lubricant can be dispensed onto the capture surface (102).

2. An ultrasonic capture device (100) according to claim 1, wherein the contact layer (106) has a thickness greater than or equal to 500 pm, and / or wherein the material of the contact layer (106) has a Young's modulus of between 1 and 200 kPa.

3. Ultrasonic capture device (100) according to one of the preceding claims, in which the contact layer (106) comprises at least one elastomer of at least one of the following families of materials and their different copolymers: natural or synthetic rubbers (polyisoprenes), silicones, thermoplastic polyurethanes and polyolefins, polybutadiene, polyethers.

4. An ultrasonic capture device (100) according to one of the preceding claims, wherein the reservoir (108) is arranged in the contact layer (106).

5. An ultrasonic capture device (100) according to claim 4, wherein walls of the reservoir (108) are formed by the material of the contact layer (106), and wherein the contact layer (106) has a Young's modulus such that pressure on the capture surface (102) causes compression of the reservoir (108) and ejection of a portion of the lubricant onto the capture surface (102).

6. An ultrasonic capture device (100) according to claim 5, wherein: - the reservoir (108) is arranged outside the transmission path of ultrasonic acoustic waves intended to be transmitted between the ultrasonic transducer circuit (104) and the capture surface (102), or - at least a portion of the reservoir (108) is arranged in the transmission path of ultrasonic acoustic waves intended to be transmitted between the ultrasonic transducer circuit (104) and the capture surface (102), or - at least a portion of the reservoir (108) is arranged in the transmission path of ultrasonic acoustic waves intended to be transmitted between the ultrasonic transducer circuit (104) and the capture surface (102). capture (102), and the ultrasonic capture device (100) comprises a plurality of capillary channels (110) communicating on one side with said part of the reservoir (108) and on the other with the capture surface (102).

7. An ultrasonic capture device (100) according to claim 4, wherein the reservoir (108) corresponds to porosities formed in the contact layer (106).

8. An ultrasonic capture device (100) according to one of claims 1 to 3, wherein the reservoir (108) is disposed outside the contact layer (106), and further comprising an actuator (112) configured to control the extraction of the lubricant from the reservoir (108) towards the capture surface (102).

9. An ultrasonic capture device (100) according to claim 8, wherein the actuator (112) comprises a micro-pump communicating on one side with the reservoir (108) and on the other with the capture surface (102), and / or is configured to apply a mechanical force to the reservoir (108) causing compression of the reservoir (108) and ejection of a portion of the lubricant onto the capture surface (102).

10. An ultrasonic capture device (100) according to claim 8, wherein the actuator (112) is configured to control movement of the lubricant by electrowetting and / or by applying electrical attractive and / or repulsive forces.

11. An ultrasonic capture device (100) according to claim 8, wherein the actuator (112) is configured to apply a temperature causing displacement of the lubricant by thermal expansion and / or by phase change of the lubricant.

12. The ultrasonic capture device (100) of claim 11, further comprising at least one sensor (114) configured to detect the presence of the element near or on the capture surface (102) and to control the actuator (112) when the element is detected near or on the capture surface (102).

13. An ultrasonic capture device (100) according to one of the preceding claims, configured to perform an acquisition of at least one surface image of the element and an acquisition of volume information of the element, and wherein the device is configured to dispense the lubricant onto the capture surface (102) after the acquisition of the surface image and before the acquisition of the volume information.

14. An ultrasonic capture device (100) according to one of the claims previous, corresponding to a biometric identification device configured to implement biometric identification from a part of a user's body intended to be placed on the capture surface (102).

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