Ultrasound and reverse iontophoresis capture device

Abstract

Ultrasonic and Reverse Iontophoresis Capture Device This description relates to an ultrasonic capture device (100) comprising at least: - an ultrasonic transducer circuit (104); - a capture surface (102) disposed on a face (101) of the ultrasonic capture device (100) and configured so that at least a part of a user's body is positioned on it during capture by the ultrasonic capture device (100); - a reverse iontophoresis circuit (108) comprising electrodes (110) disposed on said face (101) of the ultrasonic capture device (100) and configured to be in contact with said part of the user's body when it is positioned on the capture surface. Figure for the abbreviation: Fig. 2

Description

Title of the invention: Ultrasonic and reverse iontophoresis capture device. Technical field

[0001] This description relates generally to the field of devices based on the capture, reading and / or measurement of information by ultrasonic transduction, finding applications, for example, in the fields of biometric identification, medicine, or other consumer sectors. 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, facial shape, iris pattern, retinal pattern, etc. The various techniques for measuring one or another of these characteristics each have advantages and disadvantages according to different criteria, including: error rate (more or less significant), ease or difficulty of stealing the template with which the measurements are compared, possibility of detecting a forgery, proof or not of life, ease and comfort of use, size of the sensor required, energy consumption required, etc.

[0003] In the case of an ultrasonic transduction biometric identification device where the measurement of a biometric characteristic involves contact between the device and the user, it is sometimes advantageous to optimize the acoustic coupling between the part of the user's body on which the measurement is intended to be performed (corresponding, for example, to one or more of the user's fingers) and the device's capture surface with which this part of the user's body is intended to come into contact. This is particularly the case for identification devices measuring biometric characteristics present under the user's skin, for example, devices that perform vasculature recognition of the user's finger(s), i.e., that capture images of the blood vessels or microvessels of this or these fingers.Optimizing this acoustic coupling generally involves applying a lubricant, such as a water-based gel or hydrogel, to the capture surface of the device. The lubricant can be applied directly or via a container, such as a bottle or container, to the capture surface by the user. However, this user intervention to apply the lubricant to the capture surface is a drawback. For example, this application can be incomplete (uncontrolled quantity of lubricant, dispersion of the lubricant). lubricant off the capture surface, etc). Furthermore, 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 or 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 present at least some of the disadvantages 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 capture surface disposed on one face of the capture device ultrasound and configured so that at least one part of a user's body is positioned on it during capture by the ultrasonic capture device;

[0009] - a reverse iontophoresis circuit comprising electrodes arranged at the level of said face of the ultrasonic capture device and configured to be in contact with said part of the user's body when it is placed on the capture surface.

[0010] According to a particular embodiment, the electrodes of the reverse iontophoresis circuit are flexible and deformable.

[0011] According to a particular embodiment, the electrodes of the reverse iontophoresis circuit comprise at least a metallic ink and / or a transparent metallic oxide and / or a conductive polymer.

[0012] According to a particular embodiment, each of the electrodes has a thickness of less than 10 pm, and the ultrasonic transducer circuit is configured to emit ultrasound with a frequency greater than 1 MHz.

[0013] According to a particular embodiment, the electrodes are arranged in the capture surface.

[0014] According to a particular embodiment, the reverse iontophoresis circuit comprises several electrodes distributed around the capture surface.

[0015] According to a particular embodiment, the ultrasonic capture device is configured to apply to said part of the user's body at least one chemical compound promoting perspiration.

[0016] According to a particular embodiment, the reverse iontophoresis circuit includes an electrical energy source coupled to the electrodes.

[0017] According to a particular embodiment, the ultrasonic capture device further comprises a contact layer disposed on the ultrasonic transducer circuit and forming the capture surface.

[0018] According to a particular embodiment, the contact layer has a thickness greater than or equal to 500 pm, and / or the material of the contact layer has a Young's modulus between 1 and 200 kPa, and / or the contact layer comprises at least one elastomer and / or one gel.

[0019] According to a particular embodiment, the ultrasonic capture device further comprises at least one sensor configured to detect the presence of said part of the user's body near or on the capture surface and to control an activation of the reverse iontophoresis circuit when said part of the user's body is detected near or on the capture surface.

[0020] According to a particular embodiment, the ultrasound capture device is configured to perform an acquisition of at least one surface image of said user body part and an acquisition of volume information of said user body part, and the ultrasound capture device is configured to command an activation of the reverse iontophoresis circuit after the acquisition of the surface image and before the acquisition of the volume information.

[0021] According to a particular embodiment, the ultrasonic capture device corresponds to a biometric identification device configured to implement biometric identification from the part of the user's body intended to be placed on the capture surface. Brief description of the drawings

[0022] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0023] - Figures [Fig. 1] and [Fig. 2] schematically represent top and cross-sectional views of an ultrasonic capture device according to a particular embodiment. Description of the implementation methods

[0024] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0025] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, various elements (ultrasonic transducer circuit, control circuit, data processing circuit, etc.) of the device are not detailed. A person skilled in the art will be able to to implement these elements in detail based on the functional description given here.

[0026] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0027] 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", "superior", "inferior", 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.

[0028] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0029] Throughout this document, the term "vasculature" is used interchangeably to refer to blood vessels and / or micro-blood vessels, of the artery and / or vein type, and is used as a synonym for the term "microvasculature".

[0030] An ultrasonic capture device 100 according to a particular embodiment is described below in relation to figures 1 and 2 representing respectively a top view and a cross-sectional view of the device 100.

[0031] In the example described, the device 100 corresponds to a biometric identification device configured to perform biometric measurements of a part of the user's body. In the various embodiments described, this part of the user's body corresponds to one or more of the user's fingers. Alternatively, other parts of the user's body can be used to perform biometric identification by the device 100. Furthermore, in the various examples described here, the part of the user's body used to perform biometric identification corresponds to a single finger of the user.

[0032] The device 100 comprises, on a face 101 in the example shown in Figures 1 and 2, a capture surface 102 on which the finger of the user of the device 100 is intended to be placed during biometric identification. In the described embodiment, the face 101 corresponds to the upper face of the device 100.

[0033] The device 100 further includes an ultrasonic transducer circuit 104 configured to transmit and receive ultrasonic signals during measurements used, in the described embodiment, for the biometric identification of the user of the device 100. According to one embodiment, the circuit 104 can The circuit 104 comprises a plurality of ultrasonic transducers configured to perform the image acquisitions required for biometric identification. The ultrasonic transducers are, for example, arranged in a matrix or in another manner suitable for the captures to be performed. The number of ultrasonic transducers in 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, include CMUT (Capacitive Micromachined Ultrasonic Transducer) or PMUT (Piezoelectric Micromachined Ultrasonic Transducer) type transducers, or another type.

[0034] In the described embodiment, the device 100 can be configured to acquire at least one surface image of the user's finger placed on and in contact with the capture surface 102, i.e., to acquire 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 and in contact with the capture surface 102 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 circuit 104 that were reflected off the valleys and those that were reflected off the ridges can be exploited to reconstruct the image of the fingerprint of the user's finger present on the capture surface 102.

[0035] Furthermore, in a particular configuration, the device 100 can also be configured to acquire volume or depth information of the finger placed on and in contact with the capture surface 102 of the device 100. From this volume information, it is possible, for example, to determine, through processing, overall information about the finger's vasculature, such as a global volume image of the finger's vasculature. The finger's vasculature corresponds to the blood vessels and / or microvessels of the finger of the user of the device 100. In one particular example, the acquired volume information can correspond to volume or depth images of the finger placed on the capture surface 102.The overall volume information obtained can be deduced from several volume information captured successively at non-zero depths (dimension parallel to the Z axis visible on [Fig.1] and which is for example substantially perpendicular to the capture surface 102) of the finger present on the capture surface 102.

[0036] Alternatively, it is possible that the device 100 is configured to perform only one of the two types of acquisitions described above.

[0037] In the described embodiment, the device 100 further comprises a contact layer 106 disposed on the circuit 104 and forming the capture surface 102. In the example of [Fig. 1], a face of the contact layer 106 opposite the capture surface 102 is disposed against the circuit 104. Alternatively, it is possible that one or more other materials may be present between the circuit 104 and the contact layer 106.

[0038] In the described example, 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 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, or less than approximately 0.5 N). Thus, the layer 106 can deform so as to at least partially conform to the microtopography of the finger applying pressure to the layer 106.

[0039] Furthermore, the characteristics of the contact layer 106 can be such that they give it good acoustic properties 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 can be achieved 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 l7 7 with Z a and Z h corresponding respectively to the acoustic impedances of circuit 104 and the target.

[0040] According to one embodiment, the contact layer 106 may have a thickness (dimension parallel to the Z-axis shown in Figures 1 and 2) greater than or equal to 500 µm, or even greater than or equal to 2 mm. Furthermore, the material of the contact layer 106 may have a Young's modulus 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 A (for example, measured in accordance with ASTM D2240). In the described embodiment, the material of the contact layer 106 may comprise an elastomer and / or a gel. The gel may, for example, be encapsulated by a polymer film. In addition, the contact layer 106 may consist of a stack of several distinct layers of materials.

[0041] The device 100 further comprises a reverse iontophoresis circuit 108, enabling the triggering, or promotion, of transpiration, or sweating, The part of the user's body positioned on face 101 of device 100 during the capture operation, i.e., the user's finger in the example described. The circuit 108 includes, in particular, electrodes 110 positioned on face 101 of device 100 and on the capture surface 102, and configured to be in contact with said part of the user's body when it is positioned on the capture surface 102.

[0042] According to one embodiment, the electrodes 110 of the circuit 108 comprise at least one metallic ink, for example silver-based, and / or a transparent metal oxide such as indium tin oxide, and / or a conductive polymer such as PEDOT:PSS.

[0043] Alternatively, it is possible that the electrodes 110 comprise at least one metallic material that is not in the form of an ink, for example silver, silver chloride, stainless steel, or MXene (two-dimensional structure transition metal carbide, of formula Ti3C2Tx).

[0044] The electrodes 110 are advantageously made so that they are flexible and deformable, and so that they do not disturb or only very slightly disturb the acoustic coupling between the part of the user's body disposed on the capture surface 102 and the ultrasonic transducer circuit 104. The electrodes 110 can be flexible and deformable so as to conform at least partially to the part of the user's body applying pressure on the layer 106.

[0045] In a first configuration, the circuit 108 may comprise several electrodes 110 distributed around the capture surface 102. In the example of [Fig. 1], the circuit 108 comprises several groups (four in the example shown) of electrodes 110 distributed around the surface 102, each of these groups comprising a positive electrode and a negative electrode. The sign of each of the electrodes 110 is symbolically represented in [Fig. 1].

[0046] In a second configuration, the electrodes 110 can be arranged in the capture surface 102, and therefore in the path of the ultrasound emitted and received by the circuit 104. In order that the presence of the electrodes 110 does not disrupt the transmission of the ultrasound, either at emission or reception, each of the electrodes 110 can have a thickness of less than 10 pm, and the circuit 104 can be configured to emit ultrasound of a frequency greater than 1 MHz.

[0047] Regardless of the arrangement and distribution of the electrodes 110 on the face 101 of the device 100, these electrodes 110 are intended to be in contact with the part of the user's body subjected to the capture implemented, so that this part of the user's body is traversed by a weak electric current (for example, an electric current that may be direct and / or between 1 and 5 mA) flowing between at least two electrodes 110, one positive and the other negative, triggering or promoting perspiration through the skin through which this electric current passes.

[0048] In the described embodiment, the circuit 108 includes an electrical energy source 112 coupled to the electrodes 110 and enabling the generation of the electric current flowing between the electrodes 110.

[0049] Thus, the perspiration generated by the skin of the part of the user's body through which the current generated by the circuit 108 passes forms a lubricant that spreads by capillary action between the skin on the capture surface 102 and this capture surface 102. The bodily fluid generated by the perspiration (composed of sweat, and possibly lymph and / or interstitial fluid) improves the acoustic coupling between the part of the user's body on which the capture is performed and the capture surface 102 of the device 100. The device 100 thus allows the user to avoid having to apply lubricant to the capture surface 102 before placing said part of their body (their finger(s) in the example described) on the capture surface 102.

[0050] When the skin is subjected to the current generated by the circuit 108, the amount of body fluid generated can be on the order of 350 g / (m2.h), that is to say, an amount four to eight times greater than that naturally secreted by the skin.

[0051] In a particular configuration, the device 100 can be configured to apply at least one sweat-promoting chemical compound to the part of the body in contact with the capture surface 102. This compound may, for example, be present in a gel acting as a coupling layer and may be in the form of a pebble a few millimeters to a few centimeters thick. Such a chemical compound may, for example, contain at least one of the following molecules: acetylcholine, bethanechol, carbachol, methacholine, pilocarpine.

[0052] In a particular configuration, the device 100 includes at least one sensor 114 configured to detect the presence of said part of the user's body near or on the capture surface 102. When the sensor 114 detects this presence, the activation of the circuit 108 can be triggered to initiate the flow of current, and thus the perspiration process, when said part of the user's body comes into contact with the electrodes 110. By way of example, the sensor 114 can be configured to detect the force, contact, or proximity of the user's finger. For example, the sensor 114 can correspond to electrical sensing electrodes. According to other examples, the sensor 114 can be configured to detect capacitive coupling between the finger and the sensor 114.Alternatively, it is possible to implement a measurement of the pressure of the finger on the capture surface 102, or a measurement of the thermal properties of the capture surface 102, etc.

[0053] Alternatively, this detection of the presence of the user's body part near or on the capture surface 102 can be achieved 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 achieve this detection).

[0054] When the device 100 is configured to measure biometric features present on the surface of the user's skin, for example a capture of the user's finger's fingerprint, and other biometric features 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 command the activation of the circuit 108 when the device 100 performs the capture of 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 a bodily fluid.

[0055] In such a configuration, the dispensing of lubricant on the capture surface 102 during the capture of volume information allows that the entire contact surface between the capture surface 102 and the skin is well acoustically coupled, without the presence of air or any interface defect introducing significant differences in velocity or acoustic impedance, or strong attenuation.

[0056] The device 100 includes other elements which are not described in detail in this description, such as a control circuit for controlling the circuit 108, a data processing circuit, etc.

[0057] Device 100 can implement additional functions to those previously described, such as a contribution to the detection of living things from the information captured.

[0058] In all embodiments, the device 100 allows for the automatic dispensing of lubricant (corresponding to a bodily fluid from the user) onto the capture surface 102, without any user intervention related solely to this lubricant dispensing. Furthermore, the device 100 eliminates the need for the user to carry lubricant. Finally, the use of a bodily fluid from the user as a lubricant has the advantage of being constantly available, unlike a conventional lubricant applied to the capture surface 102.

[0059] In the various embodiments described above, the ultrasonic capture device 100 corresponds to a biometric identification device. Alternatively, these different embodiments can be applied to a device 100 performing ultrasonic capture that does not correspond to biometric identification, such as, for example, capture performed for medical purposes.

[0060] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variants could be combined, and other variants will appear to the person of the trade.

[0061] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Ultrasonic capture device (100) comprising at least: - an ultrasonic transducer circuit (104); - a capture surface (102) disposed on a face (101) of the ultrasonic capture device (100) and configured so that at least a part of a user's body is disposed on it during capture by the ultrasonic capture device (100); - a reverse iontophoresis circuit (108) comprising electrodes (110) disposed on said face (101) of the ultrasonic capture device (100) and configured to be in contact with said part of the user's body when it is disposed on the capture surface (102).

2. Ultrasonic capture device (100) according to claim 1, wherein the electrodes (110) of the reverse iontophoresis circuit (108) are flexible and deformable.

3. Ultrasonic capture device (100) according to any one of the preceding claims, wherein the electrodes (110) of the reverse iontophoresis circuit (108) comprise at least a metallic ink and / or a transparent metal oxide and / or a conductive polymer.

4. Ultrasonic capture device (100) according to any one of the preceding claims, wherein each of the electrodes (110) has a thickness of less than 10 pm, and wherein the ultrasonic transducer circuit (104) is configured to emit ultrasound of a frequency greater than 1 MHz.

5. Ultrasonic capture device (100) according to claim 4, wherein the electrodes (110) are arranged in the capture surface (102).

6. Ultrasonic capture device (100) according to any one of claims 1 to 4, wherein the reverse iontophoresis circuit (108) comprises several electrodes (110) distributed around the capture surface (102).

7. Ultrasonic capture device (100) according to any one of the preceding claims, configured to apply to said part of the user's body at least one sweat-promoting chemical compound.

8. Ultrasonic capture device (100) according to any one of the preceding claims, wherein the reverse iontophoresis circuit (108) comprises an electrical power source (112) coupled to the electrodes (110).

9. Ultrasonic capture device (100) according to any one of the preceding claims, further comprising a contact layer (106) disposed on the ultrasonic transducer circuit (104) and forming the capture surface (102).

10. Ultrasonic capture device (100) according to claim 9, 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 between 1 and 200 kPa, and / or wherein the contact layer (106) comprises at least one elastomer and / or a gel.

11. Ultrasonic capture device (100) according to any one of the preceding claims, further comprising at least one sensor (114) configured to detect the presence of said user body part near or on the capture surface (102) and to command an activation of the reverse iontophoresis circuit (108) when said user body part is detected near or on the capture surface (102).

12. Ultrasonic capture device (100) according to any one of the preceding claims, configured to perform an acquisition of at least one surface image of said user body part and an acquisition of volume information of said user body part, and wherein the ultrasonic capture device (100) is configured to command an activation of the reverse iontophoresis circuit (108) after the acquisition of the surface image and before the acquisition of the volume information.

13. Ultrasonic capture device (100) according to any one of the preceding claims and corresponding to a biometric identification device configured to implement biometric identification from the part of the user's body intended to be disposed of on the capture surface (102).

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