Optically tactile device and method for assessing the mechanical properties of a sample material

Abstract

To provide an optical palpation device for evaluating a mechanical property of a sample material.SOLUTION: The device includes: a body having a sensing portion; and a sensing layer positioned at the sensing portion of the body and having a sensing surface positioned for direct or indirect contact with a surface area of a sample material. The sensing layer is deformable and has a predetermined deformation-dependent optical property. The device further includes a light detector positioned to detect light transmitted through at least a portion of the sensing layer. The optical palpation device is arranged such that, when the sensing surface of the sensing layer is in direct or indirect contact with the surface area of the sample material and a pressure is applied through both the sensing layer and at least a portion of the surface area of the sample material, because of the predetermined deformation or pressure-dependent optical property of the sensing layer the mechanical property of the sample material is measurable by detecting the light that transmitted through at least a portion of the sensing layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to an apparatus and method for assessing the mechanical properties of a sample material using optical tactility, and more particularly, but not exclusively, to a digital camera-based optical tactile apparatus and method for characterizing the elasticity of a sample material. [Background technology]

[0002] Elastography techniques based on optical imaging, ultrasound imaging, and MRI are commonly used to measure deformation in sample materials such as biological tissues, as well as to assess the stiffness and other mechanical properties of the sample.

[0003] In recent years, optical coherence tomography (OCT)-based elastography has made great strides, providing information down to several millimeters into sample materials with a resolution of several micrometers. For example, the present applicant has developed an optical palpation (OP) technique, which is disclosed in PCT International Patent Application No. PCT / AU2016 / 000019. The disclosed OP technique uses a compliant sensing layer that is pressed against the surface of a biological sample and compressed, and measures the change in layer thickness induced by the compression based on the force between the sensing layer and the tissue using OCT. OCT-based optical palpation typically utilizes interferometry. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a further improvement. [Means for solving the problem]

[0005] According to a first aspect of the present invention there is provided an optically tactile apparatus for assessing mechanical properties of a sample material, the apparatus comprising: a body having a sensing portion; a sensing layer disposed in the sensing portion of the body, the sensing layer having a sensing surface disposed in direct or indirect contact with the surface area of ​​the sample material, the sensing layer being deformable and having defined deformation-dependent optical properties; a photodetector arranged to detect light transmitted through at least a portion of the sensing layer; The optical tactile device is constructed such that when pressure is applied through both the sensing layer and at least a portion of the surface area of ​​the sample material with the sensing surface of the sensing layer in direct or indirect contact with the surface area of ​​the sample material, the sensing layer deforms and, due to optical properties that depend on the defined deformation of the sensing layer, the mechanical properties of the sample material can be measured by detecting light transmitted through at least a portion of the sensing layer.

[0006] Embodiments of the present invention provide a simplified, cost-effective opto-tactile device. Furthermore, use of the opto-tactile device is simplified compared to OCT-based opto-tactile devices. The device may be relatively lightweight, handheld, and may be configured for wireless coupling to a computer or the like.

[0007] In one particular embodiment, the sensing layer is compressible and the deformation-dependent optical property is a compression-dependent optical property. The sensing layer may be compressible such that it undergoes minimal lateral extension when subjected to an axial load.

[0008] The deformation-dependent optical property of the sensing layer may be compression-dependent transmittance, polarization, light absorption or light scattering. Alternatively, the deformation-dependent optical property may relate to the wavelength range of light transmitted through at least a portion of the sensing layer, e.g. the light transmitted through at least a portion of the sensing layer has a deformation-dependent color.

[0009] In one example, the deformable sensing layer may comprise a silicone material and have air cavities dispersed throughout such that the sensing layer has a defined opacity.

[0010] The photodetector may be a charge-coupled device (CCD) or a camera with a CCD array.

[0011] The body may be elongate and may have a sensing portion at one end where the sensing layer is disposed.

[0012] The optical-tactile device may be a handheld device.

[0013] The optically tactile device may further comprise a light source for directing light into the sensing layer.

[0014] The light source and the light detector may be disposed within the body.

[0015] The optical device may further comprise a motion detector for detecting the position of the sensing layer or device relative to the sample material as the device is moved or scanned relative to the surface of the sample material.

[0016] The mechanical property may be elastic and the detected light may indicate a distribution of stress and / or deformation across the sensing layer in response to an applied pressure, the distribution of stress and / or deformation being related to the mechanical property of the sample material.

[0017] In one embodiment, assessing the mechanical properties of the sample material includes determining the strain of the sample material as a result of the applied pressure.

[0018] The optical tactile device may further comprise at least one displacement and force measuring device disposed on the sensing surface of the sensing layer for measuring force and the resulting displacement of an area of ​​the sensing surface. The displacement and force measuring device may comprise an indenter. In one embodiment, multiple indenters are incorporated into the sensing layer at the sensing surface and contact the sample material, allowing measurement of both the force exerted on the sample material and the distance the indenter is pressed into the tissue.

[0019] The sample material may be a biological tissue or material. Alternatively, the sample material may comprise another elastic or deformable material, such as a polymeric material that may have non-uniform hardness or flexibility.

[0020] The optically tactile device may further comprise a thin layer, such as a transparent sheath, for protecting the sample material from direct contact with the sensing layer when the sensing layer is in indirect contact with the surface area of ​​the sample material. In one embodiment, the sensing layer forms part of or is provided in the form of a sheath.

[0021] The light detector may include a camera, such as a stereo camera. The light detector may include a smartphone-type device, which may include detachable microlenses and / or a 3D printed platform for placing the sample material.

[0022] In one embodiment of the invention, the optical-tactile device is part of a robotic surgical device.

[0023] In another embodiment of the invention, some or all of the components of the optically tactile device are disposed on or within a balloon catheter, the balloon catheter being constructed such that, in use, the mechanical properties of a portion of a sample material in which the balloon catheter is disposed can be determined using the optically tactile device. The sensing layer may be disposed on the outside of and / or attached to the balloon of the balloon catheter.

[0024] At least some or all of the components of the optical-tactile device may be disposed on or within a needle, probe, or arthroscope having a window in which the sensing layer is disposed so that the mechanical properties of a sample material into which the needle, probe, or arthroscope is placed during use can be determined.

[0025] The optical-tactile device may include a glove, and the components of the optical-tactile device may be incorporated into the glove such that, when the glove is worn by a user, the portion of the glove comprising the components of the optical-tactile device may be moved over a material sample to enable optical-tactile measurements.

[0026] Additionally, the sensing layer may be provided in the form of a lens and an opto-tactile device constructed for placement on a patient's eye to determine variations in pressure and / or stiffness of the eye.

[0027] According to a second aspect of the present invention there is provided an optically tactile apparatus for assessing mechanical properties of a sample material, the apparatus comprising: a body having a sensing portion; a sensing layer disposed on the sensing portion of the body, the sensing layer having a sensing surface disposed in direct or indirect contact with a surface area of ​​the sample material, the sensing layer being deformable and having optically detectable markers or patterns; an optical system capable of providing information usable to determine movement of a marker or pattern relative to the optical system when the sensing layer is deformed, the information being provided in a plane orthogonal to the direction of light propagation; The optical tactile device is constructed such that when pressure is applied across both the sensing layer and at least a portion of the surface area of ​​the sample material, with the sensing surface of the sensing layer in direct or indirect contact with the surface area of ​​the sample material, the sensing layer deforms and measuring the change in position of the marker or pattern relative to the optical system can provide information about the mechanical properties of the sample material.

[0028] The detectable marker or pattern may be intrinsic to the sensing layer, or alternatively, the detectable marker or pattern may be an externally coated, recessed, or structure created in the sensing surface of the sensing layer by a light source.

[0029] In one embodiment, the optical system comprises at least two spaced apart photodetector components positioned to detect light reflected or transmitted from the marker or pattern. The light detected by each of the at least two detectors may be used to obtain information related to the depth distribution of the deformation across the sensing layer. Each photodetector may be a camera comprising a charge-coupled device (CCD) or a CCD array.

[0030] In an alternative embodiment, the optical system comprises an array of optical elements such as microlenses for detecting light transmitted through the sensing layer, the optical elements being arranged such that the depth position of the marker or pattern can be determined. The optical system may comprise a photodetector which may be provided in the form of a camera which may comprise a charge coupled device (CCD) or a CCD array.

[0031] The body may be elongate and may have a sensing portion at one end where the sensing layer is disposed.

[0032] The optical tactile device may further comprise a light source for directing light into the sensing layer. The light source and the light detector may be disposed within the body.

[0033] The optical-tactile device may be a handheld device.

[0034] The optical system includes a camera, such as a stereo camera. The optical system may include a smartphone-based device, which may include detachable microlenses and / or a 3D printed stage for placing the sample material.

[0035] The markers may include transparent particles. The markers may include fluorescent or photoluminescent particles.

[0036] An optical tactile device is constructed such that photographs and mechanical properties of the sample material can be acquired simultaneously.

[0037] The optical device may comprise a motion detector for detecting the position of the sensing layer or device relative to the sample material as the device is moved or scanned relative to the surface of the sample material.

[0038] The mechanical property may be elastic and the detected light may indicate a distribution of stress and / or deformation across the sensing layer in response to an applied pressure, the distribution of stress and / or deformation being related to the mechanical property of the sample material.

[0039] In one embodiment, assessing the mechanical properties of the sample material includes determining the strain of the sample material as a result of the applied pressure.

[0040] According to a third aspect of the present invention there is provided a system for assessing mechanical properties of a sample material, the system comprising: An optical tactile device according to the first or second aspect of the present invention; a processor coupled to the optical-tactile device and configured to receive a signal indicative of information related to the light detected by the light detector; The information can be used to obtain an indication of the mechanical properties of the sample material.

[0041] The system may further comprise a graphical interface in communication with the processor and facilitating the use of the information to form an image of the sensing layer, the image including features indicative of the distribution of stress and / or deformation across the sensing layer caused by pressure applied through the sensing layer and at least through the (underlying) sample material.

[0042] The processor may be provided in the form of a computer, such as a desktop computer, a mobile phone, any other mobile device, such as a tablet, or in any other suitable form.

[0043] The processor may be coupled to the opto-tactile device in a wired manner or wirelessly, such as using Wi-Fi or Bluetooth technology.

[0044] The processor may include a graphics processing unit (GPU) and may use GPU algorithms to speed up processing to obtain a real-time image of the sensing layer, as well as a real-time image including features indicative of the distribution of stress and / or deformation across the sensing layer caused by the applied pressure.

[0045] The processor may be further configured to provide augmented reality (AR) or virtual reality (VR), where each real-time image of the sensing layer is overlaid with a respective real-time image including features indicative of the distribution of stress and / or deformation across the sensing layer. Each overlaid image may be projected onto a screen or embedded within VR goggles, along with a corresponding quantitative value of the mechanical property of the sample material.

[0046] The processor may be configured to receive a signal from each of at least two spaced apart photodetectors, each signal indicative of information related to light detected by the at least two photodetectors. Each signal may be used to form an optical image of the sensing layer using a graphical interface, the optical image including features indicative of a depth distribution of deformation across the sensing layer. Further, the processor may be configured to control the photodetector, which may be an image detector, to take a series of images at a defined frequency when the device is stationary or when the device is moved or scanned across the sample material.

[0047] Furthermore, the processor may be configured to receive signals from a motion detector to detect (changes in) the position of the sensing layer or device relative to the sample material as the device is moved or scanned relative to the surface of the sample material, whereby a map or scan of the distribution of deformations in the sensing layer can be formed using the series of images and information from the motion detector as the device is moved or scanned across the sample material.

[0048] According to a fourth aspect of the present invention there is provided a method for assessing mechanical properties of a sample material, the method comprising: providing a sample material; Providing a system according to the third aspect; The above method is placing the sensing layer relative to the sample material such that the sensing surface is in direct or indirect contact with a surface area of ​​the sample material; applying pressure through both the sensing layer and at least a portion of the surface area of ​​the sample material; and detecting light transmitted or reflected from at least a portion of the sensing layer.

[0049] The processor of the system according to the third aspect of the invention may further be configured to receive a signal indicative of the position of the sensing layer or the opto-tactile device relative to the sample material.

[0050] In one embodiment, the method includes providing a graphical interface in communication with a processor to use the information to form an image of the sensing layer, the image including features indicative of a distribution of stress and / or deformation across the sensing layer caused by pressure applied through the sensing layer and through at least a portion of a surface area of ​​the underlying sample material.

[0051] The processor may be provided in the form of a computer, such as a desktop computer, or any other mobile device, such as a mobile phone or tablet.

[0052] The method may further comprise determining the strain of the sample material as a result of the applied pressure to assess the mechanical properties of the sample material.

[0053] The distortion of the sample material may be determined by analyzing the pixel distribution in the formed optical image using a microprocessor or GPU.

[0054] According to a further embodiment of the present invention, the method further comprises the steps of: providing a motion detector for detecting the position of the sensing layer or device relative to the sample material as the device is moved or scanned relative to the surface of the sample material; (i) applying pressure through both the sensing layer and at least a portion of each surface area of ​​the sample material such that the sensing layer is compressed; and (ii) moving the optical-tactile device across a plurality of surface areas of the sample material while either simultaneously detecting light transmitted through or reflected from at least a portion of the sensing layer for each of the plurality of surface areas of the sample material, or sequentially detecting light as the device moves across the sample material; Detecting movement or change in coordinates of the sensing layer or device relative to the sample material.

[0055] The method may further include using a processor and a graphical interface to combine the series of images according to the detected coordinate movements or changes to obtain a stress map showing the distribution of stress across the sensing layer in relation to multiple surface areas of the sample material.

[0056] In one embodiment, the method may include providing an optical tactile device comprising at least two photodetectors arranged to detect light transmitted or reflected through the same portion of the sensing layer to obtain information related to the depth distribution of deformation across the sensing layer.

[0057] The method may include forming a strain image showing the depth distribution of the deformation, integrating the strain image with a stress map showing the distribution of stress across the sensing layer, and displaying both the strain image and the stress map on an AR device or a VR device such as VR goggles.

[0058] In one particular embodiment, the optically tactile device comprises a camera and a motion detector for detecting the position or movement of the sensing layer or device relative to the sample material, and the method comprises: providing a motion detector for detecting the position of the sensing layer or device relative to the sample material when the device is moved or scanned relative to the surface of the sample material; the step of applying pressure through both the sensing layer and at least a portion of the surface area of ​​the sample material comprises applying varying pressures through both the sensing layer and at least a portion of the sample material, and comprises moving a portion of the optically tactile device comprising the sensing layer relative to the material sample to apply varying pressures; the step of detecting light transmitted or reflected from at least a portion of the sensing layer is performed using a camera while varying different pressures are applied such that images for a series of pressures are detected; a mechanical property such as stress of the sample material can be determined from a change in the optical property of the sensing layer detected using images recorded for a series of pressures; a distortion of the material sample can be determined from a determined movement of the probe relative to the material sample, the movement being determined using a provided motion detector; Thereby, the nonlinear mechanical properties of the material sample can be determined.

[0059] The present invention will be more fully understood from the following description of specific embodiments thereof, the description being given with reference to the accompanying drawings.

[0060] Notwithstanding other forms that may fall within the scope of the present disclosure set forth in the Summary of the Invention, specific embodiments will now be described by way of example only with reference to the accompanying drawings. [Brief explanation of the drawings]

[0061] [Figure 1] 1 is a diagram of an optical tactile device according to one embodiment of the present invention; [Figure 2a-2h] 10 is a photograph illustrating the effect of a given compression of the sensing layer on the transmission of light through the sensing layer, according to an embodiment of the present invention. [Figure 3(a)] 10 is a photograph of a sensing layer used to assess mechanical properties of a sample material according to a further embodiment of the present invention; [Figure 3(b)] 7(b) is a photograph showing the depth distribution of deformation using the sensing layer shown in FIG. 7(b) using an optical tactile system according to a further embodiment of the present invention; [Figure 4] 1 is a schematic representation of an optical system used to evaluate mechanical properties of a sample material according to a further embodiment of the present invention; [Figure 5] 10 is a schematic representation of an alternative optical system used to assess mechanical properties of a sample material according to a further embodiment of the present invention; [Figure 6] 1 is a flowchart of an optical tactile method for assessing mechanical properties of a sample material, according to one embodiment of the present invention. [Figure 7] 1 is a schematic representation of a robotic surgical device with an optical-tactile device according to one embodiment. [Figure 8] 1 is a schematic representation of a balloon catheter equipped with an optical tactile device according to one embodiment. [Figure 9] 5 is a schematic representation illustrating a method for assessing mechanical properties of a sample material using the optical-tactile device of FIG. 1 or FIG. 4 according to a further embodiment. [Figure 10] 1 is a schematic representation of an optical-tactile device incorporated into a glove, according to one embodiment. [Figure 11] 1 is a schematic representation of an optically tactile device incorporated into a contact lens system, according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0062] SUMMARY OF THE INVENTION Embodiments of the present invention relate to an apparatus and method for assessing the mechanical properties of a sample material using optical tactility.

[0063] Optical tactility is a technique that can be used to map the surface stress of a sample material, such as biological tissue or material, by applying a compressive load to a sensing layer placed against the sample material. It is known to have a deformable sensing layer that includes a transparent silicone material and is incompressible so that under the application of a compressive load, it compresses and deforms by stretching in a plane transverse to the applied load to maintain its volume. Thus, the thickness of the sensing layer varies depending on the local stiffness of the underlying material, and optical coherence tomography (OCT) is typically used to measure and image the thickness changes induced by compression in the sensing layer placed on the sample material. The OCT image encodes the stress distribution or stress map of the sensing layer, which is related to the surface stress of the sample material. OCT-based optical tactility typically requires back-and-forth scanning (or depth sectioning) of the entire thickness of the sensing layer to obtain information about the depth distribution of deformation and further determine the strain experienced by the sensing layer. The stress experienced by the sensing layer can then be determined based on the determined strain and the known stress-strain curve of the sensing layer material. The determined stress and strain can then be used to quantitatively determine the elasticity of the sample material.

[0064] The present invention proposes a simplified optical tactile technique that makes it possible to obtain an indication of the surface stress experienced by the sensing layer (and indicative of the stress at the surface of the sample material) without the need for OCT pre- and post-scanning, and subsequently to evaluate the mechanical properties of the sample material.

[0065] According to an embodiment of the present invention, an optical tactile device and method are based on a digital camera. The mechanical properties relate to the elasticity or stiffness of the sample material, which may be biological tissue. Therefore, the method and device may be particularly useful for medical applications such as cancer margin imaging, where information about tumor location and size may be obtained for cancer treatment, or scar assessment in dermatology. In the medical field, it is known that abnormalities, such as diseased tissue, can alter the elasticity of biological tissue. For example, cancerous tissue is typically "stiffer" than surrounding healthy soft tissue. Alternatively, the sample material may be a biological material, such as food material, in which case the application may be food quality monitoring. In another embodiment, the sample material may be any elastic or deformable material, such as a polymeric material, which may have non-uniform hardness or flexibility. For example, a non-medical application may be textile sensing, in which the sample material may consist of rubber or gel.

[0066] It will further be understood by those skilled in the art that other sample materials may be considered and other applications and other mechanical properties, such as viscoelasticity and even non-linear mechanical properties, may be evaluated.

[0067] In one particular embodiment, the proposed technology uses a deformable and compressible sensing layer, which has defined optical properties that change upon application of pressure or load to at least one surface portion of the sensing layer and upon subsequent compression of the sensing layer, i.e. the sensing layer comprises a material with defined optical properties that depend on compression.

[0068] The use of a compressible sensing layer is advantageous for the following reasons: when a load is applied to the surface of the compressible sensing layer, the sensing layer is compressed without stretching laterally, i.e., the sensing layer does not stretch in a plane transverse to the applied load, and the volume of the sensing layer is not conserved. As a result, friction and / or surface roughness that are likely to occur when using an incompressible sensing layer can be significantly reduced, and more abrupt changes in the thickness of the sensing layer can be observed and measured in response to different "stiffness" of the underlying sample material. Subsequently, the effective spatial resolution of the optical tactile technique can be improved, which may further enable improved precision with which mechanical properties can be determined.

[0069] Referring to FIG. 1 , an optical-tactile device 100 according to a specific embodiment of the present invention is a pen-shaped handheld device 100 comprising a body 102 having a sensing portion 104, a sensing layer 106 disposed on the sensing portion 104, and a photodetector 108 positioned to detect light transmitted through the sensing layer 106 during use. In this embodiment, the body 102 is elongated and includes the photodetector 108 in the form of a camera, such as a digital charge-coupled device (CCD) camera. The sensing layer 106 is compressible, has compression-dependent optical properties, and is preferably rigidly secured to the sensing portion 104 at an end 109 of the elongated body 102. The sensing portion 104 is preferably an imaging window secured to the end 109 of the elongated body 102 and easily replaceable if broken or damaged. The sensing layer 106 has a sensing surface 110 positioned in direct contact with a surface area 112 of a sample material 114. Alternatively, the sensing surface 110 may be in indirect contact with the sample material 114, and a thin layer (not shown) of latex or another plastic material, such as a conformable transparent surgical sheath, may be placed between the sensing surface 110 and the sample material 114, for example, to prevent contamination of the biological tissue and ensure sterility. The camera 108 is typically positioned so that the working distance between the camera 108 and the surface area 112 of the sample material 114 corresponds to approximately a few centimeters. The optical-tactile device 100 is constructed such that when pressure is applied across both the sensing layer 106 and at least a portion of the surface area 112 of the sample material 114, with the sensing surface 110 of the sensing layer 106 in contact with the surface area 112 of the sample material 114, the sensing layer 106 is compressed, and optical properties dependent on the defined compression of the sensing layer 106 affect light within the sensing layer 106, such that the light detected by the camera 108 is indicative of a mechanical property of the sample material 114.

[0070] In a particular embodiment of the present invention, the compression-dependent optical property of the sensing layer 106 is a compression-dependent transmittance, as shown in Figures 2a to 2h. The sensing layer 106 is configured to be opaque when no compression is applied and to become more transparent when pressure is applied, i.e., when pressure is applied across the sensing layer 106, allowing more light to be transmitted through the sensing layer 106.

[0071] Referring to FIGS. 2a through 2h, a diagram 200 of how loads applied at different pressure levels affect light within the sensing layer 106 is shown. Specifically, FIGS. 2a through 2d correspond to images showing a simulation of applying loads with increasing pressure across the sensing layer 106 using a finger. The sensing layer 106 is fixed to the glass plate 202, such as with glue, to prevent the sensing layer 106 from "sliding" or moving relative to the glass plate 202, and the application of the load essentially results in compression of the sensing layer 106 along its thickness and no lateral movement of the sensing layer 106. FIG. 2a corresponds to the application of the load with the lowest pressure, and FIG. 2d corresponds to the application of the load with the highest pressure. FIGS. 2e through 2h are images formed using a digital CCD camera and relate to FIGS. 2a through 2d, respectively. It can be seen that as the load is applied with increasing pressure, the sensing layer 106 becomes more transparent in the regions of the applied load, such as areas 204 and 206 in Figures 2g and 2h, i.e., where the finger applies pressure.

[0072] In a specific embodiment, the sensing layer 106 is made of a mixture of sugar and silicone and is manufactured according to a method that allows the sensing layer to achieve a specific opacity without any compression applied. Sugar is mixed with the silicone as the silicone cures, and the sugar is subsequently dissolved and removed with water, resulting in a sensing silicone layer 106 with air cavities dispersed throughout, giving the sensing layer 106 a sponge-like texture. The air-silicone interface within the sensing layer 106 causes light reflection, giving the sensing layer 106 an initial opaque appearance when no compressive load is applied. Figures 2a and 2e show examples of the opacity of the sensing layer 106 when very little pressure is applied to the sensing layer.

[0073] Application of a compressive load to the surface area of ​​the sensing layer 106 causes compression and closure of air cavities within the sensing layer 106, thereby allowing an increased amount of light to be transmitted through the sensing layer 106. By placing a digital camera near a surface of the sensing layer 106 that is not in contact with the surface of the sample material 114, i.e., near the surface of the sensing layer 106 opposite the sensing surface 110, the change in light detected by the digital camera becomes directly related to the stress in the surface area 112 of the sample material 114. The presence of air cavities within the sensing layer helps to provide a compressible property of the sensing layer, i.e., a sensing layer characterized by a relatively low Poisson's ratio, such that the tendency of the sensing layer to stretch in a direction transverse to the direction of compression is relatively minimized.

[0074] The sensing layer 106 may have any dimensions suitable for being secured to a given sensing portion of a body portion of an opto-tactile device according to embodiments of the present invention. In a particular embodiment of the pen-shaped opto-tactile device 100, it is envisioned that the sensing layer 106 is cylindrical in shape, with a diameter of approximately 10 mm and a height of approximately 1 mm. However, it will be understood that any other shape and / or dimensions are also envisioned.

[0075] The camera-based optical-tactile device 100 is wirelessly coupled, such as using Wi-Fi or Bluetooth, to a microprocessor 116 that communicates with a graphical interface 118, thereby forming a system 120 for assessing the mechanical properties of a sample material 114. The microprocessor 116 may be provided in the form of a computer, such as a desktop computer, or in the form of a mobile device, such as a tablet or mobile phone. In use, the microprocessor 116 is configured to receive electrical signals from the optical-tactile device 100, the signals being information related to the light detected by the CCD camera 108. The information may then be used by the microprocessor 116 and the graphical interface to convert into an image. The image may be of the type shown in Figures 2e-2h, showing the distribution of stress and deformation across the sensing layer 106 in relation to the surface area 112 of the sample material 114 as affected by an applied pressure.

[0076] Implementation of device 100 as a handheld, pen-shaped device 100 wirelessly connected to microprocessor 116 and graphical interface 118 allows for the provision of a compact opto-tactile device with enhanced usability. Handheld, pen-shaped opto-tactile device 100 can reach, for example, remote areas of a sample material, which is particularly advantageous in medical applications for reaching areas of biological tissue that are not easily accessible using conventional OCT-based opto-tactile systems or devices. Additionally, costs associated with opto-tactile devices defined by embodiments of the present invention are significantly lower than costs associated with conventional OCT-based opto-tactile devices.

[0077] However, it will be appreciated that the camera-based optical-tactile device 100 may alternatively be hardwired to a microprocessor 116 that communicates with a graphical interface 118 .

[0078] It will also be appreciated that alternative embodiments envision using sensing layers configured to have other optical properties that depend on compression, for example, that are transparent when no compression is applied and become increasingly hazy as pressure is applied. Furthermore, in other embodiments, the sensing layer may have defined compression-dependent polarization, light absorption, or light scattering properties.

[0079] In an alternative embodiment, it is also envisaged to have a sensing layer that is deformable but not compressible and has optical properties that depend on a defined deformation, in which case the sensing layer comprises a material that changes colour when pressure is applied, and in use the colour change can be detected by the digital camera 108 and used to form an image showing the distribution of stress and deformation across the sensing layer 106 related to the stress in the surface area 112 of the sample material 114.

[0080] To assess the elasticity of the sample material 114 in the surface area 112, the strain across the sensing layer 106 as a result of applying a load must be determined, either directly or indirectly, by measuring the change in thickness of the sensing layer 106 as a result of the applied load.

[0081] The strain can be determined indirectly using the formed image. In this embodiment, the compression-dependent optical property of the sensing layer 106 is calibrated so that the change in light intensity detected by the photodetector 108 (in embodiments where the compression-dependent optical property is compression-dependent light transmittance) can be related to the value of the strain. As a result, the change in light detected by the photodetector 108 can be used as a measure of the strain experienced by the sensing layer 106.

[0082] Alternatively, the strain and elasticity of the sample material 114 at the surface area 112 may be directly quantitatively assessed using an indenter or an array of indenters placed on the sensing surface 110 of the sensing layer 106 in contact with the surface area 112 of the sample material 114. Small indenters make it possible to measure the depth of displacement of the sensing surface 110 along the thickness of the sensing layer 106 when pressure is applied, which is related to the displacement of the surface area 112 of the sample material 114 in a direction transverse to the applied load.

[0083] The strain ε experienced by the sensing layer 106 as a result of the applied pressure can generally be determined as follows:

number

[0084] As a measure of the elasticity of the sample material 114 in the area of ​​the surface area 112, the Young's modulus E of the sample material 114 can typically be quantitatively determined according to the following equation (1):

number

[0085] In an embodiment using an indenter placed on the sensing surface 110 of the sensing layer 106 in contact with the surface area 112 of the sample material 114, a quantitative indicator of the elasticity of the sample material 114 can be determined more specifically according to the following equation (2):

number

number

[0086] Additionally, a light source (not shown) may be provided within the body 102 to direct light into the sensing layer, and a camera 108 within the body 102 is configured to capture light transmitted by the sensing layer 106 in response to receiving light from the light source.

[0087] According to another particular embodiment of the present invention, the sensing layer 106 may be deformable or movable and incompressible. The sensing layer 106 comprises optically detectable markers or patterns printed on the sensing surface 110 of the sensing layer 106. Alternatively, the markers or patterns may be in the form of a coating or depressions on the sensing surface 110 of the sensing layer 106, or may be created by a light source projecting a given light structure or pattern onto the sample material.

[0088] Referring to FIG. 3( a ), a photograph 300 of the sensing layer 106 with a speckle pattern 302 is shown. In this embodiment, the optical-tactile device 100 comprises an optical system capable of providing information that can be used to determine the movement of a marker or pattern, such as a speckle pattern 302, relative to the optical system when the sensing layer 106 deforms in response to an applied load.

[0089] The optical system in this embodiment comprises two spaced apart photodetectors, such as the two spaced apart photodetectors 108. Referring to Figure 4, a stereoscopic optical system 400 of the optical-tactile device 100 according to this particular embodiment of the invention is shown. The optical system 400 comprises two photodetectors 402, 404 provided in the form of cameras spaced apart by a distance d and positioned to detect light reflected or transmitted from the speckle pattern 302 in a plane perpendicular to the direction of light propagation. The optical system 400 creates a stereoscopic vision to mimic the binocular vision of two eyes, which further makes it possible, in use, to obtain information about the depth of deformation features distributed across the sensing layer 106 when pressure is applied.

[0090] In this embodiment, a microprocessor similar to microprocessor 116 receives information from two cameras 402, 404, and two respective images of surface areas 406, 408 of the sensing surface 110 of the sensing layer 106 can be formed in association with the cameras 402, 404, respectively. The speckle pattern 302 is constructed such that it can be relatively well recognized and mutually aligned by the two cameras 402, 404, and correlation between the two images can be obtained. Because the features within the speckle pattern are unique everywhere, minimal mutual alignment errors can be achieved by a simple correlation algorithm.

[0091] As can be seen in Fig. 4, in stereoscopic vision, an element located at a relatively large distance D from the cameras 402, 404 will be focused on the two corresponding photodetectors with a small coordinate difference or small displacement, as shown in Fig. 4 by the "uL-uR" line segment relating to point 410, which is at the furthest distance from the surface areas 406, 408. In contrast, an element located at a relatively small distance D from the cameras 402, 404 will be focused on the two corresponding photodetectors with a large coordinate difference or large displacement, as shown by the "uL-uR" line segment relating to point 412. By mutually registering the two images obtained from the cameras 402, 404, respectively, it is possible to obtain a displacement map, which is a direct qualitative indication of the depth distribution of the elements of deformation within the sensing layer 106. Figure 3(b) shows an image 303 illustrating the depth distribution of deformation obtained using the sensing layer 106 of Figure 3(a) and the optical system of Figure 4. The depth distribution of deformation is qualitatively represented in the form of a color scale, with the red end 304 of the color scale 306 indicating that the corresponding portion of the sensing layer 106 experiences a more significant deformation as a result of the applied load, compared to the blue end 308 of the color scale 306 indicating that the corresponding portion of the sensing layer 106 experiences a less significant deformation as a result of the applied load.

[0092] Analysis of the pixel distribution of the image 300 using digital image processing algorithms makes it possible to obtain quantitative depth information of the elements of deformation within the sensing layer 106 related to the strain experienced by the sample material 114 in the surface area 112.

[0093] The stereoscope with the cameras 402, 404 may be made from some off-the-shelf components, such as, for example, a USB endoscope camera. 3D printing technology may be used to customize the form or shape of the stereoscope, such as a 3D printed case to support the two cameras 402, 404.

[0094] While the present embodiment shown in FIG. 4 has been described with respect to two cameras 402, 404, it will be appreciated that three or more cameras may be used, which may enable more accurate information to be obtained for constraining the depth distribution of deformation across the sensing layer 106.

[0095] Additionally, in one embodiment, it is envisioned that the optical detector of the optical-tactile device, such as optical detector 108 of optical-tactile device 100, is provided in the form of a camera of a smartphone device or other smartphone-based device. In embodiments of optical-tactile device 100 comprising optical system 400, it is also envisioned that optical system 400 comprises a smartphone-based device. In those embodiments, the smartphone-based device may further comprise a removable microlens and / or a 3D printed platform for placing the sample material.

[0096] Referring to FIG. 5, an alternative optical system 500 is shown that can be used to obtain a direct indication of the depth distribution of deformation elements (deformable or movable, incompressible, and comprising a speckle pattern) in the sensing layer 106. The optical system 500 comprises an array of microlenses 502 for detecting light transmitted through the sensing layer, the microlenses 502 being positioned such that the depth position d of the speckle pattern elements can be determined. The optical system 500 allows bright-field imaging of the deformable, incompressible sensing layer 106 to be performed, where an image can be formed that shows the depth distribution of the deformation elements in the sensing layer 106. The optical system 500 further comprises a photodetector 504 and a main lens 506 positioned in a sensing portion similar to the sensing portion 104 of the optical tactile device 100. The microlenses 502 are positioned at a distance d from the main lens 506. in and from the photodetector 604 to the position f x 5, the lateral location and angle of each light ray 510 transmitted through the sensing layer 106 can be detected by the photodetector 504 using the microlenses 502. Similar to the telescope-type optical system 400, elements located at different distances d, d', d'' from the photodetector 504 will result in different pixel distributions D, D', D'' of the elements, and depth information can be obtained by analyzing the pixel distributions in the formed image, for example using digital image processing. For the embodiment of the stereoscopic optical system 400, the speckle pattern of the sensing layer can be relatively well recognized by the microlenses 502 and the photodetector 504 and aligned with each other.

[0097] Referring to FIG. 6, a flow chart of a camera-based optical tactile method 600 for assessing mechanical properties of a sample material is shown, according to certain embodiments of the present invention.

[0098] Similar to OCT-based optical tactile techniques, the present method allows obtaining information about the elasticity of the sample material 114. However, the present method is significantly simplified as it can be implemented using compact systems and devices and can be implemented wirelessly, which may be advantageous for medical applications, particularly on biological tissues, as it may allow reaching areas of the sample material that are relatively difficult to access otherwise.

[0099] In step 602, a sample material is provided, such as sample material 114. In one particular embodiment, sample material 114 is biological tissue. However, as noted above, sample material 114 may alternatively be any elastic or deformable material, such as, for example, a biological material or a polymeric material that may have non-uniform hardness or flexibility.

[0100] In step 604, an optical-tactile device, such as optical-tactile device 100 or an optical-tactile device with optical system 400 or 500, for assessing the mechanical properties of sample material 114 is provided.

[0101] In step 606, the sensing layer 106 is positioned relative to the sample material 114 such that the sensing surface 110 is in direct contact with the surface area 112. It will be appreciated that the sensing layer 106 may alternatively be positioned such that the sensing surface 110 is in indirect contact with the surface area 112, for example, using a thin layer of latex or another plastic material (not shown), such as a surgical sheath, positioned between the sensing surface 110 and the sample material 114 to prevent contamination of the biological tissue and ensure sterility.

[0102] In step 608 , pressure is applied across the sensing layer 106 and across at least a portion of the surface area 112 of the sample material 114 .

[0103] In step 610, the photodetector 108 of the optical tactile device 100, or the photodetectors 402 and 404 of the optical system 400, or the photodetector 504 of the optical system 500, detects light transmitted or reflected from at least a portion of the sensing layer 106. The detected light is indicative of the mechanical properties of the sample material. In particular, the detected light is used to determine the distribution of stress and / or deformation across the sensing layer 106 in response to an applied pressure.

[0104] A microprocessor 116 in communication with the graphical interface 118 is further provided in the form of a computer, such as a desktop computer, or in the form of any mobile device, such as a tablet or mobile phone. The microprocessor 116 is coupled to the optical-tactile device 100 and configured to receive electrical signals from the device 100, the signals representing information related to the light detected by the photodetector 108. The received signals and corresponding information are then used by the graphical interface 118 to form an image of the sensing layer 106. The image includes features indicative of a distribution of stress and / or deformation across the sensing layer 106 caused by pressure applied through the sensing layer 106 and through at least a portion of the underlying surface area 112 of the sample material 114. The distribution of stress and / or deformation is therefore related to the surface area 112 of the sample material 114 affected by the applied pressure. The microprocessor 116 can then be further used to perform an analysis of the pixel distribution across the optical image to quantify the strain of the sample material 114 at the surface area 112.

[0105] The optical resolution of the measurements typically depends on how the deformation-dependent optical properties of the sensing layer 106 affect the light transmitted through the sensing layer 106, and more specifically on the dynamic range of the deformation-dependent optical properties. Furthermore, the optical resolution of the measurements depends on the sensitivity of the camera 108 to detect changes in the light transmitted through the sensing layer 106 or on the sensitivity of the cameras 402, 404 or the photodetector 504 to align the features of the speckle pattern with each other.

[0106] The optical resolution provided by conventional OCT-based optical tactile devices typically ranges between 100 μm and 200 μm. According to embodiments of the present invention, the optical resolution of the camera-based optical tactile device can vary between 10 μm and 200 μm depending on the resolution of the optical system used and the physical deformation of the sensing layer 106. In particular, according to embodiments in which the sensing layer 106 is compressible, i.e., the lateral movement of the sensing layer 106 is constrained, an optical resolution of the camera-based optical tactile device in the range between 10 μm and 20 μm may be achieved. Furthermore, the elasticity of the sample material 114 in the area of ​​the surface area 112 can be evaluated at a depth of up to 3 mm below the surface of the sample material 114. In comparison, one known OCT-based optical tactile technique allows the elasticity of the sample material to be evaluated at a depth of 1 to 2 mm below the surface. Thus, the camera-based optical tactile device 100 and method 600 according to an embodiment of the present invention provides the advantage of an improved optical tactile technique with comparable optical resolution and improved field of view within the sample material 114 compared to currently known optical tactile techniques.

[0107] Further, the method 600 may include providing a motion detector (not shown) for detecting the position of the sensing layer 106 or the device 100 relative to the sample material 114 as the device 100 is moved or scanned relative to the surface of the sample material 114. Thus, x and y coordinates corresponding to the sensing layer 106 or the device 100 across the surface of the sample material 114 are obtained. The method 600 may then include moving the optical-tactile device 100 across multiple surface areas 112 of the sample material 114 in a plane parallel to the surface of the sample material 114, and performing steps 608 and 610 simultaneously for each of the multiple surface areas 112 across the sample material 114. Thus, the microprocessor 116 and the graphical interface 118 may be used to form a series of images of the sensing layer 106 as the device 100 is moved across the sample material 114, so that changes in the distribution of deformation across the sensing layer 106 can be tracked and observed as the device 100 is moved or scanned across the sample material 114. Alternatively, an image of the sensing layer 106 may be acquired for each of the multiple surface areas 112, and the microprocessor 116 and graphical interface 118 may then be used to combine the respective images according to the (x,y) coordinates of the sensing layer or device across the sample material to form a single image specific to the distribution of deformation across the sensing layer for an area of ​​the sample material 114 that includes the multiple surface areas 112 under consideration. By detecting movement or changes in the coordinates of the sensing layer 106 relative to the sample material 114 in a plane parallel to the surface of the sample material 114 and acquiring images for each of the multiple surface areas 112, the position of the sensing layer 106 or device 100 relative to the sample material 114 can be tracked, and a global representation of the deformation and / or stress distribution across the various scanned areas 112 of the sample material 114 can be obtained and observed in a single image. A stress and / or strain map of the sample material 114 is thus obtained. The pixel distribution of each of the multiple optical images can then be analyzed by digital image processing to obtain a quantitative measure of strain.The stress value can then be determined from the known stress-strain curve of the material comprising the sensing layer 106, and the elasticity of the sample material 114 can then be quantitatively determined using equation (1) defined above.

[0108] The processor 116 may further include a GPU and may use GPU algorithms to speed up processing so that real-time images of the sensing layer 106 and real-time images including features indicative of the distribution of stress and / or deformation across the sensing layer caused by the applied pressure can be obtained.

[0109] It is further envisioned that method 600 may be implemented using an AR device or a VR device such as VR goggles, whereby respective real-time images including features indicative of the distribution of stress and / or deformation across the sensing layer 106 may be overlaid with respective real-time images of the sensing layer 106 and projected onto a screen or embedded within the VR goggles such that the sense of touch may be enhanced.

[0110] Furthermore, a camera-based optical-tactile device such as device 100, or an optical-tactile device with optical system 400 or 500, may be incorporated into a surgical robot or video endoscope, with the respective superimposed images projected onto a screen, thus providing tactile sensations during a surgical procedure.

[0111] 7 shows an example of a robotic surgical device 700 incorporating a camera-based optical-tactile device 702, which may correspond to optical-tactile device 100 or an optical-tactile device comprising optical systems 400 or 500. Optical-tactile device 702 acts as one of the surgical arms, enabling robotic surgical device 700 to view the surgical site using a digital camera and measure mechanical properties of sample material (not shown) using sensing layer 106 and method 600. Furthermore, information regarding the measured mechanical properties of the sample material may be used to guide an operator of robotic surgical device 700 through tactile sensing and / or imaging of the surgical site, i.e., the sample material being inspected. The robotic surgical device 700 may further include other surgical arms or instruments 704 .

[0112] FIG. 8 shows an embodiment in which some components of a camera-based optical-tactile device, which may correspond to the optical-tactile device 100 or an optical system 400 or 500, are disposed on or within a balloon catheter 800. The balloon catheter 800 includes a balloon 802 and a catheter 804. As shown in FIG. 8, the camera 806 of the optical-tactile device (or a stereoscopic camera 806, 806' for an optical-tactile device with optical system 400 or 500) is disposed within the balloon 802, and the sensing layer 808 of the optical-tactile device is disposed outside the balloon 802 and attached to its outer surface. To measure the mechanical properties of a sample material (not shown), the balloon 802 is first deflated, and the catheter 804 is inserted into a target site of the sample material, such as an airway or a vessel if the sample material is biological tissue. When the catheter reaches the target site, the balloon is inflated so that the sensing layer 808 is compressed against the sample material. One or more cameras of the optical tactile device can then be used to measure the mechanical properties of the sample material, such as elasticity, using method 600. The optical tactile device and balloon catheter may further be constructed to acquire photographs of the target site using one or more cameras simultaneously while measuring the mechanical properties. In certain instances where the sample material is biological tissue, the catheter may further incorporate other surgical instruments, such as blades or fluid ejectors, that work in conjunction with the optical tactile device. Once the measurements and procedures are complete, balloon 802 may be deflated again and the catheter may be withdrawn from the measurement site.

[0113] Alternatively, it is envisioned that at least some or all of the components of the optical-tactile device (such as optical-tactile device 100 or one comprising optical system 400 or 500) may be disposed on or within a needle, probe or arthroscope, it being further understood that the needle, probe or arthroscope has a window in which the sensing layer of the optical-tactile device is disposed such that the mechanical properties of a sample material into which the needle, probe or arthroscope is placed during use can be determined.

[0114] FIG. 9 illustrates a further application in which a camera-based optical-tactile device according to an embodiment of the present disclosure is used to determine the nonlinear mechanical properties of a sample material. FIG. 9 illustrates an embodiment in which the method 600 is further used to measure the nonlinear mechanical properties of a sample material 900 by applying varying pressures, as shown at 902, 902′, and 902″. The optical-tactile device 904, in this particular embodiment, consists of a stereoscope with two cameras 906, 906′, an imaging window 908, and a silicone sensing layer 910. It will be understood that the optical-tactile device 904 may alternatively comprise a single camera 906. The optical-tactile device 904 is used to continuously compress the sensing layer 910 and a portion 912 of the sample material 900, and the optical-tactile device 904 with the sensing layer 910 is moved relative to the sample material 900 to apply varying pressures. One or more cameras 906 may record continuous video of the compressed layer, e.g., at a frame rate of 24 frames per second or more, while varying pressures are applied and as the optical-tactile device 904 moves relative to the sample material 900. A stress map of the sample material 900 can be obtained from the recorded video of the sensing layer 910, and strain of the sample material 900 can be calculated from the rate of movement of the optical-tactile device 904 relative to the sample material 900, which can be measured using a gyroscope embedded in the optical-tactile device 904. By determining the stress and strain of the sample material 900, the elasticity of the sample material 900 can be estimated. In particular, because successive stress maps can be obtained at different strain points, nonlinear mechanical properties of the sample material, such as the nonlinear tangent modulus of the sample material, can be measured.

[0115] FIG. 10 illustrates a further embodiment in which a camera-based optical-tactile device provided in accordance with embodiments of the present disclosure, such as optical-tactile device 100 or an optical system 400 or 500, is incorporated into a surgical glove 1000. The camera-based optical-tactile device 1002 is attached to a portion of the glove 1000, which is configured such that, during use, a surgical operator dons the glove and then proceeds to measure stress in a target sample material, such as a target biological tissue, and evaluate the target sample material's mechanical properties by performing steps 606 through 610 of method 600. Photographs of the target sample material or tissue can also be obtained. Additionally, a gloved surgical operator may move the portion of the glove 1000 including the optical-tactile device 1002 over the sample material to obtain stress measurements and evaluate the sample material's mechanical properties across a defined area of ​​the material. Once measurements are complete, the camera-based optical-tactile device 1002 can be removed from the surgical glove 1000 so that the surgical operator can perform other surgical tasks. The compatibility of the camera-based optical tactile device with surgical gloves can provide the advantage that the time required to obtain measurements of the mechanical properties of a sample material, such as tissue in this particular example, can be significantly reduced.

[0116] Although this embodiment has been described in the context of surgical gloves, it will be appreciated that the optical-tactile device may be incorporated into other types of gloves and may be used in connection with other applications where the sample material is not necessarily limited to biological tissue.

[0117] 11 illustrates another embodiment in which a camera-based opto-tactile device provided in accordance with an embodiment of the present disclosure, such as opto-tactile device 100 or an opto-tactile device comprising optical system 400 or 500, is incorporated into a contact lens system 1100. In this embodiment, the sensing layer of the opto-tactile device is provided in the form of a lens 1102 constructed for placement on the surface of a patient's eye 1104. As the pressure in the eye changes, the thickness of the sensing layer 1104 changes accordingly. The camera 1106 of the opto-tactile device is constructed such that changes in the thickness of the sensing layer 1104 are measurable, allowing variations in intraocular pressure and / or eye stiffness to be determined.

[0118] In the following claims and the foregoing description of the invention, unless the context requires otherwise by express language or necessary implication, the word "comprise" or variations thereof such as "comprises" or "comprising" are used in an inclusive sense, i.e., to specify the presence of stated features but not to exclude the presence or addition of still other features in various embodiments of the invention.

Claims

1. 1. An optical tactile device for assessing mechanical properties of a sample material, comprising: a body having a sensing portion; a sensing layer disposed on the sensing portion of the body, the sensing layer having a sensing surface disposed in direct or indirect contact with a surface area of ​​the sample material, the sensing layer being deformable and having optically detectable markers or patterns; an optical system capable of providing information usable to determine movement of the marker or pattern relative to the optical system when the sensing layer is deformed, the information being provided in a plane orthogonal to the direction of light propagation; the optical system includes a stereo camera; the marker or pattern is intrinsic to the sensing layer; the optical-tactile device is constructed such that when pressure is applied across both the sensing layer and at least a portion of the surface area of ​​the sample material, with the sensing surface of the sensing layer in direct or indirect contact with the surface area of ​​the sample material, the sensing layer deforms and measuring the change in position of the marker or pattern relative to the optical system can provide information about the mechanical properties of the sample material, an optical tactile device, wherein the mechanical property is elastic, and wherein the light detected using the stereoscopic camera indicates a distribution of stress and / or deformation across the sensing layer in response to the applied pressure, the distribution of stress and / or deformation being related to the mechanical property of the sample material.

2. the marker or pattern is illuminated by a light source that projects light; the marker or pattern features are unique anywhere on the sensing surface; the stereoscopic camera comprising at least two spaced apart photodetector elements positioned to detect light reflected or transmitted from the marker or pattern; The information provided by the optical system is forming images of the surface area of ​​the sample material such that each image is associated with a respective photodetector element of the stereoscopic camera; aligning the markers or patterns so as to obtain correlation between the images; The optical-tactile device according to claim 1, which is used for:

3. 3. The optical tactile device of claim 1 or 2, wherein the optical system comprises an array of optical elements such as microlenses for detecting light transmitted through the sensing layer, the optical elements being positioned such that the depth position of the marker or pattern can be determined.

4. The opto-tactile device of claim 1 , wherein the opto-tactile device is a handheld device.

5. The optical-tactile device of claim 1 , wherein the optical system comprises a smartphone-based device.

6. The optical-tactile device of claim 5 , wherein the smartphone-based device comprises a detachable microlens and / or a 3D printed stage for placing the sample material.

7. The optical-tactile device of claim 1 , wherein the marker comprises at least one of a transparent particle, a fluorescent particle, or a photoluminescent particle.

8. 8. The optical-tactile device of claim 1, wherein the device is constructed such that photographs and mechanical properties of the sample material can be acquired simultaneously.

9. 9. The optically tactile device of claim 1, comprising a motion detector for detecting the position or motion of the sensing layer or the device relative to the sample material when the device is moved or scanned relative to the surface of the sample material.

10. 1. A system for evaluating mechanical properties of a sample material, comprising: An optical tactile device according to any one of claims 1 to 9; a processor coupled to the optical-tactile device and configured to receive signals indicative of information related to light detected by the optical system; The information is usable to obtain an indication of the mechanical property of the sample material.

11. the processor is coupled to the opto-tactile device in a wired or wireless manner, such as using Wi-Fi or Bluetooth technology; The processor: aligning the images of the marker or pattern acquired using the stereoscopic camera so as to obtain correlation between different images; using the results of the alignment to determine a displacement map that provides a qualitative indication of the depth distribution of elements of deformation within the sensing layer; The system of claim 10 configured to execute:

Images