Quant-haptical device for quantitative measurement

Abstract

A device includes a holder. The holder has a body defining a longitudinal axis extending through a distal end and a proximal end. A rod has a stem with a distal tip and a proximal head. The stem is in slidable engagement with the holder. The rod is slidable relative to the holder toward the distal end to enable the distal tip to extend beyond the distal end of the holder. A pressure sensing unit is disposed at the proximal end of the holder. An intermediate component is elastically deformable between a first component end and a second component end. A pocket is defined between a membrane and the second component end. The pocket may include a pocket of air. The resistive sensor is disposed on the membrane and configured to output a signal responsive to a membrane deformation.

Description

QUANT-HAPTICAL DEVICE FOR QUANTITATIVE MEASUREMENTRELATED APPLICATION

[0001] This application claims the benefit of priority to the Singapore application no. 10202303395P filed November 30, 2023, which is incorporated herein by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to devices and systems for testing or characterizing materials and, more particularly, to a device and system configured to provide a quantitative determination of the softness of a material.BACKGROUND

[0003] The human haptic perception of softness provides useful sensory feedback for a variety of applications. Despite technological advancements, achieving humanoid capabilities in softness sensing remains challenging because of the complexity of the human sense of touch and the fragility of soft materials.SUMMARY

[0004] In one aspect, the present application discloses a device. The device includes a holder; a rod; and a pressure sensing unit. The holder has a body with a distal end and a proximal end. The body defines a longitudinal axis extending through the distal end and the proximal end. The rod has a stem with a distal tip and a proximal head. The stem is in slidable engagement with the holder. The rod is slidable relative to the holder toward the distal end to enable the distal tip to extend beyond the distal end of the holder. The pressure sensing unit is disposed at the proximal end of the holder. The pressure sensing unit includes an intermediate component, a membrane, a pocket and a resistive sensor. The intermediate component has a first component end and a second component end. The intermediate component is elastically deformable between the first component end and the second component end. The membrane is coupled to a frame. The pocket is defined between the membrane and the second component end, and thepocket includes a pocket of air. The resistive sensor is disposed on the membrane, in which the resistive sensor is configured to output a signal responsive to a membrane deformation of the membrane.

[0005] The rod may be slidable toward the proximal end of the holder to push against the first component end of the intermediate component.

[0006] The pocket of air may be compressible by the intermediate component in response to a component deformation of the intermediate component.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1A is a side view of a schematic diagram of a device according to various embodiments of the present disclosure;

[0008] FIG. 1 B is a simplified schematic diagram of the device of FIG. 1 A;

[0009] FIG. 2A shows an exploded perspective view of an electronic system of the device;

[0010] FIG. 2B shows an exploded view of the rest of the sensor assembly;

[0011] FIG. 3A and FIG. 3B schematically illustrate alternative embodiments of an intermediate component;

[0012] FIG. 4A is a schematic diagram of the intermediate component in a default state;

[0013] FIG. 4B is a schematic diagram of the intermediate component in a deformed state;

[0014] FIG. 5 shows schematic diagrams of the Wheatstone bridge circuit;

[0015] FIG. 6A to FIG. 6C show the device in different states;

[0016] FIG. 7 shows a locking unit according to one embodiment of the device;

[0017] FIG. 8 shows the locking unit according to another embodiment of the device;

[0018] FIG. 9A and FIG. 9B illustrate parameter analyses of the locking unit of FIG. 7;

[0019] FIG. 10A and FIG. 10B compare the experimental analysis results of a flexible pressure sensing unit against the results obtained using a tensile machine;

[0020] FIG. 11 A is a schematic diagram showing the rod in relation to the holder;

[0021] FIG. 11 B illustrates the rod and a proximal head of the rod in a default state and in a displaced state;

[0022] FIG. 12A shows images and corresponding profile drawings of various embodiments of the distal tip of the rod;

[0023] FIG. 12B shows plots of the mechanical indentation according to theory and finite element analysis, and a comparison with the experimental results;

[0024] FIG. 13 shows the experimental, finite element analysis, and theoretical results of mechanical indentation for different embodiments of the distal tip; and

[0025] FIG. 14 compares the readings obtainable using the proposed palpation device to measure the softness of various materials.DETAILED DESCRIPTION

[0026] The following detailed description is made with reference to the accompanying drawings, showing details and embodiments of the present disclosure for the purposes of illustration. Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments, even if not explicitly described in these other embodiments. Additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0027] The term “and / or” includes any and all combinations of one or more of the associated listed items.

[0028] The terms "about" and "approximately" as applied to a stated numeric value encompasses the exact value and a reasonable variance and the terms “generally” and “substantially” are to be understood in a comparable manner, unless otherwise specified. For example, in the context of various embodiments, the term “about” or “approximately” as applied to a stated numeric value will be generally understood by one skilled in the art to encompass the exact value and a reasonable variance as generally understood in the relevant technical field, e.g., within 10% of the specified value.

[0029] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0030] As used herein, the singular “a”, “an”, and “the" may be construed as including the plural “one or more" unless apparent from the context to be otherwise.

[0031] Terms such as “first” and “second”, etc., are used in the description and claims only for the sake of brevity and clarity, and do not necessarily imply a priority or order, unless required by the context.

[0032] Device

[0033] FIG. 1A schematically illustrates a portable quant-haptical device (also referred to as “device” for the sake of brevity) according to embodiments of the present disclosure, useful for quantitative measurements of softness. The device 100 may include a holder 120 that has a generally elongated shape. For the sake of brevity, reference may be made to a longitudinal axis 190 or a longitudinally extending direction, in which the longitudinal axis 190 is defined by the holder 120 or by a body of the holder 120. The holder 120 may be described as having two ends, e.g., a distal end 1 10 and a proximal end 130. The distal end 110 and the proximal end 130 may be defined generally as opposite terminal parts of the holder 120. The holder 120 (or the body of the holder 120) may extend between the distal end 110 and the proximal end 130 along the longitudinal axis 190. The body of the holder 120 defines a passage 125 (e.g., FIG. 11 A), extending generally along the longitudinal axis 190 from the distal end 110 of the holder 120 to the proximal end 130 of the holder 120.

[0034] The device 100 includes a rod 121 disposed in the passage 125. As shown, the passage 125 leads to an opening at the distal end 110 of the holder 120. The rod 121 is displaceable along the longitudinal axis 190, relative to the holder 120 (or relative to the passage 125). The rod 121 may be described as being in slidable engagement with the holder 120.

[0035] The rod 121 includes a stem 123 with a distal tip 122 and a proximal head 124. The distal tip 122 of the rod 121 may extend beyond the distal end 1 10 of the holder 120. For example, the rod 121 may be slidable relative to the holder 120 toward the distal end 110 to enable the distal tip 122 to extend beyond the distalend 110 of the holder 120.

[0036] The distal tip 122 of the rod 121 may be retracted toward the proximal end 130 of the holder 120, e.g., the distal tip 122 may be described as retractable relative to the holder 120 resulting in a decrease in the length of the rod 121 protruding beyond the distal end of the holder 120.

[0037] According to various embodiments of the present disclosure, the device 100 includes a sensor assembly 102 that is disposed at the proximal end 130 of the holder 120. The sensor assembly 102 may include a limiting mechanism 140 and a pressure sensing unit 160. The sensor assembly 102 may further include an electronic system 180 operably connected to the pressure sensing unit 160. To avoid obfuscation, various embodiments of the device 100 may be alternatively represented by a simplified block diagram, such as one shown in FIG. 1 B. As illustrated, the limiting mechanism 140 and the pressure sensing unit 160 may be disposed at the proximal end 130 of the holder 120. The electronic system 180 may be disposed at the proximal end 130 of the holder 120.

[0038] The device 100 may be configured to have an overall substantially elongate profile. The holder 120 may be shaped and sized to enable the holder 120 to be held and manipulated by a user using one hand, e.g., between a thumb and one or more fingers of the same hand. The distal end 110 can be sized and shaped with a smaller diameter and / or a smaller footprint than the device 100 at the proximal end 130. The user may hold the device 100 at the holder 120 relatively near to the distal end 110, enabling small movements and a more precise location of the device 100. Other than the distal tip 122 of the rod 121 and the distal end 110 of the holder 120, the rest of the device 100 (or the sensor assembly 102) is disposed at or near the proximal end 130 of the holder 120, spaced apart from the distal end 110. This configuration enables the user to have a relatively unblocked view of the target location of the distal end 110 (or the distal tip 122) of the device 100.

[0039] The electronic system 180 may be variously configured and FIG. 2A shows an exploded perspective view of one example of the electronic system 180 merely for illustrative purposes and not to be limiting. For example, the electronic system 180 may include a printed circuit board (PCB) 181 that is disposed on a firstmajor surface 157 of a cap 156. For example, the electronic system 180 may include a microcontroller chip unit (MCU) 183 in place of the PCB 181 . For example, the electronic system 180 may include the MCU 183 mounted to the PCB 181. For example, the electronic system 180 may include one or more other chips 182 in place of or in addition to the MCU 183.

[0040] Coupling the electronic system 180 to the first major surface 157 of the cap 156 provides a relatively large degree of flexibility in the configuration of the electronic system 180 and in the choice of electronic components. For example, the electronic components selected for use in the electronic system 180 do not necessarily have to be the most miniature electronic components. For example, slightly bulkier but more cost-efficient electronic components may be used without affecting the single-handed usability of the device 100. For example, the electronic system 180 may be variously configured with more “layers” of electronic components added on to the first major surface 157 without significantly increasing the footprint of the device 100.

[0041] The electronic system 180 may further include a Bluetooth module and / or communications module. The electronic system 180 may include one or more circuit elements, e.g., including but not limited to operational amplifiers, resistors, capacitors, wiring, battery, etc. The electronic system 180 may include one or more memory devices as part of the MCU 183, other chips 182, and / or the PCB 181.

[0042] The electronic system 180 may be configured to acquire a signal from the pressure sensing unit 160. The MCU 183 and / or a processor forming a part of the electronic system 180 may be configured to determine a softness measurement based on the signal. In some examples, the electronic system 180 is configured to preprocess the signal. In some examples, the electronic system 180 is configured to compute a computed result, e.g., a quantitative measurement indicative of a degree of softness (e.g., quantitative softness value). In some examples, the electronic system 180 is configured to acquire the signal and save data associated with the signal in a memory. In some examples, the electronic system 180 is configured to communicate the computed result to a user interface (e.g., a display) data associated with the signal in a memory. In some embodiments, the electronic system 180 is configured to transmit the signal to a remote computing unit, whichin turn is configured to compute a quantitative measurement of softness, e.g., a quantitative softness value or a softness measurement in quantitative terms.

[0043] FIG. 2B shows an exploded view of the rest of the sensor assembly 102, including the pressure sensing unit 160 disposed at the proximal end 130 of the holder 120. The pressure sensing unit 160 may be configured as a hybrid device, e.g., integrating two or more sub-systems operable by different working principles.

[0044] The cap 156 includes one or more support extensions 155 that are coupled to a second flange 151 via one or more fasteners 152. The support extensions 155 enable the cap 156 to be spaced apart from the second flange 151 by a fixed spacing.

[0045] The pressure sensing unit 160 may include a push column 165. A first end 162 of the push column 165 may be coupled with an elastic member 170. A second end 166 of the push column 166 may be in an abutment with a second major surface 159 of the cap 156.

[0046] An intermediate component 161 is disposed between the cap 156 and a protective cover 154. The protective cover 154 is disposed at the proximal head of the rod 121. In some examples, the protective cover 154 is integrally formed as the proximal head of the rod 121. In some examples, the protective cover 154 is assembled over the proximal head of the rod 121 . The protective cover 154 may be dimensioned and shaped to complement the intermediate component 161. For example, in some embodiments, the protective cover 154 has a greater diameter than the stem 123 of the rod 121 . The proximal head 124 may directly or indirectly push against or be in abutment with the intermediate component 161 . For example, the proximal head 124 may directly push against a protective cover 154 which in turn can be pushed against a first component end 167 of the intermediate component 161 .

[0047] In use, the distal end 110 of the holder 120 may be brought to contact the target surface to be tested. The abutment of the distal tip 122 of the rod 121 against the target surface may result in the rod 121 sliding relative to the holder 120. The distal tip retracts relative to the distal end 110 of the holder 120 and, correspondingly, the proximal head of the rod 121 extends further relative to the proximal end 130 of the holder 120. The proximal head pushes against the firstcomponent end 167 of the intermediate component 161 , e.g., via the protective cover.

[0048] With the spacing between cap 156 and the second flange 151 being fixed, the longitudinal displacement of the protective cover 154 toward the cap 156 will result in the pressure sensing unit 160 responsively generating a signal that can be picked up by the electronic system 180.

[0049] FIG. 3A and FIG. 3B schematically illustrate various embodiments of the intermediate component 161. The intermediate component 161 includes a frame 163. The frame 163 supports a membrane 164 between the push column 165 and the elastic member 170. The push column 165 extends longitudinally from one end of the frame 163. An elastic member 170 is disposed at an opposing end of the frame 163. The intermediate component 161 includes a membrane 164 supported by a frame 163. A push column 165 extends longitudinally from the frame 163 to abut against the second major surface 159 of the cap 156. The frame 163 provides a support to the perimeter or edge of the membrane 164 such that the membrane (e.g., in a default state 202 as shown in FIG. 4A) is transversely disposed relative to the longitudinal axis 190. When the elastic member 170 is pushed by the proximal head 124, the elastic member 170 will absorb some of the forces. At the same time, the elastic member 170 will compress a pocket 200 (e.g., pocket of air or other gaseous matter) between the elastic member 170 and the membrane 164. In response, the membrane 164 may deform (e.g., a deformed state 204 as shown in FIG. 4B).

[0050] Referring again to FIG. 3A, in some embodiments, the elastic member 170 includes a compression spring 171. Referring to FIG. 3B, in some embodiments, the elastic member 170 includes an elastically deformable foam 172. The elastic member 170 may include one or more elastic materials, rubber, and / or resiliently elastic elements, for example. Examples of the elastic member 170 may include (but are not limited to) helical springs, leaf springs, etc.

[0051] Displacement of the rod 121 along the longitudinal axis 190 does not result in a deformation or displacement of the membrane 164 by a similar or the same amount (displacement / distance) along the longitudinal axis 190. Displacement of the rod 121 , e.g., displacement of the proximal head 124, ismitigated by at least two intermediate buffers. For example, some of the kinetic energy from the displacement of the rod 121 / proximal head 124 may be absorbed by the elastic member 170. For example, some of the kinetic energy from the displacement of the rod 121 (or the proximal head 124) may be further absorbed by the compressible air or gaseous matter in the pocket 200.

[0052] In some embodiments, as illustrated in FIG. 4B and FIG. 4B, the membrane 164 may be supported by the frame 163 of the intermediate component 161 , longitudinally spaced apart from the elastic component 170. The pocket 200 is defined between the membrane 164 and the elastic component 170. The pocket 200 may be configured to hold a compressible mass of gaseous matter so that the height of the pocket 200 or the volume of the pocket 200 can be varied according to the amount of force exerted by the push column 165 on the pocket 200.

[0053] FIG. 4A and FIG. 4B illustrate an embodiment where the pocket 200 may be filled with a certain volume of air or other gaseous matter. The pocket 200 may be disposed adjacent and in physical contact with the elastic member 170 via a second component end 168. The membrane 164 may form one surface of the pocket 200, with the membrane 164 being spaced apart from the elastic member 170.

[0054] As illustrated in FIG. 4A, a Wheatstone bridge circuit (also referred to as the Wheatstone bridge 190) may be disposed on the membrane 164, with wires 194 connecting the Wheatstone bridge 190 to electronic system 180. FIG. 4A shows the intermediate component 161 before a mechanical indentation is made on a target surface by the distal tip 122 of the rod 121. The membrane 164 in a relatively flat shape, substantially transversely disposed across the frame 163. Correspondingly, the plurality of resistors 169 forming the Wheatstone bridge 190 are laid out on a relatively levelled plane. FIG. 4B shows the intermediate component 161 during a mechanical indentation event (e.g., the device 100 is used to test a target surface). The membrane 164 deforms in response to forces applied to the push column 165 as buffered by the elastic member 170 as well as the pocket 200. The respective resistance of the plurality of resistors 169 are correspondingly changed and a signal can be obtained from the Wheatstone bridge 190.

[0055] FIG. 5 schematically illustrates the Wheatstone bridge circuit, whichincludes four piezoresistive elements. During mechanical indentation, The Wheatstone bridge 190 is configured to correspondingly vary the resistance across the respective piezoresistive elements in response to a deformation of the membrane 164.

[0056] For example, if the elastic member 170 is compressed with a relatively large deformation, the force will be transmitted through the elastic member 170 to act on the pocket 200 of air. The pocket 200 of air will undergo a comparatively smaller deformation. The pressure in the pocket 200 will further deform the membrane 164. Responsive to the membrane 164 being deformed, the Wheatstone bridge disposed on the membrane 164 may be deformed, producing a change in the resistance of the strain gauges of the Wheatstone bridge circuit. The resistance change of the strain gauges on the membrane 164 corresponds to the pressure sensed by the pressure sensing unit 160.

[0057] In other embodiments, circuit variations such as the voltage divider circuit, the operational amplifier (Op-Amp) based circuit, the differential amplifier circuit and the oscillator-based circuit among others may also be used as an alternative to the Wheatstone bridge 190. As used herein, the term “resistive sensor” is used in a generic sense to refer to other types of sensors which can output a signal in response to a change in resistance.

[0058] Referring again to FIG. 2B, the device 100 includes a limiting mechanism 140 that operates in cooperation with the pressure sensing unit 160. The limiting mechanism 140 may be disposed at the proximal end 130 of the holder 120 between the pressure sensing unit 160 and the holder 120. The comparatively bulky parts of the device 100 may all be located at the proximal end 130 of the holder 120, leaving the rest of the device 100, e.g., the holder 120, to define a relatively compact and slim profile that can be held and manipulated by a user singlehandedly.

[0059] The limiting mechanism 140 may include a first flange 141 and the second flange 151 . The first flange 141 is fixed at the proximal end 130 of the holder 120. The second flange 151 is fixed to the cap 156. The first flange 141 and the second flange 151 may be spaced apart from one another along the longitudinal axis 190. The first flange 141 and the second flange 151 may be coupled to one another by bolts 142 and a plurality of resiliently compressible elements 143, e.g., to provide adegree of resilient elasticity in the separation between the first flange 141 and the second flange 151. The bolts 142 may be fixed with respective nuts 145. FIG. 6A, FIG. 6B, and FIG. 6C illustrate the resiliency variable gap between the first flange141 and the second flange 151. Taking reference to the first flange 141 , the bolt142 and nut 145 configuration enable the second flange 151 to slide along the bolts parallel to the longitudinal axis 190. This in turn limits the displacement of the rod 121 relative to the holder 120.

[0060] FIG. 6A illustrates a first state 212 where the one or more support extensions 155 extend longitudinally through the second flange 151 to abut against the first flange 141 , defining a minimum longitudinal displacement position of the cap 156 relative to the second flange 151 . The minimum longitudinal displacement position is a feature that allows for an adequate depth-of-penetration range between the distal tip 122 and a sample during mechanical indentation. The first flange 141 serves as a catch to prevent over-penetration of the distal tip 122 which may damage the sample.

[0061] FIG. 6B illustrates a second state 214, e.g., a fully extended state, where the one or more support extensions 155 may hook against the second flange 151 to define a maximum longitudinal displacement position of the cap 156 relative to the second flange 151 while ensuring that the cap 156 cannot completely disengage from the second flange 151 .

[0062] FIG. 6C shows a third state 216, e.g., a pre-lock state, the locking unit 144 has yet to be wedged against the hole defined in the first flange 141 .

[0063] As shown in FIG. 7, the limiting mechanism 140 may further include a locking unit 144. The locking unit 144 may be in the form of a partial ‘sleeve’ disposed about the rod 121 that extends into and beyond the holder 120. The locking unit 144 may have an increasingly larger diameter along the longitudinal direction along a longitudinally disposed length of the locking unit 144, extending from the first flange 141 to the second flange 151. The first flange 141 may define a hole 146 that is sized to partially receive the smaller end of the locking unit 144. For example, the locking unit 144 may have a tapering profile with a narrower distal end that is slidable relative to the hole 146 and a broader proximal end that cannot fit through the hole 146. The proximal end of the locking unit 144 may be fixedlycoupled with the second flange 151. If the cap 156 is pushed towards the distal end with too large a force, the locking unit 144 will be wedged or jammed against the hole 146 defined in the first flange 141 .

[0064] The device 100 includes three spring-loaded bolts 142 and one locking unit 144. The three spring-loaded bolts 142 may be distributed in radial symmetry about the longitudinal axis. The plurality of spring-loaded bolts 142 are distributed equidistant from one another on the first flange 141 / the second flange 151 to provide uniform resilient forces in response to the contact force experienced during a mechanical indentation. The locking unit 144 may be a partial sleeve disposed about the rod 121. The locking unit 144 and the rod 121 may extend longitudinally through the holder 120. The locking unit 144 may be a part of the limiting mechanism 140 that prevents the rod 121 from excessively displacing relative to the holder 120 by having the locking unit 144 jamming or being wedged against a corresponding hole 146 in the first flange 141.

[0065] In some other embodiments, as illustrated in FIG. 8, the limiting mechanism 140 may include a plurality of locking units 144 and correspondingly a plurality of the holes 146. The plurality of locking units 144 (and correspondingly the plurality of holes 146) may be distributed in radial symmetry about the longitudinal axis 190, on the first flange 141 and the second flange 151 , respectively.

[0066] The device 100 may include a plurality of spring-loaded bolts 142 and plurality of locking units 144. In this example, each of the three locking units 144 is partially wrapped by a sleeve. The three locking units 144 have equidistance intervals between one another to provide uniform support to fix the device 100, e.g., the locking units 144 are distributed in a regular pattern relative to the first flange 141 and / or the longitudinal axis 190.

[0067] The partial tapered ‘sleeve’, also known as a wedge-shaped cantilever beam, has its bending stiffness primarily determined by the dimensions of the tapered structure and the width at the root. FIG. 9A illustrates the various geometrical parameters present. The geometrical parameters include radius: n , r2, ra and r4 and height: hi and h2. r2 and ra are the key parameters in determining the bending stiffness for the tapered structure. A comprehensive mechanical analysis was conducted, and FIG. 9B shows that the larger the radii r2 and rs, the strongerthe bending stiffness of the structure. When r2 and rs satisfy a certain linear relation, their variations no longer affect the bending stiffness of the structure. Notably, when the two radii satisfy a certain linear relationship, their variations no longer affect the bending stiffness of the structure.

[0068] Experiments & Applications

[0069] Additionally, an analysis of the mechanical characteristics of the pressure sensing unit 160 was carried out. FIG. 10A presents the results of 200 cycles of performance testing of the pressure sensing unit 160 and indicates an excellent agreement with the force magnitude and trend obtained from the standard tensile machine (FIG. 10B).

[0070] Referring to FIG. 11 A, the device 100 further includes a rod 121 in slidable engagement with the holder 120. For example, the holder 120 may define a hollow passage 125 and permit the rod 121 to be slidable in the passage 125, relative to the holder 120. The rod 121 includes a distal tip 122, a stem 123, and the proximal head 124. The rod 121 is slidable to have the distal tip 122 extend beyond the distal end 110 of the holder 120. The rod 121 is disposed in and extends through the passage 125. The proximal head 124 may be of a resilient material that provides feedback in the longitudinal and transverse directions in respond to external forces such as in an event of a mechanical indentation.

[0071] The distal tip 122 and the proximal head 124 can reduce the compressive stability of the rod 121 . As schematically illustrated in FIG. 11 B, a buckling instability can be further emphasised when the contact force is transferred from the distal tip 122 to the pressure sensing unit 160 which is itself relatively flexible or deformable. The presence of the locking unit 144 ensures that the rod 121 is secured in place during operation. A corresponding distal tip 122 of the rod 121 may be any one of various shapes and geometry, for example, including but not limited to conical, hemispherical, cylindrical shapes, etc.

[0072] FIG. 12A shows three tip prototypes of varying shapes including a cone, a sphere (hemisphere) and a cylinder. A mechanical analysis of the different tip shapes was conducted based on the Hertz model. For the spherical (hemispherical) tip, FIG. 12B depicts that the Hertz theory results exhibit good agreement between both finite element analysis and theoretical findings. During the indentation process,the material deformation remains relatively uniform, minimising the risk of causing damage to the object. Under the same hardness / softness conditions, the required force for indentation by the circular tip falls between that of the cylindrical and conical tips.

[0073] As shown in FIG. 13, the cylindrical indenter requires the highest force, while the conical indenter requires the least. Furthermore, the conical tip can be considered equivalent to the cylindrical tip with an infinitely small top surface area. Based on the classical Hertz model for cylindrical and conical indentation, an empirical formula was established to predict the force distribution during indentation by different gradient tips. The finite element results show good agreement with experimental and theoretical findings.

[0074] FIG. 14 illustrates three functional tests conducted using a prototype of device 100. Three different softness scenarios, in decreasing softness, were utilised: (i) an open palm, (ii) the back of the hand when making a fist; and (iii) an acrylic sheet. From this functional test, the prototype of the device 100 demonstrated that it can distinguish between samples with relatively large softness differences (e.g., open palm versus an acrylic sheet). The prototype of the device 100 was also experimentally verified to be capable of distinguishing between different regions of the same object (e.g., an open palm versus the back of a fisted hand).

[0075] One useful application for the device 100 is to monitor and assess patients with scleroderma. Scleroderma, also known as systemic sclerosis, is a rare autoimmune disease characterised by the hardening and tightening of the skin and connective tissues. It falls under the category of rheumatic diseases and can affect internal organs, blood vessels and the digestive tract. The name “scleroderma” is derived from Greek words meaning “hard” (sclero) and “skin” (derma). One of the main symptoms is the thickening and hardening of the skin, especially on the hands and face. Therefore, quantitative palpation, or the measurement of the softness of tissues through touch, can be a valuable component is assessing and monitoring patients with scleroderma.

[0076] In accordance with one protocol, skin softness measurements were characterised in healthy individuals using the proposed device 100. The measurements included assessments of softness at different skin sites for the sameindividual and / or measurements of the same skin site across different individuals. The skin softness was tested for patients with scleroderma using the device 100. The overall skin hardness was categorised based on the existing modified Rodnan skin score to enable early screening of the scleroderma disease. Owing to the ability of the proposed device 100 to collect quantitative softness measurements, libraries of quantitative data could be collected and leveraged upon to provide a digital or data-based diagnostic approach. The existing modified Rodnan skin score could then be refined to offer a more accurate screening for scleroderma.

[0077] The proposed device 100 enables quantitative softness measurements to be carried out without risking injury to the target surface. This is particularly useful for determining the skin softness in patients who are already suffering from skin conditions. At the same time, the device integrates mechanical-based safeguards which does not depend on a battery-powered sensor to prevent the application of excessive forces on the target surface, i.e., the safeguards remain in place regardless of the state of battery. Advantageously, the structure ingeniously integrates an anti-buckling function with the safeguard features, while enabling almost instantaneous and automatic determination of the softness of the target surface in quantitative values.

[0078] The present application discloses various embodiments of a device having a holder, a rod, and a pressure sensing unit. The holder has a body with a distal end and a proximal end, and the body defines a longitudinal axis extending through the distal end and the proximal end. The rod has a stem with a distal tip and a proximal head, the stem is in slidable engagement with the holder. The rod is slidable relative to the holder toward the distal end to enable the distal tip to extend beyond the distal end of the holder. The pressure sensing unit is disposed at the proximal end of the holder. The pressure sensing unit includes an intermediate component, a membrane, a pocket, and a resistive sensor. The intermediate component has a first component end and a second component end. The intermediate component is elastically deformable between the first component end and the second component end. The membrane is coupled to a frame. The pocket is defined between the membrane and the second component end, and the pocket includes a pocket of air. The resistive sensor is disposed on the membrane,in which the resistive sensor is configured to output a signal responsive to a membrane deformation of the membrane.

[0079] The device may be one in which the rod is slidable toward the proximal end of the holder to push against the first component end of the intermediate component.

[0080] The device may be one in which the pocket of air is compressible by the intermediate component in response to a component deformation of the intermediate component.

[0081] The device may further include a first flange, a second flange, and a cap. The first flange is fixedly coupled to the holder. The second flange is fixedly coupled to the rod. The cap is fixedly coupled to the support, in which the first flange is variably spaced apart from the second flange, and the cap is spaced apart from the second flange along the longitudinal axis by a fixed cap-second flange spacing

[0082] The device may be one in which the cap includes a plurality of legs extending parallel to the longitudinal axis, each of the plurality of legs being coupled to the second flange.

[0083] The device may further include a plurality of fasteners, in which each of the plurality of fasteners includes a hooked end. The hooked end is configured to engage a respective one of the plurality of legs against the second flange.

[0084] The device may further include a sleeve. The sleeve is fixedly coupled to the second flange and configured to define a minimum spacing between the second flange and the proximal end of the holder, the minimum spacing being defined along the longitudinal axis.

[0085] The device may be one in which the holder defines a passage, the passage extending from the distal end to the proximal end.

[0086] The device may be one in which the rod is disposed in the passage, and in which the sleeve is disposed about a part of the stem extending beyond the proximal end of the holder.

[0087] The sleeve may include a wedge element. The wedge element may be wedgeable in the passage to define the minimum spacing.

[0088] The device may further include a plurality of resiliency compressible elements, the plurality of resiliency compressible elements being disposed betweenthe second flange and the proximal end of the holder. The plurality of resiliency compressible elements may be biased toward increasing a spacing between the second flange and the proximal end of the holder, the spacing being defined along the longitudinal axis.

[0089] The device may further include an electronic system. The electronic system may be disposed on the cap, in which the electronic system may be configured to acquire the signal from the resistive sensor and determine a softness measurement.

[0090] The device may include one in which the intermediate component includes a spring.

[0091] The device may include one in which the intermediate component includes an elastic intermediate component.

[0092] The device may be one in which the distal tip is configured with or may include a hemispherical tip.

[0093] The device may be one in which the distal tip is configured with or may include a flat tip.

[0094] The device may be one in which the distal tip is configured with or may include a conical tip.

[0095] The device may be one in which the resistive sensor includes a Wheatstone bridge circuit.

[0096] All examples described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding and are not intended to be limiting or exhaustive. Modifications may be made by one of ordinary skill in the art without departing from the scope of the claimed invention.

Claims

CLAIMS1. A device comprising: a holder, the holder having a body with a distal end and a proximal end, the body defining a longitudinal axis extending through the distal end and the proximal end; a rod, the rod having a stem with a distal tip and a proximal head, the stem being in slidable engagement with the holder, the rod being slidable relative to the holder toward the distal end to enable the distal tip to extend beyond the distal end of the holder; and a pressure sensing unit, the pressure sensing unit being disposed at the proximal end of the holder, the pressure sensing unit including: an intermediate component, the intermediate component having a first component end and a second component end, the intermediate component being elastically deformable between the first component end and the second component end; a membrane, the membrane being coupled to a frame; a pocket defined between the membrane and the second component end, the pocket including a pocket of air; and a resistive sensor, the resistive sensor being disposed on the membrane, wherein the resistive sensor is configured to output a signal responsive to a membrane deformation of the membrane.

2. The device as recited in claim 1 , wherein the rod is slidable toward the proximal end of the holder to push against the first component end of the intermediate component.

3. The device as recited in claim 2, wherein the pocket of air is compressible by the intermediate component in response to a component deformation of the intermediate component.

4. The device as recited in claim 3, further comprising: a first flange, the first flange being fixedly coupled to the holder; a second flange, the second flange being fixedly coupled to the rod; and a cap, the cap being fixedly coupled to the support, wherein the first flange is variably spaced apart from the second flange, and the cap is spaced apart from the second flange along the longitudinal axis by a fixed cap- second flange spacing.

5. The device as recited in claim 4, wherein the cap comprises a plurality of legs extending parallel to the longitudinal axis, each of the plurality of legs being coupled to the second flange.

6. The device as recited in claim 5, further comprising a plurality of fasteners, wherein each of the plurality of fasteners comprises a hooked end, the hooked end being configured to engage a respective one of the plurality of legs against the second flange.

7. The device as recited in any one of claims 4 to 6, further comprising a sleeve, the sleeve being fixedly coupled to the second flange and configured to define a minimum spacing between the second flange and the proximal end of the holder, the minimum spacing being defined along the longitudinal axis.

8. The device as recited in claim 7, wherein the holder defines a passage, the passage extending from the distal end to the proximal end.

9. The device as recited in claim 8, wherein the rod is disposed in the passage, and wherein the sleeve is disposed about a part of the stem extending beyond the proximal end of the holder.

10. The device as recited in claim 9, wherein the sleeve comprises a wedge element, the wedge element being wedgeable in the passage to define the minimum spacing.11 . The device as recited in any one of claims 4 to 10, further comprising a plurality of resiliently compressible elements, the plurality of resiliency compressible elements being disposed between the second flange and the proximal end of the holder, the plurality of resiliently compressible elements being biased toward increasing a spacing between the second flange and the proximal end of the holder, the spacing being defined along the longitudinal axis.

12. The device as recited in any one of claims 4 to 11 , further comprising an electronic system, the electronic system being disposed on the cap, wherein the electronic system is configured to acquire the signal from the resistive sensor and determine a softness measurement.

13. The device as recited in any one of claims 1 to 12, wherein the intermediate component comprises a spring.

14. The device as recited in any one of claims 1 to 12, wherein the intermediate component comprises an elastic intermediate component.

15. The device as recited in any one of claims 1 to 14, wherein the distal tip is configured with a hemispherical tip.

16. The device as recited in any one of claims 1 to 14, wherein the distal tip is configured with a flat tip.

17. The device as recited in any one of claims 1 to 14, wherein the distal tip is configured with a conical tip.

18. The device as recited in any one of claims 1 to 17, wherein the resistive sensor comprises a Wheatstone bridge circuit.

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