Sensor for measuring force and rehabilitation apparatus comprising such sensor

Abstract

A flexible sensor for measuring the force exerted by a subject, for example grip force, comprises a resistive layer interposed between two conductive layers. The resistive layer is made of a polymer foam, while the two conductive layers comprise a polymer fabric metallized with nickel, copper and / or silver. The sensor is configured to detect the variation in resistance of the resistive layer caused by deformation due to the applied force, to convert it into a measurement of said force. A rehabilitation apparatus for the upper limb comprises a handle and a sensor according to the present invention fitted on said handle.

Description

"SENSOR FOR MEASURING FORCE AND REHABILITATION APPARATUSCOMPRISING SUCH SENSOR" DESCRIPTIONField of application

[0001] The present invention relates to a sensor for measuring force suitable for detecting the grip force exerted by a subj ect and to a rehabi litation apparatus for the upper limb comprising a handle on which such sensor is applied .

[0002] Speci fically, the sensor of the invention is suitable to be applied to a handle assembly of a rehabilitation apparatus , in particular for upper limb rehabilitation, for example , but not exclusively, like the one described in patent application 102023000019617 in the name of the same Applicant .

[0003] The sensor for measuring force subj ect of the present invention also fits into any application in which the detection of force and / or pressure exerted by a subj ect , whether healthy or ill , is required, in particular, but not exclusively, in the biomedical , sports , and rehabilitation sectors in general , for purposes of research, therapy, training, and the like .

[0004] The present invention also provides a rehabilitation apparatus comprising a sensor for measuring force according to the invention .

[0005] Currently, it is known to measure pressure , and more generally the distribution of forces on a given surface , by means of capacitive or resistive pressure sensors .

[0006] Capacitive pressure sensors are made of conductive panels separated by a dielectric layer . The force exerted modi fies the distance between the panels , altering the capacitance of the system, which is measured to determine the applied pressure .

[0007] Resistive pressure sensors , on the other hand, use piezoresistive materials whose resistance varies with force . These sensors are made with piezoresistive elements and conductive layers , interwoven in a fabric matrix .

[0008] Both types of known sensors have the drawback of having low flexibility and consequently providing poor comfort , characteristics that limit their use in garments or in applications requiring adaptation to curved surfaces , as well as interaction with the human body .

[0009] Moreover, such devices have high production costs and are incompatible with widespread use or large-scale distribution .

[0010] Furthermore , the measurements carried out by capacitive sensors are extremely influenced by environmental phenomena such as temperature and / or humidity .

[0011] To mitigate these drawbacks , pressure sensors capable of being used in garments or the like have been devised, for example comprising conductive threads .

[0012] Document WO 2009 / 023937 , for example , describes a garment comprising sensors for measuring pressure . In one embodiment , in particular, a sock is described in which at least one section of the fabric is coated with a conductive polymer on which silver threads are sewn .

[0013] These sensors have the maj or limitation of losing their measurement ef ficiency over time , since the conductive layers are deposited on the fabric or the like by coating and therefore , i f subj ected to repeated washings , they are damaged, thus making the measurements less precise .

[0014] Moreover, such pressure sensors would be immediately deteriorated in the case of high-temperature cleaning to sterilise the garment and its sensors , an operation indispensable for the maj ority of protocols required for the use of such devices in hospitals .

[0015] Inconveniently, therefore , the pressure / force measuring devices currently available on the market are not suitable for applications on rehabilitation or therapeutic treatment devices .

[0016] Consequently, known rehabilitation devices , for example for the upper limb, are devoid of such sensorsand do not provide the possibility of directly detecting the force exerted by the subj ects in treatment , in particular do not allow the detection of the grip force exerted by the treated subj ects .

[0017] Disadvantageously, therefore , there are currently no upper limb rehabilitation devices equipped with grip force detection devices .Solution of the invention

[0018] There is therefore a strong need to provide a sensor for measuring force capable of overcoming the drawbacks typical of the prior art .

[0019] In particular, an obj ect of the present invention is to provide a flexible sensor for measuring force that is at the same time reliable and durable over time .

[0020] A further obj ect of the present invention is to provide a rehabilitation apparatus comprising such sensor .

[0021] This need is satisfied by a sensor for measuring force in accordance with claim 1 and by a rehabilitation apparatus in accordance with claim 10 . The dependent claims describe preferred or advantageous embodiments of the invention, involving further advantageous aspects . Description of the drawings

[0022] The features and advantages of the sensor for measuring force and of the rehabilitation apparatus willhowever be evident from the following description of some preferred embodiments , given by way of example and not limitation, with reference to the accompanying figures , in which :Figure 1 shows a schematic view of a sensor for measuring force in an embodiment of the present invention;Figure 2 shows a schematic sectional view of a sensor for measuring force in an embodiment of the present invention;Figure 3 shows a schematic sectional view of a sensor for measuring force in an embodiment of the present invention;Figure 4 shows a side view of a handle of a rehabilitation apparatus on which a rehabilitation sensor is fitted, in an embodiment of the present invention;Figure 5 shows a side view of a handle of a rehabilitation apparatus on which a rehabilitation sensor is fitted, in an embodiment of the present invention;Figure 6 shows an overall view of a handling unit of a rehabilitation apparatus in an embodiment of the present invention;Figure 7 shows a detailed view of a handle assembly of a rehabilitation apparatus in an embodiment of the present invention;Figure 8 shows a schematic diagram of the electronic connection of a rehabilitation apparatus in an embodiment of the present invention .Detailed description

[0023] With reference to the aforementioned figures , the reference number 1 indicates a flexible measuring sensor 1 for detecting the force exerted by a subj ect is overall denoted .

[0024] In particular, but not exclusively, reference is made to the force exerted by a subj ect on a gripping surface , for example of a handle , preferably in a rehabilitation apparatus .

[0025] The sensor 1 comprises a resistive layer 10 interposed between a first conductive layer 12 and a second conductive layer 14 .

[0026] In one embodiment , the resistive layer is directly interposed, preferably only supported, between said first and second conductive layer 12 , 14 without any further interposed layers .

[0027] In a preferred embodiment , the resistive layer 10 comprises a polymer foam, preferably polyurethane ( PU) .

[0028] In one embodiment , the resistive layer 10 consists solely of said polymer foam .

[0029] In an advantageous embodiment , the resistive layer10 comprises expanded polyurethane foam ( eTPU) ,preferably conductive .

[0030] In a variant embodiment , the resistive layer 10 is made of an open-cell polyurethane sponge of high or low density .

[0031] In one embodiment , the resistive layer 10 is made of expanded polyurethane impregnated or coated with conductive particles , i . e . it is a conductive sponge .

[0032] In one embodiment , the resistive layer 10 is made of polyether-based polyurethane , impregnated with flexible latex loaded with carbon .

[0033] In one embodiment , the first conductive layer 12 and the second conductive layer 14 are identical to each other .

[0034] In the following description, what is illustrated for the first conductive layer 12 will also be applicable to embodiments of the second conductive layer 14 .

[0035] In one embodiment , the first conductive layer 12 comprises a metalli zed polymer fabric 120 .

[0036] In the present discussion, the expression metalli zed polymer fabric refers to a fabric comprising a polymer material which has been enriched with metal by means of a physical or chemical conductive treatment and / or by electrodeposition, for example it has been coated with metal , such as copper or nickel , so as to achieve conductive functions .

[0037] In one embodiment, the polymer fabric 120 is metallized with nickel and / or copper and / or silver.

[0038] Preferably, the polymer fabric 120 comprises polyester and / or polyamide. In one embodiment, the polymer fabric 120 is entirely made of polyester or polyamide .

[0039] In one embodiment, the polymer fabric 120 is a warp and weft fabric.

[0040] In one embodiment, the polymer fabric 120 is entirely made of polyester and is preferably characterized by a weft density of about 450 threads / dm and a warp density of about 580 threads / dm.

[0041] In one embodiment, the polymer fabric 120 is entirely made of polyamide (Nylon 6.6) , preferably with a weft density between 450 and 490 threads / dm and a warp density between 480 and 500 threads / dm.

[0042] In an advantageous variant embodiment, the first conductive layer 12 comprises a polymer fabric 120 entirely made of polyester (PES) and metallized with copper (Cu) and nickel (Ni) .

[0043] Preferably, the first conductive layer 12 has the following composition: (35% PES / 61% Cu / 4% Ni) ± 10%.

[0044] In one embodiment, the first conductive layer 12 comprises a polymer fabric 120 entirely made of polyamide and metallized with silver (Ag) , copper (Cu) and nickel(Ni) .

[0045] In one embodiment, the first conductive layer 12 comprises a metal content having the following composition: 7.27 ± 2% Ag + 48.18 ± 3% Cu + 3.64 ± 1% Ni + 9.09 ± 2% CR.

[0046] In a preferred embodiment, the first conductive layer 12 comprises a fabric with Ripstop weft. Such a weft is known in the textile sector and is woven using a reinforcement technique that makes such conductive layer 12 tear-resistant.

[0047] In a preferred embodiment, the sensor 1 has an overall thickness S between 3 mm and 10 mm, preferably between 5 mm and 6.5 mm, even more preferably the overall thickness S is equal to 6 mm.

[0048] Preferably, the resistive layer 10 has a resistive layer thickness SI between 3 and 6 mm, even more preferably equal to 5 mm.

[0049] Preferably, the first conductive layer 12 has a conductive layer thickness S2 between 0.1 mm and 0.5 mm, even more preferably equal to 0.1 mm.

[0050] In one embodiment, the sensor 1 comprises a first support layer 16 and a second support layer 18, preferably made of technical fabric.

[0051] By technical fabric is preferably meant a textile material having high performance in terms of mechanicalstrength, protection from external agents, breathability, moisture management, thermal insulation, elasticity, lightness, and antimicrobial properties.

[0052] Preferably, the first support layer 16 is constrained, preferably sewn, to the first conductive layer 12, on the opposite side with respect to the resistive layer 10.

[0053] Preferably, the second support layer 18 is constrained, preferably sewn, to the second conductive layer 14, on the opposite side with respect to the resistive layer 10.

[0054] Preferably, said first and second support layer 16, 18 are identical, preferably they have a support layer thickness S3 of 0.5 mm.

[0055] Advantageously, said first and second support layer 16, 18 provide the sensor with optimal thermal insulation and moisture shielding properties, to the advantage of the durability of the sensor 1 itself.

[0056] Advantageously, said first and second support layer 16, 18 provide sufficient rigidity to maintain the shape of the object on which the sensor is placed, for example on the handle, and at the same time provide excellent flexibility to adapt to said object.

[0057] In one embodiment, the sensor 1 comprises a removable layer 20, preferably made of elastane (alsoknown as spandex, or by the trade name Lycra ) , and is preferably washable .

[0058] Advantageously, the removable layer provides protection from external agents , excellent moisture management , good elasticity to facilitate the insertion and removal of the sensor from the obj ect on which it is fitted, as well as washability and suitability for disinfection .

[0059] In a preferred embodiment , the sensor 1 has an enveloping configuration, preferably tubular, extended along and around a sensor axis Z . That is , the sensor 1 in enveloping configuration is suitable for adapting to the outer surface of an obj ect and enveloping it .

[0060] Preferably, when the sensor 1 is fitted on a handle 30 of a handle assembly 3 of a rehabilitation apparatus 9 , said sensor axis Z substantially coincides with the main extension direction Z ' of said handle 30 .

[0061] In one embodiment , the sensor 1 in enveloping, preferably tubular, configuration comprises an outer lateral surface 100 and an inner lateral surface 102 .

[0062] In an advantageous embodiment , the outer lateral surface 100 is a wall of the removable layer 20 .

[0063] In one embodiment , in enveloping, preferably tubular, configuration, the removable layer 20 is sewn at its ends to form the outer casing of the sensor 1 so thatonly the outer lateral surface 100 is exposed .

[0064] In one embodiment , the outer lateral surface 100 is a wall of the first support layer 16 .

[0065] In one embodiment , in enveloping, preferably tubular, configuration, the second support layer 18 is sewn at its ends to form the inner lateral surface 102 of the sensor 1 .

[0066] In one embodiment , the resistive layer 10 is inserted between the first conductive layer 12 and the second conductive layer 14 , to which the first support layer 16 and the second support layer 18 are externally sewn respectively .

[0067] Preferably, when the sensor 1 is fitted on a handle 30 , the inner lateral surface 102 is in contact with it .

[0068] In one embodiment , the handle 30 comprises fastening means suitable for locking the sensor 1 fitted on the handle 30 without gluing it . Said fastening means , for example , comprise locking portions of the handle itsel f , for example at its ends , suitable for maintaining the engagement between the sensor 1 and the handle 30 .

[0069] Advantageously, the fastening, even removable , of the sensor 1 to the handle makes it possible to limit undesirable relative translations between the two elements , to the advantage of more reliable and accurate detection .

[0070] In one embodiment , in the enveloping, preferably tubular, configuration, the removable layer 20 is a soft and yielding thin-walled tube , obtained by sewing a piece of fabric at its ends , i . e . the removable layer 20 comprises a first end 220 and a second end 240 sewn in a contact zone 250 . Preferably the removable layer 20 in such embodiment has dimensions suitable to fit the sensor 1 already fixed to the handle 30 and completely cover it .

[0071] Advantageously, said removable layer 20 is suitable to be removed from the sensor 1 without the need to disassemble the entire sensor 1 from the handle 30 . In this way, said removable layer 20 is washable and allows maintaining a high level of hygiene for the rehabilitation apparatus on whose handle 30 the sensor 1 is fitted .

[0072] Also forming the subj ect of the present invention is a rehabilitation apparatus 9 comprising a sensor 1 according to the present invention .

[0073] In one embodiment , the rehabilitation apparatus 9 comprises a handle 30 comprising a gripping portion that can be grasped by a subj ect and a sensor 1 according to the present invention, fitted on said handle 30 , at a gripping portion thereof .

[0074] In one embodiment , the sensor 1 is electrically connected to an electrical circuit 50 configured toconvert a resistance variation Ar measured by the sensor 1 into a voltage variation AV .

[0075] In one embodiment , the electrical circuit 50 is in turn connected to a processing unit 52 configured to convert said voltage variation AV into a force value F exerted by the subj ect on the sensor 1 .

[0076] Preferably, the processing unit 52 comprises a data acquisition board suitable to maintain an output of voltage variation AV and a conversion unit suitable to mathematically convert the voltage variation AV into a measurement of force F .

[0077] Preferably, the force value F is not a direct and absolute measurement but a relative measurement , for example in percentage , with respect to a predetermined maximum or minimum force value .

[0078] In an advantageous embodiment , the electrical circuit 50 is housed in a board seat formed in the handle 30 itsel f .

[0079] Advantageously, this configuration is very compact and allows equipping the rehabilitation apparatus with sensors without increasing its bulk . This is further made possible thanks to the use of the above-mentioned conductive layers , which are lightweight and include wiring of small si ze .

[0080] In one embodiment , the handle 30 also comprises apassage suitable to allow the passage of the electrical terminals of the electrical circuit 50 towards the processing unit 52 .

[0081] Preferably, moreover, said processing unit 52 is configured to send said force value F to an electronic control unit 900 of the rehabilitation apparatus 9 .

[0082] In one embodiment , the electronic control unit 900 is configured to modi fy the treatment and operating parameters of the rehabilitation apparatus 9 based on said force value F, preferably based on a comparison with a target force parameter .

[0083] In one embodiment , the electronic control unit 900 is configured to return a feedback to the subj ect , for example visual feedback ( an image , a colour or a light , on a suitable interface ) or auditory feedback ( a sound or a voice command, from a suitable emitter ) , or haptic feedback ( for example a vibration or a variation in the intensity of the movement ) based on the force value F, for example in comparison with a target force parameter or with a maximum or minimum force value .

[0084] Some embodiments of a rehabilitation apparatus 9 will now be described . Further embodiments and additional technical details of the rehabilitation apparatus 9 are described in Italian application number 102023000019617 in the name of the same applicant .

[0085] In one embodiment , the rehabilitation apparatus 9 comprises a handling unit comprising : a frame 90 ; a handle assembly 3 movable with respect to said frame 90 and comprising a handle 30 having a gripping portion graspable by a subj ect ; a connection assembly that connects the handle assembly 3 to the frame 90 to allow its translation and / or rotation with respect to said frame 90 and extends defining a first PS axis of pronation-supination, a second AA axis of abduction-adduction and a third FE axis of flexion-extension, said first PS axis , second AA axi s and third FE axis being mutually orthogonal .

[0086] The connection assembly comprises a pronationsupination subassembly 91 , an abduction-adduction subassembly 92 , and a flexion-extension subassembly 93 .

[0087] The pronation-supination subassembly 91 comprises a first mechanism 901 connected to the frame 90 and suitable for transmitting a rotation around the first PS axis .

[0088] The abduction-adduction subassembly 92 comprises a second right rail 902 and a second left rail 904 , which are curved and extend at least partially around the second AA axis and are slidingly engaged with the mechanism 901 so as to al low the rotation of the handleassembly around the second AA axis .

[0089] The flexion-extension subassembly 93 comprises a third mechanism 903 connected to the second right rail 902 and to the second left rail 904 so that the movement of said second right rail 902 and left rail 904 is transmitted to said third mechanism 903 .

[0090] The handle assembly 3 is slidingly engaged with the third mechanism 903 , and is suitable for following a curvilinear traj ectory to rotate around said third FE axis .

[0091] The rehabilitation apparatus 9 further comprises an electronic control unit 900 operatively and electronically connected to said handling unit , configured to process one or more electronic signals coming from the handling unit and / or to execute a plurality of assessment , exercise or correction modules .

[0092] In one embodiment , the handle assembly 3 comprises a handle 30 suitable for being grasped by the hand of a subj ect and a handle support 32 on which the handle 30 is engaged .

[0093] In an advantageous embodiment , the handle assembly 3 is movable with respect to the frame 90 in three degrees of freedom ( DOF) .

[0094] Preferably, said three degrees of freedom are designated in accordance with the three degrees offreedom of the human wrist , and in particular identi fy three main axes of movement , which can be associated with three movement axes of the wrist j oint :- a first PS axis of pronation-supination;- a second AA axis of abduction-adduction ( or radialulnar deviation) ;- a third FE axis of flexion-extension .

[0095] These three axes represent a Cartesian triad and are all mutually orthogonal .

[0096] The movements of flexion-extension, pronationsupination and abduction-adduction can be simpli fied as rotations of the wrist j oint around these axes . The complex movements of the wrist , therefore , can be broken down into a series of such simple rotations .

[0097] For example , in use , a subj ect grasps the handle 30 so that the anatomical axes of the wrist correspond to the virtual axes of the rehabilitation apparatus 9 .

[0098] The user can therefore move the handle 30 performing the rotational movements characteristic of the human wrist , either individually or coupled together in complex movements .

[0099] In one embodiment , the handle 30 extends in a preferential extension direction Z ' which is substantially vertical and is suitable to be grasped by the hand of a subj ect , preferably with the palm of thehand identi fying a substantially vertical plane in which such preferential extension direction Z ' lies , which closes around said handle 30 .

[0100] Preferably, the preferential extension direction Z ' is parallel to the third FE axis .

[0101] In one embodiment , the rehabilitation apparatus 9 comprises an upper limb locking system that fixes the forearm and the hand of the subj ect in the correct position .

[0102] Such locking system is for example as described in Italian patent application 102023000019608 in the name of the same applicant .

[0103] In one embodiment , for example with reference to figure 6 , such locking system comprises a wrist locking group 800 , a hand locking group 801 and an elbow locking group 802 .

[0104] Preferably, the hand locking group 801 is integrated into the handle 300 and the force measuring sensor 1 is such as not to interfere with said hand locking group 801 .

[0105] The force measuring sensor 1 operates as described below .

[0106] The sensor 1 is suitable to detect the force applied by a subj ect on the outermost layer thereof , be it the conductive layer, or the support layer, or theremovable layer, depending on the embodiment . The manipulation of the sensor 1 generates deformations on the surface of the conductive layer 12 .

[0107] The resistive layer 10 follows the deformations of the surface of the conductive layer 12 . Such deformations , generated by the force exerted by the subj ect , cause a variation in the electrical resistivity of the material of the resistive layer 10 and consequently a variation Ar of its electrical resistance .

[0108] In one embodiment , an external electrical circuit 50 is connected to the force detection sensor 1 and is configured to detect said resistance variation Ar and convert it into a voltage variation AV .

[0109] The resistance variation Ar of the resistive layer is converted into a voltage variation AV through the external electrical circuit 50 which is sent to a processing electronic unit 52 , preferably connected to the rehabilitation apparatus 9 , preferably to the electronic control unit 900 of the apparatus 9 .

[0110] Finally, the processing electronic unit 52 performs a calibration procedure to correlate the voltage variation AV to a force value F representing the force exerted by the user, preferably measured in Newtons .

[0111] In the case where the sensor 1 is integrated into a rehabilitation apparatus 9 , such force measurementF, whether expressed in absolute or relative terms , is sent to an electronic control unit 900 of said rehabilitation apparatus 9 .

[0112] In a preferred embodiment , the electronic control unit 900 is configured to perform one or more of the following actions , based on the force value F or on a comparison of said force value F with a target force parameter :

[0113] - generate a feedback signal , in real time , for example auditory or visual or haptic, to be shown to the subj ect , for example by means of a suitable emitter ;

[0114] - in real time , modi fy the ongoing treatment protocols , based on the detected values ;

[0115] - store progressive data on the variation of the force exerted by the subj ect on the handle and generate reports and diagrams relating to the progression of the applied protocols .

[0116] Innovatively, the present invention solves the drawbacks of force sensors typical of the known art .

[0117] Advantageously, the sensor according to the present invention is a soft and lightweight textile element , suitable to be enveloped around or fixed onto obj ects having a non-linear surface , preferably curvilinear .

[0118] According to a further advantage , thesynergistic combination of the materials used for the resistive layer and the conductive layers provides the sensor with reliability and durability and makes the sensor particularly ef ficient as well as flexible and comfortable .

[0119] In particular, the combination of conductive fabric, the use of polyurethane and of a removable layer, preferably in Lycra, also advantageously due to the respective thicknesses , allows the sensor to be sensitive over its entire surface , enabling use with both the right hand and the left hand and allowing use by hands of any shape and si ze .

[0120] Moreover, such features allow for reliable , continuous and dynamic measurements , synchronisable in real time or of fline with rehabilitative exercises and activities .

[0121] Advantageously, moreover, the output signal from the sensor according to the invention is easily processable through data acquisition systems , so as to filter and di f ferentiate the necessary information .

[0122] According to a further advantage , the outer layer in technical fabric and / or the removable fabric in elastane are synthetic and antibacterial to ensure durability and hygiene .

[0123] Advantageously, the sensor, when fitted ontothe handle , is suitable to make it ergonomic and comfortable , especially thanks to the thickness of the resistive layer, reducing its rigidity and resulting soft to the touch, and thus usable even by subj ects with sensorimotor deficits .

[0124] Advantageously, the sensor according to the present invention, with appropriate adaptations , is suitable to be integrated into existing rehabilitation apparatuses without requiring a general redesign of the entire logic of the apparatus .

[0125] According to a further advantage , the present invention also solves the drawbacks related to rehabilitation apparatuses according to the known art .

[0126] Advantageously, in fact , the force measuring sensor according to the present invention makes it possible to enhance the rehabilitation or research treatment operable through the rehabilitation apparatus on which such sensor is applied, also allowing the detection of grip force , when applied on a rehabilitation apparatus for the upper limb as described in the present discussion .

[0127] Advantageously, the sensor is suitable to detect the force exerted by di f ferent anatomical districts and is versatile and adaptable to di f ferent anatomical shapes depending on where it is appl ied .

[0128] In particular, the sensor allows for the synchronous and real-time detection of the force data exerted by the subj ect during the work, and to return real-time feedback to ful fil a plurality of treatment and data storage purposes .

[0129] Advantageously, the sensor is particularly suitable for the upper limb when applied to a handle of a rehabilitation apparatus .

[0130] Advantageously, the Applicant has veri fied that the foam used has a compression set value of around 10% . This is advantageous and indicates that after compression of the sensor and release , the foam loses only 10% of its original thickness . This result is indicative of high resilience and confirms the possibility of reuse for several work cycles .

[0131] Advantageously, the rehabilitation apparatus comprising a detection sensor like that of the present invention is suitable to provide an ef fective and highly useful parameter for formulating an initial anamnesis of the patient and at the same time for evaluating the progress of the treatment , also in real time .

[0132] According to a further advantage , the sensor according to the present invention can also be applied to further portions of the rehabilitation apparatus , also in the cushion, non-tubular configuration, for example inthe forearm support portion to detect the force exerted in that anatomical area, for example with the aim of revealing any compensations implemented by the subj ect with the elbow . A further application could involve the application of the sensor at the wrist or elbow locking systems , for example to detect the compression exerted by the locking groups on the respective anatomical j oints .

[0133] It is clear that, to the embodiments of said sensor and said rehabilitation apparatus , a person skilled in the art , in order to meet speci fic requirements , could make variants or substitutions of elements with other functionally equivalent ones .

[0134] Such variants are also included within the scope of protection as defined by the following claims . Moreover, each variant described as belonging to a possible embodiment can be implemented independently of the other described variants .

Claims

CLAIMS1. A flexible sensor (1) for measuring the force (F) exerted by a subject, comprising a resistive layer (10) interposed between a first conductive layer (12) and a second conductive layer (14) , wherein the resistive layer (10) is suitable for undergoing a resistance variation (Ar) as a function of a deformation of the first conductive layer (12) due to a force (F) applied thereon, said sensor (1) being suitable for measuring said resistance variation (Ar) of the resistive layer (10) to convert it into a measurement of said force (F) , characterized in that the resistive layer (10) comprises a polymer foam, and the first conductive layer (12) and the second conductive layer (14) each comprise a polymer fabric (120) metallized with nickel and / or copper and / or silver .

2. Sensor (1) according to claim 1, wherein the polymer foam is polyurethane foam (eTPU) .

3. Sensor (1) according to any one of the preceding claims, wherein the polymer fabric (120) is a warp and weft fabric, preferably with Ripstop weft, comprising polyester and is characterized by a weft density of about 450 threads / dm and a warp density of about 580 threads / dm.

4. Sensor (1) according to any one of the preceding claims, wherein the first conductive layer (12) has the following composition: (35% PES / 61% Cu / 4% Ni) ± 10%.

5. Sensor (1) according to any one of the preceding claims, comprising a first support layer (16) and a second support layer (18) made of a technical fabric, wherein the first support layer (16) is sewn to the first conductive layer (12) and the second support layer (18) is sewn to the second conductive layer (14) on the opposite side with respect to the resistive layer (10) .

6. Sensor (1) according to any one of the preceding claims, having an enveloping, preferably tubular, shape mainly extending along and about a sensor axis (Z) , said sensor (1) being suitable for fitting a handle (30) of a rehabilitation apparatus (9) .

7. Sensor (1) according to claims 5 and 6, comprising an outer lateral surface (100) and an inner lateral surface (102) extending along and about said sensor axis (Z) , wherein the outer lateral surface (100) is a wall of the first support layer (16) sewn at its own ends and wherein the inner lateral surface (102) is a wall of the second support layer (18) sewn at its own ends, so that said first and second support layers (16, 18) enclose the resistive layer (10) and the first and second conductive layers ( 12 , 14 ) .

8. Sensor (1) according to claims 6 and 7, comprising, when in the tubular shape, an outer removable layer (20) made of elastane.

9. Sensor (1) according to claim 8, wherein the removable layer (20) is a soft and yielding tube of thin thickness.

10. Sensor (1) according to any one of the preceding claims, having an overall thickness (S) between 3 mm and 10 mm, preferably between 5 mm and 6.5 mm, even more preferably equal to 6 mm.

11. A rehabilitation apparatus (9) for rehabilitating the upper limb, comprising a handle (30) comprising a gripping surface graspable by a subject and a sensor (1) according to any one of claims 1 to 10, applied to said handle (30) at said gripping surface.

12. Rehabilitation apparatus (9) according to claim 11, comprising :- an electrical circuit (50) electrically connected to the sensor (1) , configured to convert the resistance variation (Ar) measured by the sensor (1) into a voltage variation (AV) ; a processing unit (52) connected to the electrical circuit (50) and configured to convert said voltage variation (AV) into a force (F) datum applied by the subject to the sensor (1) ;- an electronic control unit (900) configured to generatea feedback and / or modify treatment and exercise parameters of the rehabilitation apparatus (9) as a function of a comparison of said force (F) datum with a target force parameter.

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