IT202000007813A1 - Method of measurement of biometric forces through a monolateral measurement group - Google Patents

Description

DESCRIPTION of the Industrial Invention entitled:? Method of measurement of biometric forces through a monolateral measurement group?

TEXT OF THE DESCRIPTION

The present invention relates to a method for measuring biometric forces such as the forces generated by a muscle contraction e.g. the force applied by two fingers of the same hand during a movement towards or away from the fingers themselves. Another example of biometric force? that applied between the teeth of the mandible and maxilla during e.g. chewing.

AND? felt the need both for diagnostic purposes and during a treatment or rehabilitation, to accurately measure the biometric strength, for example of two fingers of the same hand in the movement of holding a thin object such as a pen, a cutlery or the like. In particular, ? It is important to perform the measurement by minimizing the perturbation of the measurement group in order to better simulate the real conditions of application of the load. In particular ? It is important to be able to perform the measurement in conditions similar to everyday gestures such as holding a pen or cutlery.

The purpose of the present invention? to provide a method of measuring a biometric force in a complete and at the same time rapid way to generate data that allow a complete picture of useful information so that? yes it is possible to express an evaluation or to establish training exercises.

The present invention achieves the aforementioned purposes with a measurement method by means of a monolateral measurement group of muscle contractions, for example relating to the mobilization of a user's joint, comprising a deformation sensor, comprising the steps of:

acquire a predefined time interval; detect a first voluntary maximum contraction through the measurement group;

calculate a first and a second target, which can? be both constant and variable and / or extremes of an interval of force, which can? be one-dimensional or, multi-dimensional, e.g. two-dimensional how will it come? specified in more detail below, on the basis of the first maximum voluntary contraction;

using the measurement unit to detect a first temporal trend of a first muscle contraction;

generate a first response on the basis of the first time trend? sensory feedback, e.g. visual and / or acoustic and / or vibro-tactile representative of a capacity? to maintain the first muscle contraction in a first predefined interval of the first target for a time that is memorized in order to evaluate a resistance of the first muscle contraction; and / or

detect through the unit? measure a second temporal course of a second muscle contraction;

generate a second feedback on the basis of the second temporal trend? sensory feedback representative of a capacity? to exercise the second muscle contraction within a second predefined strength interval during the predefined time interval in order to evaluate the accuracy of the second muscle contraction.

According to this procedure, parameters are measured that are able to give an effective and synthetic picture of both an initial situation of a user and of subsequent activities. of operation, automatically providing the reference values applied during the operation phase, referred to the initial MVC measurements. Furthermore, the use of a monolateral measurement group allows the application of the method both in the presence of a specific pathology e.g. either in the right hand or in the left hand, or for bilateral applications. In the latter case, for example to measure the force applied between the mandible and maxilla, a monolateral measuring unit allows the right MVC to be accurately measured separately from the left MVC. The feedback can? be visual and generated in real time while the time trend is detected. The target can? be both constant and follow a predefined trend such as steps. The interval can? be one-dimensional, e.g. a minimum and maximum value, or multidimensional, e.g. two-dimensional, for example being an area around a target point as described in greater detail with reference to Figure 2. E? It is also possible to foresee an acoustic feedback, for example a volume of a sound increases with the proximity to the target and decreases with the distance from the target. Similarly, the feedback can? also be vibro-tactile, with the vibration increasing e.g. of intensity? or frequency with approaching the target and vice versa.

According to a preferred embodiment of the present invention, the steps of:

provide an additional single-sided measurement group; simultaneously detecting the first and / or second time course through the said measurement group and a third and / or fourth time course through the said further measurement group; and in which the step of generating the first or second feedback comprises the step of combining the said first and third temporal course and / or the said second and fourth temporal course respectively.

So ? bilateral measures can be carried out. The combination ? for example a vector composition in which each time course defines the modulus of a respective component of a resulting force vector. The first and the third temporal trend are appropriately sampled with modality? equal and synchronized, cos? like the second and fourth time course.

According to a preferred embodiment of the present invention,? further provided an electronic processing device connected in data input to said at least one sensor and programmed to perform at least one, preferably both, of a conditioning comprising e.g. an amplification and an analog / digital conversion, comprising e.g. a sampling of the sensor group signal and comprising at least one wireless or wired communication interface for output data to be connected to a PC, tablet, smartphone which acts as a user interface I / O and transmits said feedback to the user .

In this way, the size of the measuring group can be minimized. Furthermore, in combination with the electronic processing device, a compact kit is supplied that can be used with pre-existing intelligent electronic devices, i.e. without need? of a complete and dedicated device. The latter on the whole requires dedicated maintenance, which could take a very long time, also e.g. in case a screen is defective, and can? be relatively bulky. The processing of the electrical signals is carried out on board the electronic processing unit. When circumstances dictate, a part of the signal processing? performed on board the measurement group. There? for example can? happen for the mandible and maxilla contraction force measurement group, in which? there is a circuit to expand the measurement range.

The PC, tablet, smartphone or similar perform the function of user interface to communicate the feedback or receive input data and also, through a memory and a suitably programmed microprocessor, the calculation of targets, indicative parameters of resistance and precision performance. based on time trends etc.

According to a preferred embodiment of the present invention, the unilateral measuring group comprises:

- a first and a second cantilevered deformable element arranged in use between fingers of the same hand, said sensor being applied on one of the deformable elements;

- a first and second interface surface respectively carried by the first and second cantilevered deformable element and arranged in use in contact with the fingers to transmit the load to the sensor through the deformable elements.

AND? cos? obtained a compact and at the same time precise measuring unit both to measure maximum loads and to perform dynamic measurements in non-maximal conditions, such as holding a tool in the hand by dosing the force. In particular, ? It is important that this measurement is accurate both under static or quasi-static load conditions, e.g. when measuring the MVC, which under dynamic load conditions, i.e. variable over time e.g. during the acquisition of time histories to evaluate accuracy and endurance. There? is preferably obtained thanks to a portion with a calibrated cross-section, e.g. defining a recess or slot or other area where the material is removed in order to obtain a particularly precise geometry of the cross section through an operation subsequent to that of the production of the semi-finished product from which the deformable element is made.

In particular, ? It is possible to create a measuring device with a reduced thickness, for example less than 2 centimeters, using an extensometer for the finger force measurement unit. AND? in fact, it is important that the fingers operate without excessive disturbance of the motor task performed during the achievement of the target by the measurement group so that the data are representative of a greater number of real situations. Indeed, such a disturbance? excessive when the minimum thickness between two gripping fingers exceeds 2 centimeters, which represent a characteristic grip dimension of common objects such as a pen or cutlery. The support body for both cantilevered measuring branches allows to easily manipulate the device and protect the deformation sensor.

According to an embodiment, the interface surfaces of the first and second branches are opposite each other with respect to a plane, an arrow of the bending beam being substantially perpendicular to said plane.

This configuration allows you to adapt the device both to the thumb with another finger of the same hand and to two fingers excluding the thumb.

Preferably but not exclusively, each interface surface? a buttonhole inside which to insert a finger and peripherally closed so that both a load to bring the fingers closer or squeeze and a load to spread or remove the fingers are applicable. For example there? is obtained through an insert having a saddle shape fixed to the extremity? of the relative beam and a belt, preferably of adjustable length, fixed to the saddle as illustrated in the figure. Furthermore, the saddles have respective average planes in common so as to guide the resultant of the applied force, limiting and avoiding generating twisting moments.

In particular ? It is possible to measure both static and dynamic loads associated with an isometric muscle recruitment for the approach of the fingers or the removal of the fingers.

According to a further configuration, a cross section of at least one of the cantilevered deformable elements, e.g. beam,? flattened parallel to the plane and the sensor? a strain gauge disposed on an internal face of one of the deformable elements, i.e. a face facing the adjacent deformable element.

The flattened beam and the sensor placed on one face allow at the same time to detect arrows in both directions of deformation with the same precision, i.e. for the approach movement between two fingers and for the removal movement of two fingers, and a stiffness suitable to keep the device both compact and precise. This precision, maintained for both high and low loads, allows for high versatility. of the measuring device and its use for a relatively large number of exercises or different measures. Also, the sensor? arranged on one face of a branch facing the other branch so as to be shielded and protected from e.g. scratches.

According to a preferred but non-limiting embodiment, the buttonhole? at least partially defined by a tape having an adjustable length.

Furthermore, advantageously the elastically deformable element? a U-shaped body and the support body houses the sensor and, partially, the flexible element.

In particular, the support body protects the strain gauge applied on the surface of the beam from impact.

According to a preferred embodiment of the present invention, the unilateral measuring group comprises:

- a first elongated watertight envelope disposed in use between mandible and maxilla;

- A first deformation sensor carried by a first portion of the extremity? of the casing;

- a first and second interface surfaces opposite each other to be arranged one towards the mandible and the other towards the maxilla, the sensor being interposed between the interface surfaces so as to be pressed on the occasion of a muscular contraction between mandible and maxilla.

According to this configuration? It is possible to create a flattened measuring device for oral use, by means of a two-dimensional sensor such as a piezoelectric sensor, or for use with the fingers by means of a strain gauge. AND? in fact it is important that the teeth operate without excessive perturbation by the measuring group in order to be able to faithfully simulate the largest number e.g. of daily operations. Such a disturbance? excessive when, for oral use, the thickness between the teeth exceeds 8 millimeters.

According to a still further improvement, each interface surface has a convex shape to facilitate the conversion of the load applied by the teeth along a direction substantially perpendicular to an average plane disposed between the interface surfaces.

The convex surface allows diagonal loads to converge on the strain sensor so that they can be detected. There? gives greater measurement accuracy.

An executive form can? provide for a further single-sided measurement group comprising:

- a second elongated watertight envelope disposed in use between mandible and maxilla;

- A second deformation sensor carried by a second portion of the extremity? of the second envelope;

- a third and fourth interface surfaces opposite each other to be arranged one towards the mandible and the other towards the maxilla, the sensor being interposed between the interface surfaces so as to be pressed on the occasion of a muscular contraction between mandible and maxilla;

the said unilateral measuring groups being connected to each other by means of a support body shaped like a? U? of which the groups extend their respective extremities? free.

According to this configuration, the support body? approached but is not inserted in the mouth, therefore not? sterilization and / or sanitation required. According to a further embodiment, the measuring units are disposable or reusable and the support body, releasably connected to the measuring units, is also reused.

AND? It is also possible to provide that each casing comprises a first segment connected to the support body and a second segment arranged at an angle from the first segment and defining the respective end portion, the said second segments of the two branches diverging starting from the first segments towards the respective portions of extremities.

According to this configuration, the measurement groups are particularly effective and precise since? neighboring teeth do not interfere with the measurement.

Preferably, but not exclusively, the support body? retractable to adequately position the interface surfaces in dental arches of different sizes.

Furthermore, according to a further embodiment, the deformation sensor? piezoelectric, in particular piezoresistive.

Such a sensor? the best compromise between minimum thickness and precision in the required force ranges, i.e. up to 80 kg.

In addition, ? It is possible that each wrapper is watertight and / or sterilizable to avoid saliva infiltration and / or to be reused.

These and other features and advantages of the present invention will be more apparent. clearly from the following description of some executive examples illustrated in the attached drawings in which:

fig. 1? a flowchart of a method according to the present invention;

fig. 2 ? an example of an electronic unit for acquisition and processing, display and user interface for carrying out the method of Figure 1;

fig. 3? a view of a visual feedback screen of the method of Figure 1;

fig. 4? a perspective view of a monolateral measurement unit for measuring the muscle contraction of the fingers according to the method of Figure 1; fig. 5? an exploded view of the measuring unit of figure 4;

fig. 6? a perspective view of a further bilateral measuring unit for the force between mandible and maxilla according to the method of figure 1; And

fig. 7? a section along a longitudinal plane of one of the branches of the measuring unit of figure 6.

Figure 1 illustrates a method according to the present invention for measuring muscle contractions by means of a measurement unit described below. widely in the following reference to figures 4 to 7 and adapted to the type of muscle contraction to be measured and which will be? described in two exemplary forms in the following paragraphs.

In particular, the method comprises a first phase 1 for selecting the type of muscle contraction to be detected, e.g. unilateral right, unilateral left or bilateral, to which a particular configuration of the measuring group is suitable. This selection preferably allows you to set a first type of target, for example visual, for unilateral contractions and a second type of visual target for bilateral contractions Subsequently, in phase 2, a maximum voluntary contraction is measured, for example the maximum force applied by two fingers to tighten the measuring group or the force applied when the mandible and the maxilla clench the measuring group between the teeth.

The signals of one or more? measurement groups G are transmitted, for example via a wire F, to an acquisition and processing board 104 (figure 2) which preferably performs both the signal conditioning, which includes the amplification of the analog signal, and the conversion from the analog signal a digital, which includes sampling of the analog signal.

Preferably, the acquisition and processing card 104? an independent module e.g. includes one or more? microprocessors and one or more? memories, programmed to process the signal received from the measurement groups G and generate data for visual and / or sound feedback.

The capture card? connected in data exchange, for example via a USB cable or wireless, to an electronic processor 105, e.g. a personal computer, a tablet or a smartphone. The electronic processor 105, by means of a microprocessor operatively coupled to a memory, acts both as an input / output interface and as a data processor and, in particular, comprises a screen 106 to show a visual feedback and / or a sound actuator (not shown ) to emit an audible feedback. In this regard, the selection of step 1, when envisaged, is carried out by means of the electronic processor 105 in particular a touch screen (not shown) or a keyboard (not shown).

On the basis of the measurement of the MVC they are calculated in a phase 3a e.g. as a percentage decrease, a first load threshold for evaluating accuracy; and a first target (step 3b) based on the threshold. To measure accuracy, a user applies to the measurement group G (step 3c) a load that approaches the first target in a predetermined time interval; and a second load threshold with the related second target for the evaluation of the resistance e.g. how long a user is able to apply a force around the second target on the measurement group G.

Preferably but not exclusively, step 3c comprises the representation on a screen 106 of the processor 105 of the first and / or second force target in combination with a cursor 108. A parameter indicative of the representation on the screen 106 of the cursor 108, for example the cursor position,? influenced by the measurement through the measurement group G and is represented on the screen 106 simultaneously with the first and / or second load target in order to allow the calculation of the parameters indicative of the precision, e.g. average distance during the time interval from the first load level; and resistance, e.g. maximum residence time above the second load level. The first and second load targets can be more? in general limit trends having various forms, e.g. not only constant values, depending on the calculations performed.

Optionally, the cursor 108 is represented on the screen 106 also during the acquisition of the maximum voluntary contraction.

According to one embodiment, when the measure? unilateral, in a Cartesian reference plane XY on the screen 106 the coordinate X? time and Y coordinate? the load applied during muscle contraction is measured by measurement group G. When bilateral loads are measured, a polygonal active area 50 is defined having a lower vertex in the origin of the Cartesian axes to represent a zero load. A right vertex and a left vertex (figure 2) identified on 45? in the first and fourth quadrant of the XY plane to correspond to the corresponding unilateral loads and an upper vertex corresponding to the bilateral load. In particular, do the vertices lie on the lines at 45? when a 100% unilateral load is measured, for example in the measurement of the isometric contraction of the fingers. In the case of contraction between mandible and maxilla, due to bilateral activation of the masticatory muscles, when there are two right and left measurement groups and a unilateral contraction is applied by the user, both sensors are charged, one more? of the other. There? it involves an inclination towards the Y axis of the lateral vertex starting from the inclined directrix.

For example, the right and left vertices can be the unilateral MVC of the fingers of the right and left hand respectively, so? as the top vertex can? be the bilateral MVC. Alternatively, the right, left and top vertices are a fraction, e.g. 80% of the respective MVCs measured in step 2.

In Figure 2? illustrated an example of an active area 50 according to the invention to generate a visual feedback in the case of bilateral loads Also during phase 2, according to an application example in the case of bilateral loads, the processor 105 generates a target point 54 (see figure 2) having a predetermined position in the active area 50 corresponding to the first threshold. In this simple case, the threshold and the target coincide but? possible that the target is more? complex, e.g. a series of points, and the threshold is one of those points, such as an absolute or relative maximum. When the target? a set of points, the threshold? an independent parameter and the other points are calculated on the basis of the threshold in such a way e.g. parametric.

The user (phase 3c), while viewing the target point 54, must try to apply a load, for example between the fingers of the right and left hand, balancing it so as to overlap with the cursor 108 during a predetermined interval of time T, for example 10 seconds. The processor 105 calculates an instantaneous load error (phase 3d) as the difference between a load e.g. finger (identified by cursor position 108 on screen 106) and target point level 54 (target-cursor distance).

Similarly, during the display of the target point 54, a maximum time is measured (phase 3d) in which the user is able to keep the cursor 108 inside a circumference having a diameter calculated on the basis of the second target, for example 15. %, to evaluate the resistance.

Advantageously, the resistance target has a maximum value lower than that of the precision. For example, the precision target can? present more? levels or points and the maximum level? greater than that of resistance (30% -50% of the ceiling).

In step 3d, a number of alternative parameters can be calculated. For example, the gi? cited average distance between the target and the load applied by the measurement group G; or a number of times when? reached the target in the predefined time interval; or the root mean square value of the distance between the target and the load; or the distance between the average value of the load in the time interval and the target.

With reference to the resistance, can it? be measured a maximum time interval during which the load applied by the user to the measurement group G? within a target range.

Following the data collected in phase 3, a library of exercises to train resistance and / or precision is parameterized (phase 4). For example, each exercise includes a load trend over time and the user, through the measurement group G, must apply a muscle contraction such as to bring the cursor 108 closer to this trend. For the purpose of resistance, a parameter representative of the time in which the muscle contraction? such as to keep the cursor 108 in the predefined range of the target; and for the purpose of accuracy, a parameter representative of the distance of the cursor 108 from the target in the predefined time interval is subsequently stored. Each exercise of phase 4? stored in the processor 105 in parametric form and what is calculated in phase 3d allows to dimension the thresholds, e.g. the absolute and relative maximums, the absolute and relative minimums, of each financial year based on the user's performance.

In a phase 5 are manually selected one or more? exercises from the library in order to adapt to the particular condition of the user measured in phase 3.

Subsequently (phase 6) the selected exercises are generated point by point on the basis of the parametric thresholds of phase 4 and are shown on the screen 106 as illustrated for example in Figure 3. For example, the electronic processor 105 reproduces a target sequence 120 of variable loads over time e.g. as alternation of loading and complete unloading phases, i.e. zero load. The local maximum values of the step trend are a percentage of the MVC measured in phase 2. Furthermore, a duration of the load phases can? be a percentage of the time interval measured in step 2 to assess resistance. The target sequence 120 can? be single for unilateral muscle contraction exercises or the screen 106 can? show at the same time also a target sequence 121 when the contractions are unilateral. In both the unilateral and bilateral cases, the time histories of the cursors 108 overlaid on the respective target sequences are simultaneously displayed, preferably in real time, to provide visual feedback during the exercise.

A type of exercise similar to that of figure 3 but adapted for resistance training requires that, during the loading phase, a band is shown and not just a horizontal line. The vertical width of this band is calculated on the basis of the results of step 3, for example by reducing by 10% or more? till e.g. to 50% the average distance calculated in phase 3. Both in this phase and in phase 3, the time acquired can? for example be determined when the user stays outside the target range for a predetermined time, for example 1 second.

Finally (phase 7) the performance parameters are also calculated for the exercises performed, for example the same parameters as in phase 2, in order to highlight the evolution of the user's condition.

Figure 4 illustrates, as a whole, a biometric measurement group G for the force of two or more? fingers during an isometric contraction of approach or departure comprising a first and a second branch 2, 3 or cantilevered deformation elements adapted to be interposed between at least two fingers and a casing 4 to partially house the first and second branches 2, 3 and support the branches 2, 3. According to a modality? d? use, the casing 4? cantilevered with respect to the hand and is supported by the fingers. In the case of bilateral use, each hand carries a corresponding measurement group.

According to the present invention, each branch has a relative end portion? 6, 7 and on at least one of them? applied a sensor 8 to measure the deformation of the branches when to the latter? finger force applied. To sensor 8? connected the wire electric conductor F which supplies the sensor and transmits the signal to the electronic processing board 104. After the sensor signal? for example transformed into a digital signal, it is processed by a microprocessor on board the processor 105 for numerical and graphic operations as better specified below.

According to a non-limiting embodiment, each end portion? 6, 7? clears and defines at least one concave interface surface 11 which in use contacts a finger to guide force when the fingers are brought together. Each interface surface 11? generally preferably a peripherally closed slot so as to transmit the force resulting from the movement away from two fingers. The concave shape of the interface surfaces 11, e.g. ? saddle ?,? for example symmetrical with respect to an average plane of branches 2, 3. The average plane? substantially parallel to the resulting force applied by the fingers. Furthermore, both interface surfaces 11 are aligned to the same average plane, as illustrated in the figure, so that, in particular when the fingers apply a compressive load to each other, no twisting moments are generated on the measuring unit.

Each buttonhole? preferably defined by a concave insert 21 carried cantilevered by the respective branch with respect to the support body 4 and by a belt 22 preferably of adjustable length and anchored to the insert 21. The belt? preferably inextensible so as not to negatively impact the accuracy and readiness of the measurement, in particular of the dynamic measurement, i.e. of a temporal history.

Figure 5 illustrates in greater detail what is partially housed inside the enclosure 4, i.e. the branches 2, 3 which are rigidly connected to each other at respective end portions? 23 opposed to the portions of extremities? 6, 7 to define a U-shape. The latter are arranged overhanging from the casing 4 and support the respective inserts 21. The end portions? 6, 7 are spaced apart so as to allow the branches 2, 3 an arrow under the load of the fingers.

Are the branches 2, 3 deformable by means of the load of the fingers applied through the inserts 21 in compression or away from them through the tapes 22 and on at least one? the sensor 8 is arranged, preferably an extensometer for measuring the deflection.

Preferably, the sensor 8? applied to a portion of the branch having a controlled geometry cross section. The cross section is checked by means of a precise dimensional control following which material is removed in order to increase the compliance with respect to the other portions of the branch. In the illustrated embodiment example, a slot 24 is made having an average plane substantially perpendicular to the load applied by the fingers. A precise cross section in combination with the strain sensor 8 makes it possible to reliably calculate the force applied by the fingers.

Preferably, the sensor 8? mounted on the face of the branch 2 facing the branch 3 so that the branches themselves shield and protect the sensor from debris, such as dust, or liquids that can vary the resistance and / or damage the electrical components.

In the embodiment illustrated in Figure 5 the inserts 21 are removable, e.g. connected to sled. AND? however it is possible, as a constructive alternative, that the inserts are connected in a rigid and non-dismountable way. Preferably, the branches 2, 3 are cantilever beams of metallic material, for example steel. This material allows the best compromise between dimensions, e.g. cross section of the arms 2, 3, and reduced costs and resistance / deformation adequate to the maximum and minimum loads applicable from the fingers of one hand.

As illustrated in Figure 5, the casing 4 has rounded recesses connected with the interface surface 11 to increase ergonomics when a compression load is applied to the fingers. According to the embodiment of Figure 5, the casing comprises two half-shells which close on the branches 2, 3 and are preferably but not exclusively made by injection molding.

According to the present invention, the sensor 8, the cross section of the beams and the acquisition and processing board 104 are configured to obtain a resolution of at least 0.01 Kg both when a high load is applied, e.g. a load close to the maximum design load measurable by the device e.g. 80 kg, both when a much heavier load is measured? low, e.g. equal to 10% of the maximum design load.

A further embodiment of a measurement unit is described below in which reference numbers identical to those used in the preceding paragraphs are used to indicate elements that are functionally identical to those described for the measurement unit of Figures 4 and 5.

Figure 6 illustrates, as a whole, a pair of biometric measuring units for the force of a bite, each comprising a respective branch 2, 3 adapted to be arranged in the mouth and a support element 4 preferably U-shaped to carry the branches 2, 3. The support member 4 preferably? external in use to the mouth and? advantageously it is elastic or, as illustrated in the figure, it has a hinge 30 so as to be able to adapt the relative distance between the branches 2, 3 and, in particular, to approach or distance respective end portions? 6, 7. According to the embodiment of Figure 6, the hinge 30 allows the end portions to be mutually spaced or brought closer together. 6, 7 and, after this adjustment, maintain the relative position of the branches 2, 3 during the measurement.

Each measurement group G? detachable, for example by means of a sliding coupling from the support element 4 so as to be treated before and / or after use in a different way with respect to the support itself: for example sterilized or sanitized. AND? It is also possible that the measuring groups are disposable and, in this case, they are supplied ready for use. In the embodiment of Figure 6? a variant of bilateral measurement is shown. Each measuring group, individually or mounted on the open support body 4 e.g. for an angle of 90? or higher is used for unilateral measurements.

According to the present invention, each end portion 6, 7 incorporates a sensor 8 (figure 7) and? deformable to the force applied by a bite in order to transfer the load to the sensor. Preferably sensor 8? piezoelectric, especially a piezoresistive ink. and, even more? preferably, Flexi Force A301 manufactured by Tekscan. Such a sensor? flat, i.e. with a thickness of less than 1 mm, and measures loads up to 80 kg with good precision also with the help of the processing of card 104. Incorporated in branch 2, 3? also present a processing circuit, e.g. amplification, and an electrical connector 9 from which a relative plug 10 takes the electrical signal for subsequent processing by means of the acquisition and processing board 104.

According to a non-limiting embodiment, each end portion? 6, 7? free and defines at least one convex interface surface 11, preferably two interface surfaces 11 and 12 opposite to the sensor 8. In use, the interface surfaces 11, 12 are respectively in contact with a tooth, e.g. a molar, of a lower dental arch and the corresponding tooth of an upper dental arch.

The convex shape also allows to detect tangential loads, i.e. not orthogonal to the plane of the two-dimensional sensor 8, in addition to vertical loads i.e. perpendicular to the sensor 8 or in any case directed so as to compress the sensor 8 so as to be detected.

Preferably the sensors 8 of the branches 2, 3 lie in the same plane when the device? I unload; in this plane the support body 4? retractable to bring the portions of extremities closer or away from each other? 6, 7.

According to what is illustrated in Figures 6 and 7, each branch 2, 3 also comprises a flattened, saliva-tight envelope made of a polymeric material such as PETG, i.e. polyethylene terephthalate copolyester. The casing preferably comprises a first and a second half-shell 13, 14 which enclose and incorporate after being glued or otherwise fixed the sensor 8, an amplification circuit and the plug 10. In order to favor the effectiveness of the group of measure and avoid interference of neighboring teeth but not superimposed on the portions of the extremities? 6, 7 during the measurement, each branch 2, 3 comprises a first segment and a second segment arranged at an angle with respect to the first segment. The first segment? releasably connected to the support element 4 and the second segment carries the end portion? 6, 7. In particular, the second segments of the branches 2, 3 diverge starting from the support element 4 so that the end portions? 6 and 7 have a greater relative distance than that between the first segments. The second segments are also cantilevered with respect to the support element 4.

Preferably the half-shells of the measuring device of fig. 4 are made by injection molding.

Finally, it is clear that? It is possible to make changes or variants to the measurement method and / or to the measurement groups of the present invention without thereby departing from the scope of protection as defined by the attached claims.

For example the strain gauge? 350 Ohm resistive type but? It is possible to use similar sensors.

On board the device? It is possible to provide a circuit for processing the signal coming from the sensor 8, a power supply battery and an antenna for transmitting the signal to the microprocessor for numerical and graphic processing.

Claims (11)

CLAIMS 1. Method of measurement by means of a unilateral measurement unit of a first muscle contraction, for example relating to a joint of a user, comprising a deformation sensor, comprising the steps of: acquire a predefined time interval through a user interface; detect (phase 2) through the measurement group a first voluntary maximum contraction? maximum voluntary contraction (MVC); calculate (step 3b) a first and a second predefined force target based on the first voluntary maximum contraction; detect (phase 3c) through the measurement group a first temporal trend of a first muscle contraction; generate on the basis of the first temporal trend a first sensory feedback representative of a resistance expressed as capacity? to maintain the first muscle contraction above the predefined threshold for a time that is memorized; and / or detect through the unit? measure a second temporal course of a second muscle contraction; generate on the basis of the second temporal trend a second sensory feedback representative of a precision expressed as a capacity? to exercise the second muscle contraction within a predefined strength interval of the second target during the predefined time interval. Method according to claim 1, further comprising the steps of: provide an additional single-sided measurement group; simultaneously detecting the first and / or second time course through the said measurement group and a third and / or fourth time course through the said further measurement group; and in which the step of generating the first or second feedback comprises the step of combining respectively said first and third time course and / or said second and fourth time course to be representative of a bilateral contraction. Method according to one of claims 1 or 2, further comprising the steps of providing an electronic processing device connected in data input to said at least one sensor and programmed to perform at least one, preferably both, of an analog / digital conditioning and conversion, and comprising at least one communication interface for output data to be connected to a PC, tablet, smartphone which acts as an I / O user interface and transmits said feedback to the user. Method according to any one of the preceding claims, wherein said measuring group comprises: - a first and a second cantilevered deformable element (2, 3) arranged in use between fingers of the same hand, said sensor being applied on one of the deformable elements; - a first and second interface surface (11) respectively carried by the first and second cantilevered deformable element and arranged in use in contact with the fingers to transmit the load to the sensor through the deformable elements. The method according to claim 4, wherein each interface surface (11)? a buttonhole (22) for a peripherally closed finger so that both a load for bringing the fingers closer or together and a load for spreading or withdrawing the fingers are applicable. Method according to one of claims 4 or 5, wherein a cross section of at least one of the cantilevered deformable elements (3)? flattened parallel to a plane substantially perpendicular to that of application of the load of the fingers and the sensor (8)? a strain gauge disposed on a face of one of the deformable elements covered by the other of the deformable elements. Method according to any one of claims 1 to 3, wherein the unilateral measuring group comprises: - a first elongated watertight envelope (13, 14) disposed in use between mandible and maxilla; - A first deformation sensor (8) carried by a portion before the extremity? (6; 7) of the casing; - a first and second interface surfaces (11, 12) opposed to be arranged one towards the mandible and the other towards the maxilla, the sensor being interposed between the interface surfaces so as to be pressed on the occasion of a muscle contraction between mandible and maxilla. The method according to claim 7, wherein the housing comprises a first segment connected to the support body (4) and a second segment disposed at an angle from the first segment and defining the end portion. (6; 7), the said second segments of the two branches diverging starting from the first segments towards the respective end portions. Method according to one of claims 7 or 8 when dependent on claim 2, in which the one-sided measuring unit and the further one-sided measuring unit are connected to each other by means of a? U-shaped support body (4)? of which the groups extend their respective extremities? free. Method according to claim 9, wherein the support body (4)? retractable to adequately position the interface surfaces in dental arches of different sizes. Method according to any one of claims 7 to 10, wherein the strain sensor (8)? piezoelectric, preferably piezoresistive.