ES2631134B1 - ANTHROPOMETRIC DEVICE, PROCEDURE AND COMPUTER SYSTEM FOR THE SELECTION OF A PERSONALIZED MATTRESS - Google Patents

Abstract

An anthropometric device (100) for the selection of a custom mattress comprises at least one transverse longilinear pressure sensor, at the shoulder or hip of a reclining user, and an electronic component (20) for measuring the voltage of the electrical signals produced by said sensors under the weight of the lying user, in order to record said measurements and processed in order to select a mattress appropriate for the user's height and mass distribution. A method for such selection comprises the step of selecting the density of the custom mattress according to the level of the signals coming from the sensors. A computer system comprises a memory and a processor and contains instructions stored in the memory and executable by the processor that include a functionality to execute said procedure.

Description

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ANTHROPOMETRIC DEVICE, PROCEDURE AND COMPUTER SYSTEM FOR THE SELECTION OF A PERSONALIZED MATTRESS

DESCRIPTION

The present invention relates to an anthropometric device, a method and a computer system for the selection of a custom mattress. The invention also relates to a test mat, an apparatus and a computer program product for selecting a custom mattress.

STATE OF THE PREVIOUS TECHNIQUE

The mattress support surfaces are normally formed of synthetic foam. When the foam is crushed by a prominent part of the sleeper's body (such as the shoulder or the hip), its density, and consequently its hardness in that support area, increases and causes an overpressure reaction against said prominent parts, overpressure that It also remains substantially constant for a relatively long period of time. This leads to discomfort, skeletal pain, damage to the compliance of postural respiratory therapies, bedsores in chronic bedridden, etc. Given the diversity of human anthropometry, it is not easy to find a more or less general solution to this problem. In other words, the design of a custom mattress according to the anthropometric characteristics of the user is problematic.

On the other hand, devices are known for measuring the pressure exerted by different parts of the body of a user lying on a mattress, which usually employ a plurality of sensors distributed over the surface of the mattress. But most known devices use a large number of said sensors, of the order of hundreds (with their consequent connections), and each sensor covers a very small area of the mattress, such as twenty square centimeters. So many sensors (and the required installation) are expensive and provide a large amount of unhelpful, and even counterproductive, information (since it is not commercially viable to customize a mattress with such a high degree of detail), to address the aforementioned problem.

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Some device, such as the one described in ES2301464T3, attempts to reduce the number of sensors. ES2301464T3 describes a device comprising sensors arranged in the mattress, in the areas corresponding to the thorax and the abdomen of the sleeper. The pressures are measured with a sensor cushion and evaluated in an evaluation unit. The absolute pressures of the sensor cushions or the relative pressures between various sensor cushions can be calculated to determine sleeper parameters, such as position or position change. The sensor cushion is filled with a liquid or gaseous medium, so that a pressure can be transmitted through the medium and on a sensor element.

But the arrangement of sensors in ES2301464T3 does not provide a good measure of the pressure exerted by the shoulder and the hip, for example in a lateral recumbent position, since the sensors are located between these two zones. In addition, in this document, the sensor cushions are inserted on the upper side of the mattress, but the present inventor has found that this location is ineffective and even counterproductive, since, for example, if the user is in a lateral recumbent position in the At the time of measurement, the areas of your body that are close to the hip (for example the waist) are not detected correctly, since the greater prominence presented by the hip makes it difficult to contact the less prominent parts that surround it and, consequently, the correct measurement of the pressure they exert.

EXPLANATION OF THE INVENTION

An objective of the present disclosure is to provide a device for selecting a custom mattress that overcomes at least some of the aforementioned drawbacks. For this, in addition, the inventor has devised a way to take advantage of these pressure measures, typical of each individual (hence its anthropometric character), to improve the comfort of the sleeper and, consequently, the quality of his sleep.

According to a first aspect, an anthropometric device for the selection of a custom mattress comprises a transverse longilinear pressure sensor intended to be extended across the width and below the shoulder of a reclining user, a transverse longilinear pressure sensor intended to be extended across and below the hip of the lying user, and an electronic component to measure the voltage of the electrical signals produced by said transverse sensors under the weight of the lying user, in order to record said measurements and process them in order to select a

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mattress appropriate for the height and mass distribution of the user. Naturally there may be more than one transverse sensor corresponding to the shoulder or hip area, since said longilinear sensors can be very narrow. Normally, the electronic component will transmit the signals to a computer system for processing.

In this way you can determine the degree of concentration of the mass in the area of the shoulder and hip, which are the most relevant for the quality of sleep because they are the most prominent in the body, at least in a lateral decubitus position (which on the other hand it is the most advisable to avoid snoring and apnea problems), and you can select the density of the pig in these areas according to the indicated measurements.

Although the cross sections of the body corresponding to the shoulder and the hip are the ones that most influence the user's comfort during sleep, it is still convenient for the sensors to reach the full height of the body and provide a complete map of the pressures exerted by the user's body on a test mat arranged on the sensor assembly, in order to determine more precisely the surface densities of the custom mattress most suitable for each cross section into which the human body can be divided.

Another important advantage is precisely that the pressure map is determined by cross sections of the user's body, as they are the transverse sensors and cover the entire width of the body. In fact, the human body has a substantial transverse symmetry (the right side and the left side are substantially symmetrical), which makes the presence of two symmetric sensors arranged in the same cross section superfluous, with a single transverse sensor sufficiently long being preferable in each section to detect the pressure exerted by the full weight of the same, which can reduce the number of sensors needed without reducing the quality of the measurement, since the sensors contact the complete silhouette of the user and detect the variations pressure from the first contact.

In one example, at least one of the transverse pressure sensors can comprise a pair of conductive tracks facing and intended to operate with different polarity, and a semiconductor element that is arranged under the two tracks and encompasses them for electrical contact. . The potential difference between the two tracks

it will provide a signal representative of the pressure exerted on that sensor, since the higher the pressure on the sensor (due to a greater mass of the user in the cross section corresponding to that sensor), the better (more intimate) is the contact established between the two conductive tracks through the semiconductor element and lower is the electrical resistance between the two poles of the sensor.

The device can be placed under a test mat on which the user would lie to perform the measurement (obtain the pressure map), as explained below.

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In one example, the two tracks of at least one sensor can be digitized and arranged so that each non-extreme finger of one track is between two fingers of the other track, and vice versa. In this way the sensor sensitivity can be improved.

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In one example, each track may comprise a longer finger (although normally it will comprise a plurality of long fingers) and these two fingers (one on each track) may be consecutive and may be separated by a distance greater than the separation distance between any two consecutive shorter fingers. That is, there may be a part of the pair of tracks where they are further away and the fingers are longer, and in addition the finger density (number of fingers per unit length of the track) in these parts may be lower. This is intended for the sensor set to serve both light users and heavy users. Indeed, since each long finger covers a larger area, this larger area is more sensitive to the pressure exerted by the smaller weight of a light user; but, since the density of long fingers is lower, the possible saturation in the sensor response due to the excessive weight of a very heavy user is avoided.

The tracks of at least one of the sensors may contain silver particles. In general, the sensor can be printed with any conductive ink on, for example, a sheet (for example polymeric), for example with an ink containing graphite or copper, but the silver is so conductive that it allows an ink with a Relatively small silver particle density with hardly any loss of conductivity, which makes the tracks thinner. In addition, with silver there would hardly be a potential drop

between the sensors of the sheet that are further apart from each other, so that all sensors would provide substantially the same electrical signal.

As mentioned, the conductive tracks may be printed on a sheet. On the other hand, the semiconductor element may be provided on a base arranged under said sheet, so that intimate contact can be established between the conductive tracks and the semiconductor element.

In one example, the device may comprise a dielectric film that is arranged between the base and the sheet and comprises at least one window to allow electrical contact between the semiconductor element and the conductive tracks it encompasses. This allows the base to have more semiconductor surface than strictly necessary to establish contact with the conductive tracks, which can reduce this base by simplifying its manufacturing (the semiconductor material is very cheap, but the manufacturing process is not so much) . In case the tracks include widened parts, the windows may have corresponding widenings, that is, the window may comprise widenings corresponding to the long fingers of the conductive tracks.

20 In order that the sensors may encompass other parts of the body, in addition to the shoulder and the hip (as indicated above), the sheet can be elongated (such as a mattress, especially individual) and comprise a plurality of pairs of transverse conductive tracks, and the dielectric film may comprise a plurality of transverse windows in correspondence with said pairs, it being provided that at least one of the pairs of transverse tracks substantially covers the width of the user's body lying supine (or be, in its maximum width).

Similarly, the base may comprise a plurality of semiconductor elements in correspondence with said windows or one or more semiconductor elements that span several windows.

The electronic component for measuring the voltage of the electrical signals from the pressure sensors can transmit these signals to a computer system, in order to obtain a representation of the map of pressures exerted by the different parts of the

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body of the user from said electrical signals. The measurement of the sensor signals can be performed multiplexed.

Said electronic component can be connected by cable to said computer system and can receive from it the power supply for the operation of the sensors, so that the electronic component can dispense with its own power supply.

The electronic component can also transmit the signals to the radiofrequency computer system.

A test mat for selecting a custom mattress may comprise a plurality of internal transverse recesses and a plurality of transverse recesses, each of which extends from one of the recesses to the bottom surface of the mat, so that between two recesses Consecutive, a cross section of the mat is defined which is intended to be arranged on a corresponding pressure transverse sensor of a device as defined in previous paragraphs. In this way, the pressure exerted by each cross-section of the user's body is not distributed blurred between several cross-sectional sensors, but each cross-section of the mat can be transmitted discriminately to the transverse sensor located beneath it, so that the electrical signals produced for each transverse sensor they are truly representative of the pressure exerted by the corresponding cross section of the user's body on the cross section of the mat on which it rests.

In one example, the test mat can be divided into independent cross sections.

An apparatus for selecting a custom mattress may comprise a test mat and a device as defined in the preceding paragraphs, so that at least one of the transverse pressure sensors is arranged under one of the cross sections of the mat.

According to a second aspect, a procedure for selecting a custom mattress comprises the step of laying a user in a lateral recumbent position.

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on the test mat of the previous device. The procedure may also include the steps of:

- determine the position of the shoulder and the position of the user's hip from the electrical signals from the transverse pressure sensors;

- determine a first subset of sensors corresponding to the shoulder area;

- determine a second subset of sensors corresponding to the chain area;

- select the density of the custom mattress in the shoulder area according to the level of the signals coming from the sensors of the first subset;

- select the density of the custom mattress in the hip area according to the level of the signals coming from the sensors of the second subset.

Naturally, in case the sensor assembly extends only through the shoulder and hip areas of the user, the determination of said first and second subsets is automatic. But if the set of sensors extends over a wider area of the user's body, the determination of said first and second subsets allows to calculate the user's height, since it is estimated that the length between shoulder and hip is approximately 40% of The height of a person. And such determination is simple with the device and the mat defined above because the two cross sections of the mat corresponding to the shoulder and hip, respectively, of the user are those whose sensors provide the two strongest signals when the user is in recumbency. side.

According to a third aspect, a computer program product comprises program instructions for having a computer system execute the above procedure (except, of course, the step of laying down the user).

In two examples, the computer program product may be stored on recording media or it may be carried by a carrier signal.

According to a fourth aspect, a computer system comprises a memory and a processor and contains instructions stored in the memory that are executable by the processor. These instructions comprise a functionality to execute the above procedure.

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According to a fifth aspect, a custom mattress comprises a first insert in the user's shoulder area and a second insert in the user's hip area, whose densities have been selected with the above procedure.

In one example, at least one of the inserts can be a triangular prism and have a flush side with the upper surface of the mattress so that the upper surface of the mattress is smooth.

Other objects, advantages and features of embodiments of the invention will be apparent to the person skilled in the art from the description, or can be learned with the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Particular embodiments of the present invention will now be described by way of non-limiting example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic plan view of conductive tracks of pressure sensors;

Figure 2 is a schematic plan view of a pair of conductive tracks;

Figure 3 is a schematic exploded view of a pressure sensor;

Figure 4 is a longitudinal sectional view of a test mat;

Figure 5 is a schematic perspective view of the mat of Figure 4 on

pressure sensors;

Figure 6 is a representation of a pressure map;

Figure 7 is a schematic elevation view of a custom mattress;

Figure 8 is a schematic elevational view of another custom mattress;

Figure 9 is a schematic elevational view of another custom mattress; Y

Figure 10 is a partially sectioned perspective view of another mat of

tests on pressure sensors.

The drawings are not to scale and do not reproduce the actual proportions, but have a purely illustrative purpose.

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DETAILED EXHIBITION OF REALIZATION MODES

Figure 1 shows 32 pairs of conductive tracks 10 connected to an electric meter 20, or, more particularly, to an electronic component 20 capable of measuring the voltage between its terminals and transmitting this information to a computer system (not shown) . Each pair 10 comprises a first conductive track 11 and a second conductive track 12. Tracks 11 and 12 of each pair 10 face each other and extend in parallel in a transverse direction of a test mat 60 (fig. 5) or 160 ( fig.

10). Each conductive track 11 or 12 is digitized and comprises a plurality of fingers 13 and 14, respectively (see fig. 2), for example between 50 and 500 fingers. Each non-extreme finger 13 is between two fingers 14 and each non-extreme finger 14 is between two fingers 13; The extreme fingers are the first and last of each track.

Naturally, the number of pairs 10 may be greater or less than 32, for example 16 or 64.

Each pair 10 of conductive tracks 11 and 12 shown in Figure 1 is uniform, in the sense that all of their fingers 13 and 14 are equal, but in Figure 2 some fingers 15 and 16 are shown longer than fingers 13 and 14. Fingers 15 (from the first clue

11) and 16 (of the second track 12) are arranged in wider parts 17 provided in the tracks, which then comprise narrow portions 18 containing the short fingers 13 and 14. The separation between consecutive fingers 15 and 16 is greater than the separation between consecutive fingers 13 and 14. Long fingers 15 and 16 are more sensitive to pressure and are only useful for capturing the weight of light users. The fact that they are more separated is not to produce an excess signal with heavy loads (heavy users) and saturate the measurement.

Figure 3 shows 3 layers (30, 40 and 50) that make up a pressure sensor. A sheet 30 comprises a pair 10 of conductive tracks 11 and 12 as shown in Figure 2, although the pair 10 could be uniform, such as those shown in Figure 1. In the case of tracks with short and long fingers (such as the one shown in Fig. 3), the window 41 has widenings 47 corresponding to the wide parts 17 of the pair 10 and narrowings 48 corresponding to the narrow parts 18 of the pair 10. As well as to capture the weight of light users they are useful long fingers, to capture the weight of heavy users short fingers are more useful, since the narrowings 48 of the

window 41 restricts the flexion of the sheet 30 in the narrow portions 18 of the pair 10, which then begin to detect pressure with more load (user weight) than the threshold detected by the wide portions 17.

5 Track 11 is electrically connected to a terminal 21 of electronic component 20 and track 12 is electrically connected to another terminal 22 of component 20. Terminals 21 and 22 are of different polarities (one is the positive and the other is the negative ). Component 20 comprises an electronic board.

10 Sheet 30 is made of a polymeric material, for example polyester. Tracks 11 and 12 and their connections with terminals 21 and 22, respectively, are printed with a conductive ink on sheet 30, for example by screen printing. In Fig. 3, sheet 30 is turned upside down, that is, with tracks 11 and 12 on the bottom surface of the sheet and "facing" down.

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A dielectric film 40 is located under the sheet 30 and comprises a window 41 that frames the digitized part of the pair 10 of conductive tracks 11 and 12, that is, leaves tracks 11 and 12 of the sheet 30 exposed.

A polymer base 50 is located under the dielectric film 40 and comprises a semiconductor element 51 that extends over most of the upper surface of the base 50, so that, after joining the three layers 30, 40 and 50, the semiconductor element 51 is exposed to electrical contact with the pair 10 of tracks 11 and 12 through the window 41 (the semiconductor element 51 does not come into contact with the tracks 11 and 12 until it accuses

25 pressure: the more weight more flexion of the sheet 30 and greater contact through the window 41, whose dimensions can also influence the intensity of the contact).

The three superimposed components 10, 41 and 51 form a pressure sensor, although, in reality, the sheet 30 comprises a plurality of pairs 10 of conductive tracks 11 and 12,

30 the dielectric film 40 comprises a plurality of windows 41 in correspondence with said pairs 10, and the semiconductor element 51 of the base 50 encompasses all pairs 10 and all the windows 41 (although the base 50 may also comprise a plurality of semiconductor elements 51 in correspondence with the windows 41), so that the joined layers 30, 40 and 50 form a set of pressure sensors.

Then, a device 100 for the selection of a custom mattress comprises the three joined layers 30, 40 and 50, and the electronic component 20. The dimensions may correspond to a single or double mattress (60-160 cm wide by 170-210 cm in length). The ink of the conductive tracks 10 and 11 may comprise silver particles, and the semiconductor element 51 may comprise graphite.

In figure 4 a test mat 60 is shown provided with transverse cavities 61 of triangular section (although this geometric section may take other forms). A cut or groove 62 opens each cavity 61 from the bottom surface of the

10 mat and divide this into a plurality of cross sections 63 defined by each two consecutive slits 62. When the mat 61 is subjected to the weight of the user lying on it, the slits 62 remain closed and the cross sections 63 remain together (in permanent contact).

15 A recess 65 on the bottom surface of the mat 60 can accommodate the electronic component 20 (see fig. 5). The mat can be sheathed and can have a height of 10-20 cm.

By placing the mat 60 on the sensor assembly of the device 100, or this under

20 that, each sensor is under one of the cross sections 63 of the mat. Then, as the cross sections 63 remain together and do not move longitudinally (or just barely) even under the user's weight, said sections 63 perfectly transmit to the sensors the pressure exerted by the user lying on the mat 60.

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In another embodiment represented in Figure 10, the mat 160 comprises a plurality of independent cross sections 163, and in this case each sensor would be under one of these cross sections 163.

30 Each transverse pressure sensor can cover a cross section of the mat between 2 and 8 cm wide, for example about 5 cm wide. It is considered that the hip area covers about 15 cm in the longitudinal direction, so that 3 5 cm sensors would cover this area.

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In operation, each pair 10 receives, through the electronic component 20, an electrical potential, so that one of the tracks 11 or 12 is the positive and the other track is the negative. By laying the user on the test mat 60 (or 160), the user's mass distribution produces a different pressure on each cross section 63 (or 163) of the mat (and the pressures produced in the supine position will also be different and in position of lateral decubitus). Each cross section 62 (or 163) transmits the weight applied on it to the pressure sensor located below it, which responds as follows: the conductive tracks 11 and 12 of the pair 10 are pressed, through the window 41, against the semiconductor element 51 and come into electrical contact therethrough; the tighter they are against it the more the electrical resistance between them (provided by semiconductor 51) will decrease and the higher the voltage between track 11 and track 12. Therefore, this voltage is an adequate measure of the pressure exerted by the weight of the user on that cross section.

In the case of tracks with short and long fingers (such as that shown in Fig. 3), the window 41 has widenings 47 corresponding to wider parts 17 of the pair 10 containing the long fingers. Just as long fingers are useful for capturing the weight of light users, short fingers are more useful for capturing the weight of heavy users, since the window 41 is narrower at intervals 48 corresponding to the short fingers, which restricts the flexion of the sheet 30 and begins to capture pressure with more load than the most sensitive long fingers.

The voltages can be of the order of 2 ^ 3 volts, and the discrimination can be 0.2 volts (in which case the signal filtering threshold would be 0.2 V), so that, for example, a voltage 2.4 V indicate a small weight, a voltage of 2.6 V indicates a normal or medium weight and a voltage of 2.8 V indicates a large weight.

The electronic component 20, which receives the electrical signals from the pressure sensors in a multiplexed manner, transmits these signals to a computer system (not shown), which processes them and, based on a selection algorithm, selects a suitable mattress for the mass distribution of the user. The electronic component 20 can receive power from a computer (to which it is connected by cable and which processes the signals transmitted by the electronic component) belonging to the computer system.

Figure 6 shows a "screenshot", visible on a computer system monitor, of a pressure map representative of the user's longitudinal mass distribution, which is divided into cross sections: each vertical bar 75 represents a cross section .

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Figure 7 shows a custom mattress 80 selected with the previous device and system. The mattress 80 comprises a first triangular insert 81 arranged at the top of the mattress at the height of the shoulder of the sleeper, and a second triangular insert 82 arranged at the top of the mattress at the height of the hip of the sleeper 10. The densities of the inserts 81 and 82 are, in principle, different from the density of the rest of the mattress 80 and are selected according to the previous device and system. The inserts can take the form represented by references 83 and 84, which include a concavity 85 for housing another electronic component, for example a postural sensor 87 for detecting the position of the sleeper (for example supine or lateral recumbency).

In figures 8 and 9 another custom mattress 90 is shown. The mattress of figure 8 comprises a rectangular insert of different density 91 arranged at shoulder height and a group of rectangular or square inserts 92, also of different density both between they as compared to the rest of the mattress, arranged in the hip area. The mattress of Figure 9 is similar but comprises a group of inserts 94, analogous to the inserts 92 of Figure 8 but covering most of the length of the mattress. Both types of mattress (and also the mattress of Figure 7) may comprise a surface layer (about 4 cm high) of a soft viscoelastic material 93, in order to improve the overall comfort of the mattress. The mattress itself can be of any type (foam, springs, latex, etc.) or combination of materials.

The custom mattress can be selected, for example, from 27 references defined by 3 height sizes (high, normal or low user), 3 foam densities on the shoulder (hard, normal or soft foam) and 3 foam densities on the hip (hard, normal or soft foam, with levels equal to or different from those of the shoulder foam).

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Based on the measurements of the sensors and the references of available mattresses, an algorithm for selecting the custom mattress can comprise the following steps (the values offered are only by way of example):

- if the signal corresponding to the hip is not more than 2.4 V, then a hard foam for the hip is selected;

- if the signal corresponding to the hip is not less than 2.8 V, then a soft foam for the hip is selected;

- otherwise, a normal hip foam is selected;

- if the signal corresponding to the shoulder is not more than 2.2 V, then a hard shoulder foam is selected;

- if the signal corresponding to the shoulder is not less than 2.6 V, then a soft shoulder foam is selected;

- in another case a normal shoulder foam is selected;

- if the distance detected between the shoulder and the hip is less than 67 cm, then a short mattress is selected;

- if the distance detected between the shoulder and the hip is greater than 71 cm, then a long mattress is selected;

- in another case a mattress of normal length is selected.

This algorithm can be implemented by means of a computer program to be executed in a computer system.

Although only some particular embodiments and examples of the invention have been described herein, the person skilled in the art will understand that other alternative embodiments and / or uses of the invention are possible, as well as obvious modifications and equivalent elements. In addition, the present invention encompasses all possible combinations of the specific embodiments that have been described. The numerical signs relating to the drawings and placed in parentheses in a claim are only intended to increase the understanding of the claim, and should not be construed as limiting the scope of the claim's protection. The scope of the present invention should not be limited to specific embodiments, but should be determined only by an appropriate reading of the appended claims.

Claims (18)

5 10 fifteen twenty 25 30 35 1. Anthropometric device (100) for the selection of a custom mattress (80; 90), characterized in that it comprises a transverse longilinear pressure sensor intended to be extended across the width and below the shoulder of a reclining user, a transverse longilinear pressure sensor intended to be extended wide and below the lying user's hip, and an electronic component (20) to measure the voltage of the electrical signals produced by said transverse sensors under the weight of the lying user, of in order to record these measurements and process them in order to select an appropriate mattress for the height and mass distribution of the user. Device according to claim 1, characterized in that at least one of the transverse pressure sensors comprises a pair (10) of conductive tracks (11, 12) facing and intended to operate with different polarity, and a semiconductor element (51) which is arranged under the two tracks and covers them to put them in electrical contact. Device according to claim 2, characterized in that the two tracks (11, 12) are digitized and arranged so that each non-extreme finger (13) of a track (11) is between two fingers ( 14) from the other track (12), and vice versa. Device according to claim 3, characterized in that each track (11; 12) comprises a longer finger (15; 16) and these two fingers are consecutive and are separated by a distance greater than the separation distance between any two shorter (13, 14) consecutive fingers. 5. Device according to any of claims 2 to 4, characterized in that the tracks (11, 12) contain silver particles. Device according to any of claims 2 to 5, characterized in that the conductive tracks (11, 12) are printed on a sheet (30) and the semiconductor element (51) is provided on a base (50) arranged under the blade. Device according to claim 6, characterized in that it comprises a dielectric film (40) that is arranged between the base (50) and the sheet (30) and comprises at least one window (41) to allow electrical contact between the semiconductor element (51) and the conductive tracks (11, 12) it covers. Device according to claims 4 and 7, characterized in that the at least one window (41) comprises widenings (47) in correspondence with the long fingers (15, 16) of the conductive tracks (11, 12). Device according to claim 7 or 8, characterized in that the sheet (30) is elongated and comprises a plurality of pairs (10) of transverse conductive tracks 10 (11, 12), and the dielectric film (40) comprises a plurality of transverse windows (41) in correspondence with said pairs, it being provided that at least one of the pairs of transverse tracks substantially covers the width of the user's body lying supine. 15 10. Test mat (60; 160) to select a custom mattress (80; 90), characterized by the fact that it comprises a plurality of internal transverse recesses (61) and a plurality of transverse recesses (62), each of which extends from one of the recesses to the bottom surface of the mat, so that between two Consecutive grooves define a cross section (63) of the mat that is intended to be arranged on a corresponding transverse pressure sensor of the device (100) of any of claims 1 to 9. 11. Apparatus for the selection of a custom mattress (80; 90), characterized in that it comprises the mat (60; 160) of claim 9 and the device (100) of Any one of claims 1 to 9, such that at least one of the transverse pressure sensors is disposed under one of the cross sections (63) of the mat. 12. Procedure for selecting a custom mattress (80; 90), characterized by the fact of understanding the step of laying a user in a lateral position on the test mat (60; 160) of the apparatus of claim 10. 13. Method according to claim 12, characterized in that the steps of: 5 10 fifteen twenty 25 30 35 - determine the position of the shoulder and the position of the user's hip from the electrical signals from the transverse pressure sensors; - determine a first subset of sensors corresponding to the shoulder area; - determine a second subset of sensors corresponding to the hip area; - select the density of the custom mattress (80; 90) in the shoulder area according to the level of the signals coming from the sensors of the first subset; - select the density of the custom mattress (80; 90) in the hip area according to the level of the signals coming from the sensors of the second subset. 14. Computer program product, characterized in that it comprises program instructions for having a computer system execute a selection procedure according to claim 13. 15. Computer program product according to claim 14, characterized in that it is stored in recording media. 16. Computer program product according to claim 14, characterized in that it is carried by a carrier signal. 17. Computer system comprising a memory and a processor, characterized in that it contains instructions stored in the memory and executable by the processor, which comprise a functionality for executing a selection procedure according to claim 13. 18. Custom mattress (80; 90), characterized by comprising a first insert (81; 91) in the shoulder area of a user and a second insert (82; 92) in the hip area of the user, whose densities have been selected with the method of claim 13. 19. Mattress (80) according to claim 18, characterized in that at least one of the inserts (81; 82) is a triangular prism and has a flush side with the upper surface of the mattress.