Flexible pressure or strain mapping device, method for producing same, pressure mapping system, method for real-time digitalization and visualization of computer-implemented graphical

Abstract

The invention relates to a flexible pressure or strain mapping device comprising: a fibrous substrate layer (1) comprising at least a layer region (2) impregnated with a hydrogel; a first sensor electrode (3), a portion of which is in contact with at least a lower portion of the layer region (2) impregnated with the hydrogel; a second sensor electrode (4), a portion of which is in contact with at least an upper portion of the layer region (2) impregnated with the hydrogel. Flexible pressure or strain mapping devices include hydrogels that are flexible and have higher mechanical and sensing properties, considering that the materials are easy to tune, so they have stretchability and biocompatibility, and may exhibit self-healing properties. Further, flexible pressure or strain mapping devices may be arranged in an array to map the pressure distribution and provide more accurate output in a variety of applications.

Description

Technical Field

[0001] The present invention relates to a flexible pressure or strain mapping device configured to electrically detect different physical stimuli such as pressure, strain, touch and extension. Background Art

[0002] The number of sensing devices around us is growing rapidly, partly due to the popularity of the Internet of Things (IoT) and the prevalence of wearable devices. Among the many sensors, pressure sensors play a vital role in a variety of applications, ranging from health monitoring (by detecting multiple physiological signals such as pulse, breathing and other muscle movements) to robotic skin, functional prostheses and human-machine interfaces. However, with the growing production of wearable devices and other small electronic devices, electronic waste is becoming a serious burden, highlighting the need to find more environmentally friendly and sustainable materials. When producing these sensing devices, the manufacturing process is also crucial, which has prompted research on low-cost, simple and scalable sensor processes such as screen printing.

[0003] Pressure sensors typically rely on piezoresistive or capacitive transduction mechanisms to convert mechanical input into electrical signals. The sensitivity, hysteresis, and response and recovery time of pressure sensors are often improved by microstructuring some of their components, i.e., the sensing membrane or electrodes. Summary of the invention

[0004] In a first aspect, the present invention relates to a flexible pressure or strain mapping device, the flexible pressure or strain mapping device comprising:

[0005] A fiber substrate layer (1), the fiber substrate layer comprising at least a layer region (2) impregnated with a hydrogel;

[0006] at least a first sensor electrode (3), a portion of which is in contact with at least a lower portion of the layer region (2) impregnated with the hydrogel;

[0007] at least a second sensor electrode (4), a portion of which is in contact with at least an upper portion of the layer region (2) impregnated with the hydrogel; and wherein,

[0008] The hydrogel is a cellulose derivative; the cellulose derivative hydrogel is selected from cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, or mixtures thereof or their complexes.

[0009] Alternatively, in the first aspect, if Fig.16 As shown, the present invention relates to a flexible pressure or strain mapping device, the flexible pressure or strain mapping device comprising:

[0010] A fibrous substrate layer (1) comprising at least a layer region (2) impregnated with a hydrogel; and

[0011] at least a first interdigitated electrode (19), a portion of which is in contact with at least a portion of the layer region (2) impregnated with the hydrogel; and

[0012] at least a second interdigitated electrode (20), a portion of which contacts at least the same portion of the layer region (2) impregnated with hydrogel as the portion contacted by the first interdigitated electrode (19); wherein the portion of the layer region (2) impregnated with hydrogel is selected from the lower portion of the layer region (2) impregnated with hydrogel or the upper portion of the layer region (2) impregnated with hydrogel; and wherein (with the proviso that), when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), at least an electrically insulating layer (21) separates the first interdigitated electrodes (19) from the second interdigitated electrodes (20); and wherein

[0013] The hydrogel is a cellulose derivative; the cellulose derivative hydrogel is selected from cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, their mixtures or their complexes.

[0014] A second aspect of the present invention relates to a method for preparing a flexible pressure or strain mapping device as defined in the first aspect of the present invention, the method comprising the following steps:

[0015] a) depositing and impregnating a hydrogel into a fiber substrate layer (1) to form at least a layer region (2) impregnated with the hydrogel; and

[0016] b) connecting a portion of the first sensor electrode (3) to at least a lower portion of the layer region (2) impregnated with the hydrogel; and

[0017] c) connecting a portion of a second sensor electrode (4) to at least an upper portion of the hydrogel-impregnated layer region (2).

[0018] Alternatively, in a second aspect, there is provided a method of preparing a flexible pressure or strain mapping device as defined in the first aspect of the invention, the method comprising the steps of:

[0019] a) depositing and impregnating a hydrogel into a fiber substrate layer (1) to form at least a layer region (2) impregnated with the hydrogel; and

[0020] b) connecting a portion of a first interdigitated electrode (19) to at least a portion of the hydrogel-impregnated layer region (2); and

[0021] c) connecting a portion of the second interdigital electrode (20) to at least the same portion of the layer region (2) impregnated with hydrogel as the portion contacted by the first interdigital electrode (19); wherein the portion of the layer region (2) impregnated with hydrogel is selected from the lower portion of the layer region (2) impregnated with hydrogel or the upper portion of the layer region (2) impregnated with hydrogel; and

[0022] d) When the flexible pressure or strain mapping device comprises a plurality of pairs of the first interdigital electrodes (19) and the second interdigital electrodes (20), the first interdigital electrodes (19) and the second interdigital electrodes (20) are separated from each other by an electrical insulating layer (21).

[0023] A third aspect of the present invention relates to a pressure mapping system, the pressure mapping system comprising a pressure sensitive surface (9), wherein the pressure sensitive surface (9) comprises a flexible pressure mapping device as defined in the first aspect of the present invention, wherein the pressure mapping system further comprises:

[0024] An electronic instrument subsystem (11), the electronic instrument subsystem comprising a data transmission and reception unit (15), a microcontroller (12) and a power supply;

[0025] a hybrid connector (10) connecting the pressure sensitive surface (9) to the electronic instrument subsystem (11); and

[0026] The data sending and receiving unit (15) receives data acquired by the pressure sensitive surface (9) and transmits the data to the microcontroller (12).

[0027] A fourth aspect of the present invention relates to a computer-implemented method for real-time digitization and visualization of a graphical representation, the computer-implemented method for real-time digitization and visualization of a graphical representation comprising the following steps:

[0028] a) inputting a physical stimulus on a pressure sensitive surface (9) comprised in a pressure mapping system as defined in any one of claims 20 to 22, and

[0029] b) converting the physical stimulus into at least a digital signal by said pressure mapping system; and

[0030] c) transmitting at least the digital signal by said pressure mapping system to a computer device, thereby forming a graphical representation of the physical stimulus, wherein said computer device is adapted to allow editing of said graphical representation by means of a graphical user interface.

[0031] A fifth aspect of the present invention relates to a computer program comprising instructions which, when executed by a computer device, cause the computer device to perform the steps of the method defined in the fourth aspect.

[0032] A sixth aspect of the present invention relates to a computer-readable data carrier, on which is stored a computer program as defined in the fifth aspect.

[0033] Technical issues

[0034] Smart Skin Technologies INC.'s international patent application number WO2013113122A1, titled "PRESSURE MAPPING AND ORIENTATION SENSING SYSTEM" published on August 8, 2013, describes a pressure, force and orientation sensing system for mapping that uses a flexible electrode array and a flexible elastic piezoresistive material, such as fabrics coated with various types of conductive materials, conductive foams, nanotube-based polymers, carbon black-based polymers, and graphite-doped plastics. Each sensor is connected to an electronic circuit to measure its resistance and send the data to a microprocessor. The data can then be sent wirelessly to external devices, such as smartphones and computers, for processing, analysis, and user interaction.

[0035] There is a need to find other piezoresistive materials that can help achieve precise and accurate measurements, and these piezoresistive materials should be flexible and preferably environmentally friendly.

[0036] Furthermore, single sensing elements in the prior art may be affected by crosstalk or ghosting effects, which can affect the estimation of the mechanical stimulus distribution and may lead to misleading conclusions.

[0037] Problem Solution

[0038] The present invention impregnates the fiber substrate layer with hydrogel to form a layer area impregnated with hydrogel, and the layer area is in contact with the electrode, so that the physical stimulus applied to the fiber layer can be correctly electrically measured, thereby solving the problems existing in the prior art.

[0039] The present invention solves the problem of crosstalk or ghosting effect between sensing elements in the prior art by individualizing the sensing layer instead of using a continuous sensing film with individualized electrodes. Another method used by the present invention is to couple the sensing element with a rectifying element to prevent the current from passing through an unwanted path. The use of a rectifying element for a pressure sensing element usually requires the introduction of an additional passivation layer to prevent short circuits between the terminals of different elements.

[0040] Effects of the Invention

[0041] In the present invention, hydrogels are essential elements of flexible pressure or strain mapping devices, i.e., when the hydrogels are bio-based polymers or from naturally derived materials, they are viable sensing layers for the production of sensing devices due to their abundance, low cost, sustainability, recyclability, and flexibility. Furthermore, hydrogels are interesting materials for sensing layers because they are flexible and their mechanical and sensing properties are easily tunable, so they can be stretchable and biocompatible and can display self-healing properties.

[0042] Additionally, the flexible pressure or strain mapping devices can be arranged in an array to map the pressure or strain distribution and provide more accurate output in a variety of applications.

[0043] In incorporating rectifying elements, the layered structure proposed by the invention allows adding one rectifying element to each physical sensing element with as few added layers as possible. This fact avoids the need for additional passivation layers to prevent short circuits between the terminals of the different elements.

[0044] The flexible pressure or strain mapping device according to the present invention may provide either resistance or capacitance measurements, considering that the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". Thus, the device of the present invention may provide measurements according to any of the following situations: flexible pressure or strain mapping may provide resistance measurements; flexible pressure or strain mapping may provide capacitance measurements; or flexible pressure or strain mapping may provide both capacitance and resistance measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to promote an understanding of the principles of embodiments of the present invention, reference will be made to the embodiments shown in the drawings and the language used to describe these embodiments. In any case, it must be understood that it is never intended to limit the scope of the present invention to the contents of the drawings. Any changes or subsequent changes to the inventive features shown herein, as well as any additional applications of the principles and embodiments of the invention shown (which would normally occur to a person skilled in the art upon reading this specification) are all considered to be within the scope of the claimed invention.

[0046] Figure 1

[0047] [ Figure 1 ] shows a side view of a flexible pressure or strain mapping device in a single substrate configuration;

[0048] Figure 2

[0049] [ Figure 2 ] shows a side view of a flexible pressure or strain mapping device in a dual substrate configuration;

[0050] Figure 3

[0051] [ Figure 3 ] shows a side view of a flexible pressure or strain mapping device in a three-substrate configuration;

[0052] Figure 4

[0053] [ Figure 4 ] shows a top view of a flexible pressure or strain mapping device, which shows a first substrate, wherein the substrate has a bottom electrode on the back side and an impregnated hydrogel on the front side;

[0054] Figure 5

[0055] [ Figure 5 ] shows a top view of a flexible pressure or strain mapping device including a rectifying element including a Schottky metal contact, a patterned semiconductor element, and a top electrode on the back side of a substrate;

[0056] Figure 6

[0057] [ Figure 6 ] shows a side view of a flexible pressure or strain mapping device in a dual substrate configuration, wherein a first substrate includes a hydrogel-impregnated region and a bottom electrode, and a second substrate includes a Schottky metal contact, a patterned semiconductor, and a top electrode on the back side of the second substrate;

[0058] Figure 7

[0059] [ Figure 7 ] shows a top view of a flexible pressure or strain mapping device in a dual substrate configuration, wherein a first substrate includes a hydrogel-impregnated region and a bottom electrode, and a second substrate includes a Schottky metal contact, a patterned semiconductor, and a top electrode on the back side of the second substrate;

[0060] Figure 8

[0061] [ Figure 8 ] shows a side view of a flexible pressure or strain mapping device of a dual substrate configuration including a diode, wherein a first substrate includes a region impregnated with a hydrogel and a bottom electrode, and a second substrate includes a Schottky metal contact deposited on the front side of the substrate, a patterned semiconductor impregnated in the substrate, and a top electrode on the back side of the second substrate;

[0062] Fig. 9

[0063] [ Fig. 9 ] shows the dependence of the relative change of the output electrical measurement on the applied pressure, showing the sensitivity values ​​for the two regions of the curve;

[0064] Fig.10

[0065] [ Fig.10 ] shows a 4×4 array scheme of physical sensing elements coupled with diodes. The six elements applying pressure are represented by white stars, while the elements under measurement are represented by white dots (row 4-column 1);

[0066] Fig.11

[0067] [ Fig.11 ] shows the current-voltage (IV) curves of one physical sensing element coupled with a diode (row 4-column 1) under 10 kPa pressure (solid line) and without pressure, while the other six elements (row 1-column 1, row 1-column 4, row 2-column 1, row 2-column 3, row 4-column 3, row 4-column 4) under 10 kPa pressure (dashed line) from -2.5 V to +2.5 V;

[0068] Fig.12

[0069] [ Fig.12 ] shows the current output of all elements of the array at 2.5 V when a pressure of 10 kPa is applied to six elements (row 1-1 column, row 1-4 column, row 2-1 column, row 2-3 column, row 4-3 column, row 4-4 column) arranged orthogonally to the element in row 4-column 1;

[0070] Fig.13

[0071] [ Fig.13 ] shows a block diagram of a pressure mapping system according to the present invention, and the different elements required for smart surface implementation;

[0072] Fig.14

[0073] [ Fig.14 ] shows a top view of a flexible pressure or strain mapping device, which shows a first substrate with bottom electrodes on the back side and an impregnated hydrogel on the front side, where some of the bottom electrodes are short-circuited by conductive paths to form a larger area sensitive to pressure;

[0074] Fig.15

[0075] [ Fig.15 ] shows a top view of a flexible pressure or strain mapping device, which shows a first substrate, a back side of the substrate having a set of first and second interdigitated electrodes, and a front side having a set of impregnated hydrogels;

[0076] Fig.16

[0077] [ Fig.16 ] shows a side view of a flexible pressure or strain mapping device, which shows a first fiber substrate, which includes a layer area impregnated with a hydrogel, wherein a set of first interdigitated electrodes and second interdigitated electrodes contact a lower portion of the layer area impregnated with the hydrogel;

[0078] Fig.17

[0079] [ Fig.17 ] shows a side view of a flexible pressure or strain mapping device, which represents a first fiber substrate (which includes a layer area impregnated with a hydrogel) and a second fiber substrate (wherein the upper portion of the second fiber substrate has a set of first interdigitated electrodes and second interdigitated electrodes). DETAILED DESCRIPTION

[0080] The present invention relates to a flexible pressure or strain mapping device, such as [ Figure 1 ] as shown, the device comprises:

[0081] A fibrous substrate layer (1) comprising at least a layer region (2) impregnated with a hydrogel; and

[0082] at least a first sensor electrode (3), a portion of which is in contact with at least a lower portion of the layer region (2) impregnated with the hydrogel; and

[0083] at least a second sensor electrode (4), a portion of which is in contact with at least an upper portion of the layer region (2) impregnated with the hydrogel; and wherein,

[0084] The hydrogel is a cellulose derivative; and the cellulose derivative hydrogel is selected from the group consisting of cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, or their mixtures or their complexes.

[0085] Alternatively, the present invention relates to a flexible pressure or strain mapping device, such as Fig.15 and Fig.16 As shown, the device comprises:

[0086] A fibrous substrate layer (1) comprising at least a layer region (2) impregnated with a hydrogel; and

[0087] at least a first interdigitated electrode (19), a portion of which is in contact with at least a portion of the layer region (2) impregnated with the hydrogel; and

[0088] At least a second interdigitated electrode (20), a portion of which is in contact with at least the same portion of the layer region (2) impregnated with hydrogel as the portion contacted by the first interdigitated electrode (19); wherein the portion of the layer region (2) impregnated with hydrogel is selected from the lower portion of the layer region (2) impregnated with hydrogel or the upper portion of the layer region (2) impregnated with hydrogel; and, it is provided as follows: when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), at least an electrically insulating layer (21) separates the first interdigitated electrodes (19) and the second interdigitated electrodes (20) from each other; and wherein

[0089] The hydrogel is a cellulose derivative; and the cellulose derivative hydrogel is selected from the group consisting of cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, or mixtures thereof or their complexes.

[0090] The present invention also relates to a method for preparing a flexible pressure or strain mapping device, the method comprising the following steps:

[0091] a. depositing and impregnating the hydrogel into the fiber substrate layer (1), thereby forming at least a layer region (2) impregnated with the hydrogel; and

[0092] b. connecting a portion of the first sensor electrode (3) to at least the lower portion of the layer region (2) impregnated with the hydrogel; and

[0093] c. Connecting a portion of the second sensor electrode (4) to at least the upper portion of the hydrogel-impregnated layer region (2).

[0094] Alternatively, the present invention also relates to a method for preparing a flexible pressure or strain mapping device, the method comprising the following steps:

[0095] a. depositing and impregnating the hydrogel into the fiber substrate layer (1), thereby forming at least a layer region (2) impregnated with the hydrogel; and

[0096] b. connecting a portion of the first interdigitated electrode (19) to at least a portion of the layer region (2) impregnated with the hydrogel; and

[0097] c. connecting a portion of the second interdigital electrode (20) to at least the same portion of the layer region (2) impregnated with hydrogel as the portion contacted by the first interdigital electrode (19); wherein the portion of the layer region (2) impregnated with hydrogel is selected from the lower portion of the layer region (2) impregnated with hydrogel or the upper portion of the layer region (2) impregnated with hydrogel; and

[0098] d. When the flexible pressure or strain mapping device comprises a plurality of pairs of the first interdigital electrodes (19) and the second interdigital electrodes (20), the first interdigital electrodes (19) and the second interdigital electrodes (20) are separated from each other by an electrical insulating layer (21).

[0099] The present invention also relates to a pressure mapping system comprising a pressure sensitive surface (9), wherein the pressure sensitive surface (9) comprises a flexible pressure mapping device, as defined in the first aspect of the present invention, wherein the pressure mapping system further comprises:

[0100] An electronic instrument subsystem (11), the electronic instrument subsystem comprising a data transmission and reception unit (15), a microcontroller (12) and a power supply;

[0101] a hybrid connector (10) connecting the pressure sensitive surface (9) to the electronic instrument subsystem (11); and

[0102] The data sending and receiving unit (15) receives data obtained from the pressure sensitive surface (9) and transmits the data to the microcontroller (12).

[0103] The present invention employs an array comprising a plurality of first sensor electrodes (3) and second sensor electrodes (4), or a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), and a plurality of layer regions (2) impregnated with hydrogel, the array being configured for electrical detection of different physical stimuli, such as pressure, strain or elongation.

[0104] In an embodiment comprising a plurality of paired first interdigitated electrodes (19) and second interdigitated electrodes (20), an electrical insulating layer (21) separates the electrodes at the intersection of the electrodes to avoid short circuits between them. The electrical insulating layer (21) may comprise an uncharged hydrophobic polymer or a polycyclic aromatic hydrocarbon. More preferably, the electrical insulating layer (21) comprises at least one selected from the following: a lipid polymer, a carbohydrate polymer, a modified carbohydrate polymer, a vinyl polymer, a polycyclic aromatic hydrocarbon, a mixture thereof, or, in the case of the above polymers, a copolymer thereof.

[0105] In a preferred embodiment of the present invention, the flexible pressure or strain mapping device comprises a second fiber substrate layer (5), wherein the second sensor electrode (4) is arranged at a lower portion of the second fiber substrate layer (5), wherein the second sensor electrode (4) is simultaneously arranged and bonded above an upper portion of the layer region (2) impregnated with the hydrogel, as [ Figure 2]. Therefore, the second fiber substrate layer (5) is placed on top of the layer area (2) impregnated with hydrogel, ensuring electrical contact between the top surface of the fiber substrate layer (1) and the second sensor electrode (4) placed on the back of the second fiber substrate layer (5). Alternatively, the flexible pressure or strain mapping device includes a second fiber substrate layer (5), wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are arranged in the lower part of the second fiber substrate layer (5), wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are simultaneously arranged and joined in the upper part of the layer area (2) impregnated with hydrogel, and wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are separated from each other by an electrical insulating layer (21), as shown in Figure

[15] . In these preferred embodiments, the method for preparing a flexible pressure or strain mapping device further comprises the step of connecting and bonding a second fiber substrate layer (5) to the second sensor electrode (4), the second sensor electrode (4) being arranged on a lower portion of the second fiber substrate layer (5) and arranged above an upper portion of the hydrogel-impregnated region (2), wherein the second sensor electrode (4) is also arranged and bonded above the upper portion of the hydrogel-impregnated layer region (2); or the method for preparing a flexible pressure or strain mapping device comprises connecting a second fiber substrate layer (5) to the first interdigitated electrode (19) and the second interdigitated electrode (20). The first interdigital electrode (19) and the second interdigital electrode (20) are arranged on the lower part of the second fiber substrate layer (5) and arranged above the upper part of the region (2) impregnated with hydrogel; wherein the first interdigital electrode (19) and the second interdigital electrode (20) are also arranged and joined to the upper part of the layer region (2) impregnated with hydrogel, and wherein: when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20), the first interdigital electrodes (19) and the second interdigital electrodes (20) are separated from each other by at least an electrical insulating layer (21). The remaining part of the second fiber substrate layer (5) (which is not connected and not joined to the upper part of the layer region (2) impregnated with hydrogel) is connected and joined to the upper part of the fiber substrate layer (1).

[0106] In other preferred embodiments of the present invention, the flexible pressure or strain mapping device comprises a third fiber substrate layer (6), the first sensor electrode (3) being arranged on an upper portion of the third fiber substrate layer (6) and being arranged and bonded below a lower portion of the hydrogel-impregnated region (2), as shown in [ Figure 3] as shown. The remaining portion of the third fiber substrate layer (6) (the remaining portion is not connected and not joined above the lower portion of the area impregnated with hydrogel (2)) is connected and joined above the lower portion of the fiber substrate layer (1). Alternatively, the flexible pressure or strain mapping device includes a third fiber substrate layer (6), the first interdigital electrode (19) and the second interdigital electrode (20) are arranged at the upper portion of the third fiber substrate layer (6), wherein the first interdigital electrode (19) and the second interdigital electrode (20) are simultaneously arranged and joined below the lower portion of the layer area impregnated with hydrogel, as shown in [ Fig.17 ] as shown. Fig.15 ] is similar to the embodiment of the present invention, when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20), at least the electrical insulating layer (21) separates the first interdigital electrodes (19) and the second interdigital electrodes (20) from each other. In these preferred embodiments, the method for preparing the flexible pressure or strain mapping device also includes the step of connecting and bonding the third fiber substrate layer (6) to the first sensor electrode (3), the first sensor electrode (3) being arranged on the upper part of the third fiber substrate layer (6) and arranged below the lower part of the area (2) impregnated with the hydrogel, wherein the first sensor electrode (3) is also arranged and bonded to the lower part of the area (2) impregnated with the hydrogel; or the method for preparing the flexible pressure or strain mapping device includes connecting the third fiber substrate layer (6) to the first interdigital electrodes (19) and the second interdigital electrodes (20). According to the step, the first interdigitated electrode (19) and the second interdigitated electrode (20) are arranged on the upper part of the third fiber substrate layer (6) and arranged below the lower part of the area (2) impregnated with hydrogel, wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are also arranged and joined below the lower part of the layer area (2) impregnated with hydrogel, wherein: when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), the first interdigitated electrodes (19) and the second interdigitated electrodes (20) are separated from each other by an electrical insulating layer (21).

[0107] [ Figure 3] The structure shown in FIG. 1 is realized by the bottom first sensor electrode (3) of the third fiber substrate layer (6) being in contact with the bottom surface of the hydrogel-impregnated region (2) of the first fiber substrate layer (1), and the top second sensor electrode (4) of the second fiber substrate layer (5) being in contact with the top surface of the hydrogel-impregnated region (2). In this preferred embodiment, the method for preparing the flexible pressure or strain mapping device further includes the step of connecting and bonding the third fiber substrate layer (6) to the first sensor electrode (3) and connecting below the lower portion of the hydrogel-impregnated region (2).

[0108] In other embodiments according to the present invention, the flexible pressure or strain mapping device comprises a rectifying element, the rectifying element comprising a conducting component (7) and a semiconductor component (8), wherein the semiconductor component (8) is connected to at least one of the following: the first sensor electrode (3), the second sensor electrode (4), the first interdigital electrode (19) or the second interdigital electrode (20); and the conducting component (7) is connected to the semiconductor component (8), such as Figure 5 , Figure 6 , Figure 7 or Figure 8 In this preferred embodiment, the method for preparing the flexible pressure or strain mapping device further comprises the step of connecting a rectifying element to at least one of the first sensor electrode (3), the second sensor electrode (4), the first interdigital electrode (19) or the second interdigital electrode (20), wherein the rectifying element comprises a conducting component (7) and a semiconductor component (8).

[0109] In a preferred embodiment of the present invention, the flexible pressure or strain mapping device comprises at least an array of at least one of the following groups: a first sensor electrode (3), a second sensor electrode (4), a first interdigitated electrode (19) or a second interdigitated electrode (20); and, wherein each of the first sensor electrodes (3) or the second sensor electrodes (4) contained in the array is in contact with at least a lower portion or an upper portion of a plurality of layer regions (2) impregnated with a hydrogel; and, wherein each of the first interdigitated electrode (19) or the second interdigitated electrode (20) contained in the array is in contact with at least the same portion (the portion is selected from the lower portion or the upper portion) of a plurality of layer regions (2) impregnated with a hydrogel, wherein (with the proviso that): when the flexible pressure or strain mapping device comprises a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), the first interdigitated electrodes (19) and the second interdigitated electrodes (20) are separated from each other by an electrical insulating layer (21). More preferably, a plurality of first sensor electrodes (3), or a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20) are arranged in parallel, and wherein each of the first sensor electrodes (3), or each of the pairs of first interdigital electrodes (19) and second interdigital electrodes (20) is in contact with at least a lower portion of a plurality of layer regions (2) impregnated with a hydrogel, wherein (with the proviso that): when the flexible pressure or strain mapping device comprises a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20), the first interdigital electrodes (19) and the second interdigital electrodes (20) are separated from each other by an electrical insulating layer (21) to form a planar structure, which is configured to be capable of detecting a physical stimulus selected from pressure or strain, such as [ Figure 4 ] as shown.

[0110] In other embodiments, in a flexible pressure or strain mapping device, a plurality of second sensor electrodes (4), or a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20) are arranged in parallel, wherein each of the second sensor electrodes (4), or each of the pairs of first interdigital electrodes (19) and second interdigital electrodes (20) contacts at least an upper portion of a plurality of layer regions (2) impregnated with a hydrogel, wherein (with the proviso that): when the flexible pressure or strain mapping device comprises a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20), the first interdigital electrodes (19) and the second interdigital electrodes (20) are separated from each other by an electrical insulating layer (21) to form a planar structure, which is configured to be capable of detecting a physical stimulus selected from pressure or strain.

[0111] The electrical connection of different bottom electrodes and top electrodes in series in the form of rows or columns enables the formation of different array configurations of layer areas (2) impregnated with hydrogel. This planar (XY) structure enables the detection of the exact position of a physical stimulus on the surface of the layer area (2) impregnated with hydrogel. Preferably, the rows or columns are arranged orthogonally to each other, wherein each row or column comprises a plurality of physical sensors, i.e., layer areas (2) impregnated with hydrogel and electrodes (3, 4).

[0112] As an exemplary embodiment of the reading protocol, the output of each physical sensing element of the array, the layer area (2) impregnated with hydrogel, and the electrode is read by supplying a specific voltage pulse (duration of 1 μs to 10 s and amplitude of 0.01 V to 5 V). The pulse is supplied by a microcontroller and transmitted to the row or column of the physical sensing element through a multiplexer. After the pulse passes through the physical sensing element, it is received by the microcontroller analog pin, and a multiplexer is also used to select which row or column should be selected. Once entering the microcontroller, the analog signal is converted into a digital signal and displayed in the form of a graphical array with a refresh rate of 1 ms to 10 s. In the case of physical sensing elements, the array is 20×20.

[0113] Likewise, when several layer regions (2) impregnated with hydrogel are connected to the same electrode row or electrode column, the connections between these layer regions (2) impregnated with hydrogel and the electrodes may generate crosstalk and ghosting effects in the array.

[0114] In the case of crosstalk, an element in the array is able to detect an input even though the pressure or strain stimulus is not applied directly to that element but to surrounding elements. This phenomenon is particularly severe when the sensing component of the device is a continuous material. One strategy to reduce this effect is to impregnate the hydrogel in selected layer areas and make the layer areas impregnated with hydrogel discrete (2). Since each physical sensing element is independent, the responses of different elements will be isolated from surrounding elements. In the case of ghosting, this phenomenon may be caused by current flowing in both directions of the physical sensing element, resulting in a conduction path formed by other stressed elements.

[0115] In a preferred embodiment according to the present invention, by incorporating a rectifier element in each element of the sensing array, crosstalk and ghosting problems can be solved. A rectifier element is an electronic component with two terminals that allows current to pass in a specific direction (forward). This is especially important for elements that have very low resistance in the forward current and very high resistance in the opposite direction (reverse). In a preferred embodiment, the rectifier element is a Schottky diode (also called a Schottky barrier diode), which forms an energy barrier for electrons at a metal-semiconductor junction, thereby forming a rectifier diode. Other types of rectifier elements, such as pn junctions and dual-coupled transistors, can also be integrated.

[0116] Therefore, in a preferred embodiment, the flexible pressure or strain mapping device comprises a plurality of said rectifying elements in an array, wherein each conductive member (7) is arranged orthogonally relative to at least one of the following: a first sensor electrode (3); a second sensor electrode (4); or a pair of a first interdigitated electrode (19) and a second interdigitated electrode (20), such as Figure 5 or Figure 7 shown.

[0117] Integrating a rectifying element (e.g., a Schottky diode) in series with each electrode and the hydrogel-impregnated layer region (2) will prevent current from flowing through unwanted paths, thereby reducing or eliminating crosstalk and ghosting effects in other physical sensing elements. Fig.11 and Fig.12 These advantages of reducing crosstalk and ghosting effects are shown in the scheme [ Fig.10 ] in the stress mode. Under the applied positive voltage of 2.5V, the current value of the selected element (row 4-column 1) is in [ Fig.11 ], there is a significant difference between the two different configurations. When the element is pressed at only 10 kPa (e.g., [ Fig.11 ]), the current value is higher than 6μA, which is more than 100 times higher than the current value when pressing the other six elements in the orthogonal configuration (as shown in [ Fig.11 ] is about 50nA). Fig.12 ], we can observe that the current values ​​of six different elements (row 1-column 1, row 1-column 4, row 2-column 1, row 2-column 3, row 4-column 3, row 4-column 4) at 2.5V when pressed are at least 50 times higher than the current values ​​of the unpressed elements (row 4-column 1). These facts confirm that the ghosting effect in the element being read (row 4-column 1) is reduced in the presence of a coupled rectifying element.

[0118] Preferably, the second fiber substrate layer (5) will include Schottky metal contacts deposited on the back side of the substrate, followed by patterned deposition of semiconductor components (8) and second sensor electrodes (4), such as [ Figure 5 ] is shown in the top view in FIG. The Schottky diode is formed between the Schottky metal contact and the semiconductor, while the second electrode ensures an ohmic contact with the semiconductor.

[0119] The combination of two electronic components (physical sensor comprising a first sensor electrode (3), a second sensor electrode (4), a layer region (2) impregnated with a hydrogel and a rectifying element) is achieved by placing a second fiber substrate layer (5) containing a rectifying element on top of the layer region (2) impregnated with a hydrogel, thereby ensuring electrical contact between the top surface of the fiber substrate layer (1) with the impregnated hydrogel and the top second sensor electrode (4) on the bottom surface of the second fiber substrate layer (5). Figure 6 ]and[ Figure 7 ] show the side view and top view, respectively, of two substrate configurations in which the sensing element and the diode are coupled.

[0120] This architecture is possible due to the various properties of the different components. Since the fiber substrate layer (1) has a specific area of ​​lateral electrical conduction due to the hydrogel impregnation, the bottom first sensor electrode (3) can be deposited on the bottom surface of the fiber substrate layer (1). This fact will eliminate the possibility of a short circuit between the first sensor electrode (3) and the second sensor electrode (4) at the physical sensor terminal. In addition, separating the physical sensor element consisting of two electrodes and the layer area (2) impregnated with hydrogel from the Schottky diode in the different substrates and separating the physical sensor element from the Schottky diode in the XY plane will also help to achieve a more robust technology. If the Schottky diode is aligned with the physical sensor, an electrical contact will be established between the semiconductor component (8) and the hydrogel, resulting in parasitic currents and resulting in device performance losses. This architecture can separate the two element planes without adding further material deposition for passivation.

[0121] This architecture also enables the orientation of the two terminal electrodes towards the same side, in the preferred embodiment presented, i.e. the bottom surface, thus allowing simple integration of the device with communication electronics. Thus, the architecture presented here ensures technical advantages such as reduced short circuit possibilities, avoidance of direct contact of the hydrogel with the semiconductor component (8), minimum number of layered materials and therefore minimum deposition steps.

[0122] In addition, another structure is proposed that combines the physical sensor and the rectifying element while utilizing the porous characteristics of the fiber substrate layer. Since the hydrogel is impregnated in the fiber substrate layer (1), the semiconductor component (8) can also be impregnated in certain areas of the second fiber substrate layer (5). Figure 8 ] presents a side view structure showing the conducting part (7) of the rectifying element and the second sensor electrode (4) located on different sides of the layer area (2) impregnated with hydrogel. The main advantage of this configuration is the reduction of short circuits between the two electrodes such as diodes (Schottky metal and ohmic contact) that may be caused by the deposition method, while maintaining the advantages obtained by the previous description.

[0123] Hydrogel is a piezoelectrically responsive material that can be defined as a three-dimensional (3D) network of hydrophilic polymers that can swell in water and retain large amounts of water while maintaining its structure due to chemical or physical cross-linking of individual polymer chains.

[0124] Several hydrogels may be selected based on their sustainable properties in terms of being recyclable or compostable, i.e., hydrogels comprising cellulose-based biopolymers.

[0125] In the most preferred embodiment, the hydrogel is a cellulose derivative hydrogel. More preferably, the cellulose derivative hydrogel is selected from the group consisting of cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, or mixtures thereof or their complexes. In the most preferred embodiment, the cellulose derivative hydrogel is carboxymethylcellulose or sodium carboxymethylcellulose.

[0126] As described above, hydrogels are formed by chemical or physical crosslinking of individual polymer chains. Chemical crosslinking can be achieved when the polymer is combined with an ionic salt consisting of an anion (monovalent, divalent or trivalent) and a cation (monovalent, divalent or trivalent) through a chemical reaction. Those skilled in the art will appreciate that other forms of chemical crosslinking are also possible, such as covalent crosslinking.

[0127] In a preferred embodiment according to the present invention, the layer region (2) impregnated with the hydrogel comprises at least one salt in the hydrogel matrix, wherein the salt comprises cations selected from monovalent cations, divalent cations or trivalent cations, the cations acting as ionic crosslinkers, wherein the cations are preferably zinc cations, calcium cations, magnesium cations, nickel cations or copper cations. The most preferred salts used in the present invention are zinc or calcium, which are classified as non-toxic and environmentally friendly materials.

[0128] In a preferred embodiment according to the present invention, at least one of the first sensor electrode (3) or the second sensor electrode (4) is selected from the group consisting of conductive materials, such as carbon, silver, gold, platinum, copper, aluminum or their alloys; or conductive polymers or copolymers, such as polyaniline or poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). These conductive materials ensure electrical connection between the elements and form a rectifying element.

[0129] In an embodiment according to the present invention, at least one of the group consisting of the first sensor electrode (3) or the second sensor electrode (4) is selected from the group consisting of a strip, a bar or a line.

[0130] In a preferred embodiment according to the invention, the rectifying element comprises a Schottky diode, and the conducting component (7) is selected from: a Schottky metal contact, or a conductive polymer or copolymer (e.g. polyaniline or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate); wherein the Schottky metal contact is selected from silver, gold, platinum, palladium or alloys containing said metal elements; and wherein the semiconductor component (8) of the Schottky diode is selected from n-type zinc oxide, n-type zinc tin oxide, n-type indium gallium zinc oxide or n-type silicon-based semiconductor. The second contact of the Schottky diode is an ohmic contact selected from the group consisting of carbon, aluminum, tin or alloys containing said elements. In the most preferred embodiment according to the invention, the Schottky metal contact used is silver, the semiconductor component (8) is n-type zinc oxide (ZnO) deposited by screen printing in a carboxymethylcellulose-based ink, and carbon is used as the second electrode (4).

[0131] The steps of depositing and impregnating the hydrogel in the fiber substrate layer (1), at least forming a layer region (2) impregnated with the hydrogel, can be performed to form a pattern in a specific region of the fiber substrate layer (1), thereby creating a personalized sensing element.

[0132] An elastomer may be added to the fiber substrate layer (1) to improve its mechanical properties, such as polyethylene glycol (PEG) or glycerol. Alternatively, a fabric or other fiber structure (such as glass fiber) may also be used to improve the mechanical properties of the fiber substrate layer (1).

[0133] In a preferred embodiment, the fiber substrate layer (1) is 80 g·m -2 Alternatively, the paper layer may be covered by cork, cloth fabric, cotton-based fabric or a mixture thereof, or the paper layer may incorporate cork, cloth fabric, cotton-based fabric or a mixture thereof.

[0134] In a preferred embodiment, the flexible pressure or strain mapping device comprises a plurality of superposed fiber substrate layers (1).

[0135] In other embodiments, a plurality of second fiber substrate layers (5) may be stacked, wherein a second fiber substrate layer (5) (n+1) is stacked on top of a second fiber substrate layer (5) (n), wherein n is an integer greater than or equal to 2. In this embodiment, a lower second fiber substrate layer (5) having the second sensor electrode (4) is arranged and bonded to the upper portion of the fiber substrate layer (1).

[0136] In other embodiments, a plurality of third fiber substrate layers (6) may be stacked, wherein a third fiber substrate layer (6) (n+1) is stacked on top of a third fiber substrate layer (6) (n), wherein n is an integer greater than or equal to 2. In this embodiment, a higher third fiber substrate layer (6) having the first sensor electrode (3) is arranged and bonded to the top of a lower portion of the fiber substrate layer (1).

[0137] Cellulose-based hydrogels exhibit mechanical responses to deformation due to two different properties: i) they deform easily when an external force is applied and ii) the presence of different cations in the cellulose hydrogel structure, which creates conductive permeation pathways in the material. Therefore, when the hydrogel is subjected to pressure or strain, these materials can be used as active layers in electrical pressure or strain sensors. Sensing methods can be based on the measurement of intrinsic changes in the resistance (continuous current), impedance (alternating current), or capacitance of the hydrogel, as well as the measurement of changes in the voltage or current of an electrical signal applied to the hydrogel.

[0138] The electrical measurement of these changes must be achieved by incorporating electrodes, creating a physical sensing element consisting of a layer region (2) impregnated with hydrogel, with two different electrodes on the top and bottom surfaces, namely at least a first sensor electrode (3) and at least a second sensor electrode (4). Due to the impregnation properties of the hydrogel in the fiber substrate layer (1), different electrode structures can be used, such as Figure 1 , Figure 2 and Figure 3 shown and described here:

[0139] In a preferred embodiment according to the present invention, any one of the fiber substrate layer (1), the second fiber substrate layer (5) or the third fiber substrate layer (6) is selected from the following: paper products comprising a cellulose fiber-based porous structure; woven fabrics; non-woven fabrics; silicon aerogels; polyurethane aerogels; silicon foams; melamine foams; polyurethane foams; nickel foams; sponges, for example, porous sponges, polyurethane sponges, silicon sponges, wood sponges, cork substrates, or composites or derivatives thereof. Therefore, any one of the fiber substrate layer (1), the second fiber substrate layer (5) or the third fiber substrate layer (6) includes but is not limited to an electrically insulating fiber substrate. Therefore, the area of ​​the fiber substrate layer (1) not impregnated with the hydrogel maintains its electrically insulating properties.

[0140] The preferred method for preparing the flexible pressure or strain mapping device according to the present invention is centered around a printing or drop-on-demand method. This enables the flexible pressure or strain mapping device to be mass produced and has the potential to deposit the hydrogel on a variety of substrates, i.e. metals, alloys, glass, polymers, composites, paper and fabrics, while keeping production costs low. The drop-on-demand method is applicable to large areas.

[0141] In other embodiments of preparing a flexible pressure or strain mapping device according to the present invention, the deposition step can be performed by a film application step (e.g., a doctor blade), a screen printing step, a flexographic printing step, a spraying step, or an inkjet, roll-to-roll (R2R) compatible step, as will be appreciated by those skilled in the art. Several methods that can be used in the deposition step are described in "Flexible Printed Sensors—Overview of Fabrication Technologies" by Johanna Zikulnig and Jürgen Kosel, Reference Module in Biomedical Sciences, Elsevier, 2021.

[0142] In the most preferred embodiment according to the present invention, the hydrogel is incorporated and impregnated into a fibrous substrate layer (1), such as a commercial paper or fabric substrate, with a heat treatment below 100°C to produce an active layer region (2) impregnated with the hydrogel.

[0143] Thus, using a paper or fabric based fiber substrate layer (1) allows other materials such as biopolymer hydrogels to be impregnated into the interior of the substrate structure. In this impregnation method, the porous substrate consisting of fibers or treads will be surrounded by the polymer component throughout the thickness of the substrate.

[0144] The preparation method according to the present invention also enables the personalization of the hydrogel, since the polymer component can be deposited only in selected and defined areas of a fiber substrate layer (1), such as a paper or fabric substrate. The procedure will create conductive areas on the fiber substrate layer (1) in the lateral direction of the substrate surface. Thus, a conductive path will be formed from the top surface to the bottom surface of the fiber substrate layer (1), thereby enabling the deposition of electrodes on both sides of the substrate. In addition, an electrically insulating material can also be deposited and impregnated in the substrate in selected areas to improve the patterning of the hydrogel and reduce the ionic conductivity of the natural fiber substrate. The insulating material can be a hydrophobic polymer that increases the impermeability of water-based materials. More specifically, the insulating material can be a wax, which is an organic compound that is insoluble in water, is a lipophilic and plastic solid at ambient temperature, and has a melting point above 40°C.

[0145] Furthermore, the impregnation of the hydrogel on the fibrous substrate layer (1) produces a symbiotic phenomenon for physical stimulus detection because the fibrous substrate layer (1) (eg, paper or fabric fiber structure) provides mechanical stability to the hydrogel formed therein.

[0146] Embodiments of the invention comprising an array of physical sensors (i.e., a layer region (2) impregnated with a hydrogel and electrodes coupled to a rectifying element) can be used for different mechanical deformation measurements. The surface of the array can be used to detect the presence of an object on top of it, being able to determine the location of the object, as well as its shape, weight, and thus, being able to determine a number of different objects on top. Possible objects include consumer goods, stored products, museum objects, and any other use where the location, shape, weight and / or presence of an object needs to be determined and monitored for inventory control. In addition, other applications are possible, such as determining the amount of liquid in a container, or determining the presence of a person or organism (e.g., an animal) on a surface.

[0147] In other preferred embodiments according to the present invention, Fig.14 ] As shown in the figure, a plurality of sensing elements (i.e., a layer region (2) impregnated with a hydrogel) are interconnected by connecting at least one conductive path (18) to a plurality of electrodes selected from a first sensor electrode (3), a second sensor electrode (4), or a pair of a first interdigitated electrode (19) and a second interdigitated electrode (20). The conductive path (18) is selected from the group consisting of conductive cables or conductive strips. This embodiment is particularly advantageous when a larger sensor is required, where the sensing elements can be easily combined together by short-circuiting the electrodes of the individual sensing elements via the conductive path (18). The conductive path (18) is preferably made of a material selected from the group consisting of conductive materials, such as carbon, silver, gold, platinum, copper, aluminum, or alloys thereof; or a conductive polymer or copolymer, such as polyaniline or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

[0148] Example

[0149] An exemplary formulation used in the method of making a flexible pressure or strain mapping device includes:

[0150] - Sodium carboxymethylcellulose - CMC (Sigma Aldrich Mw about 250,000): solution concentration from about 0.1 wt % to about 10.0 wt % in water;

[0151] - calcium chloride (CaCl2) - in a concentration of from about 0.01 M to about 10.0 M in water;

[0152] - Zinc chloride (ZnCl2) - in concentrations ranging from about 0.01 M to about 10.0 M in water.

[0153] The flexible pressure or strain mapping device according to the present invention is prepared according to the following specifications:

[0154] Total perceptible area of ​​the layer area (2) impregnated with hydrogel: 400 cm 2 ;

[0155] The number of sensing elements including the layer region (2) impregnated with the hydrogel: 400;

[0156] Area of ​​each sensing element: 0.09 cm 2 ;

[0157] Minimum distance between sensing elements: 0.9cm;

[0158] Sensitivity: -10 -2 kPa -1 ,like[ Fig. 9 ] as shown;

[0159] Detection limit: 1g;

[0160] The degree of reduction of ghosting effect by using Schottky diodes: >99%, such as [ Fig.10 ]and[ Fig.11 ] as shown;

[0161] Response and recovery time: <1s;

[0162] Fatigue: 1000 pressure cycles;

[0163] Temporal stability: <10%.

[0164] The invention can also be applied to touch and contour smart surfaces that are sensitive to pressure or strain for drawing and touch interfaces, capable of detecting the movement of fingers, pencils, pens or other objects on top of the surface, and for handwriting recognition.

[0165] According to a third aspect of the invention, the touch and contour smart surface is a pressure mapping system.

[0166] All physical interactions with the pressure mapping system can be digitized and visualized in real time on a computer software interface. Physical interactions assume the use of hands, fingers, pencils, pens, etc., which can serve as a means of interaction between the user and the smart surface. Subsequently, the digital content can be programmed through accessible languages ​​(especially graphics), allowing one to animate the content generated on the sensitive surface in the form of movement and sound through a computer program. This embodiment consists of a variety of functions generated by the various components of the system integrated into three parts of the system, including a pressure sensitive surface (9), including a flexible pressure mapping device, as defined in the first aspect of the invention; a computer program; and a portable device for controlling the sensitive surface electronics and communicating between it and the computer program.

[0167] [ Fig.13] shows an embodiment of a pressure mapping system, which is composed of different elements: a pressure sensitive surface (9); a hybrid connector (10); an electronic instrumentation system (11); a microcontroller (12); a remote communication unit (13); a data transmission and reception unit (15); and a power source. In a preferred embodiment, in the pressure mapping system, the power source includes at least one of the group consisting of a charging unit (14) or a battery (16). In other embodiments, in the pressure mapping system, the electronic instrumentation subsystem (11) includes an acoustic sensor (17).

[0168] The pressure sensitive surface (9) comprises a flexible pressure mapping device as defined in the first aspect of the invention.

[0169] The hybrid connector (10) electrically connects the pressure sensitive surface (9) to the electronic instrument subsystem (11) via electrodes, namely at least a first sensor electrode (3) and at least a second sensor electrode (4) included in the flexible pressure mapping device. The hybrid connector (10) may include elements such as pins, springs, clips, alligator clips or surface electrodes, which may be composed of conductive materials such as metals such as gold, silver, aluminum or copper.

[0170] As used in this description, the expressions "about" and "approximately" refer to a numerical range of approximately 10% of a specified number.

[0171] As used in this specification, the expression "substantially" means that the actual value is within an interval of about 10% of the expected value, variable or related limit, particularly within an interval of about 5% of the expected value, variable or related limit, or particularly within an interval of about 1% of the expected value, variable or related limit.

[0172] In addition, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise or clear from the context, the phrase "X employs A or B" is intended to mean any of the natural inclusive combinations. That is, the phrase "X employs A or B" satisfies any of the following: X employs A; X employs B; or X employs both A and B.

[0173] In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to the singular form.

[0174] Moreover, as used herein, the term "exemplary" is intended to mean serving as an illustration or example of something, not to imply a preference.

[0175] The above-mentioned subject matter is only used as an explanation of the present invention and should not be interpreted as limiting the present invention. According to the present invention, the terms used to describe specific embodiments should not be interpreted as limiting the present invention. As used in this specification, definite and indefinite articles, in their singular form, are intended to interpret the plural form, unless the context of the specification clearly indicates the opposite. It should be understood that when the expressions "including" and "comprising" are used in this specification, the existence of specified features, elements, parts, steps and related operations is specified, but the possibility of considering other features, elements, parts, steps and operations is not excluded.

[0176] Any modification, as long as it does not change the basic features of the appended claims, should be deemed to fall within the scope of protection of the present invention.

[0177] Reference Symbols List

[0178] 1. Fiber substrate layer;

[0179] 2. The layer area impregnated with the hydrogel;

[0180] 3. A first sensor electrode;

[0181] 4. A second sensor electrode;

[0182] 5. A second fiber substrate layer;

[0183] 6. The third fiber substrate layer;

[0184] 7. Conducting parts;

[0185] 8.Semiconductor components;

[0186] 9. Pressure sensitive surface;

[0187] 10. Hybrid connector;

[0188] 11. Electronic instrument subsystem;

[0189] 12. Microcontroller;

[0190] 13. Telecommunications unit;

[0191] 14. Charging unit;

[0192] 15. Data sending and receiving unit;

[0193] 16.Battery;

[0194] 17.Acoustic sensor;

[0195] 18.Conduction path;

[0196] 19. A first interdigital electrode;

[0197] 20. A second interdigital electrode;

[0198] 21. Electrical insulation layer.

[0199] Citation List

[0200] The citation list is as follows:

[0201] Patent Literature

[0202] PTL1: International patent application No.WO2013113122A1 of Smart SkinTechnologies INC., entitled “PRESSURE MAPPING AND ORIENTATION SENSING SYSTEM” and published on August 8, 2013. Non-patent literature

[0203] NPL1: Johanna Zikulnig, Jürgen Kosel, "Flexible Printed Sensors—Overview of Fabrication Technologies", Reference Module in BiomedicalSciences, Elsevier, 2021.

Claims

1. A flexible pressure or strain mapping device, characterized in that: The flexible pressure or strain mapping device comprises: A fibrous substrate layer (1) comprising at least a layer region (2) impregnated with a hydrogel; and at least a first sensor electrode (3), a portion of which is in contact with at least a lower portion of the layer region (2) impregnated with the hydrogel; and at least a second sensor electrode (4), a portion of which is in contact with at least an upper portion of the layer region (2) impregnated with the hydrogel; and wherein, The hydrogel is a cellulose derivative; the cellulose derivative hydrogel is selected from cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, or mixtures thereof or their complexes.

2. A flexible pressure or strain mapping device, characterized in that: The flexible pressure or strain mapping device comprises: A fibrous substrate layer (1) comprising at least a layer region (2) impregnated with a hydrogel; and at least a first interdigitated electrode (19), a portion of which is in contact with at least a portion of the layer region (2) impregnated with the hydrogel; and At least a second interdigitated electrode (20), a portion of which is in contact with at least the same portion of the layer region (2) impregnated with hydrogel as the portion contacted by the first interdigitated electrode (19); wherein the portion of the layer region (2) impregnated with hydrogel is selected from the lower portion of the layer region (2) impregnated with hydrogel or the upper portion of the layer region (2) impregnated with hydrogel; and when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), at least an electrically insulating layer (21) separates the first interdigitated electrodes (19) from the second interdigitated electrodes (20); and wherein The hydrogel is a cellulose derivative; the cellulose derivative hydrogel is selected from cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose acetate trimellitate, hydroxypropyl methylcellulose phthalate, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, their complexes or their complexes with natural polymers, polyvinyl alcohol, polyelectrolyte complexes, interpenetrating polymer networks, cellulose-inorganic hybrid hydrogels, their mixtures or their complexes.

3. A flexible pressure or strain mapping device according to any one of claims 1 or 2, wherein the flexible pressure or strain mapping device comprises a second fiber substrate layer (5), wherein: The second sensor electrode (4) is arranged on the lower part of the second fiber substrate layer (5), wherein the second sensor electrode (4) is simultaneously arranged and bonded above the upper part of the layer area (2) impregnated with hydrogel; or the flexible pressure or strain mapping device includes a second fiber substrate layer (5), wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are arranged on the lower part of the second fiber substrate layer (5), wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are simultaneously arranged and bonded above the upper part of the layer area (2) impregnated with hydrogel, wherein when the flexible pressure or strain mapping device includes a plurality of pairs of first interdigitated electrodes (19) and second interdigitated electrodes (20), the first interdigitated electrodes (19) and the second interdigitated electrodes (20) are separated from each other by an electrical insulating layer (21).

4. A flexible pressure or strain mapping device according to any one of claims 1 to 3, wherein the flexible pressure or strain mapping device comprises a third fiber substrate layer (6), wherein: The first sensor electrode (3) is arranged on the upper part of the third fiber substrate layer (6), and the first sensor electrode (3) is simultaneously arranged and joined below the lower part of the area (2) impregnated with hydrogel; or the flexible pressure or strain mapping device includes a third fiber substrate layer (6), wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are arranged on the upper part of the third fiber substrate layer (6), wherein the first interdigitated electrode (19) and the second interdigitated electrode (20) are simultaneously arranged and joined below the lower part of the layer area (2) impregnated with hydrogel.

5. A flexible pressure or strain mapping device according to any one of claims 1 to 4, wherein the flexible pressure or strain mapping device comprises a rectifying element, the rectifying element comprising a conducting component (7) and a semiconductor component (8), wherein: The semiconductor component (8) is connected to at least one of: the first sensor electrode (3), the second sensor electrode (4), the first interdigital electrode (19) or the second interdigital electrode (20); and the conductive component (7) is connected to the semiconductor component (8).

6. A flexible pressure or strain mapping device according to any one of the preceding claims, wherein: The flexible pressure or strain mapping device comprises at least an array of at least one of the following groups: a first sensor electrode (3), a second sensor electrode (4), a first interdigitated electrode (19) or a second interdigitated electrode (20); and wherein each of the first sensor electrode (3) or the second sensor electrode (4) included in the array contacts at least a lower portion or an upper portion of a plurality of layer regions (2) impregnated with a hydrogel; and wherein each of the first interdigitated electrode (19) or the second interdigitated electrode (20) included in the array contacts at least the same portion of a plurality of layer regions (2) impregnated with a hydrogel, the portion being selected from a lower portion or an upper portion.

7. A flexible pressure or strain mapping device according to the preceding claim, wherein: A plurality of first sensor electrodes (3) or a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20) are arranged in parallel; and wherein each of the first sensor electrodes (3) or each of the pairs of first interdigital electrodes (19) and second interdigital electrodes (20) contacts at least a lower portion of a plurality of layer regions (2) impregnated with a hydrogel, thereby forming a planar structure, which is configured to detect a physical stimulus selected from pressure or strain.

8. The flexible pressure or strain mapping device according to any one of claims 6 or 7, wherein: A plurality of second sensor electrodes (4) or a plurality of pairs of first interdigital electrodes (19) and second interdigital electrodes (20) are arranged in parallel; and wherein each of the second sensor electrodes (4) or each of the pairs of first interdigital electrodes (19) and second interdigital electrodes (20) contacts at least an upper portion of a plurality of layer regions (2) impregnated with a hydrogel, thereby forming a planar structure, which is configured to be capable of detecting a physical stimulus selected from pressure or strain.

9. The flexible pressure or strain mapping device according to any one of claims 5 to 8, wherein: The flexible pressure or strain mapping device comprises a plurality of the rectifying elements in an array, wherein each conductive component (7) is arranged orthogonally relative to at least one of: the first sensor electrode (3); the second sensor electrode (4); or a pair of first interdigitated electrodes (19) and second interdigitated electrodes (20).

10. The flexible pressure or strain mapping device according to any one of claims 5 to 9, wherein: A plurality of layer regions (2) impregnated with hydrogel are interconnected by connecting at least one conductive path (18) to a plurality of electrodes selected from a first sensor electrode (3), a second sensor electrode (4), or a pair of a first interdigitated electrode (19) and a second interdigitated electrode (20).

11. A flexible pressure or strain mapping device according to any one of the preceding claims, wherein: The layer region (2) impregnated with hydrogel comprises at least a salt in a hydrogel matrix, wherein the salt comprises a cation selected from monovalent cations, divalent cations or trivalent cations, and the cation serves as an ionic crosslinker, wherein, preferably, the cation is a zinc cation, a calcium cation, a magnesium cation, a nickel cation or a copper cation, or a mixture thereof.

12. A flexible pressure or strain mapping device according to any one of the preceding claims, wherein: Any one of the first fiber substrate layer (1), the second fiber substrate layer (5) or the third fiber substrate layer (6) is selected from the following: paper products including a cellulose fiber-based porous structure; woven fabrics; non-woven fabrics; silicon aerogels; polyurethane aerogels; silicon foams; melamine foams; polyurethane foams; nickel foams; Sponges, such as porifera sponges, polyurethane sponges, silicone sponges, wood sponges, cork substrates, or composites or derivatives thereof.

13. A flexible pressure or strain mapping device according to any one of the preceding claims, wherein: At least one of the first sensor electrode (3) or the second sensor electrode (4) is selected from: carbon, silver, gold, platinum, copper, aluminum or alloys thereof; or a conductive polymer or copolymer, such as polyaniline or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate.

14. A flexible pressure or strain mapping device according to any one of claims 5 to 13, wherein: The rectifying element comprises a Schottky diode, and the conducting component (7) is selected from: a Schottky metal contact; or a conductive polymer or copolymer, for example, the conductive polymer or copolymer is polyaniline or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate; wherein the Schottky metal contact is selected from silver, gold, platinum, palladium or an alloy comprising the metal element; and wherein the semiconductor component (8) of the Schottky diode is selected from n-type zinc oxide, n-type zinc tin oxide, n-type indium gallium zinc oxide or n-type silicon-based semiconductor.

15. A method of preparing a flexible pressure or strain mapping device, the flexible pressure or strain mapping device being as defined in any one of claims 1 or 3 to 14, characterized in that The method for preparing a flexible pressure or strain mapping device comprises the following steps: a. depositing and impregnating the hydrogel into the fiber substrate layer (1), thereby forming at least a layer region (2) impregnated with the hydrogel; and b. connecting a portion of the first sensor electrode (3) to at least the lower portion of the hydrogel-impregnated layer region (2); and c. Connecting a portion of the second sensor electrode (4) to at least the upper portion of the hydrogel-impregnated layer region (2).

16. A method of manufacturing a flexible pressure or strain mapping device, the flexible pressure or strain mapping device being as defined in any one of claims 2 to 14, characterized in that The method for preparing a flexible pressure or strain mapping device comprises the following steps: a. depositing and impregnating the hydrogel into the fiber substrate layer (1), thereby forming at least a layer region (2) impregnated with the hydrogel; and b. connecting a portion of the first interdigitated electrode (19) to at least a portion of the layer region (2) impregnated with the hydrogel; and c. connecting a portion of the second interdigital electrode (20) to at least the same portion of the layer region (2) impregnated with hydrogel as the portion contacted by the first interdigital electrode (19); wherein the portion of the layer region (2) impregnated with hydrogel is selected from the lower portion of the layer region (2) impregnated with hydrogel or the upper portion of the layer region (2) impregnated with hydrogel; and d. When the flexible pressure or strain mapping device comprises a plurality of pairs of the first interdigital electrodes (19) and the second interdigital electrodes (20), the first interdigital electrodes (19) and the second interdigital electrodes (20) are separated from each other by an electrical insulating layer (21).

17. A method for producing a flexible pressure or strain mapping device according to the preceding claim, wherein: The method for preparing a flexible pressure or strain mapping device also includes the step of connecting and joining a second fiber substrate layer (5) to the second sensor electrode (4), the second sensor electrode (4) being arranged on the lower part of the second fiber substrate layer (5) and arranged above the upper part of the area (2) impregnated with hydrogel, wherein the second sensor electrode (4) is also arranged and joined above the upper part of the layer area (2) impregnated with hydrogel; or the method for preparing a flexible pressure or strain mapping device includes the step of connecting and joining a second fiber substrate layer (5) to the first interdigital electrode (19) and the second interdigital electrode (20), the first interdigital electrode (19) and the second interdigital electrode (20) being arranged on the lower part of the second fiber substrate layer (5) and arranged above the upper part of the area (2) impregnated with hydrogel, wherein the first interdigital electrode (19) and the second interdigital electrode (20) are also arranged and joined above the upper part of the layer area (2) impregnated with hydrogel.

18. The method for preparing a flexible pressure or strain mapping device according to any one of claims 15 to 17, wherein: The method for preparing a flexible pressure or strain mapping device also includes the step of connecting and bonding a third fiber substrate layer (6) to the first sensor electrode (3), wherein the first sensor electrode (3) is arranged on the upper part of the third fiber substrate layer (6) and below the lower part of the area (2) impregnated with hydrogel, wherein the first sensor electrode (3) is also arranged and bonded above the lower part of the layer area (2) impregnated with hydrogel; or the method for preparing a flexible pressure or strain mapping device includes the step of connecting the third fiber substrate layer (6) to the first interdigital electrode (19) and the second interdigital electrode (20), wherein the first interdigital electrode (19) and the second interdigital electrode (20) are both arranged on the upper part of the third fiber substrate layer (6) and below the lower part of the area (2) impregnated with hydrogel, wherein the first interdigital electrode (19) and the second interdigital electrode (20) are also arranged and bonded below the lower part of the layer area (2) impregnated with hydrogel.

19. The method for preparing a flexible pressure or strain mapping device according to any one of claims 15 to 18, wherein: The method for preparing a flexible pressure or strain mapping device also includes the step of connecting a rectifying element to at least one of the first sensor electrode (3), the second sensor electrode (4), the first interdigital electrode (19) or the second interdigital electrode (20), the rectifying element comprising a conductive component (7) and a semiconductor component (8).

20. A pressure mapping system, comprising a pressure sensitive surface (9), characterized in that: The pressure sensitive surface (9) comprises a flexible pressure mapping device, the flexible pressure mapping device being as defined in any one of claims 1 to 14, wherein the pressure mapping system further comprises: An electronic instrument subsystem (11), the electronic instrument subsystem comprising a data transmission and reception unit (15), a microcontroller (12) and a power supply; and a hybrid connector (10) connecting the pressure sensitive surface (9) to the electronic instrument subsystem (11); and The data sending and receiving unit (15) receives data acquired by the pressure sensitive surface (9) and transmits the data to the microcontroller (12).

21. Pressure mapping system according to the preceding claim, wherein The power source includes at least one of a charging unit (14) or a battery (16).

22. A pressure mapping system according to any one of claims 20 to 21, wherein: The electronic instrument subsystem (11) includes an acoustic sensor (17).

23. A computer-implemented method for real-time digitization and visualization of a graphical representation, characterized in that The computer-implemented method of real-time digitization and visualization of a graphical representation comprises the following steps: a. inputting a physical stimulus on a pressure sensitive surface (9) comprised in a pressure mapping system as defined in any one of claims 20 to 22, and b. converting the physical stimulus into at least a digital signal by the pressure mapping system; and c. transmitting at least said digital signal by said pressure mapping system to a computer device, thereby forming a graphical representation of said physical stimulus, wherein said computer device is adapted to allow editing of said graphical representation by means of a graphical user interface.

24. A computer program, characterized in that The computer program comprises instructions which, when said program is executed by a computer device, cause the computing device to carry out the steps of the method defined in the preceding claim.

25. A computer-readable data carrier, characterized in that Stored on the computer-readable data carrier is a computer program as defined in the preceding claim.

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