Method for obtaining an embroidered textile electrode and embroidered textile electrode obtained using the method

Abstract

The present invention relates to a method for obtaining a textile electrode embroidered on a textile substrate and to the electrode obtained using the method, which, advantageously, enables signal acquisition by means of same with improved quality and amplitude. For this purpose, the method of the invention comprises two steps of embroidering with a conductive thread, with an intermediate step of placing a piece of foam, such that the stitches of each step of embroidering have different orientations, producing an electrode with a three-dimensional structure, which ensures continuous contact and adequate pressure against the surface from which the signal is to be obtained, ensuring optimal signal quality and amplitude for same.

Description

[0001] PROCEDURE FOR OBTAINING AN EMBROIDERED TEXTILE ELECTRODE AND EMBROIDERED TEXTILE ELECTRODE OBTAINED BY SAID PROCEDURE

[0002] TECHNICAL SECTOR

[0003] The present invention relates to a process for obtaining a textile electrode embroidered on a textile substrate, as well as to the electrode obtained by said process, which advantageously allows the acquisition of signals with improved quality and amplitude.

[0004] To this end, the invention's procedure incorporates embroidery stages with a conductive thread, as well as a stage of incorporating a three-dimensional foam piece, which allows obtaining an electrode with a three-dimensional structure, which ensures continuous contact and adequate pressure against the surface from which the signal is to be collected, ensuring optimal quality and amplitude for it.

[0005] BACKGROUND OF THE INVENTION

[0006] Textile smart devices, in the form of garments, upholstery, wearable devices or similar, are known in the state of the art, and are provided with sensors or electrodes integrated within them in order to acquire a signal.

[0007] Specifically, flat or two-dimensional textile electrodes are known to operate dry, meaning they do not require the application of a conductive cream or gel to transmit the signal from the signal-generating surface (such as human skin) to the electrode. Therefore, these types of electrodes require high-quality contact—firm, continuous, and without movement—with the user's skin or the surface from which the signal is to be captured. The known flat electrodes have the drawback that the contact they establish with the surface may not be constant and / or with the pressure required to acquire the signal to be measured with the necessary amplitude and quality. Thus, poor contact results in signal ripple noise due to persistent electromagnetic interference and, furthermore, a tendency to move caused by the user's breathing, in the case of electrodes designed to capture physiological signals.Additionally, the signals acquired by this type of electrode often generate abundant noise from nearby lights, equipment, or electromagnetic fields.

[0008] For all the above reasons, the applicant of the present invention detects the need to develop a obtaining procedure that results in an embroidered textile electrode that overcomes the detailed drawbacks, ensuring continuous contact and with the required pressure, guaranteeing the quality of the signal acquired by the electrode.

[0009] DESCRIPTION OF THE INVENTION

[0010] The proposed procedure solves the described problem, based on a process that results in obtaining a three-dimensional textile electrode, that is, one that offers a certain volume, which ensures the pressure and contact necessary for the correct acquisition of the signal.

[0011] To achieve this, the procedure for obtaining an embroidered textile electrode comprises the following steps:

[0012] - a first embroidery on a textile substrate of at least one pass of embroidery with a conductive thread;

[0013] - placement of a three-dimensional foam piece over the embroidery done in the first stage, which will be responsible for providing volume to the final electrode obtained, while maintaining the required flexibility; and

[0014] - a second embroidery on the three-dimensional foam piece of at least one pass of embroidery with the conductive thread, where the second pass / s of embroidery are arranged with a different orientation than the first pass of embroidery, which favors a homogeneous distribution of conductivity.

[0015] Thus, through the described steps, a three-dimensional embroidered textile electrode is obtained, in which the foam piece is interspersed between the embroidery passes of the first and second embroidery, being completely covered by the passes of the second embroidery, and removing the excess material of the foam piece if necessary.

[0016] Optionally, and in order to facilitate an electrical contact point with the electrode and other elements, such as a cable that connects the electrode to a control electronics or integrated circuit that processes the acquired signal; prior to the first embroidery, an embroidery stage is included on the textile substrate with an additional conductive connecting thread, which preferably has a count or thickness greater than that of the conductive thread with which the passes that make up the textile electrode are embroidered.

[0017] Preferably, the connecting wire used to embroider the electrode and / or the connecting wire are made of silver-plated polyamide 6.6. Also preferably, the wire used to embroider the electrode has 3 strands of 34 filaments each (100 denier), while the connecting wire has 8 strands of 34 filaments each (210 denier).

[0018] The three-dimensional foam piece that houses the electrode can be made of any flexible or deformable material, such as ethylene-vinyl acetate (EVA) foam, to facilitate the sensor's flexibility and allow it to conform to the skin surface or the signal source. Preferably, the three-dimensional foam piece has a thickness between 3 mm and 6 mm.

[0019] It should be noted that the greater the number of layers embroidered with conductive thread, the greater the conductivity will be. However, the preferred number of embroidery passes is 10, in order to avoid breakage of the conductive thread due to excessive friction from the needles of the embroidery head. As detailed above, the different embroidery passes are arranged with varying orientations relative to each other, which ensures a homogeneous distribution of conductivity.

[0020] Thus, according to a preferred embodiment of the invention, the procedure involves a total of 6 embroidery passes with the conductive thread. For this purpose, both the first and second embroidery passes include one pass with a +45° orientation. e with respect to one of the axes of the textile substrate, for example, the horizontal axis, followed by an embroidery pass with an orientation of -45 ewith respect to the aforementioned axis and a final stitch with an orientation parallel to said axis, that is, with a horizontal orientation. Thus, after the first three stitches (+45 e -45 e and horizontal) the three-dimensional foam piece is placed, and then the same sequence of three passes described is embroidered over it, so that the embroidered textile electrode has 6 embroidery passes between which the three-dimensional foam piece is positioned. In an alternative embodiment, 8 embroidery passes in total are considered, following the same scheme described: a first embroidery consisting of four passes with conductive thread (one pass with a +45 orientation) e with respect to one of the axes of the textile substrate, an embroidery pass with an orientation of -45 ewith respect to the same axis, one embroidery pass with an orientation parallel to the aforementioned axis and one embroidery pass with an orientation perpendicular to the aforementioned axis of the textile substrate), placement of the three-dimensional foam and embroidery on it of four additional passes following the same scheme, so that the embroidered textile electrode has 8 embroidery passes between which the three-dimensional foam piece is arranged.

[0021] Thus, the resulting three-dimensional electrode preferably has a thickness between 5 and 8 mm.

[0022] By including in the procedure of the invention a step of placing a piece of foam, the result is that the pressure exerted on the central point of the resulting electrode is much greater than in a conventional flat electrode, which prevents the electrode from slipping on the skin or surface, increasing the electrode-skin conductivity.

[0023] This translates into two fundamental effects: on the one hand, the reduction or even elimination of external electromagnetic interference; and on the other hand, the increase in the amplitude of the signal, which allows for easier identification of the characteristic waves of the different signals to be acquired by the electrode, commonly bioelectric signals when it comes into contact with the skin of a user.

[0024] Advantageously, the described procedure for obtaining a textile electrode offers a wide range of possibilities in the development of embroidered electrodes, namely:

[0025] - Shape and dimensions: allows the development of electrodes of any design / shape and any dimension.

[0026] - In order to achieve greater or lesser conductivity, the claimed procedure allows a surface to be embroidered with a smaller or larger number of layers.

[0027] - When creating a pattern for embroidery on a surface, in this case an electrode, the digitizing software allows for the configuration of various parameters: stitch density, stitch distance, etc., in order to achieve optimal embroidery. Therefore, the embroidered textile electrodes obtained by the invention can be used for a multitude of applications, with the advantage of optimized signal quality and amplitude, such as:

[0028] - Acquisition of biomedical or bioelectric signals, such as:

[0029] - Electrocardiogram (ECG): Records the electrical activity of the heart.

[0030] - Electroencephalogram (EEG): Measures the electrical activity of the brain.

[0031] - Electromyogram (EMG): Records the electrical activity of the muscles.

[0032] - Electrodermal activity (EDA): This signal measures variations in the electrical conductance of the skin, which are related to the activity of a person's nervous system.

[0033] - Bioimpedance measurement: a technique used to measure body composition, particularly to estimate the amount of fat, muscle, and water in the body.

[0034] - Development of garments with electrostimulation capabilities, both to strengthen, tone or rehabilitate muscles and to relieve pain.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] To complement the description that follows and to aid in a better understanding of the characteristics of the invention, according to a preferred embodiment thereof, a set of drawings is included as an integral part of said description, in which, for illustrative and non-limiting purposes, the following has been represented:

[0037] Figure 1 shows the stage prior to the first embroidery of inclusion of a connecting conductive thread.

[0038] Figure 2 shows the first embroidery according to an example of an embodiment of the invention, the first embroidery including three passes at +45 e -45 e and horizontal.

[0039] Figure 3 shows the three-dimensional foam placement stage.

[0040] Figure 4 shows the second embroidery that is done on the three-dimensional foam piece, which according to the illustrated example includes three passes at +45e -45 e and horizontal, as well as an image of the final result of the embroidered textile electrode.

[0041] Figure 5 shows an example of the embodiment of the embroidered textile electrodes obtained according to the procedure of the present invention, applied to a textile piece that collects bioelectric signals from the hand of a user.

[0042] Figure 6 shows an example of an ECG signal measured with a two-dimensional flat embroidered textile electrode, where the time in seconds has been represented on the x-axis, so that five minimum division units of the x-axis are equivalent to 0.45 seconds, while the voltage in mV has been represented on the y-axis.

[0043] Figure 7 shows an example of an ECG signal measured with a textile electrode with volume as contemplated in the smart garment according to the present invention, where the time in seconds has been represented on the abscissa axis, such that five minimum division units of the abscissa axis are equivalent to 0.45 seconds, while the voltage in mV has been represented on the ordinate axis.

[0044] PREFERRED EMBODIMENT OF THE INVENTION

[0045] Figures 1 to 4 show the procedure for obtaining an embroidered textile electrode according to a preferred embodiment of the invention, in which the textile electrode (5) embroidered on a textile substrate (1) has 6 embroidery passes with the conductive thread (2). Solutions equivalent to the present invention include flexible substrates such as a cellulosic substrate or a flexible polymer sheet, alone or in combination with a purely textile substrate.

[0046] To achieve this, as illustrated in the figures mentioned, the following stages are followed:

[0047] - embroidery on the textile substrate (1) of a conductive connecting thread (3), as shown in Figure 1, by means of an embroidery head (7), which will provide a connection point (6) between the electrode (5) and, for example, a control electronics;

[0048] - a first embroidery on the textile substrate (1) in a selected area (8) thereof, the first embroidery including, sequentially, a pass of embroidery with conductive thread (2) with an orientation of +45 e with respect to the horizontal axis of the textile substrate (1 ), an embroidery pass with an orientation of -45 e with respect to the horizontal axis, and a stitch with a horizontal orientation, as shown in Figure 2;

[0049] - placement of a three-dimensional foam piece (4) on the result of the first embroidery, a piece which can be seen in detail in figure 3; and

[0050] - a second embroidery on the three-dimensional foam piece (4) which includes, sequentially, a pass of embroidery with conductive thread (2) with an orientation of +45 e with respect to the horizontal axis of the textile substrate (1 ), an embroidery pass with an orientation of -45 ewith respect to the horizontal axis, and a pass of embroidery with a horizontal orientation, obtaining the embroidered textile electrode (5) with a three-dimensional structure, as seen in figure 4.

[0051] Thus, the described procedure yields a three-dimensional embroidered textile electrode (5) with six stitches of conductive thread (2) interspersed with the foam piece (4). This configuration advantageously offers improved signal quality and minimizes signal noise, as demonstrated in the experiments shown in Figures 6 and 7. Specifically, Figure 6 shows an ECG signal acquired by a flat, dry electrode (without the three-dimensional foam piece (4)). This type of electrode provides poor contact with the user's skin, resulting in ripple noise from persistent electromagnetic interference, an effect exacerbated by movement caused by the user's breathing.

[0052] On the other hand, Figure 7 shows the ECG signal acquired by an electrode (5) that includes the three-dimensional foam piece (4) according to the described embodiment. Thus, it can be observed that, in the textile electrode (5) of the described embodiment, external electromagnetic interference is reduced or even eliminated, and the signal amplitude is increased, allowing for easier identification of the characteristic waves of the different bioelectrical signals. Additionally, a clear reduction in signal ripple is observed, reaching a point where it does not interfere with the identification of small-amplitude waves such as the P wave of the electrocardiogram.

[0053] As for the peak-to-peak voltage of the signal, in the textile electrode (5) that includes the foam piece (4) it has been increased from 0.5 mV to 3 mV, that is, the amplitude of the signal has been multiplied by 6, which demonstrates the quality of the signals that are acquired with the electrodes obtained according to the procedure of the present invention.

Claims

CLAIMS 1 a - Procedure for obtaining an embroidered textile electrode characterized in that it comprises the following steps: - first embroidery on a textile substrate (1) of at least one pass of embroidery with a conductive thread (2); - placement of a three-dimensional foam piece (4) over the embroidery; and - a second embroidery on the three-dimensional foam piece (4) of at least one pass of embroidery with the conductive thread (2), where the second pass of embroidery is arranged with a different orientation than the first pass of embroidery; where both the first and second embroidery include a pass of embroidery with conductive thread (2) with an orientation of +45 e with respect to one of the axes of the textile substrate (1 ), an embroidery pass with an orientation of -45 ewith respect to the aforementioned axis of the textile substrate (1) and an embroidery pass with an orientation parallel to the aforementioned axis of the textile substrate (1), so that a three-dimensional embroidered textile electrode is obtained, in which the foam piece (4) is interspersed between the embroidery passes. 2 a - Method for obtaining an embroidered textile electrode, according to claim 1 a , characterized in that, prior to the first embroidery, a stage of embroidering a connecting conductive thread is included (3). 3 a - Method of obtaining an embroidered textile electrode, according to any of the preceding claims, characterized in that the conductive thread (2) and / or the connecting conductive thread (3) are polyamide 6.6 threads with a silver coating. 4 a - Method for obtaining an embroidered textile electrode, according to claim 1 a or 3 a, characterized in that the conducting wire (2) has 3 strands of 34 filaments each. 5 a - Method for obtaining an embroidered textile electrode, according to claim 2 a or 3 a , characterized in that the connecting conductor wire (3) has 8 strands of 34 filaments each. 6 a - Procedure for obtaining an embroidered textile electrode, according to any of the previous claims, characterized in that the three-dimensional foam piece (4) has a thickness between 3 mm and 6 mm. 7 a .- Procedure for obtaining an embroidered textile electrode, according to any of the preceding claims, characterized in that the three-dimensional foam piece (4) is obtained from ethylene vinyl acetate. 8 a- Procedure for obtaining an embroidered textile electrode, according to any of the preceding claims, characterized in that the embroidered textile electrode has 6 embroidery passes between which the three-dimensional foam piece (4) is arranged. 9 a - Method of obtaining an embroidered textile electrode, according to any of the previous claims, characterized in that both the first embroidery and the second embroidery include an embroidery pass with an orientation perpendicular to the said axis of the textile substrate (1), so that the embroidered textile electrode has 8 embroidery passes between which the three-dimensional foam piece (4) is arranged. 10 a - Procedure for obtaining an embroidered textile electrode, according to any of the preceding claims, characterized in that the embroidered textile electrode obtained has a thickness between 5 and 8 mm. 1 1 a- An embroidered textile electrode obtained by the process according to any of the preceding claims, characterized in that it comprises at least two passes of a conductive thread (2) embroidered onto a textile substrate (1), the passes being arranged with different orientations with respect to each other, and where a three-dimensional foam piece (4) is interposed between the embroidery passes, so that the embroidered textile electrode has a three-dimensional configuration, and where both the first and second embroidery include an embroidery pass with conductive thread (2) with a +45 orientation e with respect to one of the axes of the textile substrate (1 ), an embroidery pass with an orientation of -45 e with respect to the aforementioned axis of the textile substrate (1) and a pass of embroidery with an orientation parallel to the aforementioned axis of the textile substrate (1),. 12 a - Embroidered textile electrode, according to claim 11 a, characterized in that the three-dimensional foam piece (4) has a thickness between 3 mm and 6 mm. 13 a - Embroidered textile electrode, according to claim 11 a , characterized by having a thickness between 5 and 8 mm.

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