Multi-frequency detection and estimation of moisture content

Abstract

This disclosure provides a method for detecting and estimating moisture content in an absorbent article using multiple frequencies. The method includes: applying driving signals of multiple frequencies to a driving electrode in the absorbent article via capacitive coupling; sensing sensing signals of multiple frequencies from a sensing electrode in the absorbent article via capacitive coupling; detecting a first wetting event in the absorbent article using the sensing signal of one of the multiple frequencies; and detecting the saturation of the absorbent article using the sensing signal of another of the multiple frequencies.

Description

[0001] Cross-referencing related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 148,440, filed February 11, 2021, entitled "Multi-frequency detection and estimation of moisture content". The entire contents of that U.S. Provisional Patent Application are incorporated herein by reference for all purposes.

[0003] Names of the parties to the joint research agreement

[0004] not applicable.

[0005] Citations of materials submitted in text file format on compact CDs or via the Office Electronic File System (EFS-WEB) are included.

[0006] not applicable.

[0007] Statements previously disclosed by the inventors or co-inventors

[0008] not applicable. Technical Field

[0009] This disclosure relates to the detection and estimation of moisture content in absorbent articles such as diapers. Background Technology

[0010] Related technical descriptions

[0011] Disposable absorbent articles, such as disposable diapers, are products that can absorb and retain bodily excretions or waste to prevent soiling of clothing or the external environment. For example, using disposable diapers allows a user to urinate or defecate without using a toilet. Besides diapers, there are many other types of disposable absorbent articles, such as pads, incontinence pads, joggers, panty liners, underwear liners, one-piece panty liners, pull-up incontinence pants, training pants, protective underwear, menstrual pads, and incontinence protection products. It should be understood that the list of disposable absorbent articles above is not exhaustive, and these and other absorbent articles can be used in conjunction with this disclosure and are within the scope of this disclosure. It should also be understood that any reference to any such article (such as a "diaper") in this specification should be construed as a reference to any and all other suitable absorbent articles, including incontinence clothing, pads, etc.

[0012] To prevent soiling clothing or the external environment, disposable absorbent items have an absorbent core that receives and retains bodily excretions or waste, and a layer that is essentially impermeable to liquids. Generally, disposable absorbent products consist of a multi-layered structure that allows bodily excretions or waste to be distributed and transferred into the absorbent core and retained therein. In daily use, disposable absorbent items can be used until the absorbent core is saturated with, for example, bodily excretions or waste. When the absorbent core is saturated, the disposable absorbent item needs to be removed, disposed of, and replaced with a clean, dry product.

[0013] Without a solution for detecting and estimating the moisture content of absorbent materials, users wearing such materials may be in contact with their own urine and feces for extended periods, leading to numerous health problems.

[0014] Therefore, a method is needed for the detection and estimation of moisture content in absorbent materials.

[0015] This disclosure addresses this drawback, as well as other drawbacks in the prior art. Summary of the Invention

[0016] This disclosure provides embodiments for detecting and estimating moisture content in absorbent articles using multiple frequencies.

[0017] In one embodiment of this disclosure, a method for detecting and estimating moisture content in an absorbent article using multiple frequencies is provided, comprising: applying driving signals of multiple frequencies to a driving electrode in the absorbent article via capacitive coupling; sensing sensing signals of multiple frequencies from a sensing electrode in the absorbent article via capacitive coupling; detecting a first wetting event in the absorbent article using the sensing signal of one of the multiple frequencies; and detecting saturation of the absorbent article using the sensing signal of another of the multiple frequencies.

[0018] This section is intended to provide a brief overview of some of the subject matter described in this disclosure. Therefore, it should be understood that the features described above are merely examples and should not be construed as limiting or affecting the scope or spirit of the subject matter described in this disclosure in any way. Other features, aspects, and advantages of the subject matter described in this disclosure will become apparent from the following detailed description, drawings, and claims. Attached Figure Description

[0019] The various preferred embodiments described in this disclosure will be understood by those skilled in the art upon referring to the accompanying drawings and reading the following detailed description. Components in the drawings are not necessarily drawn to scale, and any reference numerals used to identify elements in one drawing will represent the same element in all drawings. A brief summary of the drawings is as follows:

[0020] Figure 1An exploded perspective view of an exemplary disposable absorbent article according to one embodiment of the present disclosure is shown.

[0021] Figure 2 An exemplary disposable absorbent article according to one embodiment of the present disclosure is shown, which has four spaced-apart wires disposed on the top side of a substantially completely liquid-impermeable layer.

[0022] Figure 3 An exemplary pod container according to one embodiment of the present disclosure is shown, the pod container being compatible with... Figure 2 The exemplary disposable absorbent articles shown are used together to detect and estimate the moisture content of the absorbent articles.

[0023] Figure 4 An amplitude-time graph of an exemplary drive signal Sd according to one embodiment of the present disclosure is shown.

[0024] Figure 5 An amplitude-time curve G of a sensing signal Ss at various frequencies according to one embodiment of the present disclosure is shown.

[0025] While the features described herein are susceptible to various modifications and alternatives, specific embodiments thereof are illustrated by way of example in the accompanying drawings and described in detail herein. However, it should be understood that the drawings and their detailed description are not intended to limit the particular forms disclosed, but rather are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter defined by the appended claims. Detailed Implementation

[0026] Figure 1 An exploded perspective view of an exemplary disposable absorbent article is shown. As shown, the disposable absorbent article 100 mainly consists of an absorbent core 140 sandwiched between a liquid-permeable layer 120 and a substantially liquid-impermeable layer 160.

[0027] like Figure 1 The exemplary diaper shown, the disposable absorbent article 100, has a substantially liquid-impermeable layer 160 configured to prevent absorbed and retained bodily excretions or waste products from wetting items in contact with the disposable absorbent article 100, such as sheets and underwear. An absorbent core 140 made of a superabsorbent material is disposed on top of the layer 160. On top of the absorbent core 140 is a liquid-permeable layer 120, which is attached to the layer 160 in the assembled state of the disposable absorbent article and is in close contact with the user's skin during use. Additional structural features may also be included, such as additional layers, elastic members, and fastening devices for securing the article in place, such as strip fasteners.

[0028] The liquid-permeable layer 120 is configured to allow bodily exudates and waste to penetrate in a specific direction into the absorbent core 140, whereby they can be absorbed and retained by the underlying absorbent core 140. It should be understood that layer 120 can be made of various liquid-permeable materials, such as nonwoven fabric.

[0029] As a non-limiting example, the absorbent core 140 is made of hydrophilic superabsorbent polymers (SAP) and fibrous materials. These polymers act like tiny sponges, capable of retaining several times their own weight in liquid.

[0030] The substantially liquid-impermeable layer 160 is made of a substantially liquid-impermeable material. For example, the substantially liquid-impermeable layer 160 can be made of a plastic film, although other liquid-impermeable materials may also be used. As described above, the substantially liquid-impermeable layer 160 is configured to prevent absorbed and retained bodily excretions or waste from wetting items in contact with the diaper, such as sheets and underwear.

[0031] like Figure 1 The exemplary diaper shown has layers 120 and 160 that extend together and generally have a larger dimension in length and / or width than the absorbent core 140.

[0032] In one embodiment of this disclosure, for the detection and estimation of moisture content, particularly for detecting the presence and / or amount of bodily exudates or excretions in disposable absorbent articles, especially in their absorbent cores, a plurality (e.g., at least two) spaced-apart wires are provided as electrodes along the length of the disposable absorbent article on the top layer of the substantially impermeable layer (i.e., the side facing the absorbent core). Figure 2 The illustration shows an exemplary disposable absorbent article 100', which has four spaced-apart wires 180' disposed on the top side of a substantially liquid-impermeable layer 160'. The spaced-apart wires 180' are connected within the disposable absorbent article 100' to a pod-type container 200 (which will be referenced below). Figure 3 (Description) Working together to detect and estimate the moisture content in absorbent articles 100'.

[0033] like Figure 3 As shown, an exemplary pod container 200 mainly consists of two halves 220 and 240, which are pivotally connected by a pivot connector 260. At least one of the halves 220 and 240 has a plurality of (e.g., at least two) contacts 280 or 280' on its inner side (i.e., the side facing the other half). As a non-limiting example, each of the halves 220 and 240 has a plurality of contacts 280 or 280' on its respective inner side, such as... Figure 3 As shown. In Figure 3In the example shown, the two halves 220 and 240 are respectively provided with four contacts 280 and 280' (to... Figure 2 The number of wires 180' shown is the same.

[0034] During operation, such as Figure 3 The pod-shaped container 200 shown is sandwiched within a disposable absorbent material (such as...) Figure 2 At one of the waist edges of the 100' shown, and through the contacts 280 and / or 280' on the pod container 200 with the wire (such as Figure 2 (180') coupling. During use, it is absorbed and retained in the absorbent core of the absorbent article (such as...). Figure 2 Body exudates or excretions in the 140' section will cause at least two spaced electrodes (wires, such as...) to... Figure 2 The pod container 200 is interconnected at 180', so it can detect disposable absorbent articles (e.g., pods) by applying a driving signal to at least one electrode (driving electrode) and sensing a sensing signal from at least another electrode (sensing electrode). Figure 2 The presence and / or amount of exudate or excretion in 100').

[0035] As described above, in disposable absorbent articles, spaced-apart wires can be disposed on any layer, provided that at least two spaced-apart conductive wires on that layer are connected to each other with the aid of bodily exudates or excretions absorbed and retained in the disposable absorbent article, thereby enabling the detection of the presence and / or quantity of exudates or excretions in the disposable absorbent article.

[0036] It should be noted that the pod container 200, and particularly its contacts 280 and 280', are affected by the presence of an outer layer or layer of material or material of the disposable absorbent article, such as a material or layer further away from the absorbent core than the wire, like a substantially impermeable layer (e.g., ...). Figure 2 160' in the middle) and / or liquid permeable layer (e.g. Figure 2 (120'), and cannot be used with disposable absorbent items (e.g. Figure 2 The electrode (wire, e.g., in 100') on the wire. Figure 2 The pod container 200 makes physical contact with wires (e.g., 180') at its contacts 280 and 280'. That is, during use, the pod container 200 makes physical contact with wires (e.g., 180') at its contacts 280 and 280'. Figure 2 Align the 180's of the electrodes (wires, e.g.) with them and place them close together. Figure 2 The 180' in the middle forms a capacitive coupling.

[0037] As described above, in one embodiment of this disclosure, an absorbent article (such as a diaper) has at least two electrodes, namely at least one driving electrode and at least one sensing electrode. Furthermore, a pod-like container is provided to form capacitive contact with the electrodes in the absorbent article; that is, the pod-like container touches the electrodes but does not make physical contact with them.

[0038] In one embodiment of this disclosure, in order to detect and estimate moisture content, a drive signal is applied to a drive electrode in the absorbent article, and in response, a sensing signal is sensed from a sensing electrode in the absorbent article. It should be understood that the drive signal cannot be a direct current (DC) signal due to capacitive coupling.

[0039] During the first wetting event in an absorbent article, the amplitude of a low-frequency (e.g., about 10 kHz) sensing signal shows a significant increase (e.g., a sharp jump or a gradually rising slope), but this sensing signal does not change much even before or after the first wetting event, even if more wetting events occur in the absorbent article later.

[0040] Furthermore, the amplitude of high-frequency sensing signals, such as those in the range of 70kHz to 500kHz, gradually increases with the increasing number of wetting events occurring in absorbent articles.

[0041] Based on the above, in one embodiment of this disclosure, multiple frequencies can be used to detect and estimate the moisture content of absorbent articles.

[0042] In particular, in one embodiment of this disclosure, the drive signal to be applied to the drive electrode of the absorbent article can be a periodic signal that scans at a series of frequencies f1, f2, ..., fm with the same amplitude within one cycle, for example, 5 kHz, 10 kHz, ..., 3 MHz. For example, in one cycle, the drive signal Sd is a sine wave signal that scans within a frequency range from f1 to fm, such as from 5 kHz to 3 MHz, with each frequency having the same amplitude and lasting for the same time interval, such as 10 ms. In particular, as an example, in one cycle, the drive signal 100 is a 5 kHz sine wave signal from 0 ms to 10 ms, then a 10 kHz sine wave signal from 10 ms to 20 ms, then a 15 kHz sine wave signal from 20 ms to 30 ms, ..., and finally a 3 MHz sine wave signal from 1.99 s to 2 s, and then repeats periodically. It should be understood that there may be time intervals without a signal between different frequencies. For example, as an example, the drive signal could be a 5kHz sine wave from 0ms to 10ms, then 0 (no signal) from 10ms to 20ms, then a 10kHz sine wave from 20ms to 30ms, then 0 from 30ms to 40ms, then a 15kHz sine wave from 40ms to 50ms, and so on, finally a 3MHz sine wave from 3.98s to 3.99s and 0 from 3.99s to 4s, and repeat periodically. As an example, Figure 4 A graph of the amplitude versus time for an exemplary drive signal Sd according to an embodiment of the present disclosure is shown.

[0043] In response to the application of the driving signal Sd to a driving electrode of the absorbent article, a sensing signal 200 is sensed from a sensing electrode of the absorbent article. It should be understood that, in response to the application of a sinusoidal signal of a specific frequency to a driving electrode of the absorbent article, a sinusoidal signal of the same specific frequency, but with a smaller amplitude, is sensed from the sensing electrode of the absorbent article.

[0044] By using a bandpass filter at the sensing electrode, configured to allow only one specific frequency to pass through and filter out all other frequencies, the sensing signal for each frequency can be obtained. Figure 5 An embodiment of the present disclosure is shown, displaying amplitude-time curves G of sensing signals Ss at various frequencies.

[0045] As an example, in Figure 5In the diagram, from top to bottom, the topmost graph G1 shows the 5 kHz sensing signal 200-1, the second topmost graph G2 shows the 10 kHz sensing signal 200-2, ..., graph Ga shows the 5a kHz sensing signal 200-a, graph Gb shows the 5b kHz sensing signal 200-b, graph Gm shows the 5m kHz sensing signal 200-m, graph Gn shows the 5n kHz sensing signal 200-n, ... These are sensed from the sensing electrodes, as a result of the signals applied to the driving electrodes, such as... Figure 4 The response to the drive signal 100 shown is given, where a, b, m, and n are all integers.

[0046] exist Figure 5 In the illustrated embodiment, it is assumed that the first wetting event occurs at time t1, causing a connection between the electrodes (driving electrode and sensing electrode) in the absorbent article. In response to the first wetting event, in a low-frequency sensing signal, within a period shorter than the threshold period Tj, the amplitude may experience a sharp jump (abrupt transition) exceeding the threshold height Hj at or near time t1. The amplitude of this low-frequency sensing signal does not change significantly before and after this jump, even as more wetting events occur subsequently in the absorbent article. Figure 5 As can be seen, as an example, signal 200-a exhibits an amplitude jump with height H and period T near time t1, and the amplitude of signal 200-a does not change much before and after this jump.

[0047] Based on the above, in one embodiment of this disclosure, in a low-frequency sensing signal, a sharp jump in amplitude change exceeding a threshold height Hj within a time period shorter than the threshold period Tj can be used to determine the first wetting event in an absorbent article.

[0048] It should be noted that the amplitude of the low-frequency sensing signal may change more smoothly in response to the first wetting event, for example, gradually increasing. In some cases, a threshold height Hs greater than the threshold height Hj can be used to determine the first wetting event in the absorbent article. That is, in one embodiment of this disclosure, in addition to the aforementioned abrupt amplitude jump, the first wetting event in the absorbent article can also be determined by a gradual increase in the amplitude height of the low-frequency sensing signal exceeding the threshold height Hs. As an example, in Figure 5 In the sensing signal 200-b, an amplitude increase of height H' appears near time t1, but its amplitude does not change much before and after the first wetting event t1.

[0049] Based on the above, in one embodiment of this disclosure, a driving signal that periodically sweeps within a certain frequency range is applied to the driving electrode in the absorbent article, and a sensing signal at each frequency is sensed from the sensing electrode in the absorbent article by using a bandpass filter. To determine the first wetting event, the low-frequency sensing signal, for example, the sensing signal around 10 kHz, is examined to check whether its amplitude jumps sharply, for example, a sharp jump in height exceeding Hj within a period T shorter than Tj, or whether it gradually increases, for example, an increase in height exceeding Hs.

[0050] As mentioned above, low-frequency sensing signals determine the first wetting event in absorbent articles by examining the sharp jump or gradual increase in their amplitude. However, the amplitude does not change significantly after the sharp jump or gradual increase, so it cannot be further used to estimate or detect the saturation in absorbent articles.

[0051] On the other hand, the amplitude of high-frequency sensing signals, such as those from 70 kHz to 500 kHz, gradually increases as more wetting events occur in the absorbent article. Based on this, in one embodiment of this disclosure, after the first wetting event is determined, a higher-frequency sensing signal can be used to estimate or detect the saturation level in the absorbent article.

[0052] It should be understood that further wetting events occur in the absorbent article after the first wetting event. As further wetting events occur in the absorbent article, the amplitude of the higher-frequency sensing signal continues to gradually increase. In one embodiment of this disclosure, to estimate or detect saturation in the absorbent article, the amplitude of the sensing signal from the first wetting event (e.g., Figure 5 The amplitude difference of all higher frequency sensing signals starting from time t1. Once the amplitude difference of all higher frequency sensing signals starting from the first wetting event (e.g., at time t1) is determined in any of the higher frequency sensing signals... Figure 5 When the amplitude difference starting at time t1 exceeds the threshold amount Ts, saturation in the absorbent material is detected.

[0053] from Figure 5 As can be seen, at time t2, the amplitude difference from the first wetting event t1 is Dm2 in the sensing signal 200-m and Dn2 in the sensing signal 200-n. However, in all higher frequency sensing signals, the amplitude difference from t1 to t2 is less than the threshold value Ts.

[0054] Furthermore, at time t3, the amplitude difference starting from the first humidity event t1 is Dm3 in sensing signal 200-m and Dn3 in sensing signal 200-n. At this time, according to one embodiment of this disclosure, although the amplitude difference from t1 to t2 is less than a threshold amount Ts in other higher frequency sensing signals, the amplitude difference from t1 to t2 in sensing signal 200-n is greater than the threshold amount Ts, which can serve as an indication of saturation in the absorbent article. In one embodiment of this disclosure, the frequency of sensing signal 200-n, in which the amplitude difference starting from t1 is first detected to be greater than the threshold amount Ts, can be, for example, approximately 100 kHz.

[0055] Based on the above, in one embodiment of this disclosure, a driving signal that periodically sweeps within a certain frequency range is applied to the driving electrode in the absorbent article, and a sensing signal at each frequency is sensed from the sensing electrode in the absorbent article by using a bandpass filter. To estimate or detect saturation in the absorbent article, a first wetting event is determined using a low-frequency sensing signal, as described above, as a baseline, and the amplitude difference of all higher-frequency sensing signals (e.g., from 70 kHz to 500 kHz) starting from the first wetting event is compared with a threshold value Ts. When it is determined that the amplitude difference is greater than the threshold value Ts, saturation of the absorbent article is detected.

[0056] It should also be understood that the wetting point varies with the orientation of the user wearing the absorbent material, which in turn results in different distances between the wetting point and the pod container. Therefore, in one embodiment of this disclosure, the threshold amount Ts can be varied according to the user's orientation. For example, according to one embodiment of this disclosure, a smaller threshold amount Ts is assigned when the user's orientation causes the wetting point to move away from the pod container.

[0057] As described above, in one embodiment of this disclosure, multiple frequencies are used to detect and estimate the moisture content of absorbent articles. Specifically, a low frequency is used to determine the first wetting event in the absorbent article, which in turn serves as a baseline for estimating the moisture content or saturation, while another high frequency is used to estimate or detect saturation in the absorbent article. As described above, the amplitude of the low-frequency band is examined for sharp jumps or gradual increases as an indication of the first wetting event in the absorbent article. The difference between the amplitude of the high-frequency band and the baseline is then compared to a threshold quantity to detect or estimate saturation in the absorbent article.

[0058] Although the embodiments described above have been described in detail, many variations and modifications will appear once the above disclosure is fully understood, as will be apparent to those skilled in the art. The following claims are intended to be construed as covering all such variations and modifications.

Claims

1. A method of detecting and estimating moisture content in an absorbent article using multiple frequencies, characterized by, include: Multiple frequency driving signals are applied to the driving electrodes in the absorbent article through capacitive coupling. Multiple frequencies of sensing signals are sensed from sensing electrodes in an absorbent article via capacitive coupling. The first wetting event in an absorbent article is detected using a sensing signal at one of multiple frequencies; The saturation of an absorbent material is detected using a sensing signal at another frequency among multiple frequencies.

2. The method of claim 1, wherein, The method of detecting the first wetting event in an absorbent article using a sensing signal of one of multiple frequencies includes: The first wetting event in an absorbent material is detected when the amplitude of the sensed signal jumps sharply above the threshold height within a period of time below the threshold.

3. The method as described in claim 1, characterized in that, The method of detecting the first wetting event in an absorbent article using a sensing signal of one of multiple frequencies includes: The first wetting event in an absorbent material is detected when the amplitude of the sensing signal gradually increases beyond a threshold height.

4. The method as described in claim 1, characterized in that, The method of detecting the saturation of an absorbent article using a sensing signal at another frequency among a plurality of frequencies includes: Determine the amplitude difference in the sensing signal at another frequency, starting from the first wetting event; and, Saturation is detected when the amplitude difference is greater than the threshold value.

5. The method as described in claim 4, characterized in that, The threshold amount is adjusted based on the direction in which the user applies the absorbent material.

6. The method according to any one of claims 1 to 5, characterized in that, Applying drive signals at multiple frequencies includes: Apply a drive signal that periodically sweeps through multiple frequency ranges.

7. The method according to any one of claims 1 to 5, characterized in that, Sensing signals at multiple frequencies includes: Use a bandpass filter to determine the sensing signal for each frequency.

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