Patent Description:
Disposable absorbent article such as disposable diaper is a product that is capable of receiving and retaining bodily exudates or excretions so as to prevent contamination of the clothing or external environment. As an example, with a disposable diaper, the user is allowed to urinate or defecate without the use of a toilet. In addition to diapers, there are numerous other types of disposable absorbent articles such as e.g. under pads, incontinence pads, fitted briefs, belted shields, liners, all-in-one pads, pullup incontinence pants, training pants, protective underwear, catamenial napkins, and incontinence guards etc. It is to be understood that the list of disposable absorbent articles identified above is not exhaustive and that these and other absorbent articles can be used with the present disclosure and are within the scope of the present disclosure. It is also to be understood that a reference in this specification to any one such article, such as a "diaper" is to be taken to be a reference to any and all other suitable absorbent articles including incontinence garments, pads and the like.

In order to prevent contamination of the clothing or external environment, disposable absorbent article is provided with an absorbent core capable of receiving and retaining bodily exudates or excretions, and a substantially liquid impervious layer. In general, disposable absorbent products consist of a layered construction, which allows the bodily exudates or excretions to be distributed and transferred to the absorbent core where they are retained in. In everyday use, a disposable absorbent article may be used until the absorbent core is saturated with e.g. bodily exudates or excretions. When the absorbent core is saturated, the disposable absorbent article needs to be removed, disposed of, and replaced with a clean and dry article.

Without a solution for moisture detection and estimation of an absorbent article, the user wearing the absorbent article might be left in their own urine and feces for extended periods of time, causing many health problems.

Therefore, there is a need for a solution for moisture detection and estimation of an absorbent article.

The present disclosure addresses this and other prior art shortcoming.

Embodiments are presented herein of, inter alia, moisture detection and estimation in an absorbent article with use of multiple frequencies.

In an embodiment of the present disclosure, a method of moisture detection and estimation in an absorbent article with use of multiple frequencies is provided that comprises: applying, by capacitive coupling, drive signal of multiple frequencies to a drive electrode in the absorbent article; sensing, by capacitive coupling, sense signal of the multiple frequencies from a sense electrode in the absorbent article; detecting the first wetness event in the absorbent article with use of sense signal of a frequency of the multiple frequencies; and detecting the saturation of the absorbent article with use of sense signal of another frequency of the multiple frequencies.

This summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way.

The various preferred embodiments of the present invention described herein can be better understood by those skilled in the art when the following detailed description is read with reference to the accompanying drawings. The components in the figures are not necessarily drawn to scale and any reference numeral identifying an element in one drawing will represent the same element throughout the drawings. The figures of the drawing are briefly described as follows.

<FIG> illustrates an exemplary disposable absorbent article in an exploded perspective view. As illustrated, a disposable absorbent article <NUM> primarily consists of an absorbent core <NUM> sandwiched between a liquid pervious layer <NUM> and a substantially liquid impervious layer <NUM>.

As illustrated in the exemplary diaper of <FIG>, a disposable absorbent article <NUM> has a substantially liquid impervious layer <NUM> configured to prevent the bodily exudates or excretions absorbed and retained in the absorbent core <NUM> from wetting articles, such as bed sheets and undergarments, which contact the disposable absorbent article <NUM>. On top of the layer <NUM> is disposed an absorbent core <NUM> made of a superabsorbent material. On top of the absorbent core <NUM> is a liquid pervious layer <NUM> that is joined to the layer <NUM> in an assembled state of the disposable absorbent article and is placed next to the skin of the user when in use. Additional structural features such as additional layer(s), elastic members and fastening means for securing the article in place, such as tape tab fasteners, may also be included.

The liquid pervious layer <NUM> is configured to be penetrable by bodily exudates and excretions in a direction into the absorbent core <NUM> to enable them to be absorbed and retained in the underlying absorbent core <NUM>. It is appreciated that the layer <NUM> may be made of a variety of liquid pervious materials, e.g. nonwoven fabric.

The absorbent core <NUM> is made up of hydrophilic superabsorbent polymers (SAP) and fibrous material, as a non-limiting example. The polymers act like tiny sponges that retain many times their weight in liquid.

The substantially liquid impervious layer <NUM> is made of a material substantially impervious to liquids. As an example, the substantially liquid impervious layer <NUM> may be manufactured from a thin plastic film, although other liquid impervious materials may also be used. As described above, the substantially liquid impervious layer <NUM> is configured to prevent the bodily exudates or excretions absorbed and retained in the absorbent core from wetting articles, such as bed sheets and undergarments, which contact the diaper.

As illustrated in the exemplary diaper of <FIG>, the layers <NUM> and <NUM> are coextensive and have generally larger dimension, in length and/or width, than the absorbent core <NUM>.

In order for moisture detection and estimation, in particular to detect the presence and/or amount of the bodily exudates or excretions in a disposable absorbent article, in particular in its absorbent core, a number of (e.g. at least two) spaced-apart conductive lines are provided as electrodes on the top side (i.e. the side facing the absorbent core) of the substantially liquid impervious layer along the length of the disposable absorbent article, in an embodiment of the present disclosure. In <FIG>, an exemplary disposable absorbent article <NUM>' is depicted with four spaced-apart conductive lines <NUM>' being provided on the top side of the substantially liquid impervious layer <NUM>', as an example. The spaced-apart conductive lines <NUM>' in the disposable absorbent article <NUM>' operate in cooperation with a pod <NUM> (to be described below in reference to <FIG>), for moisture detection and estimation of the absorbent article <NUM>'.

As illustrated in <FIG>, an exemplary pod <NUM> primarily consists of two halves <NUM> and <NUM> that are pivotably coupled to each other with a pivotal connection <NUM>. At least one of the two halves <NUM> and <NUM> is provided with a number of (e.g. at least two) contacts <NUM> or <NUM>' on its inner side (i.e. the side facing the other half). As a non-limiting example, both the two halves <NUM> and <NUM> have each a number of contacts <NUM> or <NUM>' on their respective inner side, as illustrated in <FIG>. In the example as illustrated in <FIG>, there are four (the same number as the conductive lines <NUM>' as illustrated in <FIG>) contacts <NUM> and <NUM>' on the two halves <NUM> and <NUM> respectively.

In operation, the pod <NUM> as illustrated in <FIG> is clipped on a disposable absorbent article (e.g. <NUM>' as illustrated in <FIG>) at one of its waist end edges and coupled to the conductive lines (e.g. <NUM>' in <FIG>) with the contacts <NUM> and/or <NUM>' on the pod <NUM>. In use, the bodily exudates or excretions absorbed and retained in the absorbent core (e.g. <NUM>' in <FIG>) of the absorbent article will cause at least two of the spaced-apart electrodes (conductive lines, e.g. <NUM>' in <FIG>) to be connected to each other, and thus the pod <NUM> can detect the presence and/or amount of the exudates or excretions in the disposal absorbent article (e.g. <NUM>' in <FIG>) by applying a drive signal to at least one of the electrodes (the drive electrode) and sensing a sense signal from at least another one of the electrodes (the sense electrode).

As mentioned above, in a disposable absorbent article the spaced-apart conductive lines may be provided on any layer, on which at least two of the spaced-apart conductive lines, with the aid of the bodily exudates or excretion absorbed and retained in the disposable absorbent article, will connect to each other, which in turn enables the detection of the presence and/or amount of the exudates or excretions in the disposal absorbent article.

It is to be noted that the pod <NUM>, in particular its contacts <NUM> and <NUM>', cannot make physical contact with the electrodes (conductive lines, e.g. <NUM>' in <FIG>) on the disposable absorbent article (e.g. <NUM>' in <FIG>) due to the presence of outermore material or layer(s) of the article, e.g. material or layer(s) further away from the absorbent core, with respect to the conductive lines, e.g. the substantially liquid impervious layer (e.g. <NUM>' in <FIG>) and/or the liquid pervious layer (e.g. <NUM>' in <FIG>). That is, in use, the pod <NUM> is capacitively coupled to the electrodes (conductive lines, e.g. <NUM>' in <FIG>) by aligning its contacts <NUM> and <NUM>' with the conductive lines (e.g. <NUM>' in <FIG>) and placing them in close proximity.

As mentioned above, an absorbent article such as a diaper is provided with at least two electrodes, i.e. at least one drive electrode and at least one sense electrode, in an embodiment of the present disclosure. Further, a pod is provided to make capacitive contact with these electrodes in the absorbent article, that is, the pod touches the electrodes but does not make physic contact with electrodes.

In an embodiment of the present disclosure, in order for moisture detection and estimation, a drive signal is applied to a drive electrode in the absorbent article, and in response, a sense signal is sensed from a sense electrode in the absorbent article. It is appreciated that the drive signal cannot be a DC signal because of the capacitive coupling.

At a first wetness event in an absorbent article a significant rise (e.g. a sharp jump or a gradual upslope) in amplitude presents in a sense signal of a low frequency (e.g. around <NUM>), which however does not change much either before or after the first wetness event even though further wetness events occur in the absorbent article later.

Further, a sense signal of high frequency e.g. ranging from <NUM> - <NUM> gradually increases in its amplitude as more and more wetness events occur in the absorbent article.

Based on the above, multiple frequencies may be used for moisture detection and estimation of an absorbent article in an embodiment of the present disclosure.

In particular, in an embodiment of the present disclosure the drive signal that is to be applied to the drive electrode of the absorbent article may be a periodic signal that is swept with the same amplitude in a period over a range of frequencies f1, f2,. , fm, such as e.g. <NUM>, <NUM>,. For example, in a period the drive signal Sd is a sinewave signal that is swept over frequencies ranged from f1 to fm such as e.g. <NUM> to <NUM>, with each frequency being of the same amplitude and lasting for the same time interval e.g. <NUM>. In particular, in a period, the drive signal <NUM> is a sinewave signal of <NUM> from <NUM> to <NUM>, then a sinewave signal of <NUM> from <NUM> to <NUM>, then a sinewave signal of <NUM> from <NUM> to <NUM>,. , finally a sinewave signal of <NUM> from <NUM> to <NUM>, and then repeats periodically, as an example. It is appreciated that between different frequencies there may exist time interval with no signal. For example, the drive signal may be a sinewave signal of <NUM> from <NUM> to <NUM>, then <NUM> (i.e. no signal) from <NUM> to20ms, then a sinewave signal of <NUM> from <NUM> to <NUM>, then <NUM> from <NUM> to <NUM>, then a sinewave signal of <NUM> from <NUM> to <NUM>,. , finally a sinewave signal of <NUM> from <NUM> to <NUM>, then <NUM> from <NUM> to <NUM>, and then repeats periodically, as an example. As an example, <FIG> illustrates amplitude vs. time graph of an exemplary drive signal Sd according to an embodiment of the present disclosure.

In response to this drive signal Sd being applied to a drive electrode of an absorbent article, a sense signal <NUM> is sensed from a sense electrode of the absorbent article. It is appreciated that in response to a sinewave signal of a specific frequency being applied to a drive electrode of an absorbent article, a sinewave signal of the same specific frequency is sensed from a sense electrode of the absorbent article, but with a smaller amplitude.

By using bandpass filter at the sense electrode that is configured to allow only a specific frequency to pass through and to filter out all other frequencies, a sense signal may be obtained for each frequency. <FIG> illustrates amplitude vs. time graphs G showing the sense signals Ss of various frequencies, according to an embodiment of the present disclosure.

As an example, in <FIG> from up to down, the uppermost graph G1 illustrates the sense signal <NUM>-<NUM> of <NUM>, the second uppermost graph G2 illustrates the sense signal <NUM>-<NUM> of <NUM>,. , a graph Ga illustrates the sense signal <NUM>-a of 5a kHz, a graph Gb illustrates the sense signal <NUM>-b of 5b kHz,. , a graph Gm illustrates the sense signal <NUM>-m of <NUM> kHz, a graph Gn illustrates the sense signal <NUM>-n of 5n kHz,. , that are sensed from the sense electrode in response to the drive signal <NUM> as illustrated in <FIG> being applied to the drive electrode, where a, b, m, and n are integers.

In the embodiment as illustrated in <FIG>, a first wetness event is assumed to occur at time t1, which causes the connection between the electrodes (the drive electrode and the sense electrode) in the absorbent article. In response to the first wetness event, a sharp jump in amplitude that changes beyond a threshold height Hj within a period shorter than a threshold period Tj may occur at or around t1 in a sense signal of a low frequency. This sense signal of the low frequency does not change in its amplitude much before and after this jump, even though further wetness events occur in the absorbent article later. It can be seen from <FIG> that a jump in amplitude of a height H within a period T appears around t1 in signal <NUM>-a and the signal <NUM>-a does not change in its amplitude much before and after this jump, as an example.

Based on the above, in an embodiment of the present disclosure, a sharp jump in amplitude that changes beyond a threshold height Hj within a period shorter than a threshold period Tj in a sense signal of a low frequency can be used to determine the first wetness event in an absorbent article.

It is to be noted that, the change in amplitude of the sense signal of a low frequency in response to the first wetness event might be smoother, e.g. a gradual upslope, In some circumstances, in which case a threshold height Hs greater than the threshold height Hj may be used to determine the first wetness event in an absorbent article. That is, in addition or alternatively to the sharp jump in amplitude as described above, a gradual upslope in amplitude with a height beyond a threshold height Hs in a sense signal of a low frequency may be used to determine the first wetness event in an absorbent article, in an embodiment of the present disclosure. As an example, in <FIG> an upslope in amplitude of a height H' occurs around t1 in the sense signal <NUM>-b that also does not change much before and after the first wetness event t1.

Based on the above, in an embodiment of the present disclosure, a periodic drive signal that is swept in a period over a range of frequencies is applied to a drive electrode in an absorbent article, and by using bandpass filter, a sense signal is sensed from a sense electrode in the absorbent article for each frequency in the frequency range. In order to determine the first wetness event, the sense signals of low frequencies e.g. around <NUM> are checked for a sharp jump e.g. of a height beyond Hj within a period T shorter than Tj or for a gradual slop e.g. of a height beyond Hs in their amplitudes.

As mentioned above, the sense signal of low frequency, with which the first wetness event in an absorbent article is determined by checking a sharp jump or a gradual upslope in its amplitude, does not change in amplitude much after the sharp jump or the gradual upslope, and thus cannot be further used to estimate or detect the saturation in the absorbent article.

On the other hand, a sense signal of high frequency e.g. ranging from <NUM> - <NUM> gradually increases in its amplitude as more and more wetness events occur in the absorbent article. Based on this, the sense signals of higher frequencies may be used to estimate or detect the saturation in the absorbent article after the first wetness event is determined, in an embodiment of the present disclosure.

It is understood that, after the first wetness event, further wetness events occur in the absorbent article. As further wetness events occur in the absorbent article, the sense signals of higher frequencies continue to increase in their amplitude gradually. In an embodiment of the present disclosure, in order to estimate or detect the saturation in the absorbent article, the difference in amplitude from the first wetness event (e.g. time t1 in <FIG>) is determined in each of all sense signals of higher frequencies. Once the difference in amplitude from the first wetness event (e.g. time t1 in <FIG>) is determined in any one of the sense signals of higher frequencies to be beyond a threshold amount Ts, the saturation is detected in the absorbent article.

As can be seen from <FIG>, at time t2 the difference in amplitude from the first wetness event t1 is Dm2 in the sense signal <NUM>-m, and is Dn2 in the sense signal <NUM>-n. However, the differences in amplitude from t1 to t2 are all less than the threshold amount Ts in all the sense signals of higher frequencies.

Further, at time t3, the difference in amplitude from the first wetness event t1 is Dm3 in the sense signal <NUM>-m, and is Dn3 in the sense signal <NUM>-n. At this time, while the differences in amplitude from t1 to t2 are less than the threshold amount Ts in other sense signals of higher frequencies, the difference in amplitude of the sense signal <NUM>-n from t1 to t2 is greater than the threshold amount Ts, which may be used as indication of the saturation in the absorbent article, according to an embodiment of the present disclosure. In an embodiment of the present disclosure, the sense signal 200n, in which a difference in amplitude from t1 greater than the threshold amount Ts is first detected, may be e.g. about <NUM>.

Based on above, in an embodiment of the present disclosure, a periodic drive signal that is swept in a period over a range of frequencies is applied to a drive electrode in an absorbent article, and by using bandpass filter, a sense signal is sensed from a sense electrode in the absorbent article for each frequency in the frequency range. In order to estimate or detect the saturation in the absorbent article, the first wetness event, which is determined as described above with use of a sense signal of low frequency, is used as baseline, and the difference in amplitude from the first wetness event is compared to a threshold amount Ts in each of all sense signals of higher frequencies e.g. ranging from <NUM> to <NUM>, and whenever a difference in amplitude is determined to be greater than the threshold amount Ts, the saturation is detected in the absorbent article.

It is also appreciated that, the wetness spot changes in different orientations of the user wearing the absorbent article, which in turn results in different distances between the wetness spot and the pod. Therefore, in an embodiment of the present disclosure, the threshold amount Ts may be changed depending on the orientation of the user. For example, according to an embodiment of the present disclosure, a smaller threshold amount Ts is assigned to an orientation of user in which the wetness spot is further away from the pod.

Claim 1:
A method of moisture detection and estimation in an absorbent article with use of multiple frequencies, comprising:
applying, by capacitive coupling, drive signal of multiple frequencies to a drive electrode in the absorbent article;
sensing, by capacitive coupling, sense signal of the multiple frequencies from a sense electrode in the absorbent article;
detecting the first wetness event in the absorbent article with use of sense signal of a frequency of the multiple frequencies; and
detecting the saturation of the absorbent article with use of sense signal of another frequency of the multiple frequencies.