Get an indication of the fat content of your milk

Abstract

A breast pump device (1) is provided with or used in conjunction with an acoustic milk expression assessment system (6) to obtain an indication of the fat content of expressed milk. The acoustic milk expression assessment system (6) comprises an acoustic sensor (61) and a processor (62), the processor (62) being configured to process acoustic signals received from the acoustic sensor (61) during operation of the breast pump device (1) when a milk container (4) is used with the device (1). By recording the sound during pumping, a frequency shift of the sound of a milk droplet falling into the container (4) and impacting the surface of the milk contained in the container (4) can be determined relative to a reference situation of liquid with a fat content of 0%, which frequency shift can be factored into an estimate of a value related to the fat content of the milk.

Description

Technical Field

[0001] In one aspect, the invention relates to a method of obtaining an indication of the fat content of milk.

[0002] In another aspect, the invention relates to an apparatus for obtaining an indication of the fat content of milk.

[0003] In another aspect, the present invention relates to a breast pump device comprising: an expression kit including a breast receiving funnel, a milk outlet and an air outlet; and a vacuum unit configured to achieve pressure circulation in the expression kit, comprising an air inlet for connection to the air outlet of the expression kit and a pump mechanism for sucking air from the expression kit through the air outlet of the expression kit and the air inlet of the vacuum unit. According to the present invention, the breast pump device is designed to have a function of providing an indication to the user about the fat content of milk expressed by the breast pump device during an actual pumping period and / or one or more past pumping periods. Background Art

[0004] Generally, a breast pump device is a known tool for extracting milk from one breast or both breasts of a lactating woman. A breast pump device can be used in various situations, for example, when a child or baby cannot extract milk from the breast by itself, or when the mother is separated from the child or baby and the child or baby is breastfed by the mother or another person at a later stage. Therefore, women use breast pump devices to express breast milk at a convenient time and store it for their children or babies to consume later. Breast pumps are also helpful in situations where it is necessary to stimulate and increase milk production in women with low milk production or to relieve the pressure of breast congestion.

[0005] Breast pump devices are usually operated with one or two expression kits. In addition, the expression kit comprises a breast receiving funnel for accommodating the female breast, which funnel may be equipped with a pad or the like for massaging the breast in a specific way and is designed to be connected to a vacuum unit to achieve a pressure cycle in the expression kit, by which the milk can be expressed from the breast. In practical cases, the vacuum unit comprises an electric vacuum pump device, but manually operated breast pump devices are also known and are also used in daily life. The fact is that by generating a pressure cycle, in particular a vacuum cycle, which may be accompanied by a certain form of massage of the breast, a feeding action is simulated, which triggers the necessary milk let-down reflex of a lactating woman using a breast pump device. For the sake of completeness, it is noted that the term "vacuum" as used herein refers to a relatively low pressure, i.e. a pressure that is significantly lower than the ambient pressure.

[0006] It is known that at the beginning of breastfeeding, the so-called foremilk is expressed from the breast in a limited time, followed by the so-called hindmilk, which differs significantly in terms of milk fat concentration, with the hindmilk having a much higher milk fat content and a much lower water content than the foremilk. In order to mimic natural / direct breastfeeding as closely as possible when using expressed breast milk, it is therefore desirable to have two batches of milk, one of foremilk and the other of hindmilk. However, the fact is that during pumping, it is virtually impossible for the user to visually distinguish between hindmilk and foremilk, and it is impossible to identify the period when the milk composition changes, so that it is virtually impossible for the user to achieve the collection of two batches of milk as described above.

[0007] In view of the above, it is an object of the present invention to provide a new design of breast pump device, in particular such a new design which allows to provide the user with an indication of the fat content of the milk and preferably allows to alert the user immediately when the expressed milk changes from foremilk to hindmilk during pumping, thereby enabling the user to collect different types of milk in different containers. More generally, it is an object of the present invention to provide a method of obtaining an indication of the fat content of the milk in a simple and reliable manner, without the need for chemical analysis of the milk. Summary of the invention

[0008] The invention is defined by the claims.

[0009] In a first aspect, the invention provides a method of obtaining an indication of the fat content of milk, wherein at least one droplet is caused to fall on a quantity of milk, wherein the sound of the event of the droplet impacting the surface of the quantity of milk is detected so as to obtain an acoustic signal of the event, and wherein the acoustic signal is analyzed by executing a routine designed to generate an estimate of a value related to the fat content of the milk from the acoustic signal.

[0010] The first aspect relates in particular to the analysis of acoustic signals.

[0011] In a second aspect, the invention provides an apparatus for obtaining an indication of the fat content of milk, for causing at least one droplet to fall on a volume of milk, wherein the sound of the event of the droplet impacting the surface of the volume of milk is detected to obtain an acoustic signal of the event. The apparatus comprises a processor for analyzing the acoustic signal by executing a routine to generate an estimate of a value related to the fat content of the milk from the acoustic signal.

[0012] The device for example comprises an input device end for receiving an acoustic signal. Thus, the acoustic signal may be sensed remotely and the sensed signal provided to the device. Alternatively, the device may comprise an acoustic sensor for obtaining the acoustic signal. The device for example comprises an output end for providing an estimate of the value to a user. In any embodiment, the device may be arranged as an attachment or insert for a milk container, for example a milk container for use with or in a breast pump. The attachment may be configured as a sleeve or sleeve-like element, for example used as a base for a milk container (i.e. the attachment is configured to accommodate the base of a milk container), or placed around such a milk container.

[0013] The present invention relates to the recognition that the fat content of milk affects the surface tension and viscosity of a certain amount of milk, and this may affect the acoustic signal of a droplet impacting the surface of the certain amount of milk. The acoustic signal can be detected and analyzed by using any suitable technology, wherein no complex measurements need to be performed. For example, the method according to the invention can be carried out in a laboratory. The main purpose of the invention is to provide information about human milk, but the invention can also be applied in the field of analyzing milk obtained from cows, goats or camels or other mammals. In any case, a breast pump device can be designed so as to be able to implement the situation in which the method is performed in the upper and lower parts of the device to obtain an indication of the fat content of the milk expressed during pumping. Such a breast pump device may in particular have the function of indicating to the user when the foremilk becomes hindmilk. The invention is also applicable to milking machines and other devices for processing animal milk.

[0014] As mentioned above, the method according to the invention consists in causing at least one droplet to fall on a quantity of milk. On this basis, the method is very suitable for use in breast pump devices, since usually during operation of such devices milk is collected in at least one container and the droplet of milk falls on the quantity of milk present in the at least one container. Therefore, in order to use the method according to the invention in the case mentioned, i.e. in the case of a breast pump device, no changes need to be made in the basic design of the device. Instead, it is sufficient to add means for detecting sound and means for processing the acoustic signal. In order to obtain a reliable indication about the fat content in the milk, a practical option is to detect the sound caused by a series of drops hitting the surface of the quantity of milk, i.e. the sound caused by a plurality of drops hitting the surface of the quantity of milk one after another at a certain time interval, so that the acoustic signal is a representation of the sound associated with a single droplet, and to perform a step of averaging in the process of deriving information from the acoustic signal.

[0015] In the context of the present invention, the acoustic signal may be analyzed by executing a routine designed to generate an estimate of an absolute value related to the milk fat content from the acoustic signal. Alternatively or additionally, the acoustic signal may be analyzed by executing a routine designed to generate an estimate of a relative value related to the milk fat content from the acoustic signal. For example, an indication about the milk fat content may be provided in the form of a percentage of a predetermined maximum fat content. This may be useful if it is desired to track the actual progress of milk expression during pumping and compare it with one or more previous milk expression processes. Furthermore, less computing power may be required when only relative values ​​are estimated.

[0016] The analysis of the acoustic signal actually consists in determining the spectrum of the acoustic signal, i.e. determining the relationship between amplitude and frequency. This can be done in any suitable way, for example by performing a Fast Fourier Transform on a segment of the acoustic signal. The spectrum can be used to determine the frequency value of at least one peak of the spectrum of the acoustic signal and to compare this value with a reference value in order to determine a frequency shift which is used as a factor for estimating a value related to the fat content of the milk. According to one possible option, the reference value is established relative to a liquid with a fat content of 0%, which does not change the fact that the invention also covers other options.

[0017] Assuming that the volume of the milk is a factor influencing the frequency shift, it is advantageous if first a routine designed to generate a real-time estimate of the volume of the milk from the acoustic signal is performed, which routine may include determining a duration value between the moment of release of at least one droplet to fall towards the amount of milk and the first moment of the appearance of a peak in the acoustic signal after the moment of release. Other methods of estimating the volume of the milk are also possible within the framework of the present invention, but it is understood that the use of the acoustic signal is also very practical.

[0018] The at least one droplet that lands on the amount of milk to be analyzed may be a drop of milk. This is particularly advantageous in the case of a breast pump device, since drops of milk that land on the amount of milk are already available. This does not change the purpose that drops of another liquid may be used to obtain an indication about the fat content of the milk in the manner of the invention, such as drops of water.

[0019] The invention also relates to a breast pump device using the above device.

[0020] Accordingly, there is provided a breast pump device comprising:

[0021] an expression kit, including a breast receiving funnel and a milk outlet;

[0022] Pump mechanism;

[0023] An acoustic milk expression assessment system comprising an apparatus as defined above (for obtaining an indication of the fat content of milk); and

[0024] Acoustic sensors for obtaining acoustic signals,

[0025] Wherein the processor of the apparatus is configured to analyse acoustic signals received from the acoustic sensor during operation of the breast pump device.

[0026] The analysis preferably comprises determining the acoustic signal spectrum. The analysis for example comprises determining the frequency value of at least one peak of the acoustic signal spectrum and comparing this value with a reference value in order to determine a frequency shift which is used as a factor in estimating a value related to the fat content of the milk. The reference value relates to a liquid with a fat content of 0%.

[0027] More specifically, the expression kit may further comprise an air outlet, the breast pump device may further comprise a vacuum unit configured to achieve pressure circulation in the expression kit, comprising an air inlet for connection to the air outlet of the expression kit and a pump mechanism for sucking air from the expression kit through the air outlet of the expression kit and the air inlet of the vacuum unit, and the processor is configured to analyse acoustic signals received from the acoustic sensor during operation of the breast pump device when the container is used together with the breast pump device to receive milk from the milk outlet of the expression kit.

[0028] The processor is preferably configured to execute a routine designed to generate a real-time estimate of a value related to the fat content of the milk from the acoustic signal.

[0029] As mentioned above, the present invention relies on the application of acoustic techniques to obtain information representative of the fat content of milk. The invention is based on the recognition that the fat content affects the surface tension and viscosity and that this may affect the acoustic signature of milk (or another liquid) impinging on the surface of a quantity of milk present in a container. During pumping performed by a breast pump device, under the influence of pressure cycles, a repetitive process is performed in which freshly expressed milk is allowed to accumulate at a location upstream of the milk outlet in the expression kit and is allowed to fall from this location through the milk outlet as milk droplets. By detecting the sound of the milk droplets impinging on the surface of a quantity of milk present in a container for collecting the milk, an estimate of a value related to the fat content of the quantity of milk can ultimately be obtained, without the need to use complex analysis equipment and without the need to contact the milk to be analyzed.

[0030] The processor of the breast pump device may be particularly adapted to perform calculations intended to provide the user with a real-time indication of the fat content of the expressed milk during pumping. For example, the user may be provided with a real-time indication of whether the expressed milk is available as foremilk or hindmilk, an indication of the fat content of the milk, an indication of the overall (average) fat content of the milk, and / or advice on how to ensure that the envisaged mixture of foremilk and hindmilk is collected in the container in order to obtain an optimal mixture for use during feeding without the need to take further (mixing) action.

[0031] Note that the processor may be of any suitable type and may be part of a central processing unit (CPU) of the breast pump device which is further configured to control the operation of the breast pump device, in particular the operation of the pump mechanism.

[0032] For optimal ease of use, the present invention may include transmitting the automatically determined indication of fat content to a smartphone or tablet application or computer program, for example, which application or program may be further designed to track other characteristics of the pumping period, such as start time, duration, and expression rate.

[0033] Within the framework of the present invention, any suitable type of container may be used. As in many conventional cases, the expression kit may be provided with threads at a location around the milk outlet, so that the container can be screwed onto the expression kit at a suitable location to receive milk from the expression kit during operation of the breast pump device. However, other possibilities of attaching the container to the breast pump device are also covered by the present invention.

[0034] Various aspects of the method according to the invention are equally applicable to a breast pump device. Two of these aspects are as follows: i) this is feasible if the routine comprises determining a frequency spectrum of the acoustic signal, wherein optionally a Fast Fourier Transform is applied, and ii) the routine may in particular comprise determining a frequency value of at least one peak of the spectrum of the acoustic signal and comparing this value with a reference value in order to determine a frequency shift which is used as a factor for estimating a value related to the fat content of the milk, wherein the reference value may relate to a liquid with a fat content of 0%, or be predetermined in another suitable manner.

[0035] In the case of a breast pump device, the need to provide the user with an indication of the change of the initially obtained foremilk to hindmilk can be met if the routine includes a real-time comparison of the estimated value related to the fat content of the milk with the discrimination value, and the processor is configured to issue a reminder signal at the moment when the estimated value related to the fat content of the milk is found to increase from below the discrimination value to above the discrimination value. Naturally, the discrimination value is chosen to represent the transition of foremilk to hindmilk. As mentioned above, the user who receives real-time information about the transition of foremilk to hindmilk has the opportunity to change the container for receiving the milk so that the foremilk and hindmilk can actually be separated from each other. This can be particularly useful when it is desired to bottle-feed in a more or less natural way, or when it is desired to feed a toddler or baby who requires highly nutritious milk using only hindmilk.

[0036] The present invention enables pathological detection, that is to say detection of conditions that in some way affect the fat content of the milk. In this regard, an embodiment of a breast pump device according to the invention is feasible, wherein the routine comprises comparing an estimate related to the fat content of the milk over a period of a predetermined length of time starting from a pumping session with a threshold value, and wherein the processor is configured to issue an alert signal when the estimate related to the fat content of the milk is found to be above the threshold value. Such an embodiment is particularly useful as a screening tool for mastitis, and as a monitor of the effectiveness of treatment. Indeed, mastitis, i.e. inflammation of the mammary glands in the breast, involves the production of abnormally large sized fat globules in the milk, and therefore an abnormally high fat content of the milk.

[0037] It may be advantageous if the processor is further configured to execute a routine designed to generate a real-time estimate of the volume of milk in the container based on the acoustic signal. Such a routine may include determining a duration value between a release time and a first time after the release time at which a peak in the acoustic signal occurs, the release time being the time at which the vacuum is released during the pressure cycle and at which milk is correspondingly released from a location in the expression kit through the milk outlet. The pumping period includes a repetitive process of accumulating newly expressed milk in the expression kit and releasing the milk through the milk outlet. When the vacuum is applied during the pressure cycle, milk is removed from the breast of the woman. When the vacuum is released during the pressure cycle, milk is allowed to leave the expression kit through the milk outlet so that the milk, as it falls, enters a container used with the breast pump device for receiving milk from the milk outlet until the milk strikes a surface of the container, or, if the surface of the container is covered with a certain amount of milk, strikes a surface of milk present in the container, causing a peak in the acoustic signal to occur. Once the value of the duration between the moment of release and the first moment of occurrence of an acoustic signal peak after the moment of release is determined, a value directly related to the total milk volume in the container is obtained and is therefore suitable for use in determining the actual value of the total milk volume in the container.

[0038] Preferably, the processor is configured to communicate with an external device or system, separate from the expression kit and vacuum unit, and configured to provide information to a user. Examples of such external devices or systems are smartphones, smart watches, tablets, laptops and computers. The external device or system may be used to run an application / program to provide information to a user about the breast pump device and a pumping session performed by the device. The communication with the external device or system is preferably wireless.

[0039] Various positions of the acoustic sensor are feasible within the framework of the present invention. A practical and useful position may be a position at the extrusion kit downstream of the breast receiving funnel. Generally, a position is preferred where the acoustic signal to be detected is strong enough and is as free from interference as possible. The acoustic sensor may comprise, for example, a microphone, or a suitable pressure sensor or accelerometer.

[0040] The present invention also covers embodiments of the breast pump device, wherein the acoustic sensor of the acoustic milk expression assessment system is located in an external device or system separate from the expression kit and the vacuum unit.

[0041] In one example, the breast pump device may further comprise a holder mechanism for holding an external device or system on an extrusion kit or a container for use with the breast pump device. In the context of the present invention, it has been found that it is feasible not to equip the breast pump device with an acoustic sensor, but to provide an external device or system comprising an acoustic sensor and to hold the external device or system on the extrusion kit or container. For example, a microphone typically present in a smartphone may be used. By holding the smartphone in a suitable position on the extrusion kit or container, an acoustic signal to be processed may be detected to obtain an indication of the fat content of the milk. The holder mechanism may comprise a holder element which is an integral part of the extrusion kit or container, but it may even be more practical if a holder element which is connectable to and removable from the extrusion kit or container is provided. For example, a sleeve comprising a microphone may be provided which is designed to be wrapped around the container.

[0042] In fact, the entire acoustic milk expression assessment system can be incorporated into an external device or system, in which case the external device or system is not only equipped with an acoustic sensor, but also equipped with a processor configured to process the acoustic signals received from the acoustic sensor. The various options for the processor configuration described above also apply to this case.

[0043] So there are all sorts of possibilities.

[0044] The acoustic sensor may be mounted on the extrusion kit and the processor may be mounted on the pump mechanism.

[0045] Alternatively, the expression kit and pump mechanism may form part of a breast pump, and the breast pump device further comprises a user interface device external to the breast pump. In this case, the acoustic sensor may be part of the breast pump and the processor may be part of the external user interface device; or both the acoustic sensor and the processor may be part of the external user interface device.

[0046] The above and other aspects of the invention will become apparent from and will be elucidated with reference to the following detailed description of the manner in which values ​​are determined which are directly related to milk fat content and which are therefore suitable as a measure of milk fat content. The description is made in the context of expressing human milk and a breast pump device for use in this process and should not be construed as implying that the invention is limited to this context. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will now be explained in more detail with reference to the accompanying drawings, in which the same or similar parts are indicated by the same reference numerals, and in which:

[0048] Figure 1 schematically showing a breast pump device comprising an expression kit, a vacuum unit and a flexible tube interconnecting the expression kit and the vacuum unit, and schematically showing a smartphone for receiving information from the breast pump device and displaying the information to a user;

[0049] Figure 2 The stages of collecting expressed milk in an expression kit, releasing the milk into a container attached to the expression kit, and the milk hitting the surface of a quantity of milk in a container of a portion are shown respectively;

[0050] Figure 3 shows a spectrum obtained from an experiment in which milk liquid was dropped into a certain amount of milk and in which sound was detected;

[0051] Figure 4 A schematic diagram of a system for milk fat content estimation and milk volume estimation is given;

[0052] Figure 5 illustrates how volume thresholds and / or the number of letdown reflex events may be used to determine the transition between foremilk and hindmilk; and

[0053] Figures 6A to 6E Five possible ways of configuring a breast pump device and acoustic treatment are shown. DETAILED DESCRIPTION

[0054] The present invention belongs to the field of breast pump devices, and is particularly applicable to electric breast pump devices. Figure 1, an electric breast pump device is first generally described in order to clearly understand the background aspects of the present invention.

[0055] The breast pump device 1 comprises an expression kit 2 and a vacuum unit 3 for generating pressure cycles during which a vacuum (low pressure) is alternately generated and released. In order to receive expressed milk during operation of the breast pump device 1, a milk container 4 is used, which can be connected to the expression kit 2, for example by a threaded connection, thereby closing the lower end of the expression kit 2. The vacuum unit 3 is an electric vacuum unit and comprises an electric pump 31 and an air valve for alternately achieving a vacuum during operation, i.e. during pumping to be performed by the breast pump device 1. The pump 31, the air valve and a central processing unit (CPU) 32 for achieving correct operation of the pump 31 and the air valve are designed to function in a manner known in the field of breast pump devices. Therefore, further details of these components will not be explained in this document, and the same applies to other practical aspects of the vacuum unit 3 known per se. The pump 31 is electrically connected to a power supply, which can be, for example, mains electricity or a battery. The pump 31 and the CPU 32 are connected in a manner known in the art to the vacuum unit 3. Figure 1 The air valve is schematically shown in the figure as a dotted rectangle, and the air valve is not shown. The path allowing the exchange of control signals, etc. between the pump 31 and the CPU 32 is shown in FIG. Figure 1 For example, the path may be implemented as any suitable type of communication line.

[0056] The expression kit 2 includes a breast receiving funnel 21, a hole for a milk outlet 22, and a milk path 23 from the breast receiving funnel 21 to the milk outlet 22. Therefore, the breast receiving funnel 21 is in fluid communication with the milk outlet 22 via the milk path 23. The milk path 23 can be closed by a valve assembly 24 (e.g., Figure 2 Schematically shown). The breast receiving funnel 21 may include a massage pad or the like (not shown) for providing a soft and warm feeling to the breast and / or simulating the sucking action of a toddler or baby.

[0057] exist Figure 1 , the breast pump device 1 is shown in an assembled state, wherein the vacuum unit 3 is connected to the expression kit 2 by a flexible tube 5, wherein the air inlet 33 of the vacuum unit 3 is connected to the air outlet 25 of the expression kit 2. This configuration allows the vacuum unit 3 to be remotely arranged relative to the expression kit 2, so that the size of the part of the breast pump device 1 applied to the female breast can be kept within reasonable limits. It should be noted that the breast pump device 1 may include two expression kits 2 for enabling a lactating woman using the breast pump device 1 to extract milk from both breasts at the same time, in which case the expression kits 2 may share a common vacuum unit 3.

[0058] Advantageously, as shown, the breast pump device 1 comprises a user interface 34 for allowing a user to control the operation of the breast pump device 1. In the example shown, the user interface 34 is arranged on the vacuum unit 3 and enables a user to provide input to the CPU 32. The user interface 34 may be implemented in any suitable manner, such as by a plurality of buttons as shown, or by a touch screen. By way of example, it should be noted that the user interface 34 may comprise one button 35 for activating the stimulation mode and three buttons 36 for selecting one of the three expression settings.

[0059] The present invention provides a method of estimating the fat content of milk by means of a breast pump device 1, i.e. by means of an apparatus suitable for use in a home environment and in the presence of a medical professional, without the need for complex, bulky and expensive analytical equipment. To this end, the breast pump device 1 is provided with an acoustic milk expression assessment system 6, comprising an acoustic sensor 61 and a processor 62, the processor 62 being configured to process acoustic signals received from the acoustic sensor 61 during operation of the breast pump device 1. In the example shown, the acoustic sensor 61 is a microphone, which is integrated in the expression kit 2 at a position along the milk path 23 and upstream of the valve assembly 24. This does not change the fact that another type of acoustic sensor 61, such as a suitable pressure sensor or accelerometer, may be used in the breast pump device 1 according to the present invention. In the case where the acoustic sensor 61 is a microphone, it is preferred that the microphone is unidirectional or cardioid, in order to minimize external noise and to optimally obtain the acoustic signature of milk droplets falling on the surface of a certain amount of milk contained in the milk container 4 and the milk container 4. Furthermore, other positions of the acoustic sensor 61 are also feasible within the framework of the invention. When it comes to minimizing background noise, it is feasible within the framework of the invention to add suitable sound shielding.

[0060] The acoustic sensor 61 and the processor 62 are Figure 1 The path that allows the acoustic signal to be transmitted from the acoustic sensor 61 to the processor 62 is Figure 1 The path is preferably implemented wirelessly, but this should not be understood as implying that the present invention does not cover wired paths.

[0061] like Figure 1 As shown, the processor 62 may be part of the CPU 32. In addition to the breast pump device 1, Figure 1Also shown is a smartphone 7 for providing information generated by the processor 62 to the user during operation of the breast pump device 1. The processor 62 is configured to communicate with the smartphone 7, wherein the smartphone 7 may be used to run an application designed to display relevant information about the breast pump device 1 and a pumping session performed by the breast pump device 1 on a screen 71 of the smartphone 7, and possibly also to receive relevant input from the user, in which case the smartphone 7 serves as a user interface. Figure 1 Schematically shown in dotted lines is a path that allows information to be exchanged between the processor 62 and the smartphone 7. This path is preferably implemented wirelessly, but this should not be understood as implying that the present invention does not cover wired paths.

[0062] When it comes to holding a smartphone 7 or other external device or system to a milk container 4, any suitable holder mechanism may be designed and applied. Generally, such a suitable holder mechanism may include a holder designed to securely wrap around the container 4 and also be able to securely hold the smartphone 7, wherein preferably the holder is adaptable for use with containers 4 of different diameters, for example based on flexibility characteristics.

[0063] Furthermore, any holder attachment may be designed for supporting and positioning any wireless earbud / headphone near the desired sound detection location on the breast pump device 1. The microphone of the earbud / headphone may be used instead of the smartphone 7 to collect information suitable for estimating a value related to milk fat content.

[0064] The process of detecting the acoustic signal in order to obtain an indication about the fat content of the milk can be well performed in the case of a double electric breast pump device, i.e. a breast pump device designed to extract milk from two breasts simultaneously and comprising two expression kits 2. According to a first option, the acoustic sensor 61 can be integrated on each of the two expression kits 2 and the two acoustic signals obtained in this way can be analyzed to find the required information. According to a second option, only the acoustic sensor 61 can be used on only one of the two expression kits 2, provided that the acoustic sensor 61 is arranged at a position capable of detecting the sound of milk drops falling in each container 4 connected to the respective expression kit 2. Based on the amplitude of the peaks detected in the acoustic signal (or another suitable feature), the milk drops falling in one container 4 can be distinguished from the milk drops falling in the other container 4. In fact, it can be expected that the milk drops falling in the container 4 closer to the acoustic sensor 61 produce a sound with a greater amplitude than the milk drops falling in the container 4 at a greater distance. In the case of a double electric breast pump device, it may be advantageous to use a bidirectional or omnidirectional microphone as the acoustic sensor 61 rather than a unidirectional microphone.

[0065] In the following, the working manner of the acoustic milk expression assessment system 6 will be explained, wherein details of the theoretical background of the working principle of the acoustic milk expression assessment system 6 will also be given.

[0066] Typically, a breast pump device 1 is used to express milk from a woman's breast. To this end, a vacuum is alternately applied to the breast (pressure cycle). During the low pressure or vacuum period, the actual process of expressing milk from the breast takes place. Each time the vacuum is released, newly expressed milk drips into the container 4. The amount of milk that falls from the expression kit 2 is small and can be expected to emerge from the expression kit 2 in the form of drops. Figure 2 In FIG. 1 , the first (leftmost) illustration of the expression kit 2 and the container 4 connected thereto is used to illustrate that during vacuum, the valve assembly 24 is closed so that milk is collected above the valve assembly 24. The milk (to be) released from the expression kit 2 is Figure 2 4 is schematically depicted as a circle, and the valve assembly 24 is also schematically shown by a plurality of lines. In the second illustration of the expression kit 2 and the container 4 connected thereto, it is shown that when the pressure is released, the milk falls in the container 4 towards the amount of milk already present in the container 4. The third illustration of the expression kit 2 and the container 4 connected thereto is used to illustrate that the milk released from the expression kit 2 eventually reaches the surface of the amount of milk contained in the container 4.

[0067] It is known that during pumping the fat content of the expressed milk changes. In the first case, the so-called foremilk is expressed, and in the latter case the so-called hindmilk is expressed, wherein it should be noted that the foremilk is more diluted and has a lower fat content than the hindmilk, and that there is no clear distinction between foremilk and hindmilk, since the composition of the milk will gradually change. The main function of the foremilk for an infant or toddler is to quench thirst, while the main function of the hindmilk is to provide satisfaction and relieve hunger. In order to achieve a natural feeding scheme with expressed milk, it is desirable to first feed the toddler or infant with the foremilk and then with the hindmilk. For this purpose, during the expression process, the milk should be stored in at least two different containers. The containers should be changed when the fat content of the milk increases above a certain threshold, which indicates that the milk is changing from foremilk to hindmilk.

[0068] The breast pump device 1 is adapted to automatically estimate the fat content of breast milk during expression in real time using an acoustic milk expression assessment system 6 by analysing the frequency spectrum of the splashes produced by milk droplets as they fall into the container 4. The processor 62 processes the acoustic signal acquired by the acoustic sensor 61 in order to calculate the frequency spectrum. One possible method of achieving this involves separating consecutive milk droplet splash events and performing a fast Fourier transform on the milk droplet signal segments. For example, 5 to 10 events collected over a time range of approximately 10 to 20 seconds may be isolated. The spectrum of each milk droplet may be averaged, so that the influence of noise and outliers may be reduced. Thus, an average milk droplet frequency spectrum is obtained.

[0069] Preferably, the acoustic signal is first used to determine the volume of milk in the container 4. This can be achieved by collecting information about the time required for a drop of milk to fall from the valve assembly 24 to the surface of the milk present in the container 4. The acoustic milk expression assessment system 6 may be configured to perform a process of estimating a value related to the fat content of the milk once a certain volume has been reached.

[0070] Figure 3 The average spectrum of milk droplets obtained experimentally when the volume of milk in the container 4 is 60 ml is shown. In the example shown, only the part of the average spectrum between 0 and 4 kHz is used to make the analysis of the milk fat content easier. A peak detector is used to isolate the frequency of the main peak in the average milk droplet spectrum. Figure 3 In the spectrum shown, four main peaks A, B, C and D can be distinguished for the frequency range 0 to 4 kHz.

[0071] A practical method of analyzing the spectrum and the routine (algorithm) followed in the process is explained below. It should be noted that this is one of a large number of approaches that exist within the framework of the present invention, in particular one aimed at determining the moment of transition from foremilk to hindmilk during pumping.

[0072] This routine uses a first order parametric transfer function according to which two variables, namely the volume of milk in the container 4 (V, ml) and the measured frequency (f m , Hz)) and use these two variables to estimate fat content (F, %) based on the following basic formula determined empirically, where K 1 , K 2 and c represent empirically derived constants:

[0073] F=K 2 (f m -(K 1 V+c)).

[0074] The transfer function consists of two sub-transfer functions that describe the behavior of the fourth peak in response to i) the volume at 0% fat content (ie water) and ii) changes in fat content, where f w represents the expected peak position (Hz) for a fat content of 0%, and Δf represents the change in frequency (Hz):

[0075] f w =K 1 V+c

[0076] F=K 2 Δf.

[0077] In the experiments conducted in the context of the present invention, K was found by collecting the position of the fourth peak D at 11 different volumes ranging from 50 ml to 150 ml. 1 and c. K is found by varying the fat content and observing the position of the same fourth peak D 2 Thus, regarding K 1 and c, a nonlinear model is obtained, which is expressed by the following equation:

[0078] f w =-11.2V+2,966

[0079] For volumes less than 80 ml, and

[0080] f w =-6.2V+2,306.

[0081] For volumes above 80 ml. Therefore, for volumes less than 80 ml, K 1 =-11.2Hz ml -1 and c = 2,966 Hz, and for volumes greater than 80 ml, K 1 =-6.2Hz ml -1 and c = 2,306 Hz. In addition, regardless of volume, it is found that K 2 The appropriate value is 0.075% Hz -1 .

[0082] When K 1 , K 2 When the values ​​of and c are substituted into the basic formula provided above, the following model is obtained:

[0083] V<80ml F=0.075(f m +11.2V-2,966)

[0084] V>80ml F=0.075(fm+6.2V-2,306).

[0085] A first order model is used in this analysis to approximate the behavior of the system. Higher order models, or even alternative nonlinear models such as lookup tables, can be used to improve accuracy.

[0086] The use of the model is illustrated by an example where the volume is 150 ml and when analysing the spectrum of the splash a fourth peak D is found at 1400 Hz. In this example the estimated absolute value of the fat content is:

[0087] F=0.075(1,400+6.2·150-2,306)=1.8%.

[0088] It should be noted that other features may be considered, such as the ratio of two or more peaks A, B, C and D in the frequency domain and the damping coefficient of the time domain signal envelope. Combinations of these features may also be used to establish a "fingerprint" for a given milk formation.

[0089] Figure 4 A schematic diagram of the aforementioned system for estimating milk fat content and milk volume by acoustically detecting two milk droplets released during milking by a double electric breast pump is given. In this figure, x(t) = splash audio signal, t d = time (s) that the valve assembly 24 is open, t s = Splashing time (s), i.e. the time it takes for the milk droplets to hit the milk surface, T TOF = flight time (s), i.e. the time required for the milk droplet to fall into the container 4 before hitting the milk surface, V = volume of milk in the container 4 (ml), X(f) = frequency spectrum of the splashing audio signal, f m = peak position of milk (Hz), F = fat content of milk (%). In addition, V(T TOF ) represents the function that calculates the volume based on the flight time, and F(V, f m ) represents a function for calculating fat content from the volume and peak position of milk. A further input to the function for calculating volume from flight time is a user input on aspects such as the type of container 4, so that the geometric and dimensional factors of the container 4 can be taken into account when executing the function.

[0090] The basic theory behind the present invention is now outlined to enhance understanding.

[0091] It is assumed that the peak frequency shift observed in the average milk droplet spectrum occurs due to two coupled factors: i) the change in volume when the container 4 is filled with milk, and ii) the change in surface tension / viscosity which is directly related to the actual content of the milk. Surface tension changes caused by other factors such as mineral content, impurities or temperature are ignored because they are considered negligible. Temperature can greatly affect surface tension and viscosity, however, it is assumed in this article that the expressed milk does not undergo large temperature changes during the expression process and therefore does not vary greatly from about 37°C (i.e. the approximate temperature of milk expressed from the human body).

[0092] It is further assumed that the volume and fat content factors are additive and can be completely decoupled by considering the effects of volume and fat content separately. As the volume change effect is two orders of magnitude larger than the fat content change effect, within the functionality of the breast pump device 1, the magnitude of the volume effect is first isolated by comparison with the same volume of water. Water is a useful comparison medium because it contains no fat. This implicitly assumes that if a given volume of milk is compared to the same volume of water, and if the milk contains no fat, the frequency of the fourth peak will be the same. It is therefore assumed that any difference between the frequency of the fourth peak D of milk and the frequency of the corresponding peak of water is only caused by changes in surface tension / viscosity which are directly related to the fat content of the milk. This assumption further implies that the effect of fat content on surface tension and viscosity is the same at all milk volumes, i.e. fat content will change the frequency spectrum with the same amplitude and direction at all milk volumes.

[0093] To demonstrate the above method, additional details of the setup in which the experiment was conducted are given. In the experiment, a pipette, container, milk, 50 ml graduated cylinder, microphone, clamp stand and a personal computer with Matlab and Audacity installed were used. The pipette was held at a slight angle by the clamp stand at 300 mm from the edge of the container. The pipette was used instead of a pump to allow for better control of the formation of milk droplets. The microphone was taped to the bottom of the container. The milk was diluted to the desired fat content and the container was filled to the desired volume by means of a graduated cylinder. Fifteen drops of milk of the same fat content as the milk in the container were pipetted into the container at a slow, regular rate of approximately 0.5 to 1.0 Hz. This allowed the surface of the diluted milk to calm down between each drop. The acoustic signal from the microphone was then captured using Audacity on the personal computer and the data was exported as a .wav file and imported into Matlab.

[0094] Through Matlab, the audio signal is made to reach f mThe acoustic signal is first passed through a series of post-processing steps before being averaged (i.e. the frequency of the fourth peak). First, the acoustic signal is passed through a peak detector to extract peaks A, B, C, D. The signal is then windowed to leave only a single splash. Some artifacts are captured at this point, but these are filtered out in a later averaging process. The Fast Fourier Transform of the splash is calculated before averaging. At this point, outliers are removed and a peak detector is applied in the range of 0 to 4 kHz. The fourth peak D, which occurs in the range of 1.2 to 3.0 kHz found in the experimental setup, is extracted and f m Set to its frequency position.

[0095] The above procedure was run for a number of different volume-fat content combinations. The different fat contents were obtained by diluting whole milk (3.5% fat). The milk to water ratio was calculated by the following equation, where V w Represents the volume of water, V m Indicates the volume of milk, C 1 represents the initial fat content, C 2 Indicates the final fat content:

[0096] V w / V m =(C 1 / C 2 )-1.

[0097] The above equation is derived from the following basic equation:

[0098] Concentration = mass / volume.

[0099] When diluted, the mass of fat remains the same, but the volume changes, so

[0100] C 1 V 1 =C 2 V 2 .

[0101] As previously mentioned, the present invention provides an alternative for determining the fat content of milk in real time during milk expression. This allows the expressed milk to be separated into foremilk and hindmilk to achieve a more natural feeding, i.e., feeding the expressed milk to a toddler or infant in a manner similar to the way a toddler or infant sucks milk directly at the breast. For practical implementation, several practical issues need to be considered. First, it is known that since the expressed breast milk gradually changes from the less fat foremilk to the more fat hindmilk, a fat content threshold is used to distinguish between these two types of milk. Due to the lack of an established gold standard for this transition, an arbitrary threshold is set to, for example, 4% fat content. However, it should be understood that the threshold can be easily changed to a higher or lower value, which can vary from person to person based on, for example, the range of fat content in the milk expressed by lactating women. Therefore, the 4% fat content threshold is used herein for illustration only. Second, it is known that since the first milk expressed from the breast is the more watery foremilk, after a certain amount of milk is expressed, before the end of the expression period, a transition point to the more fat hindmilk will occur.

[0102] refer to Figure 5 It should be noted that in order to facilitate the process of finding the transition point, several methods can be used alone or in combination. First, based on the lactating woman's historical milk expression, milk volume thresholds can be used to increase the likelihood of finding the transition point. For example, if a lactating woman typically expresses 80 ml of milk from each breast, a lower threshold of 25 ml and an upper threshold of 50 ml can be used. Thus, the transition point between foremilk and hindmilk will be limited to a smaller range of 25 ml. Figure 5 In, V UT Represents the upper threshold, V LT Represents the lower threshold. Secondly, the number of letdown reflex events that have occurred can serve as a basis for finding the transition point. It is known that milk expression is a discontinuous process in which lactating women release milk after consecutive letdown reflex events, and letdown reflex events may occur 3 to 5 times during the milk expression process. By identifying such events based on periods of rapid increase in milk volume and subsequent periods of very slow increase in milk volume, it will be easier to determine the transition between foremilk and hindmilk. For example, the second or third letdown reflex event is more likely to cause this transition than the first letdown reflex event. Figure 5 In the figure, the indicator "MER" is used to identify various letdown reflex events. The window where the transition between foremilk and hindmilk occurs is indicated by a dashed rectangle.

[0103] According to a practical solution, once the fat content reaches 4%, the breastfeeding woman is notified and prompted to change the container so that the fatter hind milk is stored separately from the waterier foremilk. This can be done through an application or any other suitable communication method. In practice, the action of changing the container may not exceed about 1 minute and can be easily performed by temporarily stopping the pump 31, then quickly removing the first container from the breast pump device 1, and connecting another container to the breast pump device 1 instead of the first container.

[0104] During the experiment, it was observed that the color of the milk changes at different dilutions. In view of this, steps can be taken to verify the estimated fat content using optical sensing. For example, a smartphone 7 can be used to acquire an image of the milk present in the container 4, which can then be processed to estimate the fat content of the milk by correlating it with the expected color of the milk.

[0105] The data on the volume and fat content of milk can be used to provide guidance or instructions to a lactating woman. For example, the following goals can be achieved: i) a lactating woman can be prevented from ending expression too early, i.e., before all the fat-containing, highly nutritious milk has been extracted, ii) a lactating woman who is concerned about the quality of her milk can be assured that the amount of milk produced is sufficient and of good quality, thus preventing the lactating woman from stopping breastfeeding at an early stage (premature stage), and iii) the expression period can be optimized to ensure that the expressed milk is optimized in terms of both amount and fat content, taking into account the assumption that the amount and fat content of milk expressed relatively quickly or in a relatively short period of time may be inferior to that of milk expressed at a relatively slow rate.

[0106] As previously mentioned, it is known that when a lactating woman suffers from mastitis, abnormally large fat globule sizes are produced in the milk. Assuming that large globular fat size is associated with increased fat content, the fact content tracking technology according to the present invention can be used to provide an early warning system for diagnosing mastitis. Therefore, the present invention can be used to screen for mastitis and monitor the effectiveness of treatment.

[0107] The acoustic milk expression assessment system 6 may be configured to output relative fat content, i.e. fat content as a percentage of maximum fat content, rather than absolute fat content. This may be a useful indicator for lactating women who want to track current expression and compare it to previous expression. This may also simplify the above routine as it means that there is no need to find the constant K which is usually required to determine absolute fat content. 2 .

[0108] As mentioned above, the milk expression assessment system may be integrated into a breast pump, or may be part of an external device.

[0109] Figures 6A to 6E Various possible options are shown. In all cases there is an acoustic sensor 61 for capturing an acoustic signal and a processor 62 for analysing the acoustic signal by executing a routine to produce from the acoustic signal an estimate of a value related to the fat content of the milk.

[0110] exist Fig. 6A In the milk expression assessment system, Figure 1 The acoustic sensor is located on the expression kit 2 for optimal acoustic coupling with the sound of milk droplets. The processor 62 can be anywhere, but Figure 1 The value related to the fat content of the milk can be displayed by the output interface of the breast pump device, or an external device can be used to Figure 1 The manner shown is more convenient for displaying information to the user.However, the acoustic signal capture and processing is performed as part of the breast pump device.

[0111] In one aspect, the invention relates to a breast pump device with an integrated acoustic sensor and processor.

[0112] Figure 6B A version is shown in which the breast pump apparatus comprises an acoustic sensor 61, but the sensor signal is relayed (preferably wirelessly) to a remote device such as a smartphone 7. The processor of the smartphone then acts as the processor 62 of the system and signal processing takes place in the smartphone.

[0113] In another aspect, the invention more generally relates to a program operated by a processor, and to any device incorporating a suitably programmed processor, such as a smartphone 7. Thus, in this respect, the invention does not involve generating acoustic signals, but rather processing acoustic signals received as input.

[0114] Figure 6C A version is shown in which an external device such as a smartphone 7 integrates an acoustic sensor 61 and a processor 62. The microphone of the smartphone is used as the acoustic sensor. For example, there may be a docking area in which the smartphone is placed to receive a consistent audio signal from the expression kit 2, or this is not necessary if a suitable audio processing algorithm is used. Thus, a completely standard breast pump can be used in this system configuration.

[0115] Fig.6D A version is shown in which the breast pump device includes an acoustic sensor 61, but the sensor signal is relayed (preferably wirelessly) to a remote processing center (e.g. a laboratory as described above), represented as the cloud. The smartphone 7 then retrieves the processing results from the external remote processing center, for example via the Internet. The remote processing center then performs the functions of the processor 62.

[0116] Fig. 6E A version is shown where the smartphone includes an acoustic sensor 61, but the sensor signal is wirelessly relayed to a remote processing center (e.g., a laboratory as described above), again represented as a cloud. The smartphone 7 then retrieves the processing results from the external remote processing center, for example, via the Internet. The remote processing center then performs the functions of the processor 62. Figure 6C This allows a standard breast pump to be used as shown.

[0117] It will be apparent to those skilled in the art that the scope of the present invention is not limited to the examples discussed above, and that several changes, modifications and variations may be made to the present invention without departing from the scope of the present invention as defined by the appended claims. The present invention is intended to be interpreted as including all such modifications and variations as long as they fall within the scope of the claims or their equivalents. Although the present invention has been described and illustrated in detail in the drawings and the specification, such illustration and description should be considered to be merely illustrative or exemplary and not restrictive. The present invention is not limited to the disclosed embodiments. The accompanying drawings are schematic, details not necessary for understanding the present invention may be omitted, and are not necessarily drawn to scale.

[0118] Variations to the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention by studying the drawings, the specification, and the appended claims. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0119] Unless expressly stated otherwise, elements and aspects discussed for or relating to a particular embodiment may suitably be combined with elements and aspects of other embodiments. Thus, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0120] The term "comprising" as used herein will be understood by those skilled in the art to encompass the term "consisting of. Thus, the term "comprising" may mean "consisting of" in one embodiment, but may mean "comprising / including at least the defined substances and optionally one or more other substances" in another embodiment.

[0121] The salient aspects of the invention can be summarised as follows. A breast pump device 1 comprises an expression kit 2 comprising a breast receiving funnel 21, a milk outlet 22 and an air outlet 25, and a vacuum unit 3 configured to effect pressure cycling in the expression kit 2. In order to obtain an indication of the fat content of the expressed milk, the breast pump device 1 is provided with an acoustic milk expression assessment system 6 comprising an acoustic sensor 61 and a processor 62 configured to process acoustic signals received from the acoustic sensor 61 during operation of the breast pump device 1 when a container 4 is used with the breast pump device 1 to receive milk from the milk outlet 22 of the expression kit 2. By recording the sound during pumping, a frequency shift of the sound of a milk droplet falling into the container 4 and impacting the surface of the milk contained in the container 4 can be determined relative to a reference situation of liquid having a fat content of 0%, which frequency shift can be factored into estimating a value related to the fat content of the milk.

Claims

1. A method of obtaining an indication about the fat content of milk, wherein at least one droplet is caused to fall on a volume of said milk, wherein the sound of the event of said droplet hitting the surface of said volume of said milk is detected to obtain an acoustic signal of said event, The method comprises: analyzing the acoustic signal by executing a routine so as to generate from the acoustic signal an estimate of a value related to the fat content of the milk, Therein, the analysis of the acoustic signal involves determining a frequency spectrum of the acoustic signal.

2. A method according to claim 1, wherein performing the analysis of the acoustic signal comprises determining a value of the frequency of at least one peak of the spectrum and comparing the value with a reference value to determine a frequency shift, and using the frequency shift as a factor in estimating a value related to the fat content of the milk.

3. The method according to claim 1 or 2, wherein the at least one droplet is a droplet of the milk.

4. A computer program product comprising computer program code means for performing the following steps when the computer program product is run on a computer: receiving an acoustic signal of the sound of a droplet impacting a surface of a volume of milk; and The analysis of the acoustic signal is performed by executing a routine such that an estimate of a value related to the fat content of the milk is generated from the acoustic signal, wherein the analysis of the acoustic signal involves determination of a frequency spectrum of the acoustic signal.

5. A computer program product according to claim 4, wherein performing the analysis of the acoustic signal comprises determining a value of a frequency of at least one peak of the spectrum and comparing the value to a reference value to determine a frequency shift, and using the frequency shift as a factor in estimating a value related to the fat content of the milk.

6. A processor programmed to run a computer program product according to claim 4 or 5.

7. An apparatus for obtaining an indication of the fat content of milk, wherein the apparatus comprises: a path for transmission of an acoustic signal of the sound of a droplet impacting a surface of a volume of milk, and A processor (62) is arranged for analyzing the acoustic signal by executing a routine to generate from the acoustic signal an estimate of a value related to the fat content of the milk, wherein the analysis of the acoustic signal involves determining a frequency spectrum of the acoustic signal.

8. Apparatus according to claim 7, wherein the processor is arranged to determine a value of the frequency of at least one peak of the spectrum and compare the value with a reference value to determine a frequency shift and to factor the frequency shift in estimating a value relating to the fat content of the milk.

9. Apparatus according to claim 7 or 8, wherein at least one droplet is caused to fall onto a quantity of said milk within a breast pump device, and wherein: The apparatus comprises an attachment for a milk container of the breast pump device; or The arrangement comprises an insert for a milk container of the breast pump device.

10. The device according to claim 7 or 8, further comprising an acoustic sensor (61) for obtaining the acoustic signal.

11. The device according to claim 9, further comprising an acoustic sensor (61) for obtaining the acoustic signal.

12. A breast pump device (1), comprising: An expression kit (2) comprising a breast receiving funnel (21) and a milk outlet (22); Pump mechanism; An acoustic milk expression assessment system (6) comprising an acoustic sensor (61) for obtaining said acoustic signal and a device according to claim 7 or 8; and Wherein the processor (62) of the apparatus is configured to perform said analysis of acoustic signals received from the acoustic sensor (61) during operation of the breast pump device.

13. A breast pump device (1) according to claim 12, wherein the analysis comprises: A value of the frequency of at least one peak of the spectrum of the acoustic signal is determined and compared with a reference value to determine a frequency shift which is used as a factor in estimating a value related to the fat content of the milk.

14. A breast pump device (1) according to claim 12, wherein: The analysis involves comparing the estimated value related to the fat content of the milk with an identification value in real time, and wherein the processor (62) is configured to issue a warning signal when the estimated value related to the fat content of the milk increases from below the identification value to above the identification value; or The analysis involves comparing an estimated value related to the fat content of the milk over a period of a predetermined length from the start of a pumping session with a threshold value, and wherein the processor (62) is configured to issue a warning signal when the estimated value related to the fat content of the milk is found to be above the threshold value.

15. A breast pump device (1) according to any one of claims 12 to 14, wherein the processor (62) is configured to communicate with an external device (7) or system, which is separate from the expression kit (2) and the pump mechanism, and the processor is configured to provide information to a user.

16. A breast pump device according to any one of claims 12 to 14, wherein: The acoustic sensor (61) is mounted at the extrusion kit and the processor is mounted at the pump mechanism; or The expression kit and the pump mechanism form part of a breast pump, and the breast pump device further comprises a user interface device external to the breast pump, and wherein: The acoustic sensor (61) is part of the breast pump and the processor (62) of the acoustic milk expression assessment system (6) is part of the user interface device; or The acoustic sensor (61) and the processor (62) of the acoustic milk expression assessment system (6) are both part of the user interface device.

17. A breast pump device according to claim 15, wherein: The acoustic sensor (61) is mounted at the extrusion kit and the processor is mounted at the pump mechanism; or The expression kit and the pump mechanism form part of a breast pump, and the breast pump device further comprises a user interface device external to the breast pump, and wherein: The acoustic sensor (61) is part of the breast pump and the processor (62) of the acoustic milk expression assessment system (6) is part of the user interface device; or The acoustic sensor (61) and the processor (62) of the acoustic milk expression assessment system (6) are both part of the user interface device.

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