Breast pump device comprising an expression kit, a vacuum unit and a milk expression assessment system
A breast pump device ( 1 ) comprises an expression kit ( 2 ) and a vacuum unit ( 3 ) configured to realize a pressure cycle in the expression kit ( 2 ). For a purpose of determining one or more milk expression characteristics such as total volume of expressed milk, the device ( 1 ) is equipped with an acoustic milk expression assessment system ( 6 ) including an acoustic sensor ( 61 ) and a processor ( 62 ) configured to process an acoustic signal received from the sensor ( 61 ) during operation of the device ( 1 ) when a receptacle ( 4 ) is used with the device ( 1 ) for receiving expressed the milk. By recording sound during a pumping session, it is possible to determine a value of a time duration of a free fall of droplets of expressed the milk from the expression kit ( 2 ) to the receptacle ( 4 ), which can be taken as a measure of a number of interesting milk expression characteristics.
1. A breast pump device, comprising:
an expression kit including a breast-receiving funnel, a milk outlet, and an air outlet,
a vacuum unit configured to realize a pressure cycle in the expression kit, the vacuum unit including 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
an acoustic milk expression assessment system including an acoustic sensor and a processor configured to process an acoustic signal received from the acoustic sensor during operation of the breast pump device when a receptacle is used with the breast pump device for receiving milk from the milk outlet of the expression kit,
wherein the processor is configured to process the acoustic signal received from the acoustic sensor during the operation of the breast pump device according to a routine which includes determining a value of a time duration in which a spike in the acoustic signal occurs between a release moment when a release of a vacuum takes place and a first moment following the release moment, the value of the time duration varying based on a distance along which a quantity of the milk freely falls down in an associated release from a position in the expression kit and through the milk outlet.
2. The breast pump device according to claim 1 , wherein the routine involves determining the release moment from at least one of the spike in the acoustic signal and an actual control signal of the pump mechanism.
3. The breast pump device according to claim 1 , wherein the processor is configured to perform a milk volume calculation based on the value of the time duration and values related to dimensional characteristics of the receptacle, the milk volume calculation being a calculation of an actual volume of the milk in the receptacle.
4. The breast pump device according to claim 3 , wherein the distance along which the quantity of the milk freely falls down is from the position in the expression kit and through the milk outlet and is calculated according to the following relation: s=0.5*g*t 2 , in which the s represents the distance, the g represents acceleration due to gravity and the t represents the time duration.
5. The breast pump device according to claim 4 , wherein the processor is configured to involve in the milk volume calculation a determination of a height of the milk in the receptacle according to a following relation: h m =h c +h v −s, in which the h m represents the height of the milk in the receptacle, the h c represents a total height of the receptacle, and the h v represents a height of the position from which the milk is released above the receptacle.
6. The breast pump device according to claim 4 , wherein the acoustic milk expression assessment system includes an inertial sensor located in the expression kit, and wherein the processor is configured to process an inertial signal received from the inertial sensor according to a routine in which a value of an acceleration in the z-direction is determined, a z-direction being a longitudinal direction of a body part of the expression kit where the milk outlet is located, and to involve in the milk volume calculation a determination of a correction value to the distance along which the quantity of the milk which is released from the position in the expression kit and through the milk outlet freely falls down based on an actual value of a tilting angle (θ) of the expression kit with respect to a direction of vertical acceleration.
7. The breast pump device according to claim 6 , wherein the processor is configured to determine the correction value according to following relations: f=1/cos(θ), in which the f represents the correction value and the θ represents the tilting angle, and the θ=cos −1 [(|A z /g|)], in which the A z represents the acceleration in the z-direction.
8. The breast pump device according to claim 3 , wherein the processor is configured to assess whether the value of the time duration is within a predetermined range of values and to only perform the milk volume calculation in respect of the value which is within the predetermined range.
9. The breast pump device according to claim 1 , wherein the expression kit includes a valve assembly, and wherein the position in the expression kit from which the milk is released is a position of the valve assembly in the expression kit.
10. The breast pump device according to claim 1 , wherein the processor is part of a central processing Unit (CPU) of the breast pump device which is furthermore configured to control the operation of the breast pump device.
11. The breast pump device according to claim 10 , wherein the CPU is configured to activate the acoustic milk expression assessment system only after a predetermined time from a start of the operation of the breast pump device.
12. The breast pump device according to claim 1 , wherein the processor is configured to communicate with an external device or system which is configured to provide information to a user.
13. A method of operating a breast pump device comprising an expression kit, a vacuum unit, and an acoustic milk expression assessment system, the method comprising:
realizing, by the vacuum unit, a pressure cycle in the expression kit, wherein the expression kit includes a breast-receiving funnel, a milk outlet, and an air outlet, and wherein the vacuum unit includes 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
processing, by a processor of the acoustic milk expression assessment system, an acoustic signal received from an acoustic sensor of the acoustic milk expression assessment system during the operation of the breast pump device when a receptacle is used with the breast pump device for receiving milk from the milk outlet of the expression kit and in accordance with a routine which includes determining a value of a time duration in which a spike in the acoustic signal occurs between a release moment when a release of a vacuum takes place and a first moment following the release moment, the value of the time duration varying based on a distance along which a quantity of the milk freely falls down in an associated release from a position in the expression kit and through the milk outlet.
14. The method according to claim 13 , wherein the routine involves determining the release moment from at least one of the spike in the acoustic signal and an actual control signal of the pump mechanism.
15. The method of claim 13 , further comprising:
performing, by the processor, a milk volume calculation based on the value of the time duration and values related to dimensional characteristics of the receptacle, the milk volume calculation being a calculation of an actual volume of the milk in the receptacle.
16. The method according to claim 15 , wherein the distance along which the quantity of the milk freely falls down is from the position in the expression kit and through the milk outlet and is calculated according to a following relation: s=0.5*g*t 2 , in which the s represents the distance, the g represents acceleration due to gravity and the t represents the time duration.
17. The method according to claim 16 , wherein the processor is configured to involve in the milk volume calculation a determination of a height of the milk in the receptacle according to a following relation: the h m =h c +h v −s, in which h m represents the height of the milk in the receptacle, the h c represents a total height of the receptacle, and the h v represents a height of a position from which the milk is released above the receptacle.
18. The method according to claim 16 , wherein the acoustic milk expression assessment system includes an inertial sensor located in the expression kit, and wherein the processor is configured to process an inertial signal received from the inertial sensor according to a routine in which a value of an acceleration in a z-direction is determined, the z-direction being a longitudinal direction of a body part of the expression kit where the milk outlet is located, and to involve in the milk volume calculation a determination of a correction value to the distance along which the quantity of the milk which is released from the position in the expression kit and through the milk outlet freely falls down based on an actual value of a tilting angle (θ) of the expression kit with respect to a direction of vertical acceleration.
19. The method according to claim 18 , wherein the processor is configured to determine the correction value according to following relations: f=1/cos(θ), in which the f represents the correction value and the θ represents the tilting angle, and the θ=cos −1 [(|A z /g|)], in which the A z represents the acceleration in the z-direction.
20. The method according to claim 13 , wherein the expression kit includes a valve assembly, and wherein the position in the expression kit from which the milk is released is a position of the valve assembly in the expression kit.