Method and device for measurement of liquid volume and/or flow rate

Patent metadata

Field	Value
Publication number	US-10895481-B2
Application number	US-201815921267-A
Country	US
Kind code	B2
Filing date	Mar 14, 2018
Priority date	Mar 14, 2018
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

Disclosed is a method for liquid measurements including: —providing a sensor including a surface arranged to receive a liquid thereupon, an electrical heating element arranged to heat the surface, and an arrangement for measuring a temperature of the surface; —receiving liquid on the sensor surface; —heating the surface by means of the electrical heating element at a known rate while taking a plurality of temperature measurements thereof in function of time, the heating being at an absolute temperature of at least 90% of the boiling point of the liquid under ambient pressure; and—deriving a volume or a flow rate measurement related to the liquid from the electrical heating rate and the temperature measurements.

First claim

The invention claimed is:

1. A method for liquid measurements relating to an unknown volume or an unknown flow rate, the method comprising:
providing a sensor ( 1 ) comprising a sensor surface ( 3 ) arranged to receive a liquid ( 5 ) thereupon, an electrical heating element ( 7 ) arranged to heat said surface ( 3 ), and an arrangement ( 11 , 13 ; 7 , 15 ) for measuring a temperature of said sensor surface ( 3 );
receiving liquid ( 5 ) on said sensor surface ( 3 );
heating said sensor surface ( 3 ) by means of said electrical heating element ( 7 ) at a known rate (P) while taking a plurality of temperature measurements (T) of said sensor surface ( 3 ) in function of time (t), said heating being at an absolute temperature of at least 90% of the boiling point (T b ) of said liquid ( 5 ) under ambient pressure;
deriving a volume measurement or a flow rate measurement of the unknown volume or the unknown flow rate related to said liquid ( 5 ) from said electrical heating rate (P) and said temperature measurements (T).

2. The method according to claim 1 , wherein said electrical heating element ( 7 ) is provided with a predetermined electrical current (I) from a power source ( 9 ).

3. The method according to claim 1 , wherein said temperature is measured by measuring the electrical resistance of said electrical heating element ( 7 ).

4. The method according to claim 3 , wherein said electrical resistance is measured by providing a known current (I) to said electrical heating element while measuring the voltage drop thereacross, the resistance being calculated by Ohm's Law.

5. The method according to claim 1 , wherein said heating is carried out as a series of heating pulses of predetermined duration.

6. The method according to claim 5 , wherein said predetermined duration is sufficiently long to dry said sensor surface.

7. The method according to claim 1 , wherein said heating is carried out by applying power at a predetermined rate (P) insufficient to dry said sensor surface, the flow rate measurement being derived from a steady state temperature (T) measured.

8. The method according to claim 1 , wherein said heating is carried out by applying electrical power at a rate (P) insufficient to dry said sensor surface, wherein electrical power is applied to maintain a predetermined steady state temperature (T), the flow rate measurement being derived from a measurement of said electrical power (P) applied.

9. The method according to claim 1 , wherein said deriving step derives the flow rate measurement of the unknown flow rate from said electrical heating rate (P) and said temperature measurements (T) of the sensor surface ( 3 ).

10. The method according to claim 1 , wherein said deriving step derives the volume measurement of a volume of a droplet from said electrical heating rate (P) and said temperature measurements (T) of the sensor surface ( 3 ).

11. A sensor system ( 25 ; 31 ) adapted to carry out the method of claim 1 , comprising:
a sensor ( 1 ) comprising a sensor surface ( 3 ) adapted to receive a quantity ( 5 ) of fluid thereupon, said sensor ( 1 ) comprising an electrical heating element ( 7 ) arranged to be connected to a source of electrical power ( 9 ) and an arrangement for measuring temperature ( 11 , 13 ; 7 ; 15 );
a conduit ( 21 , 23 ; 37 ) adapted to collect a liquid sample and to transport said liquid sample to said sensor surface ( 3 ).

12. The sensor system ( 25 ; 31 ) according to claim 11 , wherein said arrangement for measuring temperature ( 7 , 15 ) comprises said electrical heating element ( 7 ).

13. The sensor system ( 25 ; 31 ) according to claim 11 , wherein at least a part of said conduit ( 21 , 23 ; 37 ) comprises a wicking fabric arranged to be sandwiched between said sensor ( 1 ) and a skin surface ( 33 ) of a wearer.

14. The sensor system ( 25 ; 31 ) according to claim 13 , wherein said conduit ( 21 , 23 ; 37 ) extends around a peripheral wall of said sensor ( 1 ) so as to form at least one fluid pathway leading to said sensor surface ( 3 ).

15. The sensor system ( 25 ; 31 ) according to claim 13 , further comprising a substantially impermeable cover ( 39 ) arranged to at least partially seal said sensor system ( 25 ; 31 ) to said skin surface ( 33 ).

16. The sensor system ( 25 ; 31 ) according to claim 15 , wherein said cover ( 39 ) is at least partially self-adhesive.

17. The sensor system ( 25 ; 31 ) according to claim 11 , further comprising an analysis sensor ( 19 ) in fluid communication with said conduit and arranged such that said liquid passes through said analysis sensor ( 19 ) on its way to the sensor surface ( 3 ) of the sensor ( 1 ).

18. The method according to claim 1 , wherein in said providing the sensor step, a temperature sensor is provided and in said heating said surface ( 3 ) step, the plurality of temperature measurements (T) are taken on the sensor surface ( 3 ) of the temperature sensor.

19. The method according to claim 18 , wherein in said providing the sensor step, the temperature sensor that is provided is a thermistor and in said heating said surface ( 3 ) step, the plurality of temperature measurements (T) are taken on the sensor surface ( 3 ) of the thermistor.

Assignees

• Csem Ct Suisse Delectronique Microtechnique Sa Rech Developpement
• Csem Centre Suisse Delectronique Et De Microtechnique Sa—Recherche Et Dev

Inventors

• Schmid David
• Generelli Silvia
• Pereira Fiona

Classifications

• G01F22/00 Primary

  Methods or apparatus for measuring volume of fluids or fluent solid material, not otherwise provided for · CPC title

• G01F1/6986

  with pulsed heating, e.g. dynamic methods · CPC title

• G01F1/69 Primary

  of resistive type · CPC title