Microdosing system

Patent metadata

Field	Value
Publication number	US-10550833-B2
Application number	US-201615372280-A
Country	US
Kind code	B2
Filing date	Dec 7, 2016
Priority date	Dec 8, 2015
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

The invention relates to a method as well as a microdosing system for dosing an amount of fluid to be dispensed, wherein the microdosing system includes a micropump including an inlet and an outlet and configured to suck the fluid to be dispensed through the inlet and to dispense at least part of the fluid from the outlet. Further, the inventive microdosing system includes a first flow sensor arranged on the inlet side or the outlet side having an opening and a flow rate meter, wherein the flow rate meter is configured to determine the flow rate of the fluid passing through this opening. Additionally, the inventive microdosing system includes calibrators and/or fault detectors of the first flow sensor.

First claim

The invention claimed is:

1. Microdosing system for dosing an amount of fluid to be dispensed, comprising:
a micropump comprising a membrane, an inlet and an outlet and configured to suck the fluid to be dispensed through the inlet and to dispense at least part of the fluid from the outlet,
a first semiconductor chip flow sensor arranged on the inlet side or the outlet side comprising an opening and a flow rate meter, wherein the flow rate meter is configured to determine the flow rate of the fluid passing through this opening, and
a calibrator and fault detector for calibration and fault detection of the microdosing system;
wherein the calibrator and fault detector of the microdosing system comprises a controller that is configured to detect an actual sensor signal of the first flow sensor when the micropump is inactive and to correct subsequent sensor signals of the first flow sensor based thereon in order to counteract a sensor drift of the first flow sensor and to calibrate the microdosing system.

2. Microdosing system according to claim 1 , wherein the controller is configured to subtract a correction value, prior to performing a measurement of the first flow sensor, from the amount of a previously detected actual sensor signal, or to store the amount of the previously detected actual sensor signal as a correction value at first and to subtract the same only after performing a subsequent measurement of the first flow sensor from the amount of the sensor signal measured thereby, in order to subtract the stored correction value as an offset from the acquired measurement value only after the measurement has been performed.

3. Microdosing system according to claim 1 , wherein the controller is configured to determine a correction value and to subtract the same from the amount of the detected actual sensor signal of the first flow sensor, wherein the acquired difference value forms a corrected starting point for subsequent sensor signals of the first flow sensor.

4. Microdosing system according to claim 3 , wherein the amount of the correction value corresponds to the amount of the detected actual sensor signal of the first flow sensor, or wherein the amount of the correction value is within a range of the amount of the detected actual sensor signal plus a tolerance value in the amount of ±10% of the measured sensor signal or plus a tolerance value in the amount of ±20% of the measured sensor signal.

5. Microdosing system according to claim 1 , wherein the controller is configured to perform detection of the actual sensor signal of the first flow sensor and correction of subsequent sensor signals prior to any pump stroke or prior to each pump stroke.

6. Microdosing system according to claim 1 , wherein the microdosing system comprises units that are configured to provide, on the inlet side, the same pressure as on the outlet side or a lower pressure than on the outlet side in order to prevent free flow of the fluid to be dispensed through the micropump.

7. Microdosing system according to claim 1 , wherein the microdosing system comprises a valve arranged on the inlet side and/or the outlet side, wherein the valve is an active normally closed valve and/or an active normally open valve and/or a valve with operation threshold pressure closed below a threshold pressure and/or a double normally closed microvalve and/or a safety valve.

8. Microdosing system according to claim 1 , wherein the flow rate meter is configured as a differential pressure sensor that is configured to measure the pressure applied in front of the opening as well as the pressure applied behind the opening and to determine the differential pressure, and wherein the controller is configured to determine, by means of integrating the flow rate Q of the fluid according to the formula

V
=

∫

t
1

t
2

⁢

Q
⁢

⁢
d
⁢

⁢
t

,

the fluid volume V of the fluid that has flowed through the flow rate meter.

9. Microdosing system according to claim 8 , wherein the controller is configured to determine a stroke volume of the micropump in the suction stroke by integrating the flow rate determined by means of the differential pressure sensor arranged on the inlet side, and to determine the stroke volume of the micropump in the pressure stroke by integrating the flow rate determined by means of the differential pressure sensor arranged on the outlet side.

10. Microdosing system according to claim 1 , wherein the controller is configured to compare stroke volumes determined in the suction stroke and in the pressure stroke and to determine volume stroke differences for detecting a fault of the micropump.

11. Microdosing system according to claim 1 , wherein the microdosing system comprises a second flow sensor comprising an opening and a flow rate meter, wherein the flow rate meter is configured to determine the flow rate of the fluid passing through this opening, wherein the second flow sensor is arranged on the inlet side and the first flow sensor on the outlet side.

12. Microdosing system according to claim 11 , wherein the controller is configured to control the micropump as well as the first flow sensor arranged on the outlet side and the second flow sensor arranged on the inlet side, such that both the first and the second flow sensor determine the flow rate of the fluid flowing through the respective opening of the first and second flow sensor when the micropump sucks the fluid to be dispensed, and wherein the controller is further configured to compare the flow rate determined by the first flow sensor and the flow rate determined by the second flow sensor, such that the calibrator and/or fault detector can detect a leakage flow on the outlet side at the valve on the outlet side in the suction stroke of the micropump.

13. Microdosing system according to claim 11 , wherein the controller is configured to control the micropump as well as the first flow sensor arranged on the first outlet side and the second flow sensor arranged on the inlet side, such that the first and second flow sensor determine the flow rate of the fluid flowing through the respective opening of the first and second flow sensor when the micropump dispenses the fluid to be dispensed from the outlet, and wherein the controller is further configured to compare the flow rate determined by the first flow sensor and the flow rate determined by the second flow sensor, such that the calibrator and/or fault detector can detect a leakage flow on the inlet side at the valve on the inlet side in the pressure stroke of the micropump.

14. Microdosing system according to claim 1 , wherein the micropump comprises a pump chamber arranged between the inlet and the outlet, the membrane being arranged at least in sections in the region of the pump chamber and a membrane deflector, wherein the membrane deflector is configured to deflect the membrane such that the v

Assignees

• Fraunhofer Ges Forschung

Inventors

• Richter Martin
• Wackerle Martin
• Kibler Sebastian

Classifications

• G01F1/38

  the pressure or differential pressure being measured by means of a movable element, e.g. diaphragm, piston, Bourdon tube or flexible capsule · CPC title

• G01F11/28

  with stationary measuring chambers having constant volume during measurement · CPC title

• F16K99/0001

  Microvalves (microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006) · CPC title

• F04B43/046 Primary

  with piezoelectric drive · CPC title

• G01M3/2846

  for tubes (G01M3/30 takes precedence) · CPC title