SENSOR SYSTEM FOR DETECTING THE FILL LEVEL OF A FLUID IN A VESSEL

• US 20130026084A1
• Filed: 02/04/2011
• Published: 01/31/2013
• Est. Priority Date: 02/04/2010
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius Medical Care AG)
• Original Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius Medical Care AG)
• Inventors: Schneider, Jochen, Gagel, Alfred
• Granted Patent: US 9,316,523 B2
• Time in Patent Office: Days
• US Class Current: 210/97
• CPC Class Codes: G01F 23/266 measuring circuits therefor
• CPC Class Codes: G01F 23/268 mounting arrangements of probes

Abstract

The invention relates to a sensor system 10 for the capacitive measurement of the fill level of a fluid medium 22 in a container, preferably a bubble catcher of a dialysis device, comprising a receptacle 30 on which two contact areas are provided for contact with an external surface of the accommodated container and with at least one level detection electrode C₁, C₂, C₁₁, C₁₂, C₂₁, C₂₂ disposed in each contact area for capacitive detection of the fluid level in the container. The sensor system has a coupling measurement device C₁₁, C₁₂, C₂₁, C₂₂ for capacitive determination of the correct coupling.

Claims

1. Sensor system (10) for the capacitive measurement of the fill level of a fluid medium (22) in a container, comprising a receptacle (30) on which two contact areas are provided for contact with an external surface of the accommodated container and with at least one level detection electrode (C₁, C₂, C₁₁, C₁₂, C₂₁, C₂₂) disposed in each contact area for capacitive detection of the fluid level in the container, characterized in that

the sensor system has a coupling measurement device (C₁₁, C₁₂, C₂₁, C₂₂) for capacitive determination of the correct coupling of the container in the receptacle.

2. Sensor system according to claim 1, characterized in that the level detection electrodes comprise divided electrode areas and in that the coupling measurement device determines the coupling via a capacitive measurement via the electrode areas of each level detection electrode.

3. Sensor system according to claim 1, characterized in that the coupling measurement device on each contact area comprises two coupling electrodes (C_11′

, C_12′

, C₂₁, C₂₂) which are different from the level detection electrodes (C₁, C₂).

4. Sensor system according to claim 3, characterized in that the coupling electrodes are axially displaced in the longitudinal direction of the container with respect to the level detection electrodes.

5. Sensor system according to claim 1, characterized in that the coupling measurement device is capable of detecting both a coupling that is too low, as for example in the case of a gap between the container and the receptacle, and also a coupling that is too high, such as for example in the case of fluids or other foreign substances in the contact areas.

6. Sensor system according to claim 1, characterized in that the coupling measurement device is capable, in the event that the measurement of the fluid level in the container detects a sufficient level and at the same time the coupling measurement detects an insufficient coupling, of triggering a pre-alarm to notify the user of insufficient coupling.

7. Sensor system according to claim 1, characterized in that said sensor system is configured to determine a complex total impedance Z_tot via the level detection electrodes, and to carry out the level detection via the evaluation of said total impedance.

8. Sensor system according to claim 7, characterized in that said sensor system is configured to carry out the level detection via the evaluation of the real part of the total impedance.

9. Sensor system according to claim 1, characterized in that said sensor system is configured to determine a complex total impedance Z_tot via the level detection electrodes, and to receive variations over time in the complex total impedance Z_tot via a demodulator, to be used in an evaluation unit together with the complex total impedance Z_tot for determination of the level detection, in order by this means to recognize inhomogenities such as for example a void fraction.

10. Sensor system according to claim 1, characterized in that said sensor system is configured to carry out the measurement of the level detection with a frequency preferably greater than 60 MHz, particularly preferably greater than 70 MHz.

11. Sensor system according to claim 1, characterized in that said sensor system is configured to carry out the measurement of the level detection with a frequency preferably lower than 90 MHz, particularly preferably lower than 78 MHz.

12. Sensor system according to claim 1, characterized in that means are present for generating electrical fields for the level and coupling measurement, and means are present for capturing the complex impedance of different measurement electrodes (C₁₁, C₁₂, C₂₁, C₂₂) according to magnitude, phase, and the changes to these over time.

13. Sensor system according to claim 1, characterized in that the container is a bubble catcher of a dialysis device, infusion apparatus or transfusion apparatus.

16. Medical device, in particular a dialysis device, with a sensor system according to claim 1 and a fluid circulation of an electrically conductive aqueous medium with a bubble catcher, wherein said sensor system is configured to measure the fluid level in the bubble catcher and, depending on the measurement result, to control a feed pump or valve or throttle in the fluid circulation.

14. Method for the capacitive measurement of the fill level of a fluid medium (22) in a container, wherein the container is held in a receptacle of the sensor system and a level detection device (C₁, C₂, C₁₁, C₁₂, C₂₁, C₂₂) of the sensor system measures capacitatively the level of fluid in the container, characterized in that the correct coupling of the container in the receptacle is determined using a coupling measurement device (C₁₁, C₁₂, C₂₁, C₂₂).

15. Method according to claim 14, characterized in that the level detection measurement and the coupling measurement are chronologically staggered.