DETECTION OF THE PRESENCE OR ABSENCE OF A GAS BUBBLE BY DYNAMIC SENSOR RESPONSE

• US 20110067483A1
• Filed: 12/01/2010
• Published: 03/24/2011
• Est. Priority Date: 09/02/2004
• Status: Active Grant

• Current Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Grübler, Robert, Landschützer, Egon, Kaltenbeck, Heinz
• Granted Patent: US 8,354,015 B2
• Time in Patent Office: Days
• US Class Current: 73/31.04
• CPC Class Codes: G01N 2035/1018 Detecting inhomogeneities, e.g. foam, bubbles, clots
• CPC Class Codes: G01N 27/4163 checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence
• CPC Class Codes: G01N 33/4925 measuring blood gas content, e.g. O2, CO2 , HCO3

Abstract

A method for detecting the presence or absence of a gas bubble in an aqueous liquid is provided comprising providing a sensor positioned within a measuring chamber, wherein the sensor is configured to determine the concentration of a gaseous component dissolved in a liquid, the sensor comprising a sensitive region; setting a gas partial pressure at the sensor, wherein the gas partial pressure differs from an expected value of the gas partial pressure of the gaseous component of a liquid to be measured; exposing the sensor to the liquid to be measured; resting the liquid until standstill is attained; recording a signal from the sensor as a function of time until the signal becomes constant; and detecting the presence or absence of a gas bubble from the variation of the signal over time. The gas bubble, if present, is in at least partial contact with the sensitive region of the sensor.

Claims

1. A method for detecting the presence or absence of a gas bubble in an aqueous liquid, where a gas bubble, if present, is in at least partial contact with a sensitive region of a sensor in a measuring chamber, the sensor for determining the concentration of a gaseous component dissolved in the liquid, the method comprising:

setting a gas partial pressure at the sensor which differs from an expected value of the gas partial pressure of the gaseous component in an aqueous liquid to be measured;

exposing the sensor to the aqueous liquid to be measured;

waiting until the aqueous liquid to be measured attains standstill;

recording a signal from the sensor as a function of time until the signal becomes constant; and

inferring the presence or absence of a gas bubble in the aqueous liquid based at least in part on a variation of the signal over time.

2. The method of claim 1, wherein inferring the presence or absence of a gas bubble comprises:

measuring a signal curve value for at least two points in time during the response time of the sensor, based at least in part upon the recorded signal; and

comparing the measured signal curve values to known values obtained from a bubble-free sample.

3. The method of claim 1, wherein setting a gas partial pressure further comprises setting a gas partial pressure at the sensor before recording the signal, where the set gas partial pressure is greater than the gas partial pressure of the gas component in the liquid to be measured.

4. The method of claim 1, wherein setting a gas partial pressure comprises setting a gas partial pressure using at least one of:

an aqueous liquid, a gas, and a mixture of gases containing the gas component to be determined in suitable concentration.

5. The method of claim 1, wherein setting a gas partial pressure comprises setting a gas partial pressure at the sensor using an aqueous liquid comprising at least one of:

a suitably tonometered calibrating fluid, a control fluid and a rinsing fluid.

6. The method of claim 1, further comprising employing the sensor as an O₂ sensor.

7. The method of claim 1, further comprising employing the sensor as a CO₂ sensor.

8. The method of claim 1, wherein the aqueous liquid to be measured comprises a select one of:

a calibrating fluid, a control fluid, and a sample fluid.

9. The method of claim 1, wherein the aqueous liquid to be measured comprises a biological fluid and exposing the sensor to the liquid to be measured comprising exposing the sensor to the biological fluid.

10. The method of claim 1, wherein the aqueous liquid comprises blood and exposing the sensor to the liquid to be measured comprising exposing the sensor to the blood.