Concentration measurement by sensing hydrogel pressure

• US 20050003517A1
• Filed: 10/04/2002
• Published: 01/06/2005
• Est. Priority Date: 10/05/2001
• Status: Active Grant

• Current Assignee: Clive Lindsay Ragless
• Original Assignee: Clive Lindsay Ragless
• Inventors: Ragless, Clive Lindsay
• Granted Patent: US 7,556,934 B2
• Time in Patent Office: Days
• US Class Current: 435/287.100
• CPC Class Codes: G01N 13/04 Investigating osmotic effects
• CPC Class Codes: G01N 33/146 containing alcohol
• CPC Class Codes: G01N 7/04 by absorption or adsorption alone
• CPC Class Codes: Y10T 436/143333 Saccharide [e.g., DNA, etc.]
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A sensor and method for measuring the concentration of one or more chemical substances within a solution. The sensor including a body of saturated hydrogel held within a sensor body. A window to allow flow through of the chemical substance to be measured. The hydrogel is held under a predetermined compressive force within the sensor body such that the hydrogel exerts a base pressure. A pressure sensor such as a strain gauge senses the pressure exerted by the hydrogel within the sensor body. The sensed pressure is stored or displayed. The hydrogel is reactive to the one or more chemical substances so that contact causes the hydrogel to either increase the pressure above the base pressure under which the hydrogel is held or to decrease the pressure relative to the base pressure of the hydrogel.

Claims

1. A sensor for measuring the concentration of a chemical substance within a solution, said sensor including a body of saturated hydrogel held within a sensor body, said sensor body having at least a window to allow flow-through of the chemical substance to be measured, the hydrogel being held under a predetermined compressive force within the sensor body such that the hydrogel exerts a base pressure, the sensor further includes a pressure sensing means to sense the pressure exerted by the hydrogel within the sensor body, the pressure sensing means communicative with a storage or display means to store or display a sensed pressure, said hydrogel reactive to the chemical substance which causes the hydrogel to either increase the pressure above the base pressure or to decrease the pressure relative to the base pressure.

2. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the base pressure is in the range of 50 kPa to 400 kPa.

3. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the base pressure is in the range of 100 kPa to 300 kPa.

4. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the base pressure is about 200 kPa.

5. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the hydrogel is a hydroxyalkyl methacrylate.

6. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the hydrogel is generally flat.

7. A sensor for measuring the concentration of a chemical substance within a solution as in claim 6 wherein the hydrogel has a thickness of less than 1 mm.

8. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the hydrogel has a thickness of less than 0.5 mm.

9. A sensor for measuring the concentration of a chemical substance within a solution as in claim 1 wherein the hydrogel has a thickness of 0.3 mm or less.

10. A sensor for measuring the concentration of a chemical substance within a solution as in claim 6 wherein the hydrogel is held between a porous rigid support and a planar compressive member, the hydrogel when wet exerting the base pressure against the compressive force of the planar compressive member, said planar compressive member contacting a strain gauge, the solution traversing the porous rigid support to contact the hydrogel to thereby vary the force exerted via the planar compressive member to the strain gauge.

11. A sensor for measuring the concentration of a chemical substance within a solution as in claim 10 wherein the hydrogel is bonded to a ceramic backing by wetting the hydrogel and holding the hydrogel against the ceramic backing during a subsequent drying, the ceramic backing providing the porous rigid support.

12. A sensor for measuring the concentration of a chemical substance within a solution as in claim 10 wherein the hydrogel is shaped to have a centrally thicker portion and tapering radially.

13. A method of monitoring the concentration of one or more chemical substances in a solution said method including the holding hydrogel under a predetermined pressure, exposing the hydrogel to the solution, recording the change in pressure in the hydrogel over time, the hydrogel chosen such that the chemical substance exerts an expansive or a contractive effect on the hydrogel at the predetermined pressure applied to the hydrogel.

14. A method of monitoring the concentration of one or more chemical substances as in claim 13, wherein the solution is predominantly of one chemical substance, the concentration of the one chemical substance being measured at one time point.

15. A method of monitoring the concentration of one or more chemical substances as in claim 14 wherein the concentration the one chemical substance is measured at two or more time points to measure a change in concentration.

16. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein the solution is of more than one chemical substance.

17. A method of monitoring the concentration of one or more chemical substances as in claim 16 but the hydrogel is chosen to be reactive predominantly to changes in concentration of one chemical substance.

18. A method of monitoring the concentration of one or more chemical substances as in claim 16 wherein the hydrogel is chosen to be reactive to changes in concentration of a first and second chemical substances, increases in concentration of the first chemical substance causing an increase in pressure exerted by the hydrogel, and increases in concentration of the second chemical substance causing a decrease in pressure exerted by the hydrogel.

19. A method of monitoring the concentration of one or more chemical substances as in claim 18 wherein the first and second chemical substances are substrate and product of a chemical transformation, and the extent of the increase relative to the decrease in pressure are a fraction one of the other.

20. A method of monitoring the concentration of one or more chemical substances as in claim 19 wherein the transformation is a conversion of the substrate sugar to the product alcohol.

21. A method of monitoring the concentration of one or more chemical substances as in claim 19 wherein the transformation is in either winemaking or brewing.

22. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein a change in concentration of a sugar is monitored.

23. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein a change in concentration of an alcohol is monitored.

24. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein a change in concentration of salt is monitored.

25. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein the base pressure is in the range of 50 kPa to 400 kpa.

26. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein the base pressure is in the range of 100 kPa to 300 kPa.

27. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein the base pressure is about 200 kPa.

28. A method of monitoring the concentration of one or more chemical substances as in claim 13 wherein the hydrogel is an hydroxyalkyl methacrylate.