Calorimetric Microfluidic Sensor

• US 20140303019A1
• Filed: 03/31/2014
• Published: 10/09/2014
• Est. Priority Date: 04/04/2013
• Status: Active Grant

• Current Assignee: Marquette University
• Original Assignee: Marquette University
• Inventors: Lee, Chung Hoon, Davaji, Benyamin
• Granted Patent: US 9,285,330 B2
• Time in Patent Office: Days
• US Class Current: 506/9
• CPC Class Codes: B01L 2200/147 Employing temperature sensors
• CPC Class Codes: B01L 2300/0627 Sensor or part of a sensor is integrated
• CPC Class Codes: B01L 2300/0825 Test strips
• CPC Class Codes: B01L 2300/126 Paper
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 3/5023 with a sample being transported to, and subsequently stored in an absorbent for analysis
• CPC Class Codes: C12Q 1/25 involving enzymes not classifiable in groups C12Q1/26 - C12Q1/66
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• CPC Class Codes: G01K 17/006 Microcalorimeters, e.g. using silicon microstructures
• CPC Class Codes: G01K 17/08 based upon measurement of temperature difference or of a temperature
• CPC Class Codes: G01N 25/4886 concerning the circulation of the sample
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: Y10T 436/143333 Saccharide [e.g., DNA, etc.]

Abstract

A microfluidic sensor includes a microchannel that includes a reaction site with a reagent and a sample inlet. A liquid substance is received at the sample inlet and travels by capillary action to the reaction site. A temperature sensor measures a temperature as a result of a reaction between the reagent and a chemical in the liquid substance. A controller is communicatively connected to the temperature sensor, receives the temperature measured by the temperature sensor, and derives a concentration of the chemical in the liquid substance from the temperature.

Claims

1. A microfluidic sensor, the microfluidic sensor comprising:

a microchannel that comprises a reaction site that comprises a reagent and a sample inlet, wherein the microchannel is configured to receive a liquid substance comprising a chemical at the sample inlet that travels by capillary action to the reaction site;

a temperature sensor located proximal the reaction site of the microchannel and configured to measure a temperature as a result of a reaction between the reagent and the chemical in the liquid substance; and

a controller communicatively connected to the temperature sensor, the controller receives the temperature measured by the temperature sensor and derives a concentration of the chemical in the liquid substance from the temperature.

2. The microfluidic sensor of claim 1, wherein the microchannel is construed of paper.

3. The microfluidic sensor of claim 1, further comprising a support layer to which the microchannel and the temperature sensor are secured.

4. The microfluidic sensor of claim 3, further comprising an adhesive layer disposed between the temperature sensor and the microchannel, wherein the adhesive layer electrically insulates the temperature sensor from the microchannel and secures the microchannel and temperature sensor to the support layer.

5. The microfluidic sensor of claim 1, wherein the temperature sensor is a resistive temperature detector.

6. The microfluidic sensor of claim 5, wherein the temperature sensor is a first temperature sensor located proximal to the reaction site on a first finger of the microchannel and the temperature is a first temperature, the microfluidic sensor further comprising:

a second temperature sensor located proximal to a second finger of the microchannel and configured to measure a second temperature;

wherein the temperature controller derives the concentration of the chemical in the liquid substance from a differential between the first temperature and the second temperature.

7. The microfluidic sensor of claim 5, wherein the microchannel overlaps the temperature sensor in a region about the reaction site and the microchannel in the region about the reaction site is dimensioned in a width dimension to be less than a dimension of the temperature sensor in a width dimension.

8. The microfluidic sensor of claim 7, wherein the controller further operates to compensate the derived concentration of the chemical based upon the reaction rate between the reagent and the liquid substance.

9. The microfluidic sensor of claim 5, further comprising an enclosure defined about at least the temperature sensor and the reaction site.

10. The microfluidic sensor of claim 5, wherein the temperature sensor measures the temperature over time and the controller derives the concentration of the chemical in the liquid substance from a local maximum temperature change from a steady state temperature of the temperature sensor.

11. The microfluidic sensor of claim 1, wherein the sample inlet is a first sample inlet and the microchannel further comprises a second sample inlet and the first sample inlet and the second sample inlet are orthogonal to a portion of the microchannel that comprises the reaction site.

12. The microfluidic sensor of claim 1, wherein the reagent is selected to detect a predetermined target chemical in the liquid substance.

13. A microfluidic sensor system comprising:

At least one microfluidic sensor, comprising;

as microchannel that comprises a reaction site that comprises a reagent and a sample inlet, wherein the microchannel is configured to receive a liquid substance comprising a chemical at the sample inlet that travels by capillary action to the reaction site; and

a temperature sensor located proximal the reaction site of the microchannel and configured to measure a temperature as a result of a reaction between the reagent and the chemical in the liquid substance;

a controller communicatively connected to the at least one microfluidic sensor, the controller receives the temperature measured by the temperature sensor of at least one microfluidic sensor and derives a concentration of the chemical in the liquid substance from the temperature;

a graphical display operated by the controller to present the derived concentration of the chemical in the liquid substance.

14. The system of claim 13, wherein the at least one microfluidic sensor is a plurality of microfluidic sensors, each of the microfluidic sensors of the plurality comprising a different reagent configured to react with a different chemical and wherein the same liquid substance comprising a chemical is received at the sample inlets of each of the plurality of microfluidic sensors, and the controller operates to identity the chemical based upon the derived concentrations from the temperatures received from the plurality of microfluidic sensors.

15. The system of claim 14, wherein the controller is as central controller communicatively connected to each of the plurality of microfluidic sensors.

16. The system of claim 14, wherein the controller is one controller of a plurality of controllers, each of the controllers in the plurality being communicatively connected to one of the microfluidic sensors of the plurality of microfluidic sensors.

17. The system of claim 13, wherein the at least one microfluidic sensor further comprises:

a support layer to which the microchannel and the temperature sensor are secured; and

an adhesive layer disposed between the temperature sensor and the microchannel, wherein the adhesive layer electrically insulates the temperature sensor from the microchannel and secures the microchannel and temperature sensor to the support layer.

18. The system of claim 17, wherein the microchannel is constructed of paper and the temperature sensor is a resistive temperature detector.

19. A method of chemical sensing, the method comprising:

Selecting a reagent specific to a chemical to be sensed;

Providing a microfluidic sensor comprising;

a microchannel that comprises a sample inlet and a reaction site that comprises the selected reagent; and

a temperature sensor located proximal the reaction site;

receiving a liquid sample at the sample inlet, wherein the liquid sample travels to the reaction site by capillary action;

measuring a temperature at the reaction site, wherein the temperature at the reaction site changes due to a reaction between the reagent and the chemical to be sensed;

calculating a change in the detected temperature;

determining, from the change in the detected temperature, if the chemical to be sensed is present in the liquid sample; and

visually presenting the determination.

20. The method of claim 19, wherein determining if the chemical to be sensed is present in the liquid sample, further comprises determining a concentration of the chemical in the liquid sample.