Photo-acoustic detection device and method

• US 20080014574A1
• Filed: 07/11/2007
• Published: 01/17/2008
• Est. Priority Date: 07/11/2006
• Status: Active Grant

• Current Assignee: Curators of the University of Missouri (University of Missouri)
• Original Assignee: Curators of the University of Missouri (University of Missouri)
• Inventors: Weight, Ryan M., Sutovsky, Peter, Viator, John A., Dale, Paul S.
• Granted Patent: US 7,968,347 B2
• Time in Patent Office: Days
• US Class Current: 435/4
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids

Abstract

An example method for detecting an analyte in a sample of a bodily fluid comprises the steps of exposing the bodily fluid sample to electromagnetic energy to cause a thermoelastic expansion in the analyte, and detecting a photoacoustic signal in the sample that results from the thermoelastic expansion.

Claims

1. A method for detecting an analyte in a sample of a bodily fluid comprising the steps of:

exposing the bodily fluid sample to electromagnetic energy to cause a thermoelastic expansion in the analyte; and

,

detecting a photoacoustic signal in the sample that results from said thermoelastic expansion.

2. A method for detecting an analyte as defined by claim 1 wherein said electromagnetic energy comprises light, wherein said thermoelastic expansion results from said analyte absorbing at least a portion of said light, and wherein said photoacoustic signal comprises an acoustic wave resulting from said thermoelastic expansion.

3. A method for detecting an analyte as defined by claim 1 wherein said electromagnetic energy source comprises a laser pulsing at a frequency faster than a microsecond, wherein said bodily fluid comprises one or more of blood, bile, sperm, urine or saliva, and wherein said analyte comprises one of a protein or a pathogen.

4. A method for detecting an analyte as defined by claim 1 wherein said bodily fluid comprises blood, wherein said component comprises a pathogen, and wherein the method further comprises the steps of preparing said bodily fluid sample through the steps of:

extracting a quantity of blood from a patient;

isolating white blood cells in said quantity of blood; and

,

forming said bodily fluid sample by suspending said white blood cells in a carrier liquid.

5. A method for detecting an analyte as defined by claim 1 wherein the method further comprises circulating said sample through a test chamber, said test chamber including an acoustic sensor configured to detect said photoacoustic signal after said thermoelastic event occurs in said test chamber, and wherein the step of exposing said sample to said electromagnetic energy comprises directing a beam of said electromagnetic energy into said test chamber.

6. A method for detecting an analyte as defined by claim 1 and further comprising the step of adding target particles to said bodily fluid sample having a diameter of less than 0.01 millimeter, said particles configured to respond to said electromagnetic energy, and said particles configured to adhere to said analyte.

7. A method for detecting an analyte as defined by claim 6 wherein said synthetic target comprises microspheres having antibodies selected to adhere to said analyte, said microspheres configured to absorb said electromagnetic energy.

8. A method for detecting an analyte as defined by claim 1 wherein the step of detecting said photoacoustic signal comprises detecting a deflection in a diaphragm that is in fluid contact with said bodily fluid sample, said deflection resulting when an acoustic wave contacts said diaphragm.

9. A method for detecting an analyte as defined by claim 1 wherein the step of detecting said photoacoustic signal comprises measuring an electrical perturbation that results when a piezoelectric layer is deflected.

10. A method for detecting an analyte as defined by claim 1 wherein said photoacoustic signal comprises a pressure wave traveling through said bodily fluid sample.

11. A method for detecting an analyte as defined by claim 1 wherein the step of detecting said photoacoustic signal further includes using the magnitude of said signal to estimate one or more of analyte size, density, and concentration.

12. A method for detecting an analyte as defined by claim 1 wherein said electromagnetic energy source comprises a beam, and wherein the step of exposing the bodily fluid sample to said electromagnetic energy further comprises capturing the entire flow of said bodily fluid sample with said beam.

13. An in vitro method for detecting one or more circulating cancer cells comprising the steps of:

separating white blood cells from a quantity of blood;

suspending said white blood cells in a carrier liquid to create a test sample;

communicating said test sample through a test chamber;

using a laser to induce a thermoelastic expansion of said one or more cancer cells in said test sample as it is communicated through said test chamber; and

,

using an acoustic sensor to detect an acoustic signal that results from said thermoelastic expansion in said test chamber.

14. A method for detecting one or more circulating cancer cells as defined by claim 13 and further including the steps of:

adhering a plurality of microsphere targets to each of said one or more cancer cells;

wherein the step of using said laser comprises directing a laser ray pulsing at a frequency of faster than about 1 microsecond into said test sample through a transparent test chamber sidewall; and

,

wherein said acoustic signal comprises an acoustic wave traveling through said sample; and

,

wherein said acoustic sensor includes a diaphragm in fluid contact with said test sample in said test chamber, said diaphragm deflected when said acoustic wave strikes it.

15. A system for detecting one or more analytes in a bodily fluid comprising:

a test chamber having at least one sidewall and configured to contain at least a portion of a bodily fluid sample;

an electromagnetic energy source configured to direct an energy source into said test chamber through said at least one sidewall and to induce a thermoelastic expansion in said one or more analytes; and

,

a sensor configured to detect said thermoelastic expansion in said bodily fluid sample in said test chamber.

16. A system as defined by claim 15 wherein said sensor comprises an acoustic sensor having a diaphragm that is deflected when an acoustic wave generated by said thermoelastic expansion strikes it, said acoustic sensor arranged on said test chamber.

17. A system as defined by claim 16 wherein said acoustic sensor diaphragm comprises a piezoelectric diaphragm in fluid contact with said test sample, wherein said acoustic sensor further comprises first and second electrodes arranged about opposing sides of said piezoelectric diaphragm.

18. A system as defined by claim 15 wherein said electromagnetic energy source comprises a laser pulsing at a frequency faster than a millisecond.

19. A system as defined by claim 15 and further comprising:

a reservoir, a conduit, and a pump, said reservoir communicating with said test chamber via said conduit, said pump arranged along said conduit to urge said sample from said reservoir to said test chamber;

wherein said electromagnetic energy source comprises a pulsed laser; and

,

wherein said test chamber at least one sidewall comprises at least a first and a second sidewall, said first sidewall being narrower than said second sidewall, said pulsed laser directed through said first sidewall and said sensor arranged on said second sidewall.

20. A system as defined by claim 15 and wherein said test chamber is transparent and wherein said electromagnetic energy source comprises a pulsed laser having a beam that illuminates an entire cross section of said test sample as it passes through said test chamber.