Claims for Patent: 8,171,795

Summary for Patent: 8,171,795

Title:	Self-exciting, self-sensing piezoelectric cantilever sensor for detection of airborne analytes directly in air
Abstract:	A method for detection of airborne biological agent using a piezoelectric cantilever sensor that includes a piezoelectric layer and a non-piezoelectric layer. A recognition entity is placed on one or both of the two layers. The antibody that recognizes and binds to the airborne species may be chemically immobilized on the cantilever sensor surface. In one embodiment, the cantilever sensor is attached to a base at only one end. In another embodiment, the sensor includes first and second bases and at least one of the piezoelectric layer and the non-piezoelectric layer is affixed to each of the first and second bases to form a piezoelectric cantilever beam sensor. In this embodiment, resonance is measured via stress on the piezoelectric layer and it has been demonstrated that such sensors are robust and exhibit excellent sensing characteristics in gaseous media with sufficient sensitivity to detect airborne species at relatively low concentrations.
Inventor(s):	Mutharasan; Rajakkannu (West Chester, PA), deLesdernier; David L. (Kennett Square, PA), Campbell; Gossett Augustus (Gilbertsville, PA), Maraldo; David R. (Gilbertsville, PA), Nagy; Peter A. (Newtown Square, PA)
Assignee:	Drexel University (Philadelphia, PA)
Application Number:	11/747,183
Patent Claims:	1. A method for detection of an airborne target analyte comprising the steps of: providing a millimeter-sized sensor comprising; a piezoelectric layer having a first end and a second end, the first end proximate to and attached to a first base; a non-piezoelectric layer having a first end and a second end, wherein: a portion of the non-piezoelectric layer overlaps and is attached to the piezoelectric layer; and the base is not attached to the non-piezoelectric layer; a recognition entity associated with the non-piezoelectric layer, wherein the combination of the piezoelectric layer, the non-piezoelectric layer, and the recognition entity comprising a cantilever portion; and electrodes operatively attached to the piezoelectric layer, wherein electrical stimulation from the electrodes causes the cantilever portion to oscillate; mounting the millimeter-sized sensor in an airflow; exposing the recognition entity of the cantilever to the target analyte in the airflow; measuring an oscillation frequency of the cantilever; and comparing the measured oscillation frequency to a baseline oscillation frequency to determine a frequency shift indicative of a presence of the target analyte on the recognition entity. 2. The method of claim 1, wherein providing a millimeter-sized sensor further includes providing a sensor wherein the piezoelectric layer comprises both piezoelectric and non-piezoelectric portions arranged linearly. 3. The method of claim 1, wherein providing a millimeter-sized sensor further includes providing a sensor wherein the piezoelectric layer comprises two piezoelectric layers separated by an adhesive. 4. The method of claim 1, wherein providing a millimeter-sized sensor further includes providing a sensor wherein the non-piezoelectric layer comprises a plurality of linearly arranged and spaced non-piezoelectric portions. 5. The method of claim 1, further comprising: determining an amount of the target analyte present on the recognition entity. 6. The method of claim 1, wherein providing a millimeter-sized sensor further comprises providing the millimeter-sized sensor wherein the recognition entity is selected from one of the group consisting of antibodies, DNA molecules, aptamers, phage and biochemical reagents and wherein the selection is one of the group consisting of naturally and synthetically constituted. 7. The method of claim 6, wherein the recognition entity is an antibody that recognizes and binds the airborne analyte. 8. The method of claim 7, wherein the airborne analyte is chemically immobilized on the cantilever sensor surface by binding with the antibody. 9. The method of claim 1, wherein exposing the recognition entity of the cantilever to the target analyte in the airflow comprises exposing the recognition entity to one of the group consisting of a biological substance and a chemical substance in the airflow. 10. The method of claim 9, wherein the biological substance is a Bacillus anthracis spore. 11. The method of claim 1, further comprising: providing a plurality of millimeter-sized sensors in a sensor array, wherein each of the plurality of millimeter sized sensors in the array is exposed to the airflow to detect one at least one analyte. 12. The method of claim 11, wherein the at least one analyte is detected by measuring a plurality of frequency shifts, one frequency shift for each provided millimeter-sized sensor. 13. The method of claim 1, wherein mounting the millimeter-sized sensor in an airflow comprises mounting the millimeter-sized sensor substantially orthogonal to the airflow. 14. The method of claim 13, wherein the airflow is in the range of 0.01 to 10 meters/second. 15. The method of claim 1, wherein exposing the recognition entity of the cantilever to the target analyte in the airflow comprises exposing the recognition entity to the target analyte without collecting the target analyte in a liquid medium. 16. The method of claim 1, wherein measuring an oscillation frequency of the cantilever comprises measuring a resonant frequency at which the cantilever oscillates after exposure to the target analyte. 17. The method of claim 1, wherein providing a millimeter-sized sensor comprises providing a millimeter-sized sensor wherein the second end of the non-piezoelectric layer is attached to a second base. 18. A method for detection of an airborne target analyte comprising the steps of: providing a millimeter-sized sensor comprising; a first non-piezoelectric layer having a first end and a second end, the first end proximate to and attached to a base; a piezoelectric layer having a first end and a second end, wherein: a portion of the piezoelectric layer is attached to the first non-piezoelectric layer in a linear arrangement; and the base is not attached to the non-piezoelectric layer; a recognition entity associated with a second non-piezoelectric layer, wherein the second non-piezoelectric layer overlaps and is attached to the piezoelectric layer, wherein the combination of the piezoelectric layer, the first and second non-piezoelectric layers, and the recognition entity comprises a cantilever portion; and electrodes operatively attached to the piezoelectric layer, wherein electrical stimulation from the electrodes causes the cantilever portion to oscillate; mounting the millimeter-sized sensor in an airflow; exposing the recognition entity of the cantilever to the target analyte in the airflow; measuring an oscillation frequency of the cantilever; and comparing the measured oscillation frequency to a baseline oscillation frequency to determine a frequency shift indicative of a presence of the target analyte on the recognition entity. 19. An apparatus for detecting an airborne target analyte, the apparatus comprising: a millimeter-sized sensor comprising; a first layer having a first end and a second end, the first end proximate to and attached to a first base; a second layer having a first end and a second end, wherein a portion of the second layer overlaps and is attached to the first layer with an adhesive, and wherein the first layer is selected from the group consisting of a piezoelectric material and a non-piezoelectric material and the second layer is a different material from the first layer; and further wherein, the first base is not attached to the non-piezoelectric material layer; a recognition entity associated with the second layer, wherein the combination of the first layer, the second layer, and the recognition entity comprising a cantilever portion; and electrodes operatively attached to the piezoelectric material, wherein electrical stimulation from the electrodes causes the cantilever portion to oscillate; an exposure tube assembly comprising the millimeter-sized sensor; a nebulizer to aerosolize the target analyte; an air supply feeding the nebulizer, the air supply also used to pass the aerosolized target analyte into the exposure tube assembly; an analyzer that collects resonant frequency data from the millimeter sized sensor, wherein the analyzer compares the measured resonant frequency of the millimeter-sized sensor to a baseline resonant frequency to determine a frequency change, the frequency change indicating an amount of mass of the target analyte collected on the recognition entity of the millimeter-sized sensor. 20. The apparatus of claim 19, further comprising an array of millimeter-sized sensors, each sensor in the array providing frequency information to the analyzer for a determination of the presence and amount of at least one analyte. 21. The apparatus of claim 19, where the analyte is a Bacillus anthracis spore. 22. An apparatus for detection of a target analyte, the apparatus comprising: a piezoelectric layer having a first end and a second end, the first end proximate to and attached to a first base; a non-piezoelectric layer having a first end and a second end, wherein a portion of the non-piezoelectric layer overlaps and is attached to the piezoelectric layer; and the base is not attached to the non-piezoelectric layer; a recognition entity associated with the non-piezoelectric layer, wherein the combination of the piezoelectric layer, the non-piezoelectric layer, and the recognition entity comprises a cantilever portion; and electrodes operatively attached to the piezoelectric layer, wherein electrical stimulation from the electrodes causes the cantilever portion to oscillate. 23. The apparatus of claim 22, wherein the piezoelectric layer further comprises both piezoelectric and non-piezoelectric portions arranged linearly. 24. The apparatus of claim 22, wherein the piezoelectric layer further comprises two piezoelectric layers separated by an adhesive. 25. The apparatus of claim 22, wherein the non-piezoelectric layer further comprises a plurality of linearly arranged and spaced non-piezoelectric portions. 26. An apparatus for detection of a target analyte, the apparatus comprising: a first non-piezoelectric layer having a first end and a second end, the first end proximate to and attached to a base; a piezoelectric layer having a first end and a second end, wherein a portion of the piezoelectric layer is attached to the first non-piezoelectric layer in a linear arrangement, wherein the base is not attached to the non-piezoelectric layer; a recognition entity associated with a second non-piezoelectric layer, wherein the second non-piezoelectric layer overlaps and is attached to the piezoelectric layer, wherein the combination of the piezoelectric layer, the first and second non-piezoelectric layers, and the recognition entity comprises a cantilever portion; and electrodes operatively attached to the piezoelectric layer, wherein electrical stimulation from the electrodes causes the cantilever portion to oscillate. 27. An apparatus for detection of a target analyte, the apparatus comprising: a millimeter-sized sensor comprising: a base; a piezoelectric layer attached to the base at a proximate end of the piezoelectric layer; a non-piezoelectric layer attached to a distal portion of the piezoelectric layer, wherein the base is not attached to the non-piezoelectric layer; electrodes operatively attached to the piezoelectric layer, wherein electrical excitation of the electrodes causes a mechanical oscillation in the piezoelectric layer, wherein oscillations at resonance subject the sensor to higher stress levels than oscillations at non-resonance; and wherein enhanced detection of the target analyte is achieved by varying a bending modulus of the sensor to enhance stress and electrical impedance at a point of electrode attachment.

Details for Patent 8,171,795

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Emergent Biodefense Operations Lansing Llc	BIOTHRAX	anthrax vaccine adsorbed	Injection	103821	11/12/1998		2026-01-23