Ultrasensitive biochemical sensor

1. A sensor for detecting the presence of an analyte in a sample comprising a receptor for the analyte of interest bound to an active region of a field effect transistor (FET), wherein the active region overlies a p+ buried conducting channel connecting a source region and a drain region.

2. The sensor of claim 1 , wherein the active region comprises a polysilicon gate.

3. The sensor of claim 1 , wherein the active region comprises a gate dielectric layer.

4. The sensor of claim 3 , wherein the gate dielectric layer is a silicon nitride layer.

5. The sensor of claim 4 , wherein the receptor is bound to the silicon nitride layer.

6. The sensor of claim 1 , additionally comprising a back gate.

7. The sensor of claim 6 , wherein the sensitivity of the sensor is increased by applying a bias to the back gate.

8. The sensor of claim 7 , wherein the receptor is selected from the group consisting of antibodies, antibody fragments, peptides, oligonucleotides, DNA, RNA, aptamers, and organic molecules.

9. The sensor of claim 1 , comprising two or more receptors specific for the same analyte.

10. The sensor of claim 1 , comprising two or more receptors specific for different analytes.

11. The sensor of claim 10 , wherein the density and absolute number of each receptor is not equal, such that the resultant signal for binding of any anolyte of interest is approximately the same magnitude, regardless of the identity of the anolyte.

12. The sensor of claim 10 , wherein the number and density of the receptors specific for each analyte are approximately equal.

13. The sensor of claim 1 , wherein the sensor operates in enhancement mode upon binding of a negatively charged analyte.

14. The sensor of claim 1 , wherein the receptor is bound to the active region via a linker molecule.

15. The sensor of claim 14 , wherein the linker molecule further comprises a protective group that prevents binding of the receptor and must be removed by exposure to an activator prior to receptor binding.

16. The sensor of claim 1 , wherein conduction of the channel is increased by enhancement of a conducting inversion layer in the channel.

17. The sensor of claim 1 , wherein the analyte is selected from the group consisting of toxins, insecticides, polypeptides, nucleic acids, pathogens and drugs.

18. The sensor of claim 1 , wherein the number and density of receptors are chosen so that a change in conductance of the channel will occur only if a target analyte is present in the sample at a concentration greater than or equal to a predetermined minimum concentration.

19. The sensor of claim 1 , wherein the active region is as small as possible, just large enough to hold enough receptors to generate a measurable signal when the receptors bind to the target analyte, so that the sensitivity of the sensor is increased.

20. A method for identifying the presence of an analyte of interest in a sample comprising: contacting the active region of a sensor with the sample, wherein the sensor comprises one or more receptors for the analyte of interest bound to an active region and wherein the active region overlies a buried p+ conducting channel connecting a source and drain; measuring sensor output; and identifying the presence of the analyte of interest where the sensor output indicates a change in conductance of the channel upon exposing the active region to the sample.

21. The method of claim 20 , wherein the sensor output is selected from the group consisting of conductance, voltage and resistance.

22. The method of claim 20 , wherein the change in conductance is caused by binding of the analyte to the receptor.

23. The method of claim 22 , wherein the analyte is negatively charged.

24. The method of claim 22 , wherein binding of the analyte of interest enhances conductance between the source and drain.

25. The method of claim 20 , wherein the change in conduction is enhanced by contacting the bound analyte with a secondary charged molecule.

26. The method of claim 25 , wherein the secondary charged molecule is an antibody.

27. The method of claim 25 , wherein the secondary charged molecule is a bead.

28. The method of claim 20 , wherein there are two or more analytes of interest and types of receptors, wherein the density and absolute number of each type of receptor is not equal, such that the resultant signal for binding of any anolyte of interest is approximately the same magnitude, regardless of the identity of the anolyte, and further comprising determining the number of analytes of interest that are present from the sensor output.

29. The method of claim 20 , wherein the sensor output indicates a change in conductance only if the target analyte is present in the sample at a concentration greater than or equal to a predetermined minimum concentration.

30. The method of claim 20 , wherein there are two or more analytes of interest and receptors specific for each analyte of interest, wherein the number and density of the receptors specific for each analyte are approximately equal, further comprising determining the identity of the analytes present by the amplitude of the sensor output.

31. An array comprising two or more sensors for detecting the presence of an analyte in a sample, each sensor comprising a receptor for a particular analyte of interest bound to an active region of a field effect transistor (FET), wherein the active region overlies a p+ buried conducting channel connecting a source region and a drain region.

32. The array of claim 31 , comprising two or more sensors for detecting multiple toxins.

33. The array of claim 31 , comprising two or more sensors for detecting multiple disease markers.

34. The array of claim 31 , wherein at least two sensors comprise receptors that are specific for the same analyte.

35. The array of claim 31 , comprising a first sensor for detecting the presence of a first analyte of interest and a second sensor for detecting the presence of a second analyte of interest.

36. The array of claim 35 , wherein the presence of the second analyte of interest provides confirmation of the first analyte of interest.

37. The array of claim 31 , comprising at least two orthogonal receptors.