Patent ID: 7851205

Claim:
A DNA sensor comprising: (a) a p-channel field-effect transistor having as a gate an electrolyte solution and having as a channel a diamond surface which contains a mixture of at least (i) a hydrogen-terminated surface, and (ii) an oxygen terminated surface, and (iii) a surface terminated by an amino group; (b) a probe DNA constituted of a single-stranded DNA with known nucleotide sequence which is directly immobilized by a linker to the amino group of said diamond surface; and (c) a target DNA constituted of an unknown single-stranded DNA which is dropped on said diamond surface, (d) wherein an identification on whether or not said target DNA is in complementary relationship to said probe DNA is performed by detecting a shift of the threshold voltage of said p-channel field effect transistor toward positive direction, which is due to increase in hole density of the p-channel resulting from doubling the negative electric charge of the phosphate group of a double-stranded DNA produced by hybridization of said probe DNA with said target DNA both constituted of the single-stranded DNA, the hybridization which occurs when said target DNA is in complementary relationship to said probe DNA.