Fabrication and Characteristics of a Field Effect Transistor-Type Charge Sensor for Detecting Deoxyribonucleic Acid Sequence

We have fabricated an field effect transistor (FET)-type deoxyribonucleic acid (DNA) charge sensor which can detect the DNA sequence by sensing the variation of drain current due to DNA hybridization and investigated its electrical characteristics. It is fabricated as a PMOSFET-type because the DNA probe has a negative charge. Au which has a chemical affinity with thiol was used as the gate metal in order to immobilize DNA. The operating principle is very similar to that of MOSFET. The gate potential is determined by the electric charge possessed by the DNA. The variation of the drain current with time was measured. The drain current increased when thiol DNA and target DNA were injected into the solution, because of the field effect due to the electrical charge of DNA molecules. Therefore it is confirmed that the DNA sequence can be detected by measuring the variation of the drain current due to the variation of DNA charge and it is concluded that the proposed FET-type DNA charge sensor might be useful for the implementation of the DNA chip.