Electrical Characteristics of Extended Gate FET Sensing Chip Constructed for Detection of DNA
An extended gate field effect transistor (EGFET) sensing chip has been constructed by using one gold plate electrode for molecule recognition and FET part for signal transduction. By using a 70.7mV DC voltage onto a Ag/AgCl reference electrode, the electrical characteristics of immobilization of the oligonucleotide probe of P1 and hybridization with the target single strand DNA of P2 on the EGFET sensing chip were examined in detail. The electrical signals on the change of a threshold voltage (VT) shift at a constant ID (3000μA) in VG-ID characteristic were obtained, and the VT shift value due to hybridization was calculated to be 12 mV, which may be attributed to the decreased negative charges after hybridization occurred at the gate surface. The surface density of hybridized dsDNA on gold surface of the FET was evaluated to be about 1 × 1012 molecules/cm2, indicating that the EGFET was a promising sensing element for biochip.
Zhengyi Jiang and Chunliang Zhang
Z. Cao et al., "Electrical Characteristics of Extended Gate FET Sensing Chip Constructed for Detection of DNA", Advanced Materials Research, Vols. 97-101, pp. 4189-4192, 2010