Label-free detection of DNA hybridization using a porous poly-Si ion-sensitive field effect transistor

We report an ultra-sensitive, label-free detection system for DNA hybridization using a porous poly-Si gate ion-sensitive field effect transistor. Various physical and chemical characteristics of the sensor system were optimized, along with parameters affecting the immobilization of a label-free single-strand DNA and the specific hybridization of a complementary sequence on the silicon oxide layer, for quantitative detection down to the femtomole level. X-ray photoelectron spectroscopy (XPS) was employed to investigate the nature of the modifications to the porous layer by covalent bonding. Due to the utilization of nanoscopic pores at the gate region, the Debye screening length is no longer a limitation for macromolecule detection. In addition to its compatibility with the CMOS fabrication process, this sensor is a promising device for the label-free electrical detection of DNA pairs or other biomolecules at low concentrations.