ZnO nanowire-FET for charge-based sensing of protein biomolecules

Top-down method was used to fabricate zinc oxide (ZnO) nano wire field effect transistor (NWFET) biosensor. The nanosensor was used to measure the electrical characteristics of lysozyme (LYSO) and bovine serum albumin (BSA) protein solutions in phosphate buffered saline (PBS). The LYSO and BSA proteins are oppositely charged at measurement pH of 7.4. Subthreshold voltage shift of 340 mV and 700 mV due to surface charge effect on the device channel is obtained for the LYSO and BSA solutions respectively. A NWFET sensitivity of 72 % is achieved for the LYSO proteins while the BSA proteins resulted in a sensitivity of 98%.