Fabrication of silicon nanowire devices for ultrasensitive, label-free, real-time detection of biological and chemical species.

Detection and quantification of biological and chemical species are central to many areas of healthcare and the life sciences, ranging from diagnosing disease to discovery and screening of new drug molecules. Semiconductor nanowires configured as electronic devices have emerged as a general platform for ultra-sensitive direct electrical detection of biological and chemical species. Here we describe a detailed protocol for realizing nanowire electronic sensors. First, the growth of uniform, single crystal silicon nanowires, and subsequent isolation of the nanowires as stable suspensions are outlined. Second, fabrication of addressable nanowire device arrays is described. Third, covalent modification of the nanowire device surfaces with receptors is described. Fourth, an example modification and measurements of the electrical response from devices are detailed. The silicon nanowire (SiNW) devices have demonstrated applications for label-free, ultrasensitive and highly-selective real-time detection of a wide range of biological and chemical species, including proteins, nucleic acids, small molecules and viruses.