Ultrahigh Sensitivity Chemical and Biological Sensors Based on Silicon Junctionless Nanowire Transistors

Junctionless nanowire transistors (JNTs) are very promising as chemo- biosensors due to their simple structure, easy fabrication and potential for ultrahigh sensitivity. Therefore, JNT sensors with various numbers, lengths, and widths (down to 10 nm) of the nanowires were fabricated by a top-down process on positively doped SOI wafers. The nanowires were functionalised either with 3-aminopropyltriethoxysilane (APTES) or with APTES and biotin. Polydimethylsiloxane (PDMS) stamps with microfluidic channels were then attached to the chip surface and buffer solutions containing different analytes were flowed over the sensors by a syringe pump. In this way, series of experiments for sensing ionic strength, pH value, and the protein streptavidin were performed. The JNT sensors demonstrated the highest sensitivity reported to date towards streptavidin, corresponding to a detection of only few protein molecules.