Abstract
Silicon nanowire (SiNW) field-effect transistors (FETs) have been developed as very sensitive and label-free biomolecular sensors. The detection principle operating in a SiNW biosensor is indirect. The biomolecules are detected by measuring the changes in the current through the transistor. Those changes are produced by the electrical field created by the biomolecule. Here, we have combined nanolithography, chemical functionalization, electrical measurements and molecular recognition methods to correlate the current measured by the SiNW transistor with the presence of specific molecular recognition events on the surface of the SiNW. Oxidation scanning probe lithography (o-SPL) was applied to fabricate sub-12 nm SiNW field-effect transistors. The devices were applied to detect very small concentrations of proteins (500 pM). Atomic force microscopy (AFM) single-molecule force spectroscopy (SMFS) experiments allowed the identification of the protein adsorption sites on the surface of the nanowire. We detected specific interactions between the biotin-functionalized AFM tip and individual avidin molecules adsorbed to the SiNW. The measurements confirmed that electrical current changes measured by the device were associated with the deposition of avidin molecules.
Highlights
Different types of field-effect transistor were proposed to detect biomolecular processes [1,2,3,4,5]
Top-down approaches such as scanning probe lithography were applied to fabricated
The silicon nanowires were made by oxidation scanning probe lithography (o-SPL) on substrates from ultra-thin silicon on insulator (SOI) wafer (MEMC/SunEdison, Belmont, CA, USA)
Summary
Different types of field-effect transistor were proposed to detect biomolecular processes [1,2,3,4,5]. Oxidation SPL combines the high-spatial resolution capabilities of atomic force microscopy (AFM) for positioning with the capability to fabricate nanoscale features [13,14]. It has been extensively applied in nanopatterning and for the fabrication of a variety of nanoelectronics devices [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].
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