[Nanotechnology] Label-Free SnO<sub>2</sub> Nanowire FET Biosensor for Protein Detection
Novel tin oxide field-effect-transistors (SnO<sub>2</sub> NW-FET) for pH and protein detection applicable in the healthcare sector are reported. With the presented SnO<sub>2</sub> NW-FET the proof-of-concept of a bio-sensing device is demonstrated using the carrier transport control of the FET channel by a (bio-) liquid modulated gate. Ultra-thin Al<sub>2</sub>O<sub>3</sub> fabricated by a low temperature atomic layer deposition (ALD) process represents a sensitive layer to H<sup>+</sup> ions safeguarding the nanowire at the same time. Successful pH sensitivity is demonstrated for pH ranging from 3 to 10. For protein detection, the SnO<sub>2</sub> NW-FET is functionalized with a receptor molecule which specifically interacts with the protein of interest to be detected. The feasibility of this approach is demonstrated via the detection of a biotinylated protein using a NW-FET functionalized with streptavidin. An immediate label-free electronic read-out of the signal is shown. The well-established Enzyme-Linked Immunosorbent Assay (ELISA) method is used to determine the optimal experimental procedure which would enable molecular binding events to happen while being compatible with a final label-free electronic read-out on a NW-FET. Integration of the bottom-up fabricated SnO<sub>2</sub> NW-FET pH- and biosensor into a microfluidic system (lab-on-a-chip) allows the automated analysis of small volumes in the 400 μl range as would be desired in portable on-site point-of-care (POC) devices for medical diagnosis.
Markus Hubertus Jakob1, Bo Dong2, Sebastian Gutsch3, Claire Chatelle4, Abinaya Krishnaraja5, Wilfried Weber6 and Margit Zacharias7 Accepted Manuscript online 28 April 2017 • © 2017 IOP Publishing Ltd