Narrower Nanoribbon Biosensors Fabricated by Chemical Lift-off Lithography Show Higher Sensitivity

Wafer-scale nanoribbon field-effect transistor (FET) biosensors fabricated by straightforward top-down processes are demonstrated as sensing platforms with high sensitivity to a broad range of biological targets. Nanoribbons with 350-nm widths (700-nm pitch) were patterned by chemical lift-off lithography using high throughput, low-cost commercial digital versatile disks (DVDs) as masters. Lift-off lithography was also used to pattern ribbons with 2-μm or 20-μm widths (4-μm or 40-μm pitches, respectively) using masters fabricated by photolithography. For all widths, highly aligned, quasi-one-dimensional (1D) ribbon arrays were produced over centimeter length scales by sputtering to deposit 20-nm-thin-film In(2)O(3) as the semiconductor. Compared to 20-μm-wide microribbons, FET sensors with 350-nm wide nanoribbons showed higher sensitivity to pH over a broad range (pH 5 to 10). Nanoribbon FETs functionalized with a serotonin-specific aptamer demonstrated larger responses to equimolar serotonin in high ionic strength buffer compared to microribbon FETs. Field-effect transistors with 350-nm-wide nanoribbons functionalized with single-stranded DNA showed greater sensitivity to detecting complementary DNA hybridization vs 20-μm microribbon FETs. In all, we illustrate facile fabrication and use of large-area, uniform In(2)O(3) nanoribbon FETs for ion, small molecule, and oligonucleotide detection where higher surface-to-volume ratios translate to better detection sensitivities.