title: Highly scalable, uniform, and sensitive biosensors based on top-down indium oxide nanoribbons and electronic enzyme-linked immunosorbent assay.
abstract: Nanostructure field-effect transistor (FET) biosensors have shown great promise for ultra sensitive biomolecular detection. Top-down assembly of these sensors increases scalability and device uniformity but faces fabrication challenges in achieving the small dimensions needed for sensitivity. We report top-down fabricated indium oxide (In2O3) nanoribbon FET biosensors using highly scalable radio frequency (RF) sputtering to create uniform channel thicknesses ranging from 50 to 10 nm. We combine this scalable sensing platform with amplification from electronic enzyme-linked immunosorbent assay (ELISA) to achieve high sensitivity to target analytes such as streptavidin and human immunodeficiency virus type 1 (HIV-1) p24 proteins. Our approach circumvents Debye screening in ionic solutions and detects p24 protein at 20 fg/mL (about 250 viruses/mL or about 3 orders of magnitude lower than commercial ELISA) with a 35% conduction change in human serum. The In2O3 nanoribbon biosensors have 100% device yield and use a simple 2 mask photolithography process. The electrical properties of 50 In2O3 nanoribbon FETs showed good uniformity in on-state current, on/off current ratio, mobility, and threshold voltage. In addition, the sensors show excellent pH sensitivity over a broad range (pH 4 to 9) as well as over the physiological-related pH range (pH 6.8 to 8.2). With the demonstrated sensitivity, scalability, and uniformity, the In2O3 nanoribbon sensor platform makes great progress toward clinical testing, such as for early diagnosis of acquired immunodeficiency syndrome (AIDS).
authors: Department of Electrical Engineering, ‡Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
authors: Noppadol
authors: N
authors: Aroonyadet
authors: Xiaoli
authors: X
authors: Wang
authors: Yan
authors: Y
authors: Song
authors: Haitian
authors: H
authors: Chen
authors: Richard J
authors: RJ
authors: Cote
authors: Mark E
authors: ME
authors: Thompson
authors: Ram H
authors: RH
authors: Datar
authors: Chongwu
authors: C
authors: Zhou
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007204:Indium / Q000737:chemistry*; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014173:Transistors, Electronic
chemical_list: D007204:Indium; C047711:indium oxide
keywords: biosensor; electronic ELISA; indium oxide; nanoribbon; top-down fabrication