title: Surface engineering for enhancement of sensitivity in an underlap-FET biosensor by control of wettability.
abstract: The present work aims to improve the sensitivity of an electrical biosensor by simply changing a surface property of the passivation layer, which covers the background region except for the sensing site for electrical isolation among adjacent interconnection lines. The hydrophobic passivation layer dramatically enhances the sensitivity of the biosensor when compared with a hydrophilic passivation layer. A revamped metal oxide semiconductor field-effect transistor (MOSFET), which has a designed underlap region between a gate and a drain, is used as the electrical biosensor. A thin film of CYTOP(TM) and silicon nitride is used as the hydrophobic and hydrophilic passivation layers, respectively. The surface antigen and its specific antibody of the avian influenza virus were employed as the probe and target biomolecule, respectively, to confirm the enhanced sensitivity of the proposed biosensor. By using hydrophobic passivation, the limit of detection of the biosensor was improved up to 100-fold compared with that resulting from hydrophilic passivation. Therefore, a simple surface engineering to control surface wettability can notably improve the sensitivity of a biosensor without additional efforts, such as modifying the sensor structure, optimizing the bio-treatment protocol, or increasing the binding yield between a probe and its target, among other efforts.
authors.affiliation: Department of Electrical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Jee-Yeon
authors.initials: JY
authors.lastname: Kim
authors.forename: Kyungyong
authors.initials: K
authors.lastname: Choi
authors.forename: Dong-Il
authors.initials: DI
authors.lastname: Moon
authors.forename: Jae-Hyuk
authors.initials: JH
authors.lastname: Ahn
authors.forename: Tae Jung
authors.initials: TJ
authors.lastname: Park
authors.forename: Sang Yup
authors.initials: SY
authors.lastname: Lee
authors.forename: Yang-Kyu
authors.initials: YK
authors.lastname: Choi
mesh_terms: D000914:Antibodies, Viral / Q000032:analysis* / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014173:Transistors, Electronic; D017155:Wettability
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral