title: Fabrication of a Horizontal and a Vertical Large Surface Area Nanogap Electrochemical Sensor.
abstract: Nanogap sensors have a wide range of applications as they can provide accurate direct detection of biomolecules through impedimetric or amperometric signals. Signal response from nanogap sensors is dependent on both the electrode spacing and surface area. However, creating large surface area nanogap sensors presents several challenges during fabrication. We show two different approaches to achieve both horizontal and vertical coplanar nanogap geometries. In the first method we use electron-beam lithography (EBL) to pattern an 11 mm long serpentine nanogap (215 nm) between two electrodes. For the second method we use inductively-coupled plasma (ICP) reactive ion etching (RIE) to create a channel in a silicon substrate, optically pattern a buried 1.0 mm × 1.5 mm electrode before anodically bonding a second identical electrode, patterned on glass, directly above. The devices have a wide range of applicability in different sensing techniques with the large area nanogaps presenting advantages over other devices of the same family. As a case study we explore the detection of peptide nucleic acid (PNA)-DNA binding events using dielectric spectroscopy with the horizontal coplanar device.
authors.affiliation: Department of Electronic & Electrical Engineering, University of Bath, Bath BA2 7AY, UK. j.l.hammond@bath.ac.uk.
authors.forename: Jules L
authors.initials: JL
authors.lastname: Hammond
authors.affiliation: School of Electronic & Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. m.c.rosamond@leeds.ac.uk.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Rosamond
authors.affiliation: Department of Electronic & Electrical Engineering, University of Bath, Bath BA2 7AY, UK. s.sivaraya@bath.ac.uk.
authors.forename: Siva
authors.initials: S
authors.lastname: Sivaraya
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK. f.marken@bath.ac.uk.
authors.forename: Frank
authors.initials: F
authors.lastname: Marken
authors.affiliation: Department of Electronic & Electrical Engineering, University of Bath, Bath BA2 7AY, UK. p.estrela@bath.ac.uk.
authors.forename: Pedro
authors.initials: P
authors.lastname: Estrela
keywords: anodic bonding; capacitance; dielectric; horizontal coplanar; nanogap; vertical coplanar