One-dimensional nanostructures based bio-detection.

This paper presents a review on recent developments of one-dimensional (1-D) nanostructures based label-free chemiresistive/chemFET biosensors and the various sensing mechanisms used for biomolecular detection. The sensor performance including sensitivity, selectivity, and reliability is compared in terms of material synthesis of the sensor's element, relating surface functionalization schemes to their properties with respect to selected bioreceptors, its method of fabrication, and its intended operation. As a final point, we outline the prospects of chemiresistive/chemFET biosensors and recommend specific advancements in this field.

Polyaniline/poly(ε-caprolactone) composite electrospun nanofiber-based gas sensors: optimization of sensing properties by dopants and doping concentration.

Electrospinning was utilized to synthesize a polyaniline (PANI)/poly(ε-caprolactone) (PCL) composite in the form of nanofibers to examine its gas sensing performance. Electrical conductivity of the composite nanofibers was tailored by secondary doping with protonic acids including hydrochloride (HCl) or camphorsulfonic acid (HCSA). FT-IR and diffuse reflectance UV-vis spectroscopy were utilized to examine doping-dependent changes in the chemical structure and the protonation state of the nanofibers, respectively.

Palladium/single-walled carbon nanotube back-to-back Schottky contact-based hydrogen sensors and their sensing mechanism.

A Schottky contact-based hydrogen (H2) gas sensor operable at room temperature was constructed by assembling single-walled carbon nanotubes (SWNTs) on a Si/SiO2 substrate bridged by Pd microelectrodes in a chemiresistive/chemical field effect transistor (chemFET) configuration. The Schottky barrier (SB) is formed by exposing the Pd-SWNT interfacial contacts to H2 gas, the analyte it was designed to detect. Because a Schottky barrier height (SBH) acts as an exponential bottleneck to current flow, the electrical response of the sensor can be particularly sensitive to small changes in SBH, yielding an enhanced response to H2 gas.

Metal nanoparticles and DNA co-functionalized single-walled carbon nanotube gas sensors.

Metal/DNA/SWNT hybrid nanostructure-based gas sensor arrays were fabricated by means of ink jet printing of metal ion chelated DNA/SWNTs on microfabricated electrodes, followed by electroless deposition to reduce metal ions to metal. DNA served as a dispersing agent to effectively solubilize pristine SWNTs in water and as metal ion chelating centers for the formation of nanoparticles. Noble metals including palladium, platinum, and gold were used because the high binding affinity toward specific analytes enhances the selectivity and sensitivity.