A Flexible, Highly Sensitive, and Selective Chemiresistive Gas Sensor Obtained by In Situ Photopolymerization of an Acrylic Resin in the Presence of MWCNTs

A new flexible polymeric gas sensor is developed by photocrosslinking poly(ethylene glycol) diacrylate resin (PEGDA) containing multi‐walled carbon nanotubes (MWCNTs) as conductive filler. The cured material shows a percolative threshold conductivity which changes when in contact with various gas analytes with different chemical and physical properties. The different behavior of the sensors toward the different gases is explained either on the basis of chemical affinity toward the polymeric matrix or due to the interactions that can occur between the analyte and the surface of the nanotubes in the case of the aromatic gas

A Flexible, Highly Sensitive, and Selective Chemiresistive Gas Sensor Obtained by In Situ Photopolymerization of an Acrylic Resin in the Presence of MWCNTs

AbstractA new flexible polymeric gas sensor is developed by photocrosslinking poly(ethylene glycol) diacrylate resin (PEGDA) containing multi‐walled carbon nanotubes (MWCNTs) as conductive filler. The cured material shows a percolative threshold conductivity which changes when in contact with various gas analytes with different chemical and physical properties. The different behavior of the sensors toward the different gases is explained either on the basis of chemical affinity toward the polymeric matrix or due to the interactions that can occur between the analyte and the surface of the nanotubes in the case of the aromatic gas

Placement and orientation of individual DNA shapes on lithographically patterned surfaces

Artificial DNA nanostructures show promise for the organization of functional materials to create nanoelectronic or nano-optical devices. DNA origami, in which a long single strand of DNA is folded into a shape using shorter 'staple strands', can display 6-nm-resolution patterns of binding sites, in principle allowing complex arrangements of carbon nanotubes, silicon nanowires, or quantum dots. However, DNA origami are synthesized in solution and uncontrolled deposition results in random arrangements; this makes it difficult to measure the properties of attached nanodevices or to integrate them with conventionally fabricated microcircuitry. Here we describe the use of electron-beam lithography and dry oxidative etching to create DNA origami-shaped binding sites on technologically useful materials, such as SiO_2 and diamond-like carbon. In buffer with ~ 100 mM MgCl_2, DNA origami bind with high selectivity and good orientation: 70–95% of sites have individual origami aligned with an angular dispersion (±1 s.d.) as low as ±10° (on diamond-like carbon) or ±20° (on SiO_2)

Analysis of tin oxide thin films fabricated via sol-gel and delayed ignition of combustion processes

Metal oxide semiconductor (MOS) gas sensors based on thin film technology offer the potential of higher sensitivity and faster response and recovery than their thick film counterparts. Solution-based approaches are facile and inexpensive routes to prepare thin films. They also provide the means to control and tune the final MOS morphology. Here we present an analysis of tin oxide-based MOS films tens of nanometers thick prepared using two methodologies: a sol-gel process which makes use of tin (II) precursors and, alternatively, via Delayed Ignition of Combustion (DICO). The latter process offers a route to the thin film oxides at lower cure temperatures using ionic oxidizers and organic ignition fuels. We analyze and compare the morphological and compositional properties of the films by means of SEM, TEM, RBS and XRR. For films of comparable thickness, we evaluate the response to acetone down to the sub-ppm level and establish structure-property relationships