In an interesting variation on this process, suspended carbon nanowires between walls and posts were fabricated using a combination of UV lithography and electrospinning [18]. The electrospun nanowires were pyrolyzed together with the UV lithographically patterned SU-8 photoresist ensuring good ohmic contact between walls/posts and wires [19, 20]. The reason these authors wanted to fabricate suspended carbon nanowires was to avoid deleterious substrate effects and to enhance mass transport in gases and liquids

to the sensing element. In the current study, we prepared monolithic suspended carbon nanostructures, including nanowires and nanomeshes, which were patterned by two successive UV exposure processes and a single pyrolysis process. The microstructure of the carbon nanowire and

PF-02341066 concentration the development of stress along the wire were explored SYN-117 concentration using a focused ion beam (FIB) milling process, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The intrinsic tensile stress along the nanowire and its bent supports mitigated stiction problem and this structural advantage was explored by executing photolithography, metal deposition, wet etching, and electrochemical experiment on an approximately 200-nm-diameter suspended carbon nanowire. In order to confirm the feasibility of suspended carbon nanostructures as nanosensors, their electrical, electrochemical, and thermal properties were characterized experimentally and through simulations. Moreover, the carbon nanowire was selectively coated with palladium using a lift-off process and its functionality as a hydrogen gas sensor was tested.

Methods The schematic fabrication steps of the suspended carbon nanostructures are described in Figure 1. First, a 0.5-μm-thick SiO2 layer was grown on a 6-inch Si wafer (p-type, boron doped, 8 to 12 Ω · cm2, 660-μm thick) using thermal oxidation. The SiO2/Si substrate was cleaned in a hot piranha solution (H2SO4/H2O2 = 4:1) and dehydrated on a hot plate at 200°C for 5 min. After a 35-μm-thick layer of negative photoresist (SU-8 2000, MicroChem, Corp., Newton, MA, USA) was spin-coated onto the SiO2/Si substrate and soft-baked at 95°C for 9 min, a long UV exposure (200 mJ · cm−2) Rebamipide was performed through a photomask defining post structures. A second UV exposure with lower dose (22 mJ · cm−2) was subsequently performed to polymerize only the shallow area of the negative photoresist layer. The UV lithography process was finished by a post-exposure bake (95°C for 8 min) and a development step. Finally, the photoresist structures consisting of posts and suspended photoresist mircrowires were pyrolyzed in a vacuum furnace and converted into monolithic carbon structures. The pyrolysis process consisted of a pre-baking step for selleck kinase inhibitor degassing and major volume reduction and a carbonization step for forming solid carbon.