Micro-Reactors for Testing Sensor Devices Based on Suspended Carbon Nanotubes

Abstract

In this work, we report the fabrication of micro-reactors for the characterization of nano-sensors based on suspended nanoparticle-decorated carbon nanotubes (CNTs/NPs). The capsules were fabricated from a single Kovar® piece, having a small volume chamber (100µl). Gold thin films were sputtered onto Si/SiO2 substrates and the electrodes were patterned using electrochemical deposition, photolithography and wet chemical corrosion. In order to obtain devices based on suspended nanotubes, prior to CNTs deposition, a 1µm wide and 5µm deep gap was milled in the substrate by focused ion beam (FIB). The dielectrophoresis (DEP) technique was used for the deposition of the suspended CNTs over the as obtained patterned electrodes. The sensors were tested using oxygen and nitrogen atmospheres, in the pressure range between 10-5 and 10-1mbar. The small chamber volume allowed the measurement of fast sensor characteristic times, with the sensors showing good sensitivity towards gas and pressure as well as high reproducibility.