Portable microsensors based on individual SnO₂nanowires

Abstract

Individual SnO(2) nanowires were integrated in suspended micromembrane-based bottom-up devices. Electrical contacts between the nanowires and the electrodes were achieved with the help of electron- and ion-beam-assisted direct-write nanolithography processes. The stability of these nanomaterials was evaluated as function of time and applied current, showing that stable and reliable devices were obtained. Furthermore, the possibility of modulating their temperature using the integrated microheater placed in the membrane was also demonstrated, enabling these devices to be used in gas sensing procedures. We present a methodology and general strategy for the fabrication and characterization of portable and reliable nanowire-based devices.

Ultralow power consumption gas sensors based on self-heated individual nanowires

“…10 Two probe dc measurements were performed using an electronic circuit designed to guarantee and control low current levels I m ͑from 0.1 to 500 nA͒ and to avoid undesired fluctuation. 8 All the experiments were performed in a customized chamber, in which the gas flow was maintained at 200 ml min −1 . Accurate gaseous environments were provided by massflow controllers mixing synthetic air ͑SA͒ and NO 2 ͑10 ppmϮ 1% in SA͒.…”

Insight into the Role of Oxygen Diffusion in the Sensing Mechanisms of SnO2 Nanowires

“…[3,4,6] On the other hand, present nanofabrication techniques enable the development of new prototypes which combine metal oxide nanowires with well-established microelectronic technologies. [10,11] In this context, the characterization of tin oxide (SnO 2 ) nanowires is important to develop a new generation of metal oxide gas sensors, since this material is one of the most promising for sensing applications. [12][13][14] SnO 2 is a large bandgap (3.6 eV) semiconductor whose electrical properties can be adjusted for multiple uses by the incorporation of dopant ions [15] and catalytic additives.…”

Nanoscale Electrical Contacts Grown by Focused Ion Beam (FIB)-Induced Deposition

“…For example, Hernández-Ramírez et al succeeded in the contacting of tin oxide (SnO 2 ) nanowires by Pt FEBID and FIBID [ 21 ]. These nanowires were applied for gas sensing as portable gas microsensors [ 22 ]. Cronin et al contacted Bi nanowires with a thick oxide shell by fi rst sputtering away the oxide layer by FIB and then growing Pt FIBID contacts [ 23 ].…”