Design and engineering of Mn conical sculptured thin films as both electrodes for a gas sensor: ionization and field emission studies

Abstract

Paschen’s law and deviation from Paschen’s law are studied in a face to face gas sensor based on Mn helical sculptured thin films with conical shape as cathode and anode electrodes. The sensor’s performance was investigated at dynamic pressures ranging from 0.1 to 1000 mbar and 3 to 200 μm gaps between the two electrodes and for nitrogen, air and carbon monoxide gases. Results showed that at distances more than 10 μm the Paschen’s law is satisfied but at lower than 10 μm distances between the two electrodes and pressures more than 250 mbar deviations occur from the Paschen’s law. Selectivity results of the sensor showed that under all conditions studied in this work and for all gases there is a good resolution between the results and this enhances with gas pressure. Comparison of the results of the present sensor with those reported in the literature showed higher sensitivity of the present work for different gases investigated.

Review of the gas breakdown physics and nanomaterial-based ionization gas sensors and their applications

“…Very recently, the discharge characteristics of ionization gas sensors using manganese (Mn) sculptured thin films were investigated [192][193][194]. Mn helical nano-sculptured thin films with nano-flower are fabricated on top of helical nanosculptured stem and pillars [192].…”

Crystalline-to-Amorphous Phase Transformation in CuO Nanowires for Gaseous Ionization and Sensing Application

“…Field gas ionization system is capable of ionizing the gas molecules by loading a low voltage on the electrodes and is favorable for many potential applications, for example, sensors, , environmental remediation, spectrometry, − and biomedicine . Among them, ionization gas sensors have attracted extensive interest for their advantages like high selectivity and fast response/recovery. , Ionization gas sensing is substantially based on the separation of the positive and negative charges of a gas molecule. , By ionizing the target gas, a specific current–voltage characteristic can be generated as the “fingerprint” of the gas component. , The main disadvantages of traditional bulky ionization gas sensors, for example, high power consumption and risky high operation voltage, hinder their practical application. − Therefore, one-dimensional nanomaterials with ultrasharp tips, for example, carbon nanotubes, as well as ZnO, Si, or CuO nanowires (NWs), − are equipped onto the traditional macroscopic electrodes in order to lower both the operation voltage and the current. Then, intensive studies of decorating the thin film or nanoparticles have been conducted on these nanoelectrodes to further decrease the gas ionization voltages. − However, in contrast to these approaches of additional manufacturing, the study of structural evolution of these microscopic electrodes themselves during the gas ionization is still challenging, and it is worthwhile devoting effort to it, which is strongly associated with the sensing properties of current–voltage ( I – V ) characteristics, repeatability, and stability …”