Sensitivity, selectivity and stability of tin oxide nanostructures on large area arrays of microhotplates

Abstract

In this paper, the sensitivity, stability and selectivity of nanoparticle engineered tin oxide (SnO2) are reported, for microhotplate chemical sensing applications. 16 Å of metals such as nickel, cobalt, iron, copper and silver were selectively evaporated onto each column of the microhotplate array. Following evaporation, the microhotplates were heated to 500 °C and SnO2 was deposited on top of the microhotplates using a self-aligned chemical vapour deposition process. Scanning electron microscopy characterization revealed control of SnO2 nanostructures in the range of 20–121 nm. Gas sensing in seven different hydrocarbons revealed that metal nanoparticles that helped in producing faster nucleation of SnO2 resulted in smaller grain size and higher sensitivity. Sensitivity as a function of concentration and grain size is addressed for tin oxide nanostructures. Smaller grain sizes resulted in higher sensitivity of tin oxide nanostructures. Temperature programmed sensing of the devices yielded shape differences in the response between air and methanol, illustrating selectivity. Spiderweb plots were used to monitor the materials programmed selectivity. The shape differences between different gases in spiderweb plots illustrate materials selectivity as a powerful mapping approach for monitoring selectivity in various gases. Continuous monitoring in 80 ppm methanol yielded stable sensor response for more than 200 h. This comprehensive study illustrates the use of a nanoparticle engineering approach for sensitive, selective and stable gas sensing applications.

High butane sensitivity and selectivity exhibited by combustion synthesized SnO2 nanoparticles

“…The authors claim high ethanol sensitivity from 3 nm sized SnO 2 nano rods, as a consequence of the size reduction down to L D [23] . A report by Panchapakesan et al also discussed about the sensitivity and selectivity of tin oxide nanostructures on large arrays of micro hotplates [50]. Thus, it is evident from our results that butane can be detected selectively using CNP derived nano material based sensors with a high sensitivity (>91% towards 1000 ppm butane).…”

“…6, FTIR spectra of the standard, CNP1 and CNP2 SnO 2 powders are presented. The FTIR spectrum of CNP1 powder exhibited three well defined bands at 667 cm À1 and 623 cm À1 corresponding to the two IR active modes namely (E u ) and a shoulder around 530 cm À1 , attributed to an IR active mode (A 2u ) of tin (IV) oxide, respectively [44,49,50]. These three bands shift to lower wave numbers of around 657 cm À1 , 619 cm À1 and 526 cm À1 , respectively with less splitting for the larger sized CNP2 sample.…”

Room‐Temperature Gas Sensing Based on Electron Transfer between Discrete Tin Oxide Nanocrystals and Multiwalled Carbon Nanotubes

“…Rutile-structured tin oxide (SnO 2 ) is an n-type semiconducting material widely used in gas-sensing applications. [7] Tremendous efforts have been devoted to creating highly responsive miniaturized gas sensors by incorporating SnO 2 nanoparticles, [8,9] nanowires, [10] and nanobelts [11] into microfabricated platforms. One major sensing mechanism of the SnO 2 sensor is based on the fact that the adsorption of oxygen onto the n-type semiconductor oxide surface causes a significant change in the electrical resistance of the material.…”

Structural evolution of SnO2 nanostructure from core–shell faceted pyramids to nanorods and its gas-sensing properties

“…This lack of adsorption may be due to the absence of catalysts on the sensing surface. In general, the presence of catalyst on the sensing surface can result in enhanced dissociation of the molecular adsorbates [51,52]. It is known that suitable surface functionalization of nanostructures, such as homogeneously Cu doped SnO 2 single nanowire based H 2 S sensor, can improve sensitivity up to 10 5 [46,53].…”