Orthogonal gas sensor arrays by chemoresistive material design

Abstract

Gas sensor arrays often lack discrimination power to different analytes and robustness to interferants, limiting their success outside of research laboratories. This is primarily due to the widely sensitive (thus weakly-selective) nature of the constituent sensors. Here, the effect of orthogonality on array accuracy and precision by selective sensor design is investigated. Therefore, arrays of (2-5) selective and non-selective sensors are formed by systematically altering array size and composition. Their performance is evaluated with 60 random combinations of ammonia, acetone and ethanol at ppb to low ppm concentrations. Best analyte predictions with high coefficients of determination (R 2) of 0.96 for ammonia, 0.99 for acetone and 0.88 for ethanol are obtained with an array featuring high degree of orthogonality. This is achieved by using distinctly selective sensors (Si:MoO3 for ammonia and Si:WO3 for acetone together with Si:SnO2) that improve discrimination power and stability of the regression coefficients. On the other hand, arrays with collinear sensors (Pd:SnO2, Pt:SnO2 and Si:SnO2) hardly improve gas predictions having R 2 of 0.01, 0.86 and 0.28 for ammonia, acetone and ethanol, respectively. Sometimes they even exhibited lower coefficient of determination than single sensors as a Si:MoO3 sensor alone predicts ammonia better with a R 2 of 0.68.

Rapid and Selective NH3 Sensing by Porous CuBr

“…Also metal‐oxides like pure or Si‐MoO 3 possess only moderate selectivity over acetone (3.6) 25. While this can be improved by combining distinctly selective sensors in rather orthogonal30 sensor arrays that possess excellent NH 3 accuracy (21 ppb) when monitoring human breath and skin emissions,31 the complexity and cost increase. As single sensor, only organic diodes seem to have competitive selectivities to ethanol and acetone, though this needs to be confirmed under high humidity 5…”

Thickness Optimization of Highly Porous Flame-Aerosol Deposited WO3 Films for NO2 Sensing at ppb

“…Such film formation can even be monitored by in situ resistance readout [34]. The FSP has been used already for the fabrication of Cr- [35] or Si-doped [36] WO 3 sensors featuring outstanding acetone selectivity for breath analysis (e.g., fat burn monitoring during exercise [37] and dieting [38]) and in nearly-orthogonal sensor arrays [39] for human search and rescue [40]. Besides, wet-phase-deposited sensing films of flame-made Pt-doped SnO 2 have shown stable sensor performance when tested for 20 days [41], while flame-deposited Pd-doped SnO 2 sensors have featured stable performance for more than three months in a portable device for methanol and ethanol detection [42].…”

Gas sensors using ordered macroporous oxide nanostructures

“…91,92 As compared to some non-ordered porous lms, ordered porous SnO 2 sensors can exhibit enhanced response and sensing kinetics, 61 but further efforts need to be made toward improving their gas selectivities, such as zeolite membrane lters 18 and construction of even orthogonal sensor arrays (E-nose). 66 Although the 2D macroporous conguration and microspaced electrode are benecial to the overall performance, it is still a challenge to realize high-performance gas sensing for pure metal oxides, particularly with regard to selectivity. 83,93 Hence, certain modication strategies need be considered, such as heteroatom doping, surface modication, and interfacial engineering, to enhance the sensing of 2DOM metal oxides.…”

“…) on sensor substrates to build a single sensor [61][62][63][64][65] and sensors arrays [66][67][68] for the selective detection of human breath biomarkers. If combined with in situ resistance measurements during deposition, the formation of highly porous networks can be monitored with morphologydependent resistance patterns to systematically design metaloxide-based gas sensors with high performances.…”