A Novel Approach to Hydrogen Sensing

Abstract

A novel sensor for the selective detection of hydrogen in the presence of other reducing gases is presented. The device comprises a commercially available non-or partially-selective semiconductor gas sensor and an air filled centimeter-long capillary tube. The attachment is so that upon exposure, the target gas diffuses in air through the length of the capillary before affecting the sensor. The hydrogen component of the gas mixture diffuses much faster than other components, and is sensed at an earlier stage of the sensor response. The response of a capillary-attached gas sensor (CGS) to a gas mixture containing hydrogen is mathematically analyzed. The results indicate that the hydrogen concentration can readily be extracted from certain mathematical features of the transient response. The fabrication of a prototype CGS and experimental verification of the analytical results are reported. The prototype can measure hydrogen concentration at the presence of other reducing and combustible gases exceeding its concentration by two orders of magnitude.

Hydrogen detection in organic gas mixtures based on analyzing the transient response

“…Equation (3) can then be expanded for a mixture of the gases: Equation 4 In the previous study, equation (4) was approximated linear by applying m= 1 for all TG in low concentrations (Hossein‐Babaei and Orvatinia, 2004).…”

“…One of the most widely reported areas in gas mixture investigations, for a wide range of applications, is the detection and monitoring of gas mixtures which included hydrogen and volatile organic gases. Based on the temporal analysis and linear approximation, the positive feature of the CGS has been employed for detecting low ppm‐level hydrogen contaminations in highly polluted background atmospheres (Hossein‐Babaei and Orvatinia, 2004). However, the nonlinear behavior of metal oxide semiconductor (MOS) sensor cannot be disregarded.…”

Extracting discriminative information from the Padé-Z-transformed responses of a temperature-modulated chemoresistive sensor for gas recognition

“…The oscillatory parts of these exponential terms were replaced by their average numerical values within their respective time frames. This procedure was practiced, for example, in the transformation processes resulting (13)- (15). For instance, [R 4,4 ] 542 as described by (11) resulted in four exponentials including a pair of complex conjugates.…”

“…The sensitivity as well as the response level vary from one target gas to the next, but, in practice, no selective detection is expected from a single sensor as its response to gas A at concentration C A can be similar to that to gas B at a different concentration C B . Different techniques have been used to overcome the lack of selectivity in these sensors [4,[14][15][16][17][18], among which the modulation of their operating temperature is well known [18][19][20][21][22][23][24][25][26][27][28][29].…”

Comparison of different feature reduction methods in the improvement of gas diagnosis of a temperature modulated resistive gas sensor

“…However, it increases dimensions of pre-processing, the complexity of calculations and also causes a high level of noise [7]. Attempts have been made to create selectivity in a single sensor [8]. One of the techniques that's commonly used for creating the capability of selectivity in single sensors is the modulation of sensor temperature [9][10].…”