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Zeolite membranes for highly selective formaldehyde sensors
Sensors and Actuators B: Chemical ( IF 8.4 ) Pub Date : 2017-11-12 , DOI: 10.1016/j.snb.2017.11.035
Andreas T. Güntner , Sebastian Abegg , Karsten Wegner , Sotiris E. Pratsinis

A major challenge in gas sensing (e.g. breath analysis, indoor air quality monitoring, etc.) is the accurate detection of trace-level species in complex mixtures. While modern chemical gas sensors can be extremely compact, inexpensive and highly sensitive, their success is still limited by selectivity. Here, we combine sensors with highly selective zeolite membranes pre-separating gas mixtures. Zeolites – broadly applied in catalysis and gas separation – effectively separate molecules based on kinetic diameter, sorption and diffusion characteristics. Therefore, zeolite membranes are suitable filters for gas sensors removing undesired species from mixtures like exhaled breath. As proof-of-concept, a zeolite Mobile-Five (MFI)/Al2O3 membrane is placed upstream a highly sensitive but non-selective Pd-doped SnO2 sensor. Their combination exhibits exceptional selectivity (>100) for formaldehyde (down to 30 ppb) at 90% relative humidity, outperforming most state-of-the-art detectors by more than an order of magnitude. This novel concept is readily extendable to other tracers, as many combinations of widely tunable microporous membranes and gas sensors can be realized in this modular sensing device. This could enable a new class of highly sensitive and selective portable breath detectors or compact indoor air monitors.



中文翻译:

用于高选择性甲醛传感器的沸石膜

气体传感(例如呼吸分析,室内空气质量监测等)中的主要挑战是如何准确检测复杂混合物中的痕量物质。尽管现代化学气体传感器可以极其紧凑,便宜且高度灵敏,但其成功仍然受到选择性的限制。在这里,我们将传感器与高选择性的沸石膜结合起来,以预分离气体混合物。沸石-广泛用于催化和气体分离-根据动力学直径,吸附和扩散特性有效分离分子。因此,沸石膜是用于气体传感器的合适过滤器,可从呼出气等混合物中去除不需要的物质。作为概念验证,分子筛为Mobile-Five(MFI)/ Al 2 O 3膜放置在高度敏感但非选择性的Pd掺杂SnO 2传感器的上游。它们的组合在90%的相对湿度下对甲醛(低至30 ppb)表现出卓越的选择性(> 100),比大多数现有技术的检测器高出一个数量级。这个新颖的概念很容易扩展到其他示踪剂,因为可以在此模块化传感设备中实现广泛可调的微孔膜和气体传感器的许多组合。这可以使新型的高灵敏度和选择性便携式呼吸检测器或紧凑型室内空气监测器成为可能。

更新日期:2017-11-12
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