Localized collection of airborne analytes: A transport driven approach to improve the response time of existing gas sensor designs

Abstract

The detection of single binding has been a recent trend in sensor research introducing various sensor designs where the active sensing elements are nanoscopic in size. Currently, transport and collection of airborne analytes for gas sensors is either diffusion based or non-localized and it becomes increasingly unlikely for analytes to interact with sensing structures where the active area is shrunk, trading an increased sensitivity with a slow response time. This report introduces a corona discharge based analyte charging method and an electrodynamic nanolens based analyte concentration concept to effectively transport airborne analytes to sensing points to improve the response time of existing gas sensor designs. Localized collection of analytes over a wide range, including microscopic particles, nanoparticles, and small molecules, is demonstrated. In all cases, the collection rate is several orders of magnitudes higher than in the case where the collection is driven by diffusion. The collection scheme is integrated on an existing SERS (surface-enhanced Raman spectroscopy) based sensor. In terms of response time, the process is able to detect analytes at 9 ppm (parts per million) within 1 s. As a comparison, 1 h is required to reach the same signal level when diffusion-only-transport is used. In the field of sensors that target the detection of airborne analytes, the corona/lens-based-collection provide a new path to achieve high sensitivity which impacts the researches ranging from environmental monitoring systems to the detection of chemical/biological warfare agents. Specifically, it provides a route to transport, concentrate, and collect the airborn species to precise sensing points to improve the collection efficiency. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.