| Title: | Practical strategies for stable operation of HFF-QCM in continuous air flow |
| Author(s): | Wessels A; Klockner B; Siering C; Waldvogel SR; |
| Address: | "Chemische Institute, Abteilung Elektronik, Rheinische Friedrich-Wilhelm-Universitat Bonn, Gerhard-Domagk-Str. 1, Bonn D-55121, Germany. waldvogel@uni-mainz.de" |
| ISSN/ISBN: | 1424-8220 (Electronic) 1424-8220 (Linking) |
| Abstract: | "Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to-noise ratio. It was possible to reduce the noise in frequency in a continuous air flow of 7.5 m/s to 0.4 Hz [i.e., sigma(tau) = 2 x 10-9] by elucidating the major source of noise. The air flow in the vicinity of the quartz was analyzed to reduce turbulences. Furthermore, we found a dependency between the acceleration sensitivity and mechanical stress induced by an internal thermal gradient. By reducing this gradient, we achieved reduction of the sensitivity to acceleration by more than one decade. Hence, the resulting sensor is more robust to environmental conditions such as temperature, acceleration and air flow" |
| Keywords: | Air Movements Air Pollutants/*analysis Atmosphere/*analysis/*chemistry Environmental Monitoring/*instrumentation Equipment Design Equipment Failure Analysis Micro-Electrical-Mechanical Systems/*instrumentation Rheology/*instrumentation Volatile Organic Co; |
| Notes: | "MedlineWessels, Alexander Klockner, Bernhard Siering, Carsten Waldvogel, Siegfried R eng Research Support, Non-U.S. Gov't Switzerland 2013/09/12 Sensors (Basel). 2013 Sep 9; 13(9):12012-29. doi: 10.3390/s130912012" |
