A2.1 - Modeling and Signal Processing Approaches for SAW Chemical Sensors
- SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
- Proceedings SENSOR 2011
- A2 - Surface Acoustic Wave Sensors
- G. Fischerauer - Universität Bayreuth (Germany)
- 47 - 52
Microacoustic chemical sensors based, for instance, on quartz crystal microbalances (QCM) or surface acoustic wave (SAW) devices have been popular in laboratories around the world for almost 30 years. They have also met with some commercial success, and one of the underlying effects, viz., mass loading, is routinely used in thin-film technology to monitor film growth during deposition. This contribution aims at reviewing the principles of such sensors and the strategies applied to model the devices and to process their output signals.
The focus is on physical and functional aspects with an emphasis on the transduction process from analyte concentration to acoustic wave properties to device terminal characteristics. The methods used to describe the device characteristics and the response to analyte gas concentration vary from purely numerical (such as the finite element method) to purely analytical, with perturbational approaches, state-space models, equivalent circuits, transmission-line models, etc. in between. The contribution will try to assess the relative merits of the various approaches and the uniqueness of the respective model parameters (which is of importance if one desires to infer the analyte gas concentration from observed parameter changes).
Even well-designed sensors exhibit undesired characteristics such as temperature sensitivity, slow response behavior, or noise. Some of these nonidealities can be remedied by hardware or by signal processing methods. This will be demonstrated by way of examples dealing with the suppressing of temperature effects and the acceleration of the effective sensor response.