Monolithic co-resonantly coupled sensors
Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Measurement Systems
Final Report Abstract
The original aim of the project was the investigation of the applicability of microfabrication techniques for monolithic production of co-resonantly coupled sensors and the expansion of the theoretical foundation of the co-resonant concept. Due to difficulties in acquiring the necessary funding to carry out microfabrication work, the project focus was shifted towards the theoretical investigation of effective sensor properties of co-resonantly coupled cantilever structures, leading to new scientific insights for potential sensor performance. The amplitude response curve of the microcantilever within the coupled system exhibits two resonance peaks and their response to an interaction applied to the sensor depends on the properties of the individual beams and the degree of frequency matching. Consequently, while an individual cantilever is characterized by its eigenfrequency, spring constant, effective mass and quality factor, the resonance peaks of the co-resonantly coupled system can be described by effective properties which are a mixture of both subsystem's characteristics. These effective properties give insight into the amount of sensitivity of the nanocantilever that can be accessed and, consequently, into the sensitivity gain associated with the co-resonance. By modeling the co-resonantly coupled system as a coupled harmonic oscillator and using electro-mechanical analogies, analytical expressions for the effective sensor properties have been derived. The results give insight into the complex interplay between the individual subsystem's properties and the eigenfrequency matching. While the effective spring constant and effective mass mainly define the sensitivity of the coupled cantilever sensor, the effective quality factor primarily influences the detectability. Hence, a balance has to be found in optimizing both parameters in sensor design which becomes possible with the derived analytic expressions. Besides the description of effective sensor properties, it was studied how the thermal noise and, consequently, minimal detectable frequency shift for the co-resonantly coupled sensor represented by a coupled harmonic oscillator could be derived. Due to the complex nature of the coupled system's transfer function and the required analysis, a thorough study was not possible within the timeframe of the project. This will be the basis for future work. Instead, a simplified approach to estimate the minimal detectable frequency shift for the coresonant system based on the effective sensor properties was investigated. By establishing a theoretical description for the effective sensor properties, the design of such systems is facilitated as sensor parameters can easily be predicted and adapted for the desired use case. It allows to study the potential sensitivity (gain) and detectability capabilities before sensor fabrication in a fast and easy way, even for large parameter spaces. So far, such an analysis of a co-resonantly coupled sensor was only possible with numerical methods and even then only with very limited capability to include and understand the complex interplay between all contributions. Furthermore, in a broader scope, the investigations carried out within the project contribute towards extending and completing the already established theoretical basics of this novel coresonant sensor concept and open up new ways of studying the coupled system's behaviour.
Publications
- Magnetic properties of individual Co2FeGa Heusler nanoparticles studied at room temperature by a highly sensitive co-resonant cantilever sensor, Scientific Reports 7:888 (2017)
J. Körner, C. F. Reiche, R. Ghunaim, R. Fuge, S. Hampel, B. Büchner and T. Mühl
(See online at https://doi.org/10.1038/s41598-017-08340-z) - A highly sensitive co-resonant cantilever sensor for materials research: Application to nanomaterial characterization, Journal of Materials Research 33(17):2504 (2018)
J. Körner
(See online at https://doi.org/10.1557/jmr.2018.295) - A novel co-resonantly coupled cantilever sensor platform, TechConnect Briefs 4:151 (2018)
J. Körner
- Effective sensor properties of a novel co-resonant cantilever sensor, Eurosensors 2018 Proceedings 2(13) (2018)
J. Körner
(See online at https://doi.org/10.3390/proceedings2130974) - Theory and application of a novel co-resonant cantilever sensor, tm - Technisches Messen 85(6):410 (2018)
J. Körner, C. F. Reiche, B. Büchner and T. Mühl
(See online at https://doi.org/10.1515/teme-2017-0139)
