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Platform for resonant chemical and biosensors based on phononic crystals

Subject Area Microsystems
Measurement Systems
Term from 2014 to 2018
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 254691483
 
Final Report Year 2018

Final Report Abstract

We here have successfully applied the concept of phononic crystal based sensor approach integrated into a planar SAW sensor platform. We could deduct information about the liquid by analyzing the frequency dispersion of the SAW-PnC solidliquid composite arrangement. We have demonstrated the sensing capabilities of the structure consisting of 4-port SAW device and the periodic arrangement of liquid filled microfluidic channels placed above the receiving IDTs. Computational analyses of the design with numerical methods have revealed the ability of the composite structure to exhibit structural resonance modes that depend on material properties of liquid inclusions. It was demonstrated that around a specific frequency when the structure is excited at a specific resonance mode, the transmission dependence has a related minimum at the frequency that can finally be correlated to material properties of the liquid, first of all speed of sound. The sensor structures were fabricated utilizing the polymer based fabrication concept and a planar fabrication approach. Our concept merging the microacoustic platform and phononic crystal sensor concept was optimized and experimentally verified. The experimentally achieved results have confirmed the theoretical predictions but the sensor resolution was lower than expected. We address this finding to the lower Q-factor of the resonance used which is the result of small fabrication tolerances far beyond typical requirements in microfluidics and a not yet optimal mode spectrum. In order to improve the resolution of this velocimetry based sensors, special attention must be payed to the modes involved in the complete signal transduction scheme and further improvements in geometric stability of the resonant structures.

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