The optical setup assembled during the project possesses two main characteristics that place it beyond the state of the art, thanks to the use of two different tunable lasers.
On one hand, as the system uses one laser to excite the mechanical vibration, and another to measure these vibrations, it allows to obtain a significantly more precise measurement of the mechanical frequencies of the system. It is important to note that it is possible to measure several mechanical modes at the same time. The system has demonstrated relative frequency stabilities of 10-6, 5*10-5 and 2*10-5 for the first, second and third radial breathing mode, respectively.
On the other hand, the system is also able to simultaneously monitor several optical modes of the microdisks, apart from the already commented mechanical modes. By measuring both, optical and mechanical modes, the sensor provides simultaneous access to the optical and mechanical properties of the given analyte. This dual sensing approach is fully innovative and unconventional. Importantly, it significantly improves the biosensor reliability and robustness.
To validate the capabilities offered by this novel sensing approach, I have applied it on detection of environmental changes, particularly temperature and humidity. I have demonstrated that the method allows to decoupled humidity and temperature effects with extraordinary precision, becoming excellent sensors for this propose. Moreover, I have also used this approach for the detection and identification of bacteria thus, characterizing both their mechanical and optical properties.
This project has demonstrated the enormous potential of optomechanical resonators as biological sensors, for the first time. I have demonstrated that optomechanical microdisks allows not only to identify individual and alive bacteria but also their different life stages.
