Developing Novel Holographic Optomechanical Sensing Platform for Application in Volatile Organic Compounds Detection

Volatile organic compounds (VOCs) are analytes of increasing interest due to the risks they pose to human health in terms of cardiovascular and carcinogenic complications. Current state of the art VOC detectors includes MEMS and semiconductor type sensors which suffer from cross sensitivity, drift, and poor selectivity between VOCs. Furthermore, these devices often require complex and costly fabrication and readout techniques. Holographic sensors based on various types of diffractive structures have been demonstrated previously as highly sensitive, robust, and versatile sensing devices for numerous analytes including temperature, humidity and VOCs, with simple and low-cost fabrication and operation characteristics. It has also been demonstrated that the sensitivity of the holographic structures can be enhanced through coupling into an optomechanical configuration, however this coupling was only investigated for unslanted volume transmission gratings. In this work, the sensitivity of a range of structures fabricated using holographic recording techniques is investigated. The response of volume transmission holographic gratings is studied in three different configurations - fixed gratings on glass slides, optomechanical holographic cantilever and optomechanical holographic membrane. The samples are tested in a vacuum chamber for response to air with the view to optimizing the most sensitive platform as a highly accurate VOC detector. The results further validate that the coupling of volume transmission holographic gratings with a mechanical transducing method enhances sensitivity. Furthermore, the study demonstrates that the membrane configuration has the potential to provide the most sensitive, stable, and repeatable sensing platform of the three presented.