Micro and Nano-scale Photonic and Plasmonic Crystal based Thin Film Sensors

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There is increasing demand today for portable, sensitive, fast and accurate sensors in various applications ranging from bio-medical diagnostics to environmental monitoring; for example to detect hazardous compounds or to sample and analyse nanoscopic volumes of biological molecules and fluids. Micro and nano-scale photonic sensors have emerged today as an attractive solution to address these needs. Several on-chip integrated photonic micro-sensor systems are being rapidly developed to address this need including platforms based on photonic crystals, surface plasmon resonance (SPR), optical waveguide, and optical fiber gratings. In particular silicon based photonic crystal and gold nanoparticle based plasmonic crystal sensors are capable of providing high sensitivities and flexibility in design for different applications while providing the ability to integrate with existing device technologies. However the reliable fabrication and integration are only now beginning to be realized and current research efforts are into demonstrating practical applications.The main objective of the proposed research work is to build novel photonic crystal and plasmonic crystal based sensors targeted for specific applications. The first aspect will be to continue development of a novel micro-pressure sensor based on a suspended photonic crystal waveguide fabricated using planar Silicon-On-Insulator technology for which a US patent has been filed. Miniaturization of micro-pressure sensors which are not based on electrical inputs are needed in several areas ranging from catheter based pressure sensors inserted in heart, cardiac ablation surgery and harsh environmental monitoring. Lab-on-chip devices also require embedded micro pressure sensors inside microfluidic channels for monitoring inlet and outlet pressures. In the proposed research photonic crystal micro-pressure sensors will be designed for these applications and characterized in our CFI based micro-sensor facility which has the unique capability of simultaneous optical and mechanical measurements.In another aspect of the research project, bio-compatible thin film polymers along with specifically functionalized surfaces will be incorporated into silicon based photonic crystal and gold nanoparticle based plasmonic crystals for highly sensitive and specific bio-sensors for cancer markers detection. We have demonstrated novel gold nanoparticle arrays with SPR in the near infra-red spectrum which are potentially more sensitive than their visible counterparts and also tunable based on array interaction. Thin-film pH sensors have been developed by combining bio-compatible hydrogels with photonic crystals, gratings and gold nanoparticle plasmonic crystals. Our current work to date has shown improved sensitivities and selectivity and ability to integrate these sensors with required detection targets. Working in the infra-red enables integration of robust photonics technology while attaining high sensitivity devices. The nature of the proposed research in interdisciplinary in nature requiring collaborations with the physics, chemical engineering and mechanical engineering departments at the University of Western Ontario and other university partners. Since an important aim of the proposed research is to produce micro-sensor platforms targeted for specific practical applications, collaborations with both an industry partner (catheter based micro-pressure sensors) and clinician (cancer marker detection) have been established. The significant outcome of the proposed research will be the availability of miniature, highly sensitive and specific optical sensors which are in demand for faster, portable and accurate diagnostics.