Presenter: Ibrahim Abdulhalim, Electro-optical Engineering Unit and the Ilse-Katz Center for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer Sheva 84105, Israel. NEW CREATE Program, School of Materials Science and Engineering, Nanyang Technological University, Singapore
Topic: Ultrahigh enhancement of fields and sensitivity of plasmonic and photonic biosensors
TIme: 14:00 PM, Jul. 19th (Wednesday)
Several photonic and plasmonic structures and reading methods that improve the performance of bio and chemical sensors were developed in our group during the last few years: (i) a self-referenced sensor based on enhanced optical transmission through metal nanoslits, (ii) a self-referenced ultra-large penetration depth SPR sensor, (iii) a TIR sensor in which the angular edge is converted into a dip with high figure of merit, (iv) a self-referenced SPR sensor based on thin dielectric grating on top of thin metal film, and (v) polarimetric approach that improves the detection limit of SPR in the spectral interrogation mode and (vi) SERS/SEF substrates with ultrahigh enhancement of the electromagnetic field. In the spectral SPR the dip width is around 50nm and therefore the resolution is limited even though the spectral sensitivity is considered relatively high. Using a special methodology we found that the derivative of the phase difference between the TM and TE waves can give the highest resolution, although practically the more directly measured cosine function of the phase difference is the best to use. Several structures were found to reveal self-referencing, thus enabling a better detection limit. High penetration helps in detecting large bioentities more reliably such as bacteria and cells.Figure of merit is defined as the ratio between the sensitivity to the width of the resonance dip; hence its enhancement also improves the detection limit. Combining all this in one system together with compact reading methodology and unique signal processing allows refractive index sensing limits down to 10-8. Metallic nano-sculptured thin films (nSTFs) prepared by the glancing angle deposition were found by us recently to exhibit optimum SPR sensitivity, SERS and SEF signals at around 30% porosity and used for the detection of large bioentities.In addition new configuration that combines coupling between extended SPR with localized SPR was found recently to reveal ultrahigh field enhancement useful for multimodal sensing system based on SPR, SERS, SEF and SEIRA.
Professor Ibrahim Abdulhalim is with the Electro-optical Engineering Unit at Ben Gurion University.He worked in academic institutions and companies such as the OCSC in UC at Boulder, the ORC at Southampton University, the Thin Films Center of the University of Western Scotland, in KLA-Tencor in where he was the lead inventor of optical scatterometry for CD and overlay measurements, Nova and GWS Photonics, Published over 200 articles, 2 books, 10 chapters and inventor on 20 patents.He is a fellow of IoP and SPIE and an associate editor for the Journal of NanoPhotonics and for the Journal of Imaging. Research interests in nanophotonics and plasmonics for biosensing and energy devices, optical imaging techniques for diagnostics, optical metrology and liquid crystal devices.
Contact: Prof. Lin Jiang