Data and Time May 24 , 2011, 3:00-4:15 PM
Location Sanford Flemming Building, Room B560
Host Alex Wong

Photonic Crystal Slab Nanostructure Biosensors

Hooman Akhavan

The Edward S. Rogers Sr. Department of Electrical and Computer Engineering (Photonics)


Portable biosensors with simplified sample handling and processing steps are a critical component in point-of-care (POC) diagnostics. Detection modules that do not require fluorescent or radioactive labelling of target molecules substantially reduce these steps. In particular, refractive index (RI) based sensing using photonic crystal slabs (PCS) is very promising due to their easy light coupling schemes, large sensing areas, and label-free characteristics. PCS have the capacity to couple in-slab electromagnetic radiation to free-radiation, thereby providing a powerful platform for optofluidic sensing. In the context of PCS and RI-based sensing, this translates to using normal-incidence light to excite the guided resonance modes (GRMs), whose resonance wavelengths are sensitive to local RI. Biosensing can be achieved with capture agents functionalized on the surface of PCS. Capture agent/target binding changes the local RI, causing the GRMs' spectral locations to shift. This shift can be used to determine the number of binding events that have occurred.  These modes can be characterized bytheir quality factors (Q), defined as height over half-width maximum, and index change sensitivity (S), which is the GRM shift in wavelength that results from a unit change in RI (nm/RIU).

Here we demonstrate PCS designs with Q values exceeding 1000.  In principle, these high-Q sensors are able to resolve refractive index changes as small as 10-6 RIU. Preliminary results show ability to detect change in RI between water and a 0.02% IPA dilution.  This corresponds to a spectral shift of 3pm or a change of 10-5 RIU.



Hooman Akhavan obtained his B.Sc. in Applied Physics from Sharif University of echnology, Tehran, IRAN in 1997.   He entered University of Southern California (USC), Los Angeles (USA) in 2000, completed his MS and PhD both in Electrical Engineering in 2003 and 2007, respectively.  His research interest was on modeling and experimental analysis of microdisk resonators. Currently he is a post-doctoral researcher in Biophotonics group at the University of Toronto.