Abstract

Photonic crystals (PhC) have attracted exceptional interest as label-free optical biosensors because of their high sensitivity, small scale, and compatibility with fabrication methods and materials drawn from the microelectronics industry. We report the design, fabrication, and use of a nanocavity-coupled w1 PhC waveguide biosensor for label-free, high sensitivity optical detection of viruses (Figure 1). Fabricated on a silicon-on-insulator (SOI) substrate using electron-beam lithography and reactive ion etching, the PhC nanocavity provides optical detection based on resonant mode shifts in response to ambient refractive index changes produced by infiltration of target biomaterial in the nanocavity. Finite difference time domain (FDTD) calculations were performed to assist with design of the sensor, and to serve as a theoretical benchmark against which experimental results could be compared. As a model system for pathogenic viruses, we have used Human Papillomavirus virus-like particles (VLPs). Devices functionalized with anti-VLP antibodies specific for intact VLPs are able to detect VLPs with high selectivity. Specific VLP detection is observed as well in human serum, with sensitivity comparable to that observed in less-complex buffered solutions.

© 2012 Optical Society of America