Porous photonic crystal external cavity laser biosensor

Abstract

We report the design, fabrication, and testing of a photonic crystal (PC) biosensor structure that incorporates a porous high refractive index TiO 2 dielectric film that enables immobilization of capture proteins within an enhanced surface-area volume that spatially overlaps with the regions of resonant electromagnetic fields where biomolecular binding can produce the greatest shifts in photonic crystal resonant wavelength. Despite the nanoscale porosity of the sensor structure, the PC slab exhibits narrowband and high efficiency resonant reflection, enabling the structure to serve as a wavelength-tunable element of an external cavity laser. In the context of sensing small molecule interactions with much larger immobilized proteins, we demonstrate that the porous structure provides 3.7Â larger biosensor signals than an equivalent nonporous structure, while the external cavity laser (ECL) detection method provides capability for sensing picometer-scale shifts in the PC resonant wavelength caused by small molecule binding. The porous ECL achieves a record high figure of merit for label-free optical biosensors. Published by AIP Publishing.

Deterministic Nanoassembly of Quasi-Three-Dimensional Plasmonic Nanoarrays with Arbitrary Substrate Materials and Structures

“…Interaction of incident light with three-dimensional (3D) metal–dielectric composite nanoarrays provides unique capabilities to manipulate light at nanoscale length. − Diverse types of 3D or quasi-3D plasmonic nanoarrays with tailored feature shapes, sizes, and configurations have been explored for a broad range of light-driven sensors and actuators such as imagers, biosensors, lasers, and antennas. − Traditionally, the construction of 3D plasmonic nanoarrays has largely relied on the use of nanolithography techniques by exploiting either electron-beam lithography (EBL), or focused ion-beam lithography (FIB), or interference lithography (IL), but their laborious, complex, and time-consuming nature impedes practical applications. − In addition, the nanolithography processes often require the use of thermal and chemical treatments, leading to additional increase of complexity and risk in protecting the substrate materials. Alternative strategies involve the use of micro/nanoscale 3D printing techniques such as nanoimprinting and modular microtransfer printing, allowing for deterministic integration of 3D plasmonic nanoarrays with a foreign receiver substrate, and thereby circumventing the incompatibility of the nanolithography conditions with substrate materials. − Nevertheless, the choice of receiver substrates remains limited by the required physical contact forces during printing steps, yielding an increased risk of potential damages to receiver substrates particularly composed of mechanically fragile materials and structures.…”

Design for Distributed Feedback Laser Biosensors Based on the Active Grating Model

“…A large FWHM limits the capability of a sensor to precisely measure small resonant wavelength shifts [27]. However, a narrow FWHM requires light energy that is mostly confined within the structure, rather than the cover medium [31]. Therefore, the sensitivity and the FWHM are a pair of irreconcilable contradictions in sensors with passive gratings.…”

High Performance of a Metal Layer-Assisted Guided-Mode Resonance Biosensor Modulated by Double-Grating

“…However, GMR sensors typically have relatively low sensitivity (<200 nm/RIU) and a small figure of merit (FOM, <100 1/RIU), which is defined as the sensitivity of the sensor divided by the full width at half maximum (FWHM) of the resonance (Sensitivity/FWHM) [16][17][18][19][20]. Biosensors with large sensitivity and FOM are more desirable since a large signal noise ratio is achievable for accurate detection of small signals during biosensing [21][22][23]. Many research groups have proposed several ways to improve the sensitivity of GMR sensors.…”