Label-free photonic biosensors fabricated with low-loss hydrogenated amorphous silicon resonators

Abstract

Abstract. The precise detection of chemicals and biomolecules is of great interest in the areas of biotechnology and medical diagnostics. Thus, there is a need for highly sensitive, small area, and low-cost sensors. We fabricated and optically characterized hydrogenated amorphous silicon photonic resonators for label-free lab-on-chip biosensors. The sensing was performed with small-footprint microdisk and microring resonators that detect a refractive-index change via the evanescent electric field. Homogeneous sensing with NaCl and surface-sensing experiments with immobilized bovine serum albumin (BSA) were carried out. A sensitivity as high as 460 nm∕RIU was measured for NaCl dissolved in deionized water for the disk, whereas about 50 nm∕RIU was determined for the ring resonator. The intrinsic limits of detection were calculated to be 3.3 × 10 −4 and 3.2 × 10 −3 at 1550-nm wavelength. We measured the binding of BSA to functionalized ring resonators and found that molecular masses can be detected down to the clinically relevant femtogram regime. The detection and quantification of related analytes with hydrogenated amorphous silicon photonic sensors can be used in medical healthcare diagnostics like point-of-care-testing and biotechnological screening. © The Authors.Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Whispering Gallery Mode Devices for Sensing and Biosensing

“…Microdisks can also be used for bio-sensing applications [194,197,[204][205][206][207][208][209][210], much like the case for microspheres discussed earlier. The surface of the microdisks can be functionalized by methods listed in Sect.…”

“…Of course, one can detect the change of the surrounding refractive index by immersing the microdisk in different analyte fluids [192][193][194][195][196][197][198][199]. Microdisks have also been tested as displacement sensors [200], gamma ray sensors [201], gas sensors [202], surface curvature sensors, [203] and of course as biosensors [194,197,[204][205][206][207][208][209][210]. Each of these applications will be briefly discussed.…”

“…WGM shifts in microdisks were used to detect specific binding of streptavidin with a sensitivity of 0.26 nm/nm, defined as the ratio of the WGM shift to the protein layer thickness [205], and a concentration detection limit of 74 ng/mL [207]. A mass detection limit in the fg range was reported for BSA [194]. Although single bio-molecule detection experiments haven't been conducted yet, simulations imply the capability to detect as few as several tens [204] or possibly a single biomolecule [210] even without plasmon enhancement, assuming ideal coupling and a high sensitivity.…”

An Innovative Straight Resonator Incorporating a Vertical Slot as an Efficient Bio-Chemical Sensor

“…Recently, an improved bulk detection sensitivity (380 / ) of porous silicon ring resonator for biosensing applications has been reported by G. A. Rodrigues et al [10]. Other optical bio-chemical sensors have incorporated microdisk resonator [11], photonic crystal cavities [12], [13] and Mach-Zehnder interferometers [14], [15].…”

Single-waveguide-based microresonators for optical sensing

“…The devices basically rely on the overlap interaction between the evanescent wave and bioanalytes absorbed on device surfaces or in the surrounding medium [4] . They are typically based on siliconon-isolator (SOI) material systems offering extremely low absorption and bending losses, which allows many flexible geometry designs such as rings [5] , disks [6] , or toroids [7] . Their attractive properties, such as high quality factor (Q factor) and small footprint, mean that the light would circle the resonators dozens of times before being lost, which makes high power enhancement easy to achieve and, accordingly, makes attractive high sensitivity possible.…”