Optical integrated chips with micro and nanostructures for refractive index and SERS-based optical label-free sensing

Abstract

Label-free optical biosensing technologies have superior abilities of quantitative analysis, unmodified targets, and ultrasmall sample volume, compared to conventional fluorescence-label-based sensing techniques, in detecting various biomolecules. In this review article, we introduce our recent results in the field of evanescent-wavebased refractive index sensing and surface enhanced Raman scattering (SERS)-based sensing, both of which are promising platforms for label-free optical biosensors. First, silicon-on-insulator (SOI) nanowire waveguide and metallic surface plasmon resonance (SPR)-based refractive index sensing are discussed. In order to improve the detection limit, phase interrogation techniques are introduced to these types of sensors based on prism-coupled SPR and SOI microring resonators. A detection limit in the order of 10 −6 refractive index unit is achieved. Detection of 16.7 pM anti-IgG is also demonstrated based on the SPR devices. Second, SERS substrates based on various nanometallic structures are discussed. Metallic nanowire arrays and inverted nanopyramids and grooves with a thin metal surface are fabricated based on anisotropic wetetching of silicon substrates. Both structures have demonstrated a Raman signal enhancement on the order of 10 7 .In order to improve the extraction efficiency of the Raman signal at a high wave number, a nano-bowtie array substrate is fabricated, which exhibits double resonances at both the excitation wavelength and the desired Raman scattering wavelength. Experimental results have shown that this double-resonance structure can further enhance the received Raman signal, as compared to conventional SERS substrates with only one resonance at the excitation wavelength.

A low-cost integrated biosensing platform based on SiN nanophotonics for biomarker detection in urine

“…In these sensors, a change in the effective refractive index caused by the binding of an analyte to its specific bioreceptor, is converted into a measurable quantity, most commonly a resonant wavelength shift, through an integrated photonic transducer. Various types of sensors have been developed: Young and Mach-Zehnder (MZI) interferometers, bimodal sensors, ring resonators, photonic crystal based sensors and various others [1][2][3][4][5]. In general, evanescent wave sensors provide sensitivity, selectivity and versatility, which renders them applicable in a broad range of disciplines, ranging from medicine over food quality control to environmental management.…”

Facing Challenges in Real-Life Application of Surface-Enhanced Raman Scattering: Design and Nanofabrication of Surface-Enhanced Raman Scattering Substrates for Rapid Field Test of Food Contaminants

“…Several excellent review articles related to SERS have been recently published. Most reviews focus on the mechanism of the SERS effect, − applications of SERS in various fields, − fabrication of SERS-active substrates, − and advances in new SERS devices, − which are of interest to a heterogeneous readership. Naturally, this review cannot cover the entire picture of relevant topics but instead presents the reader with the recent advances of SERS from a different angle.…”

Towards the Development of Portable and In Situ Optical Devices for Detection of Micro-and Nanoplastics in Water: A Review on the Current Status

“…Instead of a particular chemistry, the surface can be patterned onto a nanostructure, leading, for instance, to fiber Bragg gratings that have demonstrated their power in sensing [ 157 ]. Such a sensing mechanism is often used for refractive index [ 158 ], fluorescence [ 159 ], and Raman/SERS [ 160 ] measurements. In the particular case of micro and nanoplastics, for which the concentration is extremely small, such a configuration is not suitable, although extreme sensitivity is possible.…”