Trends in Nanophotonics-Enabled Optofluidic Biosensors

Optofluidic sensors integrate photonics with micro/nanofluidics to realize compact devices for the label-free detection of molecules and the real-time monitoring of dynamic surface binding events with high specificity, ultrahigh sensitivity, low detection limit, and multiplexing capability. Nanophotonic structures composed of metallic and/or dielectric building blocks excel at focusing light into ultrasmall volumes, creating enhanced electromagnetic near-fields ideal for amplifying the molecular signal readout. Furthermore, fluidic control on small length scales enables precise tailoring of the spatial overlap between the electromagnetic hotspots and the analytes, boosting light-matter interaction, and can be utilized to integrate advanced functionalities for the pre-treatment of samples in real-world-use cases, such as purification, separation, or dilution. In this review, the authors highlight current trends in nanophotonics-enabled optofluidic biosensors for applications in the life sciences while providing a detailed perspective on how these approaches can synergistically amplify the optical signal readout and achieve real-time dynamic monitoring, which is crucial in biomedical assays and clinical diagnostics

Real-time label-free biosensing with integrated planar waveguide ring resonators

We review the use of planar integrated optical waveguide ring resonators for label free bio-sensing and present recent results from two European biosensor collaborations: SABIO and InTopSens. Planar waveguide ring resonators are attractive for label-free biosensing due to their small footprint, high Q-factors, and compatibility with on-chip optics and microfluidics. This enables integrated sensor arrays for compact labs-on-chip. One application of label-free sensor arrays is for point-of-care medical diagnostics. Bringing such powerful tools to the single medical practitioner is an important step towards personalized medicine, but requires addressing a number of issues: improving limit of detection, managing the influence of temperature, parallelization of the measurement for higher throughput and on-chip referencing, efficient light-coupling strategies to simplify alignment, and packaging of the optical chip and integration with microfluidics. From the SABIO project we report refractive index measurement and label-free biosensing in an 8-channel slotwaveguide ring resonator sensor array, within a compact cartridge with integrated microfluidics. The sensors show a volume sensing detection limit of 5 × 10-6 RIU and a surface sensing detection limit of 0.9 pg/mm2. From the InTopSens project we report early results on silicon-on-insulator racetrack resonators

Development of novel integrated bio/chemical sensor systems using chalcogenide glass materials

This paper reviews ongoing progress in the design and fabrication of new, on-chip, low loss planar molecular sensors. We report the details of device design, material selection and manufacturing processes used to realise high-index-contrast (HIC), compact micro-disk resonators. These structures have been fabricated in thermally evaporated As- and Ge-based chalcogenide glass films with PDMS (polydimethylsiloxane) micro-fluidic channels using standard UV lithography. Discussed are findings that demonstrate that our novel chalcogenide-based micro-fluidic device can be used as highly sensitive refractive index sensors

Chemical Surface Modifications development of Silicon Based Label Free Integrated Optical (IO) Biosensors: A Review

[EN] Increasing interest has been paid to label-free biosensors in recent years. 11 Among them, refractive index (RI) optical biosensors enable high density and the chip-12 scale integration of optical components. This makes them more appealing to help 13 develop lab-on-a-chip devices. Today, many RI integrated optical (IO) devices are made 14 using silicon-based materials. A key issue in their development is the 15 biofunctionalization of sensing surfaces because they provide a specific, sensitive 16 response to the analyte of interest. This review critically discusses the 17 biofunctionalization procedures, assay formats and characterization techniques 18 employed in setting up IO biosensors. In addition, it provides the most relevant results 19 obtained from using these devices for real sample biosensing. Finally, an overview of 20 the most promising future developments in the fields of chemical surface modification 21 and capture agent attachment for IO biosensors follows.This research has been supported by the Spanish Ministry of Science and Innovation through project CTQ2010-15943/BQU and by the Regional Valencian Government, through GVA/PROMETEO 2010/08. The authors thank Dr. Miguel Holgado, from the Universidad Politecnica de Madrid, for his helpful discussion about the classification of RI optical sensors.Bañuls Polo, MJ.; Puchades Pla, R.; Maquieira Catala, Á. (2013). Chemical Surface Modifications development of Silicon Based Label Free Integrated Optical (IO) Biosensors: A Review. Analytica Chimica Acta. 777:1-16. https://doi.org/10.1016/j.aca.2013.01.025S11677

On chip optical sensing

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Performance improvement of a silicon nitride ring resonator biosensor operated in the TM mode at 1310 nm

[EN] Silicon-based ring resonators have been demonstrated to be a key element to build lab-on-chip devices due to their ability to perform as label-free photonic sensors. In this work, we demonstrate photonic biosensing using silicon nitride ring resonators operated in the TM mode around 1310 nm wavelengths. Our results show that operating the devices using the TM mode results in an increased sensitivity in comparison with the typically used TE mode, while working at 1310 nm wavelengths compared to 1550 nm contributes to an increased quality factor. As a result, a reduction in the intrinsic limit of detection is achieved, indicating the suitability of TM modes in the 1310 nm regime for biosensing using integrated photonics.Generalitat Valenciana (IDIFEDER/2018/033, IDIFEDER/2021/061, PROMETEO/2019/123) ; Ministerio de Ciencia, Innovacion y Universidades (ICTS-2017-28-UPV-9) ; Horizon 2020 Framework Programme (958855)Castello-Pedero, L.; Gómez-Gómez, MI.; García-Rupérez, J.; Griol Barres, A.; Martínez, A. (2021). Performance improvement of a silicon nitride ring resonator biosensor operated in the TM mode at 1310 nm. Biomedical Optics Express. 12(11):7244-7260. https://doi.org/10.1364/BOE.437823S72447260121

OPTICAL AND OPTOMECHANICAL RESONATORS AND THEIR APPLICATIONS IN COMMUNICATION AND SENSING

The radiation pressure of the large circulating optical power inside micro-scale high quality factor Whispering-Gallery mode micoresonators couples the mechanical deformation of the resonator structure to the optical resonance. This coupling results in damping or amplification of the corresponding mechanical modes. Self-sustained mechanical oscillation takes place when the optomechanical gain becomes larger than mechanical loss. In this dissertation, several applications of optomechanical oscillator (OMO) in communication and sensing are proposed and explored using silica microtoroid resonator. First we investigate the spectrum of the OMO and define weak\u27 and \u27strong\u27 harmonic generation regimes based on two distinct spectral behaviors. In weak harmonic regime, an analytical method is proposed to optimize the spectral behavior of an OMO for RF-photonic communication systems. In the strong harmonic regime, we show that OMO spectrum can be used in a read-out system for resonant optical sensing applications. Next, we explore optomechanical RF mixing and its application in RF-photonics. We study optomechanical RF mixing using coupled differential equations as well as a semi-analytical model that simplifies the calculation of mixed frequency components. Furthermore, optomechanical down-conversion of various waveforms and audio signal from an RF carrier are demonstrated. Here for the first time we show that an OMO can function as a high-resolution mass sensor based on optomechanical oscillation frequency shift. In an OMO based mass sensor, optical power simultaneously servers as an efficient actuator and a sensitive probe for monitoring optomechanical oscillation frequency variations. The narrow linewidth of optomechanical oscillation and the small effective mass of the corresponding mechanical mode result in sub-pg mass sensitivity. We analyze the performance of microtoroid OMO mass sensor and evaluate its ultimate detection limit. The outcomes of our study enable combination of resonant optical sensing with optomechanical sensing in a single device. This so-called \u27dual-mode\u27 sensing can be a powerful technique for measuring the properties (mass, density and refractive index) of micro/nano-particles and molecules. To boost the optical sensitivity of the dual-mode sensor, we also demonstrate a dynamic sensing method where the resonant photonic sensitivity is improved by over 50 times through thermally induced line narrowing