A Microring Resonator Sensor for Sensitive Detection of 1,3,5-Trinitrotoluene (TNT)

A microring resonator sensor device for sensitive detection of the explosive 1,3,5-trinitrotoluene (TNT) is presented. It is based on the combination of a silicon microring resonator and tailored receptor molecules

Molecular Imprinted Polymers Coupled to Photonic Structures in Biosensors: The State of Art

Optical sensing, taking advantage of the variety of available optical structures, is a rapidly expanding area. Over recent years, whispering gallery mode resonators, photonic crystals, optical waveguides, optical fibers and surface plasmon resonance have been exploited to devise different optical sensing configurations. In the present review, we report on the state of the art of optical sensing devices based on the aforementioned optical structures and on synthetic receptors prepared by means of the molecular imprinting technology. Molecularly imprinted polymers (MIPs) are polymeric receptors, cheap and robust, with high affinity and selectivity, prepared by a template assisted synthesis. The state of the art of the MIP functionalized optical structures is critically discussed, highlighting the key progresses that enabled the achievement of improved sensing performances, the merits and the limits both in MIP synthetic strategies and in MIP coupling

A Microring Resonator Based Negative Permeability Metamaterial Sensor

Metamaterials are artificial multifunctional materials that acquire their material properties from their structure, rather than inheriting them directly from the materials they are composed of, and they may provide novel tools to significantly enhance the sensitivity and resolution of sensors. In this paper, we derive the dispersion relation of a cylindrical dielectric waveguide loaded on a negative permeability metamaterial (NPM) layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGMs). The theoretical resonant frequency and electric field distribution results are in good agreement with the full wave simulation results. We show that the NPM sensor based on a microring resonator possesses higher sensitivity than the traditional microring sensor since with the evanescent wave amplification and the increase of NPM layer thickness, the sensitivity will be greatly increased. This may open a door for designing sensors with specified sensitivity

An Optical Microsensor Utilizing Genetically Programmed Bioreceptor Layers for Selective Sensing

Protein engineering is a rich technology that holds the potential to revolutionize sensors through the creation of highly selective peptides that encode unique recognition affinities. Their robust integration with sensor platforms is very challenging. The goal of this research project is to combine expertise in micro-electro-mechanical systems (MEMS) and biological/protein engineering to develop a selective sensor platform. The key enabling technology in this work is the use of biological molecules, the Tobacco mosaic virus (TMV) and its derivative, Virus-Like-Particle (VLP), as nanoreceptor layers, in conjunction with a highly sensitive microfabricated optical disk resonator. This work will present a novel method for the integration of biological molecules assembly on MEMS devices for chemical and biological sensing applications. Particularly in this research, TMV1Cys-TNT and TMV1Cys-VLP-FLAG bioreceptor layers have been genetically engineered to bind to an ultra-low vapor pressure explosive, Trinitrotoluene (TNT), and to a widely used FLAG antibody, respectively. TNT vapor was introduce to TMV1Cys-TNT coated resonator and induced a 12 Hz resonant frequency shift, corresponding to a mass increase of 76.9 ng, a 300% larger shift compared to resonators without receptor layer coating. Subsequently, a microfabricated optical disk resonator decorated with TMV1Cys-VLP-FLAG was used to conduct enzyme-linked immunosorbent assay and label-free immunoassays on-a-chip and demonstrated a resonant wavelength shift of 5.95 nm and 0.79 nm, respectively. The significance of these developments lies in demonstrating the capability to use genetically programmable viruses and VLPs as platforms for the display and integration of receptor peptides within microsystems. The work outlined here constitutes an interdisciplinary investigation on the integration capabilities of the bio-nanostructure materials with traditional microfabrication architectures. While previous works have focused on individual components of the system, this work addresses multi-component integration, including biological molecule surface assembly and fabrication utilizing both top-down and bottom-up approaches. Integrating biologically programmable material into traditional MEMS transducers enhances selectivity, sensitivity, and simplifies fabrication and testing methodologies. This research provides a new avenue for enhancing sensor platforms through the integration of biological species as the key to remedying challenges faced by conventional systems that utilize a wide range of polymers or metals for nonspecific bindings

Nanophotonic label-free biosensors for environmental monitoring

The field of environmental monitoring has experienced a substantial progress in the last years but still the on-site control of contaminants is an elusive problem. In addition, the growing number of pollutant sources is accompanied by an increasing need of having efficient early warning systems. Several years ago biosensor devices emerged as promising environmental monitoring tools, but their level of miniaturization and their fully operation outside the laboratory prevented their use on-site. In the last period, nanophotonic biosensors based on evanescent sensing have emerged as an outstanding choice for portable point-of-care diagnosis thanks to their capability, among others, of miniaturization, multiplexing, label-free detection and integration in lab-on-chip platforms. This review covers the most relevant nanophotonic biosensors which have been proposed (including interferometric waveguides, grating-couplers, microcavity resonators, photonic crystals and localized surface plasmon resonance sensors) and their recent application for environmental surveillance

High sensitive temperature sensor silicon-based microring resonator using the broadband input spectrum

A sensitivity enhanced optical temperature sensor has been investigated and developed based on a silicon oxynitride (SiON) waveguide microring resonator (MRR). The broadband supercontinuum (SC) output from a fiber laser cavity is injected into the input port of the MRR, where the output was detected at the drop port of MRR. The results can be useful for the sensor-based waveguide devices, where the applications such as the temperature sensors can be realized. The temperature sensor has been fabricated in an MRR-silicon base structure. Experimental characterization of inserting the SC as input source into the MRR as the temperature sensors were carried out. The advantage of using the SC as input source is that the sensor covers a wide range of wavelengths, thus sensing the temperature changes in the wide wavelength ranges which can extend the sensing device applications. This study opens a way to apply optical sensors by using broadband SC as a source for manufacturing temperature environments sensors within the MRR waveguide structures. This will enhance the ability of the current temperature sensors to function at different and long wavelength band

Integration of virus-like particle macromolecular bioreceptors in electrochemical biosensors

Rapid, sensitive and selective detection of chemical hazards and biological pathogens has shown growing importance in the fields of homeland security, public safety and personal health. In the past two decades, efforts have been focusing on performing point-of-care chemical and biological detections using miniaturized biosensors. These sensors convert target molecule binding events into measurable electrical signals for quantifying target molecule concentration. However, the low receptor density and the use of complex surface chemistry in receptors immobilization on transducers are common bottlenecks in the current biosensor development, adding to the cost, complexity and time. This dissertation presents the development of selective macromolecular Tobacco mosaic virus-like particle (TMV VLP) biosensing receptor, and the microsystem integration of VLPs in microfabricated electrochemical biosensors for rapid and performance-enhanced chemical and biological sensing. Two constructs of VLPs carrying different receptor peptides targeting at 2,4,6-trinitrotoluene (TNT) explosive or anti-FLAG antibody are successfully bioengineered. The VLP-based TNT electrochemical sensor utilizes unique diffusion modulation method enabled by biological binding between target TNT and receptor VLP. The method avoids the influence from any interfering species and environmental background signals, making it extremely suitable for directly quantifying the TNT level in a sample. It is also a rapid method that does not need any sensor surface functionalization process. For antibody sensing, the VLPs carrying both antibody binding peptides and cysteine residues are assembled onto the gold electrodes of an impedance microsensor. With two-phase immunoassays, the VLP-based impedance sensor is able to quantify antibody concentrations down to 9.1 ng/mL. A capillary microfluidics and impedance sensor integrated microsystem is developed to further accelerate the process of VLP assembly on sensors and improve the sensitivity. Open channel capillary micropumps and stop-valves facilitate localized and evaporation-assisted VLP assembly on sensor electrodes within 6 minutes. The VLP-functionalized impedance sensor is capable of label-free sensing of antibodies with the detection limit of 8.8 ng/mL within 5 minutes after sensor functionalization, demonstrating great potential of VLP-based sensors for rapid and on-demand chemical and biological sensing

Graphene oxide integrated silicon photonics for detection of vapour phase volatile organic compounds

From Springer Nature via Jisc Publications RouterHistory: received 2020-01-07, accepted 2020-05-17, registration 2020-05-20, pub-electronic 2020-06-12, online 2020-06-12, collection 2020-12Publication status: PublishedAbstract: The optical response of a graphene oxide integrated silicon micro-ring resonator (GOMRR) to a range of vapour phase Volatile Organic Compounds (VOCs) is reported. The response of the GOMRR to all but one (hexane) of the VOCs tested is significantly higher than that of the uncoated (control) silicon MRR, for the same vapour flow rate. An iterative Finite Difference Eigenmode (FDE) simulation reveals that the sensitivity of the GO integrated device (in terms of RIU/nm) is enhanced by a factor of ~2, which is coupled with a lower limit of detection. Critically, the simulations reveal that the strength of the optical response is determined by molecular specific changes in the local refractive index probed by the evanescent field of the guided optical mode in the device. Analytical modelling of the experimental data, based on Hill-Langmuir adsorption characteristics, suggests that these changes in the local refractive index are determined by the degree of molecular cooperativity, which is enhanced for molecules with a polarity that is high, relative to their kinetic diameter. We believe this reflects a molecular dependent capillary condensation within the graphene oxide interlayers, which, when combined with highly sensitive optical detection, provides a potential route for discriminating between different vapour phase VOCs