Fabrication and Characterization of Slab Waveguide Based Biosensors PDF Download

Author: Sreelakshmi Talluri
Publisher:
ISBN:
Category : Biosensors
Languages : en
Pages : 152

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Author: Maryam Khodami
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In this thesis by articles, I propose and demonstrate the full design, fabrication and characterization of optical biosensors based on (Bloch) Long Range Surface Plasmon Polaritons (LRSPPs). Gold waveguides embedded in CYTOP with an etched microfluidic channel supporting LRSPPs and gold waveguides on a one-dimensional photonic crystal (1DPC) supporting Bloch LRSPPs are exploited for biosensing applications. Straight gold waveguides embedded in CYTOP supporting LRSPPs as a biosensor, are initially used to measure the kinetics constants of protein-protein interactions. The kinetics constants are extracted from binding curves using the integrated rate equation. Linear and non-linear least squares analysis are employed to obtain the kinetics constants and the results are compared. The device is also used to demonstrate enhanced assay formats (sandwich and inhibition assays) and protein concentrations as low as 10 pg/ml in solution are detected with a signal-to-noise ratio of 20 using this new optical biosensor technology. CYTOP which has a refractive index close to water is the fluoropolymer of choice in current state of the art waveguide biosensors. CYTOP has a low glass transition temperature which introduces limitations in fabrication processes. A truncated 1D photonic crystal can replace a low-index polymer cladding such as CYTOP, to support Bloch LRSPPs within the bandgap of the 1DPC over a limited ranges of wavenumber and wavelength. Motivated by quality issues with end facets, we seek to use grating couplers in a broadside coupling scheme where a laser beam emerging from an optical fiber excites Bloch LRSPPs on a Au stripe on a truncated 1D photonic crystal. Adiabatic and non-adiabatic flared stripes accommodating wide gratings size-matched to an incident Gaussian beam are designed and compared to maximise the coupling efficiency to LRSPPs. The gratings are optimized, initially, through 2D modelling using the vectorial finite element method (FEM). Different 3D grating designs were then investigated via 3D modelling using the vectorial finite difference time domain (FDTD) method. Given their compatibility with planar technologies, gratings and waveguides can be integrated into arrays of biosensors enabling multi-channel biosensing. A multi-channel platform can provide, e.g., additional measurements to improve the reliability in a disease detection problem. Thus, a novel optical biosensor based on Bloch LRSPPs on waveguide arrays integrated with electrochemical biosensors is presented. The structures were fabricated on truncated 1D photonic crystals comprised of 15 period stack of alternating layers of SiO2/Ta2O5. The optical biosensors consist of Au stripes supporting Bloch LRSPPs and integrate grating couplers as input/output means. The Au stripes also operate as a working electrode in conjunction with a neighboring Pt counter electrode to form an electrochemical sensor. The structures were fabricated using bilayer lift-off photolithography and the gratings were fabricated using overlaid e-beam lithography. The planar waveguides are integrated into arrays capable of multichannel biosensing. The wafer is covered with CYTOP as the upper cladding with etched microfluidic channels, and wafer-bonded to a borofloat silica wafer to seal the fluidic channels and enable side fluidic interfaces. The proposed device is capable in principle of simultaneous optical and electrochemical sensing and could be used to address disease detection problems using a multimodal strategy.

Author: Mohammed Zourob
Publisher: Springer Science & Business Media
ISBN: 3540882421
Category : Science
Languages : en
Pages : 241

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For the first time, distinguished scientists from key institutions worldwide provide a comprehensive approach to optical sensing techniques employing the phenomenon of guided wave propagation for chemical and biosensors. This includes both state-of the-art fundamentals and innovative applications of these techniques. The authors present a deep analysis of their particular subjects in a way to address the needs of novice researchers such as graduate students and post-doctoral scholars as well as of established researchers seeking new avenues. Researchers and practitioners who need a solid foundation or reference will find this work invaluable. This first of two volumes contains eight chapters covering planar waveguides for sensing, as well as sensing techniques based on plasmonic waveguides.

Author: Xuejin Wen
Publisher:
ISBN:
Category :
Languages : en
Pages : 188

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Abstract: Highly sensitive biological sensors are important to the development of biological and medical science. The purpose of this work is to develop highly sensitive AlGaN/GaN heterostructure field-effect transistors (HFETs) and silicon on insulator (SOI) nanowire biosensors. Impedance based lipid membrane characterization is also discussed.

Author: Terri Ayesha Wilson
Publisher:
ISBN:
Category :
Languages : en
Pages : 344

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Author: Michele Calvo
Publisher:
ISBN:
Category :
Languages : en
Pages : 200

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Lab-on-a-chip (or LOC) devices scale down the laboratory processes for detecting illnesses and monitoring sick patients without the need of medical laboratories. These criteria are made possible with a transducer that can convert the biological presence of the target molecule into electrical information. Since the early 2000s, integrated photonics have offered a possible solution for a transducer compatible with LOC needs. In particular, silicon micro-ring resonators represent a compact and sensitive choice to use as a transducer in LOC devices. In agreement with the requirements of LOC devices, the objective of this project is to design and assess the performance of a compact photonic biosensor. The system will be based on integrated photonic transduction. The requirements are that it is compatible with an industrial fabrication platform and fluidic systems, with a sensitivity equal to or higher than the state-of-the-art and simple to functionalize in order to localize the target molecules in the sensitive regions of the sensor. This project details the design, fabrication, and characterization of such a biosensor. In particular, the photonic biosensor is a ring resonators with a Hybrid Plasmonic Waveguide (HPWG) cross-section that fulfills the LOC requirements.

Author: Bonhye Koo
Publisher:
ISBN:
Category :
Languages : en
Pages : 155

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Pressing performance demands require next-generation biosensors to detect target chemical and biological molecules with higher sensitivity, shorter response times, and lower detection limit. Micro- and nanoscale devices are attractive for a wide range of biosensor applications since at small scale, in addition to being more compact, the device may exhibit improved performance. The benefits include minimization of tissue damage for implantable devices, improved spatial resolution and sensitivity, as well as increased surface charge to mass ratio, which is important for the performance of our novel technology for nucleic acid detection described below. Borrowing from the processing technologies used in the semiconductor industry, we implemented micromachining techniques to fabricate devices at both the micro- and nanoscale. In this dissertation, we present our work on the fabrication and characterization of two next-generation biosensors. The first device we fabricated is a sequence-specific nucleic acid sensor based on the blockage of a nanopore. Current methods for nucleic acid detection generally rely on polymerase chain reaction (PCR) and fluorescent labeling, however, these methods render the devices slow, expensive, complex, and bulky. In order to address these limitations, a new sensor was fabricated from a single glass wafer, consisting of a glass nanopore in a thin glass membrane. For nanopore sensing, low frequency noise is critical since it limits the discrimination of signal change based on target analyte movement from the fluctuation of noise. To further our understanding of nanopores, we observed how different pore geometries affect noise characteristics, and then compared this newly developed glass nanopore to conventional Si-based nanopores. Based on the analysis, low-noise glass nanopores, suitable for sequence-specific nucleic acid detection, were fabricated. By scaling down the pore diameter to the nano-regime, 1 aM detection of 16S rRNA from Escherichia coli was demonstrated even in the presence of a million-fold background of RNA from Pseudomona putida. This new platform for the PCR-free, optics-free, label-free sequence-specific nucleic acid detection shows the potential to detect pathogens in body fluids, food, or water. In addition, we developed a new method to transfer enzyme to a microelectrode array on an implantable microprobe, which enables fabrication of better performing microprobes for the sensing of multiple neurochemicals in vivo. Monitoring the release of neurotransmitters in real-time offers valuable information necessary to understand neurological disorders and abnormal behaviors. We employed polydimethylsiloxane (PDMS) stamping to transfer enzyme onto microelectrode array microprobes. A model enzyme, glucose oxidase (GOx), was stamped onto the surface of disk electrodes to test the feasibility of PDMS stamping for biosensor fabrication. The model sensor showed a good combination of performance (29 A/mM cm2 sensitivity and 4 M detection limit) proving that PDMS stamping offers a simple and cost-effective enzyme deposition method for construction of electroenzymatic sensors. The next step was to add an alignment function to PDMS stamping to create microprobes with dual sensing (glucose and choline) capabilities for in vivo applications. Two different enzymes, GOx and choline oxidase (ChOx), were selectively transferred onto specific sites in a 4 microelectrode array by PDMS stamping with alignment using a microscope and a custom-built stage. The dual sensor showed improved consistency and performance including sensitivity to choline and to glucose (286 and 117 A/mM cm2, respectively) as well as low detection limits (3 and 1 M, respectively). This work demonstrated the ability to immobilize specific enzymes on selected microelectrodes in an array to give a high performance microprobe for simultaneous sensing of two analytes for neuroscience application.

Author: Norbi Hayati Mohd Noor
Publisher:
ISBN:
Category : Nanobiotechnology
Languages : en
Pages : 112

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The main objective of this research is to design, fabricate, characterize, and test the silicon based vertical electrode Nanogap biosensor which will be used to detect and identify target proteins in aqueous solution.

Author: Norbi Hayati Mohd Noor
Publisher:
ISBN:
Category : Nanobiotechnology
Languages : en
Pages : 0

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The main objective of this research is to design, fabricate, characterize, and test the silicon based vertical electrode Nanogap biosensor which will be used to detect and identify target proteins in aqueous solution.

Author: Bong-Su Jung
Publisher:
ISBN:
Category : Nanoparticles
Languages : en
Pages : 256

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Label-free detection techniques have an important role in many applications, such as situations where few molecules -- rather than low molarity -- need to be detected, such as in single-cell screening. While surface plasmon resonance (SPR) scattering from metal nanoparticles has been shown to achieve significantly higher sensitivity in gene arrays, such an approach has not been demonstrated for protein arrays. SPR-based sensors could either use simple absorption measurement in a UV-Vis spectrometer or possibly surfaceenhanced Raman spectroscopy as the detection mechanism for molecules of interest. However, non-spherical particles are needed to achieve high sensitivity and field enhancement that is a requirement in both techniques, but these shapes are not easy toproduce reproducibly and preserve for extended periods of time. Here I present a carbonbased template-stripping method combined with nanosphere lithography (NSL). This fabrication allows to preserve the sharp features in atomically flat surfaces which are a composite of a non-spherical metal nano-particle (gold or silver) and a transparent embedding material such as glass. The stripping process is residue-free due to the introduction of a sacrificial carbon layer. The nanometer scale flat surface of our template stripping process is also precious for general protein absorption studies, because an inherent material contrast can resolve binding of layers on the 2 nm scale. These nanocomposite surfaces also allow us to tailor well-defined SPR extinction peaks with locations in the visible or infrared spectrum depending on the metal and the particle size and the degree of non-symmetry. As the particle thickness is reduced and the particle bisector length is increased, the peak position of the resonance shifts to the red. Not only the peak position shifts, but also the sensitivity to environmental changes increases. Therefore, the peak position of the resonance spectrum is dependent on the dielectric environmental changes of each particle, and the particle geometries. The resulting silver or gold nanoparticles in the surface of a glass slide are capable of detecting thiol surface modification, and biotin-streptavidin protein binding events. Since each gold or silver particle principally acts as an independent sensor, on the order of a few thousand molecules can be detected, and the sensor can be miniaturized without loss of sensitivity. UNSL-Au metal nanoparticle (MNP) sensors achieve the sensitivity of close to 300 nm/RIU which is higher than any other report of localized surface plasmon resonance (LSPR) sensors except gold nanocrescents. Finite-difference-time-domain (FDTD) and finite-element-method (FEM) numerical calculations display the influence of the sharp features on the resonance peak position. The maximum near-field intensity is dependent on the polarization direction, the sharpness of the feature, and the near-field confinement from the substrate. 3D FDTD simulation shows the local refractive index sensitivity of the gold truncated tetrahedron, which is in agreement with our experimental result. Both experimental and numerical calculations show that each particle can act as its own sensor.