In the last years, optical resonators have emerged as a promising tool for highly sensitive measurements. Especially for label-free measurements of biological substances, the resonators have to be functionalized by additional surface layers. Since the properties of the resonator, like the refractive index of the core and the layer as well as the layer thickness or the core radius can deeply in fluence the sensitivity. For this reason, a geometrical optics based theory is used to investigate the dependence of the resonance wavelength on the resonator properties.
New approach to increase density of sensing units for higher precision as well as the selectivity of biological components under investigation in microcavity evanescent wave optical sensor systems is proposed. Long-term functionalization
results of array sensor cells by different agents are represented.
Microcavity array sensor has been developed for biomedical objects identification. Experimental data on detection and identification of variety of biochemical agents, such as proteins, microelements, antibiotic of different generation etc. in both single and multi-component solutions analyzed on the light scattering of whispering gallery mode optical resonance are represented.
Experimental data on detection and identification of variety of biochemical agents, such as proteins, microelements,
antibiotic of different generation etc. in both single and multi component solutions under varied in wide range
concentration analyzed on the light scattering parameters of whispering gallery mode optical resonance based sensor are
represented. Multiplexing on parameters and components has been realized using developed fluidic sensor cell with
fixed in adhesive layer dielectric microspheres and data processing. Biochemical component identification has been
performed by developed network analysis techniques. Developed approach is demonstrated to be applicable both for
single agent and for multi component biochemical analysis.
Novel technique based on optical resonance on microring structures, plasmon resonance and identification tools has been
developed. To improve a sensitivity of microring structures microspheres fixed by adhesive had been treated previously
by gold nanoparticle solution. Another technique used thin film gold layers deposited on the substrate below adhesive.
Both biomolecule and nanoparticle injections caused considerable changes of optical resonance spectra. Plasmonic gold
layers under optimized thickness also improve parameters of optical resonance spectra. Biochemical component
identification has been also performed by developed network analysis techniques both for single and for multi
component solution. So advantages of plasmon enhancing optical microcavity resonance with multiparameter
identification tools is used for development of a new platform for ultra sensitive label-free biomedical sensor.
Optical resonances of spherical microresonators are of great interest measurements with high sensitivity. Usually the quantity to be measured is determined by the shift of the resonances of a single particle. Unfortunately, for this purpose, an expensive low-bandwidth tunable laser system with high accuracy is needed. When using an array of microresonators with slightly different size, each particle has a different resonance behavior. A change of the quantity to be measured leads to a change of the intensity distribution over the entire array. Therefore, using a microresonator array it is sufficient to measure the intensity distribution over all particles at a fixed wavelength.
Experimental data on detection and identification of variety of biochemical agents, such as proteins (albumin, interferon, C reactive protein), microelements (Na+, Ca+), antibiotic of different generations, in both single and multi component solutions under varied in wide range concentration are represented. Analysis has been performed on the light scattering parameters of whispering gallery mode (WGM) optical resonance based sensor with dielectric microspheres from glass and PMMA as sensitive elements fixed by spin - coating techniques in adhesive layer on the surface of substrate or directly on the coupling element. Sensitive layer was integrated into developed fluidic cell with a digital syringe. Light from tuneable laser strict focusing on and scattered by the single microsphere was detected by a CMOS camera. The image was filtered for noise reduction and integrated on two coordinates for evaluation of integrated energy of a measured signal. As the entrance data following signal parameters were used: relative (to a free spectral range) spectral shift of frequency of WGM optical resonance in microsphere and relative efficiency of WGM excitation obtained within a free spectral range which depended on both type and concentration of investigated agents. Multiplexing on parameters and components has been realized using spatial and spectral parameters of scattered by microsphere light with developed data processing. Biochemical component classification and identification of agents under investigation has been performed by network analysis techniques based on probabilistic network and multilayer perceptron. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis.
New opportunity to improve a sensetivity of a label-free biomolecule detection in sensing systems based on microcavity evanescent wave optical sensors has been recently found and is being under intensive development. Novel technique based on combination of optical resonance on microring structures with plasmon resonance. Recently developed tools based on neural network data processing can realize real-time identification of biological agents. So combining advantages of plasmon enhancing optical microcavity resonance with identification tools can give a new platform for ulta sensitive label-free biomedical sensor. Our developed technique used standard glass and polymer microspheres as sensetive elements. They are fixed in the solution flow by adhesive layer on the surface being in the field of evanescence wave. Sensitive layer have been treated by gold nanoparticel (GN) solution. Another technique used thin film gold layers deposited on the substrate below adhesive. The light from a tuneable diode laser is coupled into the microsphere through a prism and was sharply focussed on the single microsphere. Images were recorded by CMOS camera. Normalized by free spectral range resonance shift of whispering gallery mode (WGM) and a relative efficiency of their excitation were used as input data for biomolecule classification. Both biomolecules and NP injection was obtained caused WGM spectra modification. But after NP treatment spectral shift and intensity of WGM resonances in biomolecule solutions increased. WGM resonances in microspheres fixed on substrate with gold layer with optimized layer thickness in biomolecule solutions also had higher intensity and spectra modification then without gold layer.
Since the early times of Arthur Ashkins groundbreaking experiments on optical tweezers, a great number of theoretical works was dedicated to this subject. Most of them treated the optical trapping of single spherical or elliptical particles. In the last years optical tweezers have become more and more a tool for assembling three dimensional structures using single microspheres as building blocks. Since all structures and particles inside the light beams influence the properties of the traps, we investigated theoretically the influence of additional single particles and particle arrays on the properties of optical traps. For this reason a geometrical optics based model is used with the inherent flexibility to be applied for various shapes and particle numbers.
Experimental data on optical resonance spectra of whispering gallery modes of dielectric microspheres in antibiotic
solutions under varied in wide range concentration are represented. Optical resonance was demonstrated could be
detected at a laser power of less than 1 microwatt. Several antibiotics of different generations: Amoxicillin,
Azithromycin, Cephazolin, Chloramphenicol, Levofloxacin, Lincomicin Benzylpenicillin, Riphampicon both in deionized
water and physiological solution had been used for measurements. Both spectral shift and the structure of
resonance spectra were of specific interest in this investigation. Drag identification has been performed by developed
multilayer perceptron network. The network topology was designed included: a number of the hidden layers of
multilayered perceptron, a number of neurons in each of layers, a method of training of a neural network, activation
functions of layers, type and size of a deviation of the received values from required values. For a network training the
method of the back propagation error in various modifications has been used. Input vectors correspond to 6 classes of
biological substances under investigation. The result of classification was considered as positive when each of the region,
representing a certain substance in a space: relative spectral shift of an optical resonance maxima - relative efficiency of
excitation of WGM, was singly connected.
It was demonstrated that the approach described in the paper can be a promising platform for the development of
sensitive, lab-on-chip type sensors that can be used as an express diagnostic tools for different drugs and instrumentation
for proteomics, genomics, drug discovery, and membrane studies.
Optical resonances of microresonators, also known as whispering gallery modes, are attracting considerable
interest as highly sensitive measuring devices with a variety of applications. Such resonators can be used for
pressure, force or strain measurement. Droplets, embedded in an appropriate substrate, form perfect spheres
due to their surface tension and can be used as optical resonators with high quality factors. The resonance
frequencies of these droplets depend sensitively on their size and shape. Pressure changes affect the droplet
shape. Therefore, pressure change can be measured with high sensitivity. In the work presented here, ethanol
droplets embedded in a silicone matrix are considered. The shift of the resonance frequencies of microdroplets
embedded in silicone as function of the applied pressure is investigated.
A novel emerging technique for the label-free analysis of nanoparticles and biomolecules in liquid fluids using optical
micro cavity resonance of whispering-gallery-type modes is being developed.A scheme based on polymer microspheres
fixed by adhesive on the evanescence wave coupling element has been used.
We demonstrated that the only spectral shift can't be used for identification of biological agents by developed approach.
So neural network classifier for biological agents and micro/nano particles classification has been developed. The
developed technique is the following. While tuning the laser wavelength images were recorded as avi-file. All sequences
were broken into single frames and the location of the resonance was allocated in each frame. The image was filtered for
noise reduction and integrated over two coordinates for evaluation of integrated energy of a measured signal. As input
data normalized resonance shift of whispering-gallery modes and the relative efficiency of whispering-gallery modes
excitation were used. Other parameters such as polarization of excited light, "center of gravity" of a resonance spectra
etc. are also tested as input data for probabilistic neural network. After network designing and training we estimated the
accuracy of classification. The classification of antibiotics such as penicillin and cephasolin have been performed with
the accuracy of not less 97 %.
Developed techniques can be used for lab-on-chip sensor based diagnostic tools as for identification of different
biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells and
for dynamics of a delivery of medicines to bodies.
A novel technique for the label-free analysis of micro and nanoparticles including biomolecules using optical micro
cavity resonance of whispering-gallery-type modes is being developed. Various schemes of the method using both
standard and specially produced microspheres have been investigated to make further development for microbial
application. It was demonstrated that optical resonance under optimal geometry could be detected under the laser power
of less 1 microwatt. The sensitivity of developed schemes has been tested by monitoring the spectral shift of the
whispering gallery modes. Water solutions of ethanol, ascorbic acid, blood phantoms including albumin and HCl,
glucose, biotin, biomarker like C reactive protein so as bacteria and virus phantoms (gels of silica micro and
nanoparticles) have been used.
Structure of resonance spectra of the solutions was a specific subject of investigation. Probabilistic neural network
classifier for biological agents and micro/nano particles classification has been developed. Several parameters of
resonance spectra as spectral shift, broadening, diffuseness and others have been used as input parameters to develop a
network classifier for micro and nanoparticles and biological agents in solution. Classification probability of
approximately 98% for probes under investigation have been achieved.
Developed approach have been demonstrated to be a promising technology platform for sensitive, lab-on-chip type
sensor which can be used for development of diagnostic tools for different biological molecules, e.g. proteins,
oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells as well as in different experimental
contexts e.g. proteomics, genomics, drug discovery, and membrane studies.
In recent years, optical microresonators have been extensively investigated for possible applications in many
different areas of research. In optical communications such resonators can be used for switching, filtering or
multiplexing devices. Due to its high quality factors, spherical microresonators are of great interest for optical
sensing. Here we will discuss the use of a microparticle array as a spectral sensing device. Especially the accuracy
in wavelength determination for broad light sources are in the focus of this work. Beside this, results for two
light sources with different wavelengths are given.
A novel emerging technique for the label-free analysis of nano particles including biomolecules using optical
micro cavity resonance is being developed. Various schemes based on a mechanically fixed microspheres as
well as microspheres melted by laser on the tip of a standard single mode fiber have been investigated to
make further development for microbial application.
Water solutions of ethanol, HCl, glucose, vitamin C and biotin have been used to test refractive index changes
by monitoring the magnitude of the whispering gallery modes spectral shift. Particular efforts were made for
effective fixing of the micro spheres in the water flow, an optimal geometry for micro resonance observation
and material of microsphere the most appropriate for microbial application. Optical resonance in free micro
spheres from PMMA fixed in micro channels produced by photolithography has been observed under the
laser power of less then 1 microwatt. Resonance shifts of C reactive protein water solutions as well as
albumin solutions in pure water and with HCl modelling blood have been investigated. Introducing controlled
amount of glass gel nano particles into sensor microsphere surrounding were accompanied by both correlative
resonance shift (400 nm in diameter) and total reconstruct of resonance spectra (57 nm in diameter).
Developed schemes have been demonstrated to be a promising technology platform for sensitive, lab-on-chip
type sensor of diagnostic tools for different biological molecules, e.g. proteins, oligonucleotides,
oligosaccharides, lipids, small molecules, viral particles, cells as well as in different experimental contexts
e.g. proteomics, genomics, drug discovery, and membrane studies.
A novel emerging technique for the label-free analysis of nanoparticles including biomolecules using optical
micro cavity resonance of whispering-gallery-type modes is being developed. Schemes of such a method
based on microsphere melted by laser on the tip of a standard single mode fiber optical cable with a laser and
free microsphere matrix have been developed. Using a calibration principal of ultra high resolution
spectroscopy based on such a scheme the method is being transformed to make further development for
microbial application.
The sensitivity of developed schemes has been tested to refractive index changes by monitoring the
magnitude of the whispering gallery modes spectral shift. Water solutions of ethanol, glucose, vitamin C and
biotin have been used. Some other schemes using similar principals: stand-alone, array and matrix
microsphere resonators, liquid core optical ring resonators are also being under development. The influences
of the gap in whispering-gallery modes on energy coupling, resonance quality and frequency have been
investigated. An optimum gap for sensing applications has been defined at the half maximum energy coupling
where both the Q factor and coupling efficiency are high and the resonance frequency is little affected by the
gap variation.
Developed schemes have been demonstrated to be a promising technology platform for sensitive, lab-on-chip
type sensor which can be used for development of diagnostic tools for different biological molecules, e.g.
proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells as well as in
different experimental contexts e.g. proteomics, genomics, drug discovery, and membrane studies.
Microcavity optical resonators have been investigated in the last years extensively for possible applications in
optical communication (switching, filtering, and multiplexing), to investigate cavity quantum dynamic effects,
and for sensor applications. The most recent area of application is bio-sensing. The preferential resonator type
in the communication area is the disc resonator, the spherical resonator is the most prominent resonator type
in sensing applications and a rapidly growing number of groups are investigating the potential of hollow tube
resonators for detecting of bio-agents. Here we will present the concept of resonator arrays as sensing element.
Potential fields of application are similar to the single resonator sensor but also beyond. We will give an example
of an application that is not accessible for single resonators. We will describe the use of resonator arrays as
wavelength sensor and discuss several aspects such as the number of sensing elements or the line width on the
performance of such a device.
A method of noninvasive monitoring of human tissue and blood components based on optical diffuse scattering
spectroscopy combined with metabolic heat measurements has been developed. Developed compact fiber optical and
thermal sensor measures thermal generation, heat balance, blood flow rate, hemoglobin and it's derivative concentrations
and environment conditions. It contains thermal and optical detectors, halogen lamp and LEDs, multi-leg fiber optical
bundle to measure diffuse light scattering inside and through the patient body including vascular system, which
contributes to the control of the body temperature. Measurements of surface cutaneous tissue thermal radiation, ambient
room temperature and background radiation temperature are used to measure conduction, convection, and radiation of heat
from the human body. Blood flow rate in the body is estimated from the change in temperature for the contact and adjacent
thermal detectors. Multi wavelength spectroscopy provides a reflectance spectra which are converted to absorbance
values.
The calibration and measurement processes are performed independently. Methods of multivariate statistical analysis
involving the variables from sensor signals, polynomials from various variables, regression analysis of individual
patients, and cluster analysis of patients group were applied to convert various signals from the sensor pickup into
physicochemical variables.
Obtained data show that the method provides a foundation for noninvasive measuring several biochemical parameters of
blood. Further developments of the technology which is under progress now are the following: clinical studies to further
characterize the performance of this technology and development of compact and low cost sensor device for home
diagnostics.
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