Parkinson's disease is a progressive neurodegenerative disease that leads to decreased secretion of nigrostriatal dopamine, which inhibits the activity of the brain's motor cortex, Deep brain stimulation (DBS) is currently the best treatment for patients who do not respond well to drug therapy. The subthalamic nucleus (STN) is the target area for the implanting deep brain electrical stimulation electrodes. Currently, the surgical navigation for DBS depends on pre-operative CT/MRI and intra-operative MER (microelectrode recording) to know whether the electrode has reached the target area, but MER only has non-directional signals. In this project, we developed Optical Coherence Tomography-guided DBS (OCTgDBS) technology, which can obtain real-time, high-resolution images from miniature pig brain, which can assist in the accuracy of navigation and positioning during DBS surgery. Finally, postoperative CT/MRI was used as the basis for positioning in the brain. The results demonstrate that the OCT has a potential to be optical guidance system for DBS.
In this article, we present an innovative SPR sensor containing Au-TiO2-Ti planar comb-structure Schottky diodes based on Kretschmann’s configuration, and discussed the feasibility of collecting plasmon-induced hot electrons as the signal of SPR sensor instead of traditional optical measurement. Taking advantage of the intrinsic energy transition process between electromagnetic waves and electrons, i.e., Landau damping, the hot electron-hole pairs (EHPs) are excited directly where the surface plasmon waves decay into. Theoretically, the amount of EHPs is determined by the resonance state of surface plasmon, and further determined by the refractive index change in the sensing area. In this device, the effective sensing area, which is critical and limited by the propagating characters of surface plasmon, and the mean free path of EHPs, is enlarged by intensively distributed micro comb structures. We fabricated the devices on 4-inch quartz wafer with photolithography, electron-beam evaporation (EBE), and lift-off process. These fabricated devices exhibited rectified I-V relations in electrical characterization experiments. The evaluated barrier height is 0.73 eV, but series resistance and ideality factor were not ideal as expected due to fabrication defects. We measured the responsivity of 0.75 uA/mW, under illumination of a 850nm infrared laser beam through a N-BK7 prism coupler. The current response from detection of standard solutions indicated a sensitivity of 1.87×10-4 RIU/nA and a limit of detection (LoD) of 4.13×10-3 RIU. In conclusion, this article provides a feasible method to drastically simplify the conventional SPR sensing configuration with mass-produced, small, and economical comb-structure Schottky diode sensor.
A tip nanobiosensor for monitoring DNA replication was presented. The effects of excitation power and polarization on tip-enhanced fluorescence (TEF) were assessed with the tip immersed in fluorescein isothiocyanate solution first. The photon count rose on average fivefold with radially polarized illumination at 50 mW. We then used polymerase-functionalized tips for monitoring loop-mediated isothermal amplification on Hepatitis C virus cDNA. The amplicon-SYBR® Green I complex was detected and compared to real-time loop-mediated isothermal amplification. The signals of the reaction using 4 and 0.004 ng/μl templates were detected 10 and 30 min earlier, respectively. The results showed the potential of TEF in developing a nanobiosensor for real-time DNA amplification.
This paper is intended to demonstrate the effect of surface plasmon coupled emission (SPGCE) on the plasmonic
response of lamellar grating in both Au-grating/Alq3 and PR-grating/Alq3 nanostructures. Recently, intriguing studies on
an appropriate nanostructure of the corrugation allows the non-radiative SPP mode to be coupled out as light into the far
field with direction determined by the grating diffraction condition. It has also been shown that surface plasmon coupled
emissions (SPCE) from fluorescent molecules by incident wave excite an evanescent field near the periodic metallic
structure, Kretschmann configuration and multilayer grating structure to increase the radiation efficiency. In this paper,
we propose to use this technique of SPGCE has performed on the localized surface plasmon (LSP) and surface plasmon
band gap (SPBG) characteristics of the lamellar grating nanostructure.
We demonstrate the surface plasmon grating coupled emission (SPGCE) from excited organic layer on metal grating in
organic/metal structure. The emissions correspond to the resonant condition of SPPs modes on the Alq3/Au interface and
grating couple to the Au/air interface for the emission of light. In our experiments, we used different pitch sizes to
control plasmonics band-gap which produced highly directional SPGCE with enhanced intensity. In our experiments,
four different pitches, including 400 nm, 500 nm, 600 nm and 800 nm, were adopted for the one-dimensional lamellar
grating devices. They were grating devices with 1-D pattern an exposure area of 1.2×1.2 mm2 fabricated by
Electron-Beam Lithography system. The experimeantal and theoretical results showed that SPGCE at different pitch can
match a linear shifting of momentum (ΔK) of about 4.8 μm-1 per 100 nm pitch size with 4 times enhanced intensity. We
have to modify our experimental design of decreasing Au thin film thickness, it became more pronounced in the 20 nm
Au film at the pitch of 600 nm structure. In this study, the emission filtering is enabled by evanescent wave coupling
across the upper layer metal film. In this way, we can probe the response of the SPGCE system when the two modes are
brought into resonance. In our experiments, we used different pitch sizes to control plasmonic band-gap which produced
highly directional SPGCE with enhanced intensity. Based on our calculation, SPGCE showed a color change from
yellowish green to orange at a certain viewing angle, while the concentration of contacting glucose was increased from
10 to 40%, corresponding to the refractive index change from 1.3484 to 1.3968. This indicated a potential application of
low-cost, integrated, and disposable refractive-index sensor. It is proposed for the development of novel bio-devices,
which is expected to improve the capability of electroluminescent bio-plasmonic devices in the future.
The Surface Plasmon Resonance (SPR) is a label-free, highly sensitive and real time sensing technique and has been
extensively applied to biosensing and assay for decades. In a conventional SPR biosensor, a prism is used to create the
total reflection in which the evanescent wave can excite the surface plasmon mode at the metal-dielectric interface at
certain angle, at which condition the reflectivity of incident TM-polarized vanished as measured by a far-field
photodetector. This is the optical detection of surface plasmon resonance. In this research, zinc oxide (ZnO) was used as
the dielectric thin-film material above the gold surface on the glass substrate to form a co-plane Schottky diode; this
structure is designed to be an alternative way to detect SPR. The strength of plasmonic field is possible to be monitored
by measuring the photocurrent under the reverse bias. According to our experimental results, the measured photocurrents
with TM-polarized illumination (representing the SPR case), TE-polarized illumination (non-SPR case) and no
illumination conditions under DC -1.5V bias are -76.158mA (2.5μA), -76.085mA (3.6μA) and -76.089mA (3.4μA),
respectively. Based on the results, we have demonstrated this Schottky diode based co-plane device has the potential to
be used as the SPR detector and provides a possible solution for the need of a low-cost, miniaturized, electronically
integrated, and portable SPR biosensor in the near future.
SPR biosensor with OLED and nano-grating for HBV LAMP product detection is reported. Directional emissions by grating-coupler
match the resonant condition of SP modes. Concentration changes result in color shift at specific angle. Real time detection of virus
load down to 5 copies/25 ul can be achieved in 30 minutes. Surface plasmon Resonant (SPR) biosensor has been used for
quantitative measurement of molecular interactions for its advantages of high sensitivity, label-free and real-time
detection. In this paper, we report recent efforts on further enhancement of SPR biosensors by the heterogeneous
integration of organic electroluminescence light source and nano-grating structure for the feasibility study on the fast and
high sensitivity detection of HBV isothermal amplification products, Mg2P2O7. We demonstrated the surface plasmon coupled through hybrid nano-grating structure has highly directional emissions corresponding to the resonant condition
of surface plasmon modes on the Au/air interface and controllable plasmonics band-gap by pitch modulation. SPGCE
resulted in color change from yellowish green to orange at a certain viewing angle, when contacting glucose with
concentration increasing from 10 to 40%.
We report the influence of organic electroluminescence (OEL) device on the color tunability and emission efficiency
enhancement by surface plasmon grating coupled emission (SPGCE). The effect of coupling active surface plasmon
polaritons (SPPs) on the metal nanostructure grating with organic material interface was studied. The dispersion relation
was obtained from angle-resolved emission measurements. The combination of organic/metal interface SPPs mode
allows specific directional emission rather than isotropic emission. Control of light emission angle in the SPGCE is
dependent upon the index of refraction at the organic/metal/dielectric interface. Recent experimental results and potential
applications of an active plasmonics biosensor with enhanced resonant energy emission due to interactions on the
organic/metal nano-grating were presented and discussed.
The fruit fly Drosophila melanogaster is one of the most valuable organisms in studying genetics and developmental biology. To gain insight into Drosophila development, we successfully acquired label-free, in vivo images of both developing muscles and internal organs in a stage 2 larva using the minimally invasive imaging modality of multiphoton autofuorescence (MAF) and second harmonic generation (SHG) microscopy. We found that although MAF is useful in identifying structures such as the digestive system, trachea, and intestinal track, it is the SHG signal that allowed the investigation of the muscular architecture within the developing larva. Our results suggest that multiphoton microscopy is a powerful in vivo, label-free imaging technique to examine Drosophila physiology and may be used for developmental studies.
We employed atomic force microscopy (AFM) with bias control to fabricate oxided nanopatterns on silicon surface with feature size down to 50nm. The relationship of silicon dioxide nanopatterns against humidity was studied and then the optimal parameter was used to make oxide nanoarry for interaction of biotin and streptavidin. The scanning function of AFM was utilized to verify the different height of biomolecules. According to our experimental results, using nano biochip of silicon dioxide can decrease the monitoring scale to nanometer and can be the nano-platform for monitoring the behavior of biomolecular interaction. We anticipate mimicking the correlation of single molecular behavior and an array of biomolecular behavior to understand the coincidence of them.
The fruit fly Drosophila melanogaster is one of the most valuable organisms in genetic and
developmental biology studies. Drosophila is a small organism with a short life cycle, and is
inexpensive and easy to maintain. The entire genome of Drosophila has recently been sequenced (cite
the reference). These advantages make fruit fly an attractive model organism for biomedical researches.
Unlike humans, Drosophila can be subjected to genetic manipulation with relative ease. Originally,
Drosophila was mostly used in classical genetics studies. In the model era of molecular biology, the
fruit fly has become a model organ for developmental biology researches. In the past, numerous
molecularly modified mutants with well defined genetic defects affecting different aspects of the
developmental processes have been identified and studied. However, traditionally, the developmental
defects of the mutant flies are mostly examined in isolated fixed tissues which preclude the observation
of the dynamic interaction of the different cell types and the extracellular matrix. Therefore, the ability
to image different organelles of the fruit fly without extrinsic labeling is invaluable for Drosophila
biology. In this work, we successfully acquire in vivo images of both developing muscles and axons of
motor neurons in the three larval stages by using the minimially invasive imaging modality of
multiphoton (SHG) microscopy. We found that while SHG imaging is useful in revealing the muscular
architecture of the developing larva, it is the autofluorescence signal that allows label-free imaging of
various organelles to be achieved. Our results demonstrate that multiphoton imaging is a powerful
technique for investigation the development of Drosophila.
This study proposed a novel approach to replace the traditional surface plasmon resonance (SPR) bulk prism by
microlens arrays (MLAs). It demonstrated the effect that coupling SPR on the optical response of microlens arrays
structure. Surface plasmons are features specific to the interface of metal-dielectric. They are due to charge density
oscillations in the metal, accompanied by electromagnetic field dissipation in the metal and in the dielectric. SPR
biosensor bulk prism technology has been commercialized and SPR biosensors have become a central tool for
characterizing and quantifying biomolecular interactions. We will used this microlens arrays coupling SPP phenomenon,
which gives rise to selective spectral response due to a local field enhancement interrelating the optical and biochemical
domains.
We reported a reusable DNA computing platform for solving satisfiability (SAT) problem based on surface
plamon resonance (SPR) technology in this paper. Three different sequences of 18-mer ssDNAs with thiol
terminal were first immobilized on the gold surface and then hybridized with their complementary sequences at
specific sites via microfluidic channels under room temperature. We also conjugated monoclonal antibody
(human IgG) to these complementary pairs chemically to amplify the hybridization signal and thus enhance the
noise margin to distinguish Boolean value of true and false. In order to keep the reaction temperature and SPR
measurement stable, repeated DNA annealing and denaturing is doned by varying salt concentration (by
adding NaOH to denature DNA) of reaction solution rather than changing reaction temperature. The
experimental results successfully demonstrated a multi-channel microfluidic DNA computation system to solve
a three variables (X, Y, Z) Boolean SAT problem (formula) with reusability and specificity
using protein-ssDNA conjugates to link to complementary ssDNA SAM surface under room temperature within
one hour. This technique provide a feasible solution to miniaturize the DNA computation platform for possible
iterated hyperstep computing processes.
This paper is intended to demonstrate the effect of coupled long-range surface plasmon polaritons (LRSPPs) on the optical response of a lamellar grating nanostructure with organic material on the surface. This phenomenon gives rise to a selective spectral response and a local field enhancement which can be used in the context of nano-optics. This novel structure of nanofabricated device, consisting of coupled organic/metal nanostructure with specific width and symmetric dielectric structure. By designing the size and shape of the grating nanostructure, and the location of the organic Alq3 relative to the surfaces, Alq3 can be quenched, display increases in emission quantum yield, and decreasing the lifetimes. The combinations of organic/metal interface LRSPP mode can emit specific direction rather than isotropic emission. We discuss recent experimental results and potential applications in biosensor, organic light emitting diodes (OLEDs), polymer laser and organic solar cells of organic/metal grating enhanced emission resonance energy interactions.
KEYWORDS: Sensors, Amplifiers, Signal detection, Signal processing, Telecommunications, Information technology, Self-assembled monolayers, Receivers, Nanotechnology, Interfaces
Attempts to develop a Wireless Health Advanced Mobile Bio-diagnostic System (abbreviated as WHAM-BioS) have arisen from the need to monitor the health status of patients under long-term care programs. The proposed WHAM-BioS as presented here was developed by integrating various technologies: nano/MEMS technology, biotechnology, network/communication technology, and information technology. The biochips proposed not only detect certain diseases but will also report any abnormal status readings on the patient to the medical personnel immediately through the network system. Since long-term home care is typically involved, the parameters monitored must be analyzed and traced continuously over a long period of time. To minimize the intrusion to the patients, a wireless sensor embedded within a wireless network is highly recommended. To facilitate the widest possible use of various biochips, a smart sensor node concept was implemented. More specifically, various technologies and components such as built-in micro power generators, energy storage devices, initialization processes, no-waste bio-detection methodologies, embedded controllers, wireless warning signal transmissions, and power/data management were merged and integrated to create this novel technology. The design methodologies and the implementation schemes are detailed. Potential expansions of this newly developed technology to other applications regimes will be presented as well.
The longitudinal resolution of an optical coherence tomography (OCT) system is conventionally defined as the full-width at half maximum (FWHM) of the interference fringe envelope, which depends on the center wavelength as well as the spectral width of the light source. One can obtain an FWHM of an interference fringe envelope larger or smaller than that resulted from a Gaussian spectrum of the same spectral FWHM when the light source spectrum is non-Gaussian distributed. In this paper, we first study the dependencies of OCT resolution on the spectral shape and dispersion mismatch with numerical simulations. We will demonstrate the capability of enhancing the longitudinal resolution of an OCT system with a proper control of spectral distribution and dispersion mismatch. Then, in experiments we built an OCT system with its light source generated from nonlinear optics effects of 12-fsec Ti:sapphire laser pulses in an optical fiber. With proper control of dispersion mismatch between the sample and reference arms, the FWHM of the interference fringe envelope was smaller than that of a Gaussian spectrum with the same spectral FWHM by a factor of two. Furthermore, the side lobes were suppressed with a process algorithm to significantly improve the longitudinal resolution.
We proposed and demonstrated a novel technique of improving the spatial resolution of an optical coherence tomography (OCT) system given a certain light source spectrum. By using dispersive materials in the reference arm of the OCT system, the resultant dispersion compensation led to a FWHM of interference fringe envelope smaller than the Fourier transform limited value, at the expense of significant tails. The effects of the tails, which would blur the OCT images, were tremendously reduced with retrieval algorithms. Simulation results and processed OCT scanning images have shown the capability of the proposed technique. Two retrieval algorithms were proposed and compared.
A polarization controllable optical coherence tomography (OCT) system was built with the broadband source generated with femtosecond Ti:sapphire laser pulses in fiber. Spectral broadening in such fiber originated from self-phase modulation, four-wave mixing, Raman scattering, and other nonlinear-optics effects. Two different mode-locked Ti:sapphire lasers with 100 fsec and 12 fsec pulses were used. The generated spectral shape and width were compared in terms of the application to the OCT system. The relationship between the OCT resolution and the source spectrum shape was studied. Also, an algorithm was built for increasing the effective longitudinal resolution in data processing. The scheme of this algorithm meant to separate the contribution of the central portion from those of the tails in the interference fringe envelope. By removing the tail contribution to the scanning results, the effective longitudinal resolution was improved. Such a procedure is particularly important when the light source spectrum is not a well-defined shape. This procedure involved in the computation of a matrix inversion. The OCT system and the process algorithm were used for oral cancer study. Features of oral cancer were well identified. A probe was also fabricated for in vivo scan of oral tissues.
A fiber optic microsensor is described which utilizes the surface plasmon resonance (SPR) effect to detect the chemical environment surrounding the fiber. The sensor is a multimode step index optic fiber, which is constructed by removing the fiber cladding layer with hot sulfuric acid and coated with gold film on fiber core and on distal end. The changes in the light reflectivity are recorded as SPR spectra, which are highly sensitive to the optical properties of the samples adjacent to the sensor surface. The incident light is guided through a splitter to excite and record SPR in both visible and near infrared (NIR) regions. The NIR spectrum has a larger and sharper resonant peak than visible one. It thus provides a more sensitive mechanism to probe the vicinity of interface for biochip applications.
Photons are seriously scattered when entering turbid medium; this the images of objects hidden in turbid medium can not be obtained by just collecting the transmitted photons. Early-arriving photons, which are also called ballistic or snake protons, are much less scattered when passing through turbid medium, and contains more image information than the late-arriving ones. Therefore, objects embedded in turbid medium can be imaged by gathering the ballistic and snake photons. In the present research we try to recover images of objects in turbid medium by simultaneously time-gate and polarization-gate to obtain the snake photons. An Argon-pumped Ti-Sapphire laser with 100fs pulses was employed as a light source. A streak camera with a 2ps temporal resolution was used to extract the ballistic and snake photons. Two pieces of lean swine meat, measured 4mmX3mm and 5xxX4mm, respectively, were placed in a 10cmX10cmX3cm acrylic tank, which was full of diluted milk. A pair of polarizer and an analyzer was used to extract the light that keeps polarization unchanged. The combination of time gating and polarization gating resulted in good images of objects hidden in turbid medium.
Imaging of inhomogeneities in a turbid medium with transmitted optical signal represents a crucial technique for optical diagnosis of abnormal cells in human tissues, particularly important for early detection of female breast cancer. In this paper, we present the results of our simulation and experimental studies. In the simulation study, we propose a new technique using transient diffuse photon density waves for imaging reconstruction. In the experimental study, we demonstrate the assistance of ultrasounds to optical imaging through a turbid medium. For the imaging, we basically utilize transmitted ballistic and snake photons.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.