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We report a system, which combines electrochemical and surface plasmon resonance (SPR) techniques on the same sensing chip. Each channel of a four-channel laboratory SPR sensor is supplemented with two planar gold electrodes (the reference and the counter electrodes), whereas the gold layer of SPR chip is used as the working electrode. A custom electronics enables to set an arbitrary potential between the reference and working electrodes and to measure the current flow between the counter and the working electrodes. Information from standard electrochemical techniques, i.e. cyclovoltammetry and chronoamperometry can be acquired with the system while simultaneously monitoring the shift in the surface plasmon resonance. The electrochemical SPR biosensor was used to study desorption of thiolated DNA probes with a negative potential. By comparing the acquired electrochemical and SPR signals, we show that DNA probes as well as a monolayer of alkanethiols can be desorbed by applying negative potentials to the SPR chip surface. Moreover, it is shown that the DNA probes can be reabsorbed on the SPR sensor surface and the complementary DNA can be detected without loss in detection sensitivity.

This contribution reviews the present state of the art in the development of surface plasmon resonance (SPR) (bio)sensor technology, discusses emerging trends, and presents recent results of research into SPR biosensors at the Institute of Photonics and Electronics, Prague. The developments discussed in detail include a high-performance SPR sensor for parallelized observation of biomolecular interactions, a miniature fiber optic SPR sensor for localized measurements, and sensing based on localized surface plasmons on gold nanoparticles.

We report a SPR biosensor based on long-range (LR) and short-range (SR) surface plasmon (SP) modes excited simultaneously on a diffraction grating. Employing the LRSP and SRSP in the grating-coupled SPR sensor offers several interesting features such as extended probe depth of the LRSP and ability to distinguish sensor response caused by bulk and surface refractive index changes. Prototype device based on wavelength interrogation of SPs was developed and be tested in model refractometric experiment. This paper presents results of theoretical analysis and experimental characterization of the sensor. Sensitivity of the laboratory prototype of the sensor agrees well with the theory. The sensor is shown to be able to detect changes in the refractive index as small as 3.5 x 10-6 RIU (refractive index unit).

We report a surface plasmon resonance (SPR) sensor based on two-plasmon-spectroscopy on a special bi-diffractive grating and investigate its ability to distinguish contributions to sensor response due to surface refractive index changes (i.e. binding) and due to refractive index changes in the whole sample. Theoretical analysis yielding an estimate of an error of such decomposition is presented and used to compare performance of this sensor to that of an alternative approach based on simultaneous excitation of short-range and long-range surface plasmons on a thin metallic layer.

We present an optical sensor based on excitation of surface plasma waves in optical fiber structure consisting of a side-polished single-mode polarization-maintaining fiber and a metal overlayer. We describe two modes of operation of the sensor in which variations in the refractive index of the sample are determined by measuring changes in the transmitted optical power at a fixed wavelength (amplitude mode) and by measuring changes in the wavelength at which the resonant attenuation of the fiber mode occurs (spectral mode). We demonstrate that this design allows suppressing sensitivity of the sensor to deformation of the fiber yielding an improved stability and resolution.

We present a novel surface plasmon resonance (SPR) sensor based on serial organization of sensing channels and sequential spectral encoding of responses from sensing channels into an optical spectrum. This approach allows probing interfacial processes by surface plasmons of different field profiles which makes it possible to distinguish surface and bulk contributions to SPR sensor response. We illustrate this unique feature of the presented approach in a model biosensing experiment in which the detection of human chorigonadotropin (hCG) is compensated for background refractive index interference.

A novel approach to multichannel SPR sensing based on encoding information from separate sensing channels into a single optical spectrum is presented. A dual channel SPR sensor using this approach is demonstrated. Attention is given to exploitation of the dual-channel SPR sensor for compensation for background interference and non-specific adsorption of the biomolecules to the surface of the SPR biosensor. Experimental results indicate that background refractive index changes were compensated with accuracy better than 8 X 10-5 RIU (refractive index unit); the effect of a temperature change of 3.6 K was reduced by a factor of 13 by the dual-channel sensor. SPR biosensor-based detection of monoclonal anti-dinitrophenyl antibody (a-DNP) with compensation for non-specific adsorption is demonstrated.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A novel design of surface plasmon resonance fiber optic sensor is reported which leads to a compact, highly miniaturized sensing element with excellent sensitivity. The sensing device is based on a side-polished single-mode optical fiber with a thin metal overlayer supporting surface plasmon waves. The strength of interaction between a fiber mode and a surface plasmon wave depends strongly on the refractive index near the sensing surface. Therefore, refractive index changes associated with biospecific interaction between antibodies immobilized on the sensor and antigen molecules can be monitored by measuring light intensity variations. Detection of horse radish peroxidase (HRP) of the concentration of 100 ng/ml has been accomplished using the fiber optic sensor with a matrix of monoclonal antibodies against HRP immobilized on the sensor surface.

Optical waveguide surface plasmon resonance (SPR) sensors are presented which exploit the phenomenon of the resonant excitation of surface plasmon waves by guided modes of optical fibers and integrated optical waveguides. Theoretical analysis of the SPR waveguide sensing structures is based on the mode expansion and propagation method. The integrated optical waveguide SPR sensor is composed of an optical waveguide fabricated by the K + --Na + ion exchange in a glass substrate and gold as a surface plasmon resonance overlayer. The optical fiber SPR sensor is realized on a side-polished single-mode optical fiber which is locally coated with a thin gold film. Experimental study of the realized samples of the sensors has shown that variations in the refractive index of the sensed medium below 5X10 -5 can be resolved with the sensors.

The exploitation of surface plasmon resonance (SPR) sensing principle for the study of formation of multilayers of human immunoglobulin (hlgG) and monoclonal antibody against human choriogonadotropin (a-hCG) as well as for monitoring immunoreaction between the immobilized a-hCG and human choriogonadotropin (hCG) is reported. It is demonstrated that even a very small attachment of proteins (due to the adsorption or the specific interaction) may be detected by the presented SPR sensor. An immobilization technique is described which allows to form stable multilayers of antibodies on the gold surface.

International audience; SOLAR/SOLSPEC, a spectroradiometer measuring solar spectral irradiance is an instruments of the SOLAR payload mounted on the zenith external platform of the European Columbus module of the International Space Station. Solar flux is received by the SOLAR instruments thanks to the Coarse Pointing Device (CPD). A complementary Sun position tracking module, the Position Sensitive Device (PSD), is integrated in SOLAR/SOLSPEC. The PSD module has been a useful tool to monitor for misalignments between the CPD and the SOLAR payload. It is used in SOLAR/SOLSPEC's operations to follow the quality of the Sun tracking. The PSD module is also valuable to monitor for SOLAR/SOLSPEC's three spectrometers (ultraviolet, visible, infrared) angular response in orbit. We first give a detailed description of the PSD's functionalities. We then present the results of the PSD data analysis. We will show that the PSD module has, despite working in a severe space environment, preserved its full potential from 2008 up to 2017 thanks to its design and appropriate selection of components. We conclude that its robustness makes of the PSD module a simple, yet reliable, instrument useful for future long term space-based missions.

Laser beam profiling technology in the UV spectrum of light is evolving with the increase of excimer lasers and lamps applications, that span from lithography for VLSI circuits to eye surgery. The development of a beam-profiler, able to capture the excimer laser single pulse and process the acquired pixel current signals in the time period between each pulse, is mandatory for such applications. 1D and 2D array detectors have been realized on polycrystalline CVD diamond specimens. The fast diamond photoresponse, in the ns time regime, suggests the suitability of such devices for fine tuning feedback of high-power pulsed-laser cavities, whereas solar-blindness guarantees high performance in UV beam diagnostics, also under high intensity background illumination. Offering unique properties in terms of thermal conductivity and visible-light transparency, diamond represents one of the most suitable candidate for the detection of high-power UV laser emission. The relatively high resistivity of diamond in the dark has allowed the fabrication of photoconductive vertical pixel-detectors. A semitransparent light-receiving back-side contact has been used for detector biasing. Each pixel signal has been conditioned by a multi-channel read-out electronics made up of a high-sensitive integrator and a Σ-Δ A/D converter. The 500 μs conversion time has allowed a data acquisition rate up to 2 kSPS (Sample Per Second).