Since the first application of the surface plasmon resonance (SPR) phenomenon for sensing almost two decades ago, this method has made great strides both in terms of instrumentation development and applications. SPR sensor technology has been commercialized and SPR biosensors have become a central tool for characterizing and quantifying biomolecular interactions. This paper attempts to review the major developments in SPR technology. Main application areas are outlined and examples of applications of SPR sensor technology are presented. Future prospects of SPR sensor technology are discussed.

Surface plasmon resonance sensors: review

Plasmonics is a research area merging the fields of optics and nanoelectronics by confining light with relatively large free-space wavelength to the nanometer scale - thereby enabling a family of novel devices. Current plasmonic devices at telecommunication and optical frequencies face significant challenges due to losses encountered in the constituent plasmonic materials. These large losses seriously limit the practicality of these metals for many novel applications. This paper provides an overview of alternative plasmonic materials along with motivation for each material choice and important aspects of fabrication. A comparative study of various materials including metals, metal alloys and heavily doped semiconductors is presented. The performance of each material is evaluated based on quality factors defined for each class of plasmonic devices. Most importantly, this paper outlines an approach for realizing optimal plasmonic material properties for specific frequencies and applications, thereby providing a reference for those searching for better plasmonic materials.

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Searching for better plasmonic materials

https://www.uta.edu/rfmems/GI_Sensor/papers/ac040049d.pdf

Fiber-Optic Chemical Sensors and Biosensors

Searching for Better Plasmonic Materials

Hydrogen sensors are of increasing importance in connection with the development and expanded use of hydrogen gas as an energy carrier and as a chemical reactant. There are an immense number of sensors reported in the literature for hydrogen detection and in this work these sensors are classified into eight different operating principles. Characteristic performance parameters of these sensor types, such as measuring range, sensitivity, selectivity and response time are reviewed and the latest technology developments are reported. Testing and validation of sensor performance are described in relation to standardisation and use in potentially explosive atmospheres so as to identify the requirements on hydrogen sensors for practical applications.

Hydrogen Sensors - A review

An optical fibre sensor has been developed for the detection of hydrogen leakages on the cryotechnic engine of the European rocket ARIANE V. The principle of this sensor is based on the variation of reflectivity of a palladium micromirror deposited at the output end face of a multimode optical fibre. An experimental set-up using a monitored high power laser diode provides an optical heating of the palladium layer, which allows to keep up the performances in the wide range of temperatures between −196°C and +23°C. Depending on both the concentration and the temperature, detection responses between 1% and 17% with response times shorter than 5 s have been demonstrated. Fast and accurate detection of hydrogen concentrations inferior to the explosive limit has been performed.

Hydrogen leak detection using an optical fibre sensor for aerospace applications

A small and efficient hydrogen sensor using surface plasmon resonance in an integrated optical waveguide is reported. The waveguide properties are influenced by a thin palladium layer whose optical constants depend on concentration of hydrogen in surrounding gaseous medium. A modal analysis of the sensor structure is performed and a simple sensor model is proposed. Finally, experimental results are presented; detection of hydrogen concentration as low as 4% is demonstrated.

An integrated optic hydrogen sensor based on SPR on palladium

An optical fibre surface plasmon resonance (SPR) sensor has been developed for the detection of hydrogen leakages. A thin palladium layer deposited on the bare core of a multimode fibre was used as the transducer. In this device, modification of the SPR is due to variation in the complex permittivity of palladium in contact with gaseous hydrogen. This effect is enhanced by using selective injection of high-order modes in the fibre via a collimated beam with non-normal incidence on the input end of the fibre. Measurements of concentrations as low as 0.8% of hydrogen in pure nitrogen have been found to be possible. The response time varies between 3 s for pure hydrogen and 300 s for the lowest concentrations. Such a large range can be explained by the two different crystallographic phases of the palladium-hydrogen system. Moreover, the response of the sensor is dependent on the length of the sensing area. In preliminary experiments, it has been possible to split the sensing area in order to achieve a two-point detection device.

Surface plasmon resonance hydrogen sensor using an optical fibre

A new fibre optic sensor for the detection of refractive index variations is presented. The principle of the sensor is based on the generation of surface plasma waves at the interface between a thin metallic layer deposited on the fibre core and a surrounding dielectric medium. Specific injection of monochromatic light into the fibre allows the detection of a refractive index variation as low as for dielectric media lying in the 1.33 - 1.40 refractive index range. Modelling of sensing signal and experiments are performed. Potential applications are aqueous solution analyses and detection of gases and solvents with a specific polymeric layer.

https://iopscience.iop.org/article/10.1088/0963-9659/5/2/006/pdf

Chemical sensing by surface plasmon resonance in a multimode optical fibre

A 3D skew ray modeling has been developed to consistently explain the experimental phenomena for an intrinsic SPR multimode optical fiber sensor. The effects of the polarization direction of the incident light at certain conditions have been clarified. This simulation is needed to accurately detect the variations of the refractive index of the bulk medium and of the thickness of the thin surface layer. More complete knowledge about light energy transmission by the skew ray in the multimode step-index fiber is obtained by this investigation.

H. Gagnaire

Papers

Hydrogen leak detection using an optical fibre sensor for aerospace applications

An integrated optic hydrogen sensor based on SPR on palladium

Surface plasmon resonance hydrogen sensor using an optical fibre

Chemical sensing by surface plasmon resonance in a multimode optical fibre

The effects of polarization of the incident light-modeling and analysis of a SPR multimode optical fiber sensor