5.1. Detection Formats 475 5.2. Food Quality and Safety Analysis 477 5.2.1. Pathogens 477 5.2.2. Toxins 479 5.2.3. Veterinary Drugs 479 5.2.4. Vitamins 480 5.2.5. Hormones 480 5.2.6. Diagnostic Antibodies 480 5.2.7. Allergens 481 5.2.8. Proteins 481 5.2.9. Chemical Contaminants 481 5.3. Medical Diagnostics 481 5.3.1. Cancer Markers 481 5.3.2. Antibodies against Viral Pathogens 482 5.3.3. Drugs and Drug-Induced Antibodies 483 5.3.4. Hormones 483 5.3.5. Allergy Markers 483 5.3.6. Heart Attack Markers 484 5.3.7. Other Molecular Biomarkers 484 5.4. Environmental Monitoring 484 5.4.1. Pesticides 484 5.4.2. 2,4,6-Trinitrotoluene (TNT) 485 5.4.3. Aromatic Hydrocarbons 485 5.4.4. Heavy Metals 485 5.4.5. Phenols 485 5.4.6. Polychlorinated Biphenyls 487 5.4.7. Dioxins 487 5.5. Summary 488 6. Conclusions 489 7. Abbreviations 489 8. Acknowledgment 489 9. References 489

Surface Plasmon Resonance Sensors for Detection of Chemical and Biological Species

Sensitive optical biosensors for unlabeled targets: a review.

The analysis of various parameters of metal oxides and the search of criteria, which could be used during material selection for solid-state gas sensor applications, were the main objectives of this review. For these purposes the correlation between electro-physical (band gap, electroconductivity, type of conductivity, oxygen diffusion), thermodynamic, surface, electronic, structural properties, catalytic activity and gas-sensing characteristics of metal oxides designed for solid-state sensors was established. It has been discussed the role of metal oxide manufacturability, chemical activity, and parameter's stability in sensing material choice as well.

Metal oxides for solid-state gas sensors: What determines our choice?

Since the introduction of optical fiber technology in the field of sensor based on the technique of surface plasmon resonance (SPR), fiber-optic SPR sensors have witnessed a lot of advancements. This paper reports on the past, present, and future scope of fiber-optic SPR sensors in the field of sensing of different chemical, physical, and biochemical parameters. A detailed mechanism of the SPR technique for sensing purposes has been discussed. Different new techniques and models in this area that have been introduced are discussed in quite a detail. We have tried to put the different advancements in the order of their chronological evolution. The content of the review article may be of great importance for the research community who are to take the field of fiber-optic SPR sensors as its research endeavors.

Fiber-Optic Sensors Based on Surface Plasmon Resonance: A Comprehensive Review

Towards integrated and sensitive surface plasmon resonance biosensors: a review of recent progress.

A review of three commonly used classes of chemical sensor technologies as applicable to implementation in portable, handheld field instruments is presented. Solid-state gas and chemical sensors have long been heralded as the solution to a wide variety of portable chemical sensing system applications. However, advances in optical sensing technology have reduced the size of supporting infrastructure to be competitive with their solid-state counterparts. Optical, solid-state, and hybrid arrays of sensors have application for portable instruments, but issues of insufficient selectivity and sensitivity continue to hamper the widespread introduction of these miniaturized sensors for solving chemical sensing problems in environments outside the laboratory. In this article, we evaluate three of the major classes of compact chemical sensors for portable applications: (solid-state) chemiresistors, (solid-state) CHEMFETs, and (optical) surface plasmon resonance sensors (SPR). These sensors are evaluated and reviewed, according to the current state of research, in terms of their ability to operate at low-power, small-size, and relatively low-cost in environments, with numerous interferents and variable ambient conditions.

https://www.uta.edu/rfmems/BMC/0720/Background/Chemical%20Sensors%20for%20Portable,%20Handheld%20Field%20Instruments.pdf

Chemical sensors for portable, handheld field instruments

Sensitive and real-time fiber-optic-based surface plasmon resonance sensors for myoglobin and cardiac troponin I

Surface plasmon resonance (SPR) spectroscopy has been conducted on both prism and fiber optic (FO) based sensors for several years. This technique measures the refractive index (RI) of a solution or layer adsorbed to a thin (∼50 nm) Au layer on the sensor substrate. To date a succinct set of protocols have not been published regarding the optimization of fiber-based SPR dip-probe sensors. Such sensors would allow application of SPR to a wider variety of applications. This paper focuses on consideration of the choice of fiber, isolation of the mirror from the sensing area, and orientation of the probes in the metal layer sputter deposition chamber in the manufacture of SPR dip-probes for reproducibility and robustness. Optimization of the process yields sensors with a batch to batch reproducibility as low as 0.5 nm in the location of the SPR spectral minima. Further study of RI measurements by the same probe over 2 months show these SPR dip-probes have a long shelf-life. A selection of probes was exposed to various solutions to monitor their drift. The data shows the probes’ response indicated a lowering of the RI measured over a period of 3 or 7 days depending on the probe type. Evidence of surface porosity and damage upon exposure to hydrothermal water seems to indicate these sensors are prone to chemical attack. Further research is needed to characterize this attack and allow creation of more robust sensors.

Manufacture of robust surface plasmon resonance fiber optic based dip-probes

Calibration of fiber optic based surface plasmon resonance sensors in aqueous systems

The sensitivity of fiber-optic surface plasmon resonance (SPR) sensors was improved by a factor of at least thirteen for aqueous solutions by modifying the tip geometry to allow interrogation of the surface plasmon (SP) band in the near-infrared (NIR) region. This was achieved by tuning the angle at the distal end of the SPR sensor to a dual taper of 71° and 19°. Using a low numerical aperture (NA) fiber-optic sensor, NA = 0.12, is necessary to obtain a functional SPR sensor working in the NIR region. Theoretical simulations using the Maxwell equations demonstrated that even higher enhancement is theoretically possible while maintaining a narrow spectral feature upon the excitation of the SP bands on gold surfaces. The manufacture of the SPR sensors yields good agreement between theoretical simulations and experimental observations. To investigate the properties of these fiber-optic SPR-NIR sensors, sucrose solutions ranging from 0 to 15 × 10−3 in mole fraction were utilized. The increased sensitivity of the fiber-optic SPR sensors, when used to monitor biomarkers, would yield lower detection limits. The smaller sensing area, compared to planar or other fiber-optic SPR sensors, combined with an improvement of the sensitivity, would yield a dramatic reduction of the absolute amount detected by biosensors.

Louis A. Obando

Papers

Chemical sensors for portable, handheld field instruments

Sensitive and real-time fiber-optic-based surface plasmon resonance sensors for myoglobin and cardiac troponin I

Manufacture of robust surface plasmon resonance fiber optic based dip-probes

Calibration of fiber optic based surface plasmon resonance sensors in aqueous systems

Fiber-Optic Surface Plasmon Resonance Sensors in the Near-Infrared Spectral Region: