Abstract

The concept of optical antennas in physical optics is still evolving. Like the antennas used in the radio frequency (RF) regime, the aspiration of optical antennas is to localize the free propagating radiation energy, and vice versa. For this purpose, optical antennas utilize the distinctive properties of metal nanostructures, which are strong plasmonic coupling elements at the optical regime. The concept of optical antennas is being advanced technologically and they are projected to be substitute devices for detection in the millimeter, infrared, and visible regimes. At present, their potential benefits in light detection, which include polarization dependency, tunability, and quick response times have been successfully demonstrated. Optical antennas also can be seen as directionally responsive elements for point detectors. This review provides an overview of the historical background of the topic, along with the basic concepts and parameters of optical antennas. One of the major parts of this review covers the use of optical antennas in biosensing, presenting biosensing applications with a broad description using different types of data. We have also mentioned the basic challenges in the path of the universal use of optical biosensors, where we have also discussed some legal matters.

Highlights

  • The optical antennas, which represent unique optical detectors equivalent to radio frequency (RF)antennas, are a novel concept in the field of physical optics [1]

  • This review provides a clear overview of optical biosensors to the reader, a concept that arises from the contact of visible light with free electrons at a metal-dielectric boundary [7]

  • Though biosensing inside cells with different localized surface plasmon resonance (LSPR) biosensors is at the initial stages, these techniques are effective for diagnostics, drug distribution and checking the efficiency of therapies

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Summary

Introduction

The optical antennas, which represent unique optical detectors equivalent to radio frequency (RF). Optical antennas are subjected to an increasing amount of technical research. This technology has potential in the enhancement of the efficiency of sensing, light emission, photo-detection, spectroscopy, and heat transfer [1]. (ii) combine optical radiation into minute volumes for generating currents in the wire which are identified by a rectifying component of almost 0.02 μm volume. This minute material volume permits one to achieve faster responses. The metallic structures have a lossy character and as a result, the resonances are likely to be widened, which possibly limits the tuning ability [5]. This review provides a clear overview of optical biosensors to the reader, a concept that arises from the contact of visible light with free electrons at a metal-dielectric boundary [7]

History of Optical Antennas
Physical Properties of Optical Antenna
Antenna Impedance
Antenna Efficiency
Directivity
Reciprocity
Antenna Aperture
Effective Wavelength
Conductivity of Antenna Materials
2.2.10. Antenna Resonance
Following the Analogy of RF Antenna
Impedance Matching
Electro-Optical Conversion
Selection Rules
Reproducibility and Repeatability
Optical Antennas as Biosensors
SPR Biosensors and Present Research
Insecticide Detection
Bacteria Detection
Toxin Detection
LSPR Biosensors and Associated Surface Enhanced Phenomena
Wavelength-Shift Based Application
Nucleic Acid Hybridization Assays
Protein Recognition Assays
Raman Labels
Intracellular Detection
Challenges of Designing Optical Bio-Sensors
Use of Nanoantenna Gratings for Tuning of Biosensors
Human Exposure to Nanotoxicology
Prospective and Conclusions
Findings
Conflicts of Interest
Full Text
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