Absorbance based light emitting diode optical sensors and sensing devices

The ever increasing demand for in situ monitoring of health, environment and security has created a need for reliable, miniaturised sensing devices. To achieve this, appropriate analytical devices are required that possess operating characteristics of reliability, low power consumption, low cost, autonomous operation capability and compatibility with wireless communications systems. The use of light emitting diodes (LEDs) as light sources is one strategy, which has been successfully applied in chemical sensing. This paper summarises the development and advancement of LED based chemical sensors and sensing devices in terms of their configuration and application, with the focus on transmittance and reflectance absorptiometric measurements

Optical tools for ocean monitoring and research

© 2009 The Authors. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Ocean Science 5 (2009): 661-684, doi: 10.5194/os-5-661-2009Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based analytical techniques have generated a diverse offering of commercial sensors and research prototypes that perform optical measurements in water. Through inversion, these tools are now being used to determine a diverse set of related biogeochemical and physical parameters. Techniques engaged include measurement of the solar radiance distribution, absorption, scattering, stimulated fluorescence, flow cytometry, and various spectroscopy methods. Selective membranes and other techniques for material isolation further enhance specificity, leading to sensors for measurement of dissolved oxygen, methane, carbon dioxide, common nutrients and a variety of other parameters. Scientists are using these measurements to infer information related to an increasing set of parameters and wide range of applications over relevant scales in space and time

Microfabrication and Applications of Opto-Microfluidic Sensors

A review of research activities on opto-microfluidic sensors carried out by the research groups in Canada is presented. After a brief introduction of this exciting research field, detailed discussion is focused on different techniques for the fabrication of opto-microfluidic sensors, and various applications of these devices for bioanalysis, chemical detection, and optical measurement. Our current research on femtosecond laser microfabrication of optofluidic devices is introduced and some experimental results are elaborated. The research on opto-microfluidics provides highly sensitive opto-microfluidic sensors for practical applications with significant advantages of portability, efficiency, sensitivity, versatility, and low cost

Selected Papers from the 1st International Electronic Conference on Biosensors (IECB 2020)

The scope of this Special Issue is to collect some of the contributions to the First International Electronic Conference on Biosensors, which was held to bring together well-known experts currently working in biosensor technologies from around the globe, and to provide an online forum for presenting and discussing new results. The world of biosensors is definitively a versatile and universally applicable one, as demonstrated by the wide range of topics which were addressed at the Conference, such as: bioengineered and biomimetic receptors; microfluidics for biosensing; biosensors for emergency situations; nanotechnologies and nanomaterials for biosensors; intra- and extracellular biosensing; and advanced applications in clinical, environmental, food safety, and cultural heritage fields

Advances in Optofluidics

Optofluidics a niche research field that integrates optics with microfluidics. It started with elegant demonstrations of the passive interaction of light and liquid media such as liquid waveguides and liquid tunable lenses. Recently, the optofluidics continues the advance in liquid-based optical devices/systems. In addition, it has expanded rapidly into many other fields that involve lightwave (or photon) and liquid media. This Special Issue invites review articles (only review articles) that update the latest progress of the optofluidics in various aspects, such as new functional devices, new integrated systems, new fabrication techniques, new applications, etc. It covers, but is not limited to, topics such as micro-optics in liquid media, optofluidic sensors, integrated micro-optical systems, displays, optofluidics-on-fibers, optofluidic manipulation, energy and environmental applciations, and so on

Development and application of evanescent wave cavity ring-down spectroscopy as a probe of biologically relevant interfaces

The application of a hybrid instrument combining Evanescent Wave Cavity Ring-Down Spectroscopy (EW-CRDS) with electrochemical and fluidic methods is described. The electrochemical/fluidic methods were used to induce a surface process, the effects of which were subsequently monitored in situ and in real time with exquisite spectral sensitivity and excellent temporal resolution by EW-CRDS. The well-defined manner in which the surface processes were initiated allowed the extraction of kinetic rate constants by fitting the EW-CRDS data to mathematical models of the surface process coupled to convection-diffusion. The investigations described include: the study of the thermodynamics and kinetics of the adsorption of tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+) to polypeptide films using EW-CRDS with chronoamperometry; the real-time electrochemistry of cytochrome c immobilised on silica by EW-CRDS with chronoamperometry; the kinetics of adsorption and DNA-assisted desorption of 5,10,15,20-tetra(N-methylpyridinium-4-yl)porphyrin at the silica-water interface using EW-CRDS with an impinging jet flow cell; and the monitoring the adsorption of cationic phospholipid vesicles at the silica-aqueous interface and the interaction of 5,10,15,20-Tetraphenyl-21H, 23H-porphine-p,p′,p″,p′′′-tetrasulfonic acid tetrasodium hydrate with the resulting bilayer also using EW-CRDS with an impinging jet flow cell. The work described in this thesis provides a platform on which EW-CRDS can be used to study dynamics at biointerfaces, such as the association of ions, peptides, proteins and drugs with phospholipid bilayers, the electron transfer between redox enzymes in a biomimetic environment, and the lateral diffusion of protons, ions and proteins at biomembranes. Such studies are essential to the understanding of many important cellular processes in addition to the development and optimisation of a number of bio-inspired technologies

Investigate the plasmonic enhanced solar photothermal effect of gold nanorod nanofilm

Gold nanospheres (Au NSs) and gold nanorods (Au NRs) are traditional noble metal plasmonic nanomaterials. Particularly, Au NRs with tunable longitudinal plasmon resonance from visible to the near infrared (NIR) range were suitable for high efficient photothermal applications due to extended light receiving range. In this work, we synthesized Au NRs and Au NSs of similar volume, and subsequently developed them into Au NR/PVDF and Au NS/PVDF nanofilm, both of which exhibited excellent solar photothermal performance evaluated by solar photothermal experiments. We found that Au NR/PVDF nanofilm showed higher solar photothermal performance than Au NS/PVDF nanofilm. Through detailed analysis, such as morphological characterization, optical measurement, and finite element method (FEM) modeling, we found that the plasmonic coupling effects inside the aggregated Au NRs nanoclusters contributed to the spectral blue-shifts and intensified photothermal performance. Compare to Au NS/PVDF nanofilms, Au NR/PVDF nanofilm exhibited higher efficient light-to-heat conversion rate, because of the extended light receiving range and high absorbance, as the result of strong plasmonic interactions inside nanoclusters, which was further validated by monochromatic laser photothermal experiments and FEM simulations. Our work proved that the Au NRs have huge potential for plasmonic solar photothermal applications, and are envisioned for novel plasmonic applications