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

Analysis of relevant technical issues and deficiencies of the existing sensors and related initiatives currently set and working in marine environment. New generation technologies for cost-effective sensors

The last decade has seen significant growth in the field of sensor networks, which are currently collecting large amounts of environmental data. This data needs to be collected, processed, stored and made available for analysis and interpretation in a manner which is meaningful and accessible to end users and stakeholders with a range of requirements, including government agencies, environmental agencies, the research community, industry users and the public. The COMMONSENSE project aims to develop and provide cost-effective, multi-functional innovative sensors to perform reliable in-situ measurements in the marine environment. The sensors will be easily usable across several platforms, and will focus on key parameters including eutrophication, heavy metal contaminants, marine litter (microplastics) and underwater noise descriptors of the MSFD. The aims of Tasks 2.1 and 2.2 which comprise the work of this deliverable are: • To obtain a comprehensive understanding and an up-to-date state of the art of existing sensors. • To provide a working basis on “new generation” technologies in order to develop cost-effective sensors suitable for large-scale production. This deliverable will consist of an analysis of state-of-the-art solutions for the different sensors and data platforms related with COMMONSENSE project. An analysis of relevant technical issues and deficiencies of existing sensors and related initiatives currently set and working in marine environment will be performed. Existing solutions will be studied to determine the main limitations to be considered during novel sensor developments in further WP’s. Objectives & Rationale The objectives of deliverable 2.1 are: • To create a solid and robust basis for finding cheaper and innovative ways of gathering data. This is preparatory for the activities in other WPs: for WP4 (Transversal Sensor development and Sensor Integration), for WP(5-8) (Novel Sensors) to develop cost-effective sensors suitable for large-scale production, reducing costs of data collection (compared to commercially available sensors), increasing data access availability for WP9 (Field testing) when the deployment of new sensors will be drawn and then realized

Development of an Automated Detection System for Nitrite in Aquatic Environments

The main objective of the project is to develop an automated nitrite sensor for use in aquatic environments, and more specifically for use in recirculating aquaculture systems (RAS), where monitoring can help sustain a controlled environment, protect against nitrite intoxication, and promote fish health. Detecting nitrite manually with semi-quantitative colorimetric test kits, although inexpensive and simple, is prone to inter-user variability and poor sensitivity. An automated nitrite sensor has potential to provide higher resolution measurements at both concentration and time scales and can serve as a research tool for the study of filtration systems essential in maintaining a healthy RAS environment. The questions driving the project are: How to build a device that can deliver satisfactory analytical merit (e.g., sensitivity, accuracy, precision), while maintaining reliable, inexpensive, and simple operation. The research involves investigation into detection methods and state of the art instrumentation available for nitrite, production trends in chemical total analysis systems, and centers around larger questions surrounding invention and innovation. The first steps towards such a device are benchtop prototyping of the detection and fluidic modules, their integration with wet chemistry, and the validation of the analytical process carried out by the system. The project approaches the objectives with a design that relies on commercially available components and consumables and is modular and adaptable for future possible configurations. To this end, the benchtop prototype was developed as an opto-fluidic system for automated colorimetric detection. With the exception of two custom-built PVC adaptors, the entire system was built with off-the-shelf parts for around $1,000. In addition to utilizing easily replaceable components, the system was tested using commercially available and pre-made reagents based on proven chemistry (Griess assay for nitrite). Preliminary results suggest the analytical process is capable of detecting sub-micromolar nitrite concentrations (limit of detection equal to 0.18 µM) at appreciable precision, sensitivity, and accuracy in comparison to commercial instruments

Development and Application of 3D Printed Detectors for Environmental Analysis

This dissertation describes the development of a novel 3D printed fluorescence detector and a 3D printed chemiluminescence detector. The 3D printed fluorescence detector is used as a component of the haloacetic acid rapid-response (HAA-RR), a commercial system for the analysis of haloacetic acids (HAAs) in drinking water. The 3D printed chemiluminescence detector was used in the development of a free-available chlorine (FAC) analyzer and a lead (II) analyzer.The 3D printed fluorescence detector was developed for the specific application of the nicotinamide chemistry used in the HAA-RR. The detector is simple, rugged and inexpensive. The detector was compared to a commercially available Waters 474 dual monochromator detector. An MDL, accuracy and precision study was performed using the fluorescent reagent nicotinamide with the detectors in series. In addition, signal-to-noise ratios for the detectors were compared. The 3D printed fluorescence detector performed comparably, if not better, than the Waters detector. The 3D printed fluorescence detector may be used for any application requiring quantitative fluorescence detection by changing the excitation and emission filters.The first commercial automated analyzer for HAAs analysis in drinking water was developed. The HAA-RR is a commercial version of a previously reported, laboratory-grade analyzer. Components of the HAA-RR are discussed such as the post-column reagent delivery system and a low-cost, low-pressure gradient system. The 3D printed fluorescence detector is used as a detector in the HAA-RR system. MDL, accuracy and precision studies for the HAA-RR are compared to the laboratory-grade analyzer. Results of HAAs analysis from a beta test at the Lebanon, TN water treatment plant are presented where multiple methods of calibration were performed and compared. A side-by-side comparison study of the HAA-RR and the United States Environmental Protection Agency method 552.3 is presented for the analysis of HAAs for the Lebanon, TN water treatment plants quarterly compliance monitoring. Also, parameters were investigated and established to be used as daily quality control (QC) monitors for the HAA-RR. The parameters selected for the QC monitoring were: retention time, capacity factor and peak width at 50 % maximum height for the internal standard, (2-bromobutanoic acid) and the retention time of the unretained component. A (FAC) analyzer was developed using gas-diffusion flow injection analysis and detection with a 3D printed chemiluminescence detector. The FAC analyzer is able to detect microgram per liter concentrations of FAC in the presence of milligram per liter concentrations of chlorine dioxide with a sample preparation step. Multiple different fits of the FAC calibration were evaluated, and a base 10 log-log fit was the most fitting. An MDL, accuracy and precision study was performed over FAC concentrations of 1.0 to 16.0 mg L-1, with a check standard at 2.0 mg L-1. The USEPA estimated MDL of the FAC analyzer is 0.07 mg L-1. The FAC analyzer was used for the analysis of real-world samples of commercially-available chlorine dioxide, reporting no detected concentration of FAC.Preliminary development of a flow-injection system for the detection of lead (II) in drinking water is presented. The lead (II) analyzer uses luminol-hydrogen peroxide chemiluminescence for the detection of lead (II) ion with a 3D printed chemiluminescence detector. Optimization of the reagent concentrations was carried out, along with a linearity study and a preliminary MDL, accuracy and precision study. The preliminary study of the method reported poor precision high mean percent recovery for the check standard due to the check standard of 15 g L-1 Pb2+ ion being near the MDL of 16 g L-1 Pb2+. The preliminary studies of the lead (II) analyzer are promising, and proof-of-concept was demonstrated

Review of present method of glucose from human blood and body fluids assessment

The work has been aimed to create an overview of available and used methods and ways to determine the concentration of glucose in body fluids, especially from a technical point of view. It also provides an overview of the clinical features of these methods. The survey found that today's market offers a large number of options and approaches to the issue. There are accurate reference laboratory methods, self-monitoring methods for measuring glucose levels using glucometers, or continuous methods for daily monitoring of blood glucose trends and for insulin pump control. However, it must not be forgotten that the development of full closure of feedback is still not complete today. Individual methods cannot always be compared with each other, precisely because of the focus and the use of these methods. Choosing the right method of blood glucose levels in the body measuring can help patients to manage their diabetes mellitus. The methods listed in the overview are divided in terms of measurement continuity and further according to the invasiveness of the method. Finally, the issues of accuracy in the detection of glycaemia variability and the possibility of further development of these methods are discussed, as it is clear from the survey that the development is focused mainly on continuous methods improving that get to the forefront and also on developing a biosensor that is purely non-invasive and continuous.Web of Science211art. no. 11434

Development of Smartphone dual-laser waveguide based fluorescent microscopy system using 3D printing

Nowadays cellphones are present everywhere, and along with the worldwide network of devices, the concept of mobile health monitoring is changing to reshape the biosensor market. The smartphone’s camera is a proven reliable candidate as a detector for the studies performed by various research groups. This study is a proof of concept of the Smartphone detection of two fluorescent dyes which can be used as biomarkers for point-of-care diagnostics through image processing techniques. A smartphone Xiaomi Redmi Note 4 along with two fluorescent dyes DyLight™ 405 NHS Ester and DyLight™ 633 NHS Ester are used in conjunction with two lasers Thorlabs 405 nm and 638nm. The captured pictures were analyzed using Image J. The limit of detection and dynamic range values were calculated for both dyes, 28.39 nM and 20-800 nM for DyLight™ 405 NHS Ester dye and 15.85 nM and 10-600 nM for DyLight™ 633 NHS Ester dye. Then this concept is realized by developing a cheap 3D printed POC device which uses the optical microscopy technology along with a PDMS chip. Hence, this integrated novel innovation which prioritizes accuracy and the ease of usage, can be a game changer for patients who live in countries of limited resources and can moreover aid to the impoverished people who are in dire need of medical help

The development of low cost autonomous chemical sensors for environmental monitoring

Our ability to effectively monitor the aquatic environment is essential due to the increasing pressure on the environment from pollution, global climate change and the fact that water is an increasingly scarce natural resource. Nutrients such as nitrate and ammonia are essential for ecosystems but surplus levels of nutrients entering water bodies are a serious pollutant, causing eutrophication, contaminating drinking water and killing ecosystems which can cost nations up to $2.2 billion per year. There is therefore a growing need for low cost, remote sensing systems which can be deployed in sufficiently large numbers to ensure that data on key water quality parameters is readily available. This project has the overall objective of developing low cost analytical platform for autonomous monitoring of environmental water quality. This will be achieved by further development of existing monitoring platforms developed at DCU combined with modified chemical methods in order to reduce the fabrication cost of the devices by an order of magnitude. Through this strategy, a microfluidic sensing platform for the direct determination of nitrate in water using chromotropic acid has been developed. The chromotropic acid method has been modified to facilitate its implementation into an autonomous platform, resulting in a quick and simple procedure to measure nitrate. The device incorporates a low cost, highly sensitive detection with excellent correlation to the standard method, ion chromatography. Ultimately, this system provides a base in terms of monitoring waters for nitrate levels in situ in a rapid, simple and inexpensive manner. For the determination of ammonia, a simplified variation of the Berthelot method has been integrated into an autonomous sensing platform for reliable, reproducible results showing excellent correlation with ion chromatography

Advances in capillary electrophoresis using microfluidics

This thesis focuses on instrumental advances in microfluidics-based capillary electrophoresis systems for achieving various goals. Microfluidics systems and purpose-made scientific instruments in general may consist of many different hardware units, often made by different companies. This presents a challenge for system builders who want to efficiently build and use purpose-made instruments for conducting scientific experiments. As this challenge was relevant for all of the projects described in this thesis, it was the first one to be tackled by the development of the software package Instrumentino. The package allows system builders to build a useful graphical user interface (GUI) for their experimental setups, allowing automation of multiple components controlled by separate microcontrollers. A Code could be reused between projects using the same hardware units. Instrumentino was eventually used in all of the projects in this thesis, and while it required a lot of invested time for its development, it saved a lot of time in running experiments afterwards. The first CE systems built for this thesis were for a collaborative project about the use of a C4D cell array for following after separation processes, and comparing them to computer simulations. It was first (using 16 detectors) employed for CZE separations of inorganic anions and cations for the sake of demonstration, and later (using 8 detectors) for investigating CZE and ITP separations in linear polyacrylamide (LPA) coated silica capillaries, exhibiting a very low EOF. Another issue discussed in this thesis is the implementation of concurrent CZE separations for anions and cations in portable systems. Two multi-channel portable CE instruments were built in collaboration with others and two review publications were written on the subject of concurrent determination of anions and cations (also a collaboration). Relying on the experience gained from building the previous systems, a new approach for building electrophoretic separation systems was developed, based on a commercial breadboard system for miniaturized microfluidic parts, offering high design flexibility and small size as in lab-on-chip systems, yet using standard silica capillaries and obtaining comparable results to commercial CE instruments. The applicability of this method was exemplified by the implementation of various electrophoretic experiments using the same building blocks. This approach proved to be very useful and was later employed for all following projects, enabling a quick realization of new designs in a miniaturized way. A third multi-channel portable CE system was developed, offering a thermostated chamber in which separations took place and a new microfluidic design which employed a syringe pump for pressurization, enabling, among other things, a special semi- automatic mode for analyzing volume-limited samples. It was used to determine concentrations of target ions in groundwater and mine water samples in an abandoned mining site in Argentina, as well as the determination of inorganic ions in sediment porewater from Lake Baldegg in Switzerland. In parallel, another desktop system was developed for the semi-automatic analysis of volume-limited samples, employing a micro syringe for sample introduction. Finally, a novel fully automated pre-concentration approach for CE was developed, employing a purpose-made microfluidic trapping block in which a hydrodynamic flow can be applied in a channel alongside an electric field that induces electrophoretic flow of the target ions in the opposite direction. A discontinuity in the target ions’ electrophoretic flow in the channel results in a trapping point for these ions, to which their net flow is directed to from both sides (upstream and downstream). This is achieved by applying the trapping voltage through ion-exchange membranes, which only pass ions of opposite charge than that of the target ions. This trapping block was coupled to a capillary inlet, so that it could be injected and be separated in it, automatically. This approach was found to be applicable also for high conductivity samples (up to 0.1 M), which is unique as most pre-concentration approaches that are based on electrokinetic phenomena are limited to low conductivity samples. Furthermore, the system allows selectively trapping ions with mobilities over a certain level, determined by the relative strengths of the applied hydrodynamic flow and electric field