Application of Paper-Based Microfluidic Analytical Devices (µPAD) in Forensic and Clinical Toxicology: A Review

The need for providing rapid and, possibly, on-the-spot analytical results in the case of intoxication has prompted researchers to develop rapid, sensitive, and cost-effective methods and analytical devices suitable for use in nonspecialized laboratories and at the point of need (PON). In recent years, the technology of paper-based microfluidic analytical devices (μPADs) has undergone rapid development and now provides a feasible, low-cost alternative to traditional rapid tests for detecting harmful compounds. In fact, μPADs have been developed to detect toxic molecules (arsenic, cyanide, ethanol, and nitrite), drugs, and drugs of abuse (benzodiazepines, cathinones, cocaine, fentanyl, ketamine, MDMA, morphine, synthetic cannabinoids, tetrahydrocannabinol, and xylazine), and also psychoactive substances used for drug-facilitated crimes (flunitrazepam, gamma- hydroxybutyric acid (GHB), ketamine, metamizole, midazolam, and scopolamine). The present report critically evaluates the recent developments in paper-based devices, particularly in detection methods, and how these new analytical tools have been tested in forensic and clinical toxicology, also including future perspectives on their application, such as multisensing paper-based devices, microfluidic paper-based separation, and wearable paper-based sensors

Paper-based microfluidic devices for food adulterants: Cost-effective technological monitoring systems

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGAnalytical sciences have witnessed emergent techniques for efficient clinical and industrial food adulterants detection. In this review, the contributions made by the paper-based devices are highlighted for efficient and rapid detection of food adulterants and additives, which is the need of the hour and how different categories of techniques have been developed in the past decade for upgrading the performance for point-of-care testing. A simple strategy with an arrangement for detecting specific adulterants followed by the addition of samples to obtain well-defined qualitative or quantitative signals for confirming the presence of target species. The paperbased microfluidics-based technology advances and prospects for food adulterant detection are discussed given the high-demand from the food sectors and serve as a valued technology for food researchers working in interdisciplinary technological frontiers.Vision Group on Science and Technology, Government of Karnataka | Ref. KSTePS/ VGST/SMYSR-2016–17/GRD-595/2017–18Vision Group on Science and Technology, Government of Karnataka | Ref. KSTePS/VGSTRGS/F/GRD No.711/2017–18Science and Engineering Research Board (SERB), Department of Science and Technology, Govt of India | Ref. CRG/2020/00306

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

Electrochemical and microfabrication strategies for remotely operated heavy metal sensor networks for water analysis : the dual challenges of calibration-less measurement and sample pretreatment.

Current heavy metal monitoring in water utilizes sophisticated instrumental methods at centralized laboratories. For many applications, a preferable approach is the deployment of remote sensor networks. To this end, electrochemical methods in conjunction with microfabricated sensors potentially offer the required sensitivity and practical advantages including inexpensive sensors, reduced need for manual operation, reduced energy requirements, and also takes advantage of existing technologies such as communications networks for real-time data acquisition. The remote sensor platform developed herein consists of a photo-lithographically patterned gold electrode on SiO2 substrate within a custom stopped-flow thin-layer cell (TLC). Metal concentrations were evaluated by anodic stripping coulometry (ASC), where it was possible to pre-concentrate all dissolved metals from the finite TLC volume in about a minute. Unlike previously reported ASC approaches which rely on either linear sweep voltammetry or chronopotentiometry, the ASC variant described herein utilizes a potential step to simultaneously strip all deposited metals. The use of a double potential step ASC method also allowed in situ blank subtraction without the need for a separate blank solution. To achieve selectivity, several deposition potentials are used to pre-concentrate only those metals which can be reduced at a given potential. This method is demonstrated to be capable of measuring 500 ppb As(III) to better than 10% error even in the presence of high interferent levels (1.3 ppm Cu2+, 500 ppb Cd2+, 500 ppb Pb2+, and 5 ppm Zn2+). Similar performance was possible for As(III) spiked Ohio River water after pH adjustment. For more negatively reduced metals, dissolved oxygen (DO) reduction interferes with stripping analysis. An indirect in-line electrochemical DO removal device (EDOR), utilizing a silver cathode to reduce DO in a fluidically isolated chamber from the sample stream, was therefore developed. This device is capable of 98 % DO removal at flow rates approaching 50 µL/min with power consumption as low as 165 mW hr L-1. Besides our specific stripping application, this device is well suited for Lab on Chip (LOC) applications where miniaturized DO removal and/or regulation are desirable

Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors

This reprint is a collection of the Special Issue "Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors" published in Nanomaterials, which includes one editorial, six novel research articles and four review articles, showcasing the very recent advances in energy-harvesting and self-powered sensing technologies. With its broad coverage of innovations in transducing/sensing mechanisms, material and structural designs, system integration and applications, as well as the timely reviews of the progress in energy harvesting and self-powered sensing technologies, this reprint could give readers an excellent overview of the challenges, opportunities, advancements and development trends of this rapidly evolving field

Biosensors for Diagnosis and Monitoring

Biosensor technologies have received a great amount of interest in recent decades, and this has especially been the case in recent years due to the health alert caused by the COVID-19 pandemic. The sensor platform market has grown in recent decades, and the COVID-19 outbreak has led to an increase in the demand for home diagnostics and point-of-care systems. With the evolution of biosensor technology towards portable platforms with a lower cost on-site analysis and a rapid selective and sensitive response, a larger market has opened up for this technology. The evolution of biosensor systems has the opportunity to change classic analysis towards real-time and in situ detection systems, with platforms such as point-of-care and wearables as well as implantable sensors to decentralize chemical and biological analysis, thus reducing industrial and medical costs. This book is dedicated to all the research related to biosensor technologies. Reviews, perspective articles, and research articles in different biosensing areas such as wearable sensors, point-of-care platforms, and pathogen detection for biomedical applications as well as environmental monitoring will introduce the reader to these relevant topics. This book is aimed at scientists and professionals working in the field of biosensors and also provides essential knowledge for students who want to enter the field

Cellulose-Based Biosensing Platforms

Cellulose empowers measurement science and technology with a simple, low-cost, and highly transformative analytical platform. This book helps the reader to understand and build an overview of the state of the art in cellulose-based (bio)sensing, particularly in terms of the design, fabrication, and advantageous analytical performance. In addition, wearable, clinical, and environmental applications of cellulose-based (bio)sensors are reported, where novel (nano)materials, architectures, signal enhancement strategies, as well as real-time connectivity and portability play a critical role

Towards deployable analytical systems for nutrient monitoring in natural waters

The freshwater environment is intrinsically linked to human, animal and plant life and is an indispensable resource for the economy. Effective water quality monitoring is therefore one of the cornerstones of environmental protection and this importance is reflected within both European and global legislation. Nutrient pollution in water bodies can be seen as one of the largest global problems which effects the freshwater environment. Current legislation and policies governing water quality depend on grab sampling techniques, providing only instantaneous data which can result in a non-representative estimate of the nutrient pollution load status of a water body. In order to fully satisfy the water sectors need for comprehensive analysis, management and protection, effective portable in-situ nutrient monitoring systems are required. The focal point of this research was based around the current need which exists for inexpensive, robust in-situ nutrient monitoring solutions for the freshwater environment. The primary goal was to develop a low-cost, field deployable, automated IC system for nutrient anion analysis. Complimentary to this work, portable systems based on colorimetry for nutrient analysis were also explored. Through this research, a portable low-cost nitrate test kit has been developed which is based on a modified version of the Griess assay and employs zinc as a reducing agent. The developed method was validated according to ISO17025 accreditation guidelines and reliably detected nitrate in a range of freshwater samples. A portable, lightweight capillary IC system for anion analysis in water was also developed and demonstrated in a laboratory setting. The IC uses low-cost, miniaturised components and through a modular design enables flexible system modification. Progressing from this capillary system, a new low-cost, UV absorbance detector incorporating a 235 nm light emitting diode (LED) was developed for portable ion chromatography. The detector enabled selective, fast determination of nitrite and nitrate in a range of natural waters. In an attempt to develop a portable system for ammonium analysis, a multi-material 3D printed microfluidic reactor with integrated heating was fabricated and used with colorimetry to facilitate fast ammonium determination. Although the analytical range for ammonium xxii determination was narrow, the developed 3D printed heater represents a novel contribution in the area of 3D printed analytical systems. Finally, an IC which is low-cost, automated and fully deployable was developed which allows for in-situ analysis of nitrite and nitrate in a wide variety of natural waters. The system employed 3D printed pumps for eluent delivery and the 235 nm LED based optical detector which was developed during the course of the research. The system was deployed at various locations around the world and achieved an analytical performance comparable to accredited benchtop instrumentation

Holographic Point-of-Care Diagnostic Devices

Developing non-invasive and accurate diagnostics that are easily manufactured, robust and reusable will provide monitoring of high-risk individuals in any clinical or point-of-care environment, particularly in the developing world. There is currently no rapid, low-cost and generic sensor fabrication technique capable of producing narrow-band, uniform, reversible colorimetric readouts with a high-tuneability range. This thesis aims to present a theoretical and experimental basis for the rapid fabrication, optimisation and testing of holographic sensors for the quantification of pH, organic solvents, metal cations, and glucose in solutions. The sensing mechanism was computationally modelled to optimise its optical characteristics and predict the readouts. A single pulse of a laser (6 ns, 532 nm, 350 mJ) in holographic “Denisyuk” reflection mode allowed rapid production of sensors through silver-halide chemistry, in situ particle size reduction and photopolymerisation. The fabricated sensors consisted of off-axis Bragg diffraction gratings of ordered silver nanoparticles and localised refractive index changes in poly(2-hydroxyethyl methacrylate) and polyacrylamide films. The sensors exhibited reversible Bragg peak shifts, and diffracted the spectrum of narrow-band light over the wavelength range λpeak ≈ 500-1100 nm. The application of the holographic sensors was demonstrated by sensing pH in artificial urine over the physiological range (4.5-9.0), with a sensitivity of 48 nm/pH unit between pH 5.0 and 6.0. For sensing metal cations, a porphyrin derivative was synthesised to act as the crosslinker, the light absorbing material, the component of a diffraction grating, as well as the cation chelating agent. The sensor allowed reversible quantification of Cu2+ and Fe2+ ions (50 mM - 1 M) with a response time within 50 s. Clinical trials of a glucose sensor in the urine samples of diabetic patients demonstrated that the glucose sensor has an improved performance compared to a commercial high-throughput urinalysis device. The experimental sensitivity of the glucose sensor exhibited a limit of detection of 90 µM, and permitted diagnosis of glucosuria up to 350 mM. The sensor response was achieved within 5 min and the sensor could be reused about 400 times without compromising its accuracy. Holographic sensors were also tested in flake form, and integrated with paper-iron oxide composites, dyed filter and chromatography papers, and nitrocellulose-based test strips. Finally, a generic smartphone application was developed and tested to quantify colorimetric tests for both Android and iOS operating systems. The developed sensing platform and the smartphone application have implications for the development of low-cost, reusable and equipment-free point-of-care diagnostic devices

Development of wearable, screen-printable conductive polymer biosensors on flexible and textile substrates

Wearable biosensors have great potential for real-time diagnostics, but have been encumbered by costly fabrication processes, rigid materials, and inadequate sensitivity for physiological ranges. Sweat has hitherto been an understudied sample for measurement of components like pH and lactate, which can provide meaningful guidance for wound healing, eczema, and sports medicine applications. This thesis presents the development of a flexible, textile-based, screen-printed electrode system for biosensing applications. Furthermore, a flexible, pH-sensitive composite for textile substrates is developed by mixing polyaniline with dodecylbenzene sulfonic acid and textile screen-printing ink. The optimized composite’s pH response is compared to electropolymerized and drop-cast polyaniline sensors via open circuit potential measurements. A linear response is observed for all sensors between pH 3-10, with the composite demonstrating sufficient response time and a sensitivity better than -20 mV/pH, exceeding existing flexible screen-printed pH sensors. Investigations into a potentiometric, non-enzymatic lactate sensor using polyaminophenylboronic acid are also discussed