A new LED-LED portable CO2 gas sensor based on an interchangeable membrane system for industrial applications

A new system for CO2 measurement (0-100%) by based on a paired emitter-detector diode arrangement as a colorimetric detection system is described. Two different configurations were tested: configuration 1 (an opposite side configuration) where a secondary inner-filter effect accounts for CO2 sensitivity. This configuration involves the absorption of the phosphorescence emitted from a CO2-insensitive luminophore by an acid-base indicator and configuration 2 wherein the membrane containing the luminophore is removed, simplifying the sensing membrane that now only contains the acid-base indicator. In addition, two different instrumental configurations have been studied, using a paired emitter-detector diode system, consisting of two LEDs wherein one is used as the light source (emitter) and the other is used in reverse bias mode as the light detector. The first configuration uses a green LED as emitter and a red LED as detector, whereas in the second case two identical red LEDs are used as emitter and detector. The system was characterised in terms of sensitivity, dynamic response, reproducibility, stability and temperature influence. We found that configuration 2 presented a better CO2 response in terms of sensitivity

Direct replacement of antibodies with molecularly imprinted polymer (MIP) nanoparticles in ELISA - development of a novel assay for vancomycin

A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop ELISA type assays is presented here for the first time. NanoMIPs were synthesized by a solid phase approach with immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering and electron microscopy. Immobilization, blocking and washing conditions were optimized in microplate format. The detection of vancomycin was achieved in competitive binding experiments with a HRP-vancomycin conjugate. The assay was capable of measuring vancomycin in buffer and in blood plasma within the range 0.001-70 nM with a detection limit of 0.0025 nM (2.5 pM). The sensitivity of the assay was three orders of magnitude better than a previously described ELISA based on antibodies. In these experiments nanoMIPs have shown high affinity and minimal interference from blood plasma components. Immobilized nanoMIPs were stored for 1 month at room temperature without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELIS

Galaxies in voids assemble their stars slowly

MCIN/AEI AYA2017-84897-P PID2020-113689GB-I00 PID2020-114414GB-I00FEDER/Junta de Andalucia-Consejeria de Transforamcion Economica, Industria, Conocimiento y Universidades/Proyecto P20_00334 FQM108Junta de AndaluciaInstitut Universitaire de FranceCentre National D'etudes SpatialesArqus European UniversityAgence Nationale de la Recherche (ANR)Spanish Ministry of Science, Innovation and Universities (MCIU) and through the IAC project TRACESConsejeria de Economia, Industria, Comercio y Conocimiento of the Canary Islands Autonomous CommunityBeatriz Galindo senior fellowship BG20/00224Spanish GovernmentConsejeria de Transformacion Economica, Industria, Conocimiento y Universidades and University of Granada EMERGIA20_38888Juan de la Cierva Formacion fellowshipEuropean Union (EU)Ministerio de Economia y Competitividad from Junta de Andalucia Excellence PID2019-107408GB-C44State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa' award for the Instituto de Astrofisica de AndaluciaJunta de Andalucia P20-00880ESF Investing in your future' PRE2018-086111German Research Foundation (DFG) KR4598/2-

Near Infrared Sensor to Determine Carbon Dioxide Gas Based on Ionic Liquid

In this study we present an NIR carbon dioxide gas sensor based on an inner filter process that includes an ionic liquid (IL), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), to improve its stability, dynamic behavior and lifetime, which are usually the main drawbacks with these sensors. The presence of CO2 causes a displacement of a simple boron-dipyrromethene-type fluorophore, azaBODIPY, as the pH indicator towards its acid form. This increases the emission intensity of Cr(III)-doped gadolinium aluminium borate (GAB) as the luminophore. The characterization of the prepared sensor was carried out and a discussion of the results is presented. The response and recovery times improved considerably, 23 and 49 s, respectively, with respect to the sensor without IL, at 60 and 120 s, respectively,. Additionally, the measurement range is extended when using IL, able in this case to measure in the complete range up to 100% CO2; without IL the measurement range is limited to 60% CO2. The detection limit ranges from 0.57% CO2 without IL to 0.26% CO2 when IL is added. The useful lifetime of the sensing membrane was 20 days for membranes with IL and only 6 days for membranes without IL, with the sensor always kept in the dark and without the need to maintain a special atmosphere

Early warning device for detection of pollutants in water

Due to a growing need to protect water resources from contamination, there is a requirement for the development of more reliable and cost effective devices for water quality monitoring. The aim of the AQUAWARN project is to develop and deploy a fully autonomous water quality monitoring device that can measure nitrite, nitrate, phosphate and pH colorimetrically in fresh water and wastewater, and communicate the information to stakeholders in real time

Early warning pollution detection device for application in water quality

It has been well recognised that water is a valuable resource and the quality of our water systems require sampling at a higher temporal and spatial frequency than is currently taking place. The AQUAWARN project aims to meet this challenge through the development of commercially competitive water quality monitoring devices. These will be capable of performing analytical measurements in situ - primarily aimed at freshwater and wastewater systems. The analytes of interest are mainly phosphate, nitrite, nitrate, and pH. The initial focus of this project is the assessment and optimisation of appropriate colorimetric chemistries for each sensing target. These chemistries have been developed and optimised using bench-top instrumentation. Integration within microfluidic chips followed to reduce the per sample costs. Microfluidic technology uses minute amounts of reagent per sample measurement, allowing for a dramatic increase in the number of potential assays per unit volume of reagent. Moreover, the integration of LEDs and photodiodes as light sources and detectors, coupled with syringe pumps, opens the way to new generations of low-cost, portable, and autonomous devices, capable of performing multiple in-situ measurements.  For example, an analysis requiring 50 uL of reagent implies 2,000 measurements are possible per 100 mL of reagent

CO2 sensor for food application

The carbon dioxide levels inside meat packages can be used as indicator of freshness. If the CO2 concentration changes during storage it is a clear indicator that bacteria are growing inside the container and / or the package is not well sealed and the modified atmosphere has been compromised. However, a non-destructive method for determining the CO2 concentration within the package has not, as yet, been reported. To this end, the objective of the SmartPack project is to exploit the development and integration of a CO2 sensor in meat packages using the imaging and communications capabilities of Smartphones for freshness detection. Optical CO2 sensors based on the acidity of this molecule, are normally solvent-based sensors, the drawback of this approach in the food packaging industry is due to the long-term instability of the sensors, arising from the quaternary ammonium hydroxides decomposition. However, in this project we avoid the use of these compounds. Water based sensors are prepared using meta cresol purple sodium salt as indicator, glycerol as plasticizer and sodium bicarbonate as buffer in a matrix of hydroxyethyl cellulose. In this way, the lifetime is increased and also this composition creates an easily printable ink. Moreover, ionic liquids have been included in the matrix making the sensor more selective to CO2 than other gases due to its higher solubility. This new water-based sensor has been characterised in terms of carbon dioxide sensitivity, dynamic response, and stability under different conditions. The sensor responds up to 100% of carbon dioxide. In Figure 1 can be observed the change in colour from 0 to 100% of CO2. Moreover, it has been demonstrated that the stability is much higher than the solvent-based sensors making them suitable for smart packaging application. The sensitive ink has been optimised and characterized using bench-top instrumentation. Moreover, the RGB and HSV readout of standard digital photographic cameras have been used as a simple imaging techniqu

Carbon dioxide sensors for food packaging

Traditional food packaging objective is the isolation of products from the outer atmosphere to extend their shelf life. In response to current necessities, traditional food packaging has led to smart packaging. CO2 inside food packages is a key factor to control. CO2 sensors can give information about the modified atmosphere integrity, indicating that the inner atmosphere is intact or if it has been broken and therefore the used by date must not be trusted, or about how fresh is the packaged product. This article briefly describes the types of packaging (traditional and smart) and how CO2 sensors can be used in the food industry. Different approaches for their integration in packaged food are described and the characteristics that must comply in order to be integrated in the agro-alimentary industry.European Union's Horizon 2020 research and innovation programme under grant agreement No 706303 (Multisens)CTQ2016–78754-C2-1-R project from the Spanish MINECO

Introducing MINA-The Molecularly Imprinted Nanoparticles Assay

A new ELISA‐ (enzyme‐linked immunosorbent assay)‐like assay is demonstrated in which no elements of biological origin are used for molecular recognition or signaling. Composite imprinted nanoparticles that contain a catalytic core and which are synthesized by using a solid‐phase approach can simultaneously act as recognition/signaling elements, and be used with minimal modifications to standard assay protocols. This assay provides a new route towards replacement of unstable biomolecules in immunoassays

A new LED-LED portable CO2 gas sensor based on an interchangeable membrane system for industrial applications

CO2 monitoring is important for many areas of high economic relevance, like environmental monitoring, control of biotechnological processes in bio-pharmaceutical industries, and the food industry, particularly controlled atmosphere storage rooms and modified atmosphere packaging [ ]. CO2 sensing is not a trivial area of research, as is testified by the increasing numbers of publications regarding this topic over the past decade. The main reason is that CO2 chemically is relatively unreactive, and therefore finding a mechanism for signal generation is difficult. Most publications are based on its well-known acidic properties. In this communication, we present a portable optical sensor for gaseous CO2 detection based on the phosphorescence intensity variation of a platinum octaethylporphyrin (PtOEP) complex trapped in oxygen-insensitive poly(vinylidene chloride-co-vinyl chloride) (PVCD) membranes. The sensing mechanism arises from the increasing displacement of the α-naphtholphthalein acid–base equilibrium with rising CO2 concentrations [ ]. The low-power LED-based optical sensing instrumentation for monitoring CO2 is based on a pair of light emitting diodes (LEDs) arranged to face each other, wherein one LED functions as the light source and the other LED is reverse biased to function as a light detector [ ]. A transparent polymer substrate coated on both sides with the CO2 sensitive membrane placed between the two LEDs serves as a chemically responsive filter between the light source and the detector