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Urea is an important molecule in physiology and industry. The detection of urea by electrochemical sensors has broad application prospects in food detection and kidney disease screening. This paper introduces the preparation method of MWCNT/PANi electronic ink and its composite electrode, which was applied to the detection of urea. The linear range of the MWCNT/PANi composite electrode was increased by adjusting the concentration of MWCNT. The maximum linear range was 10 to 100 μM when 5.6 mg MWCNT was added. The sensitivity of the electrode was 2.435 × 10−4 mA mM−1 cm−2 and the detection limit was 53.9 nM. At the same time, an algorithm was proposed to identify and analyze the data collected by the electrochemical workstation in view of the errors existing in the calculation of the electrochemical sensor when analyzing the optimal response voltage of the electrode. This method was used to set constraints and screen the optimal working voltage. Experimental results show that this method has certain advantages. [ABSTRACT FROM AUTHOR]

In this work, a microfluidic chip-based valveless flow injection analysis (FIA) system with gravity-driven flows and liquid-core waveguide (LCW) spectrometric detection was developed. Automated sample injection in the 0.3–6.4 nL range under gated injection mode was achieved by controlling the vertical position of the waste reservoir fixed on a moving platform and the residence time of the reservoir in each position, without the requirement of microvalves or electrokinetic manipulation. An integrated LCW spectrometric detection system was built on the chip by coupling a 20 mm-long Teflon AF 2400 capillary with the microchannel to function as a LCW flow cell, using a green LED as light source and a photodiode as detector. The performance of the system was demonstrated in the determination of [NO2]2−based on the Saltzman reaction. Linear absorbance response was obtained in the range of 0.1–20 mg L−1(R2= 0.9910), and a good reproducibility of 0.34% RSD (n= 17) was achieved. [ABSTRACT FROM AUTHOR]

A compact and low-power microcantilever-based sensor array has been developed and used to detect various chemical vapor analytes. In contrast to earlier micro-electro-mechanical systems (MEMS) array sensors, this device uses the static deflection of piezoresistive cantilevers due to the swelling of glassy polyolefin coatings during sorption of chemical vapors. To maximize the sensor response to a variety of chemical analytes, the polymers are selected based on their Hildebrand solubility parameters to span a wide range of chemical properties. We utilize a novel microcontact spotting method to reproducibly coat a single side of each cantilever in the array with the polymers. To demonstrate the utility of the sensor array we have reproducibly detected 11 chemical vapors, representing a breadth of chemical properties, in real time and over a wide range of vapor concentrations. We also report the detection of the chemical warfare agents (CWAs) VX and sulfur mustard (HD), representing the first published report of CWA vapor detection by a polymer-based, cantilever sensor array. Comparisons of the theoretical polymer/vapor partition coefficient to the experimental cantilever deflection responses show that, while general trends can be reasonably predicted, a simple linear relationship does not exist. [ABSTRACT FROM AUTHOR]

An amperometric biosensor based on genetically-modified enzymes was used for the in situdetection of trace vapours from a number of explosive compounds. The vapour samples that were generated from a purpose-built vapour generator were collected and pre-concentrated using a trap able to concentrate samples at a rate of 60-fold per minute of sampling. The amperometric biosensor achieved a remarkably low vapour detection limit of 6 parts per trillion from a room temperature sample. The specific activity of the reported enzyme toward a number of explosive compounds was also confirmed using absorbance measurements. [ABSTRACT FROM AUTHOR]

Recently developed monitoring-systems show the need as also the possibilities for online- and offline-onsite-diagnostics. The limit in sensitivity for electrical pd-measurements according to IEC 60270 which is reached using filters for sinusoidal disturbances and compensation for corona impulses is still not satisfactory. The acoustic partial discharge measurement (pd-measurement) is also a well known and reliable method often used by transformer manufacturers in testing. In laboratory setups a gain in sensitivity of the acoustic in comparison to the electrical pd measurements could be established. This is reached by adapting the sensors to the propagation path, a modern but moderately priced acquisition hardware and the introduction of new signal processing algorithms. The developed sophisticated measuring, systems show remarkable results in online acoustic pd-measurements onsite. [ABSTRACT FROM AUTHOR]

A sensor installation and evaluation programme at the Institute of Ocean Sciences, Sidney, BC, Canada, shows that the weather buoys operating round Canada's coasts can be used as important new sources of surface information for satellite sensor calibration and validation. The standard instruments on the buoys provide real-time measurements to forecasters--of wind, waves, water and air temperature and air pressure. The present programme is evaluating the addition of sensors measuring chlorophyll fluorescence, Photosynthetically Available Radiation (PAR), salinity and water-leaving radiance. Time-series of these data are also of value for a variety of fisheries, ecosystem and climate studies. Data can be viewed on the web at http://www-sci.pac.dfo-mpo.gc.ca/ecobuoys. [ABSTRACT FROM AUTHOR]

The technique of vicarious calibration is used in connection with an atmospheric correction to improve the Sea viewing Wide Field of view Sensor (SeaWiFS) normalized water-leaving radiance by the first determination of mean vicarious calibration coefficients from in situ measurements in the Baltic Sea. A necessary adjustment of the SeaWiFS pre-flight calibration slope was found to be +3.5%, +0.3%, -1.7%, -0.4%, +0.8% and -1.3% for the first six SeaWiFS channels. The derived mean vicarious calibration coefficients are higher than the coefficients in the standard SeaWiFS Data Analysis System (SeaDAS) software but with similar shape and good agreement with other research results. The coefficients were used to obtain better normalized water-leaving radiance from SeaWiFS measurements in the Baltic Sea. The deviations of calculated to measured radiances in the open Baltic Sea are between 3% and 47% in the channels 412 to 670 nm, with the trend of higher deviations in the blue channels. The objective of radiance determination in all SeaWiFS channels with a maximum uncertainty of 5% in clear water regions is probably not reachable in the turbid water of the Baltic Sea. [ABSTRACT FROM AUTHOR]

Synoptic coverage of the temporal and spatial variability of aerosol distribution patterns can only be achieved with satellites. Results from the first ocean colour sensor, the Coastal Zone Color Scanner (CZCS), indicate an annual cycle of the major mineral aerosol plumes that is consistent with the published literature. Seasonality and interannual aerosol variability observed with the CZCS agrees well with that found by ground data measurements and other satellite platforms used to monitor aerosols. The successor to the CZCS--the Sea viewing Wide Field of view Sensor (SeaWiFS)--provides estimates of aerosol load and particle size, both on a global scale. Seasonal maps of both of these aerosol optical properties are in accord with well-known distribution patterns and also with independent satellite estimates. These results indicate that ocean colour sensors are capable of monitoring the variability of global aerosol loads and, more recently, with the retrieval of aerosol particle size, they can be used to characterize different aerosol events. [ABSTRACT FROM AUTHOR]

The salinity of the open ocean is important for understanding ocean dynamics and for modelling energy exchange with the atmosphere. But existing data are sparse and much of the ocean is unsampled. Sea surface salinity can be measured remotely with passive microwave sensors operating near 1.4 GHz (L-band). Salinity differences have been observed from space and aircraft instruments have demonstrated that salinity can be measured with an accuracy of better than 1 psu. Sensor technology has improved sufficiently to seriously propose a satellite system to map salinity over the open oceans. [ABSTRACT FROM AUTHOR]

For the year 1999 all Sea viewing Wide Field of view Sensor (SeaWiFS) scenes of the Danish waters from the North Sea to the Baltic Sea were browsed, and a total of 47 SeaWiFS scenes with reasonably low cloud cover and, therefore, potential in situ match-ups were found and processed. The in situ data used as match-ups were collected on routine monitoring cruises by Danish and Swedish environmental authorities. A few stations in the North Sea, Skagerak and the western Baltic Sea were sampled, while most stations were located in Kattegat and the inner Danish waters. A turbid water SeaWiFS atmospheric correction algorithm was applied, since the standard SeaWiFS algorithm for chlorophyll- a (CHL) has been shown to be fairly inaccurate in turbid coastal waters. This is due to both inaccurate atmospheric and to relatively high and variable abundance of yellow substance. The application of the turbid atmospheric correction substantially improved the SeaWiFS CHL estimates. Regressions between SeaWiFS estimates using the OC2 and OC4 algorithms used in the SeaDAS software (versions 3.3 and 4.0, respectively) and in situ CHL values were made as well, and regression with a number of other possible reflectance ratios with SeaWiFS channels. The best correlation was found to be R 2 =0.54 using a double-ratio algorithm using both R510/R555 and R443/R670, while the OC4v4 had the second best correlation of R 2 =0.39. Among other single ratios, the R510/R555 had the highest correlation with CHL, which was expected since this is also the ratio that OC4v4 most often switches to in the waters investigated here. The range of CHL concentrations in this study was rather limited (all but three points from 0.5-3 mg m -3 ) so there is a need for inclusion of more data to expand the concentration range. This should be possible using also data from 2000, 2001 and onwards and, hereafter, a more 'stable' empirical algorithm can be derived for the Danish waters. [ABSTRACT FROM AUTHOR]

The National Aeronautics & Space Administration (NASA) Sea viewing Wide Field of view Sensor (SeaWiFS) began operational measurement of ocean colour in September 1997. Upgrades to the SeaWiFS data processing system (SeaDAS) have occurred frequently and the effects of these revisions on the remotely sensed estimates of chlorophyll- a concentration (chl- a ) have been significant. Measurements of chl- a from research work in the Bay of Biscay and Gulf of Cadiz during 1998-1999 are used to validate the SeaWiFS chl- a product generated using the current version of SeaDAS (version 4.1). The validation data cover coastal and offshore waters, including those dominated by inorganic suspended sediment, and an intense dinoflagellate bloom where shipboard chl- a measurements exceeded 50 mg m -3 . The standard SeaWiFS chlorophyll algorithm (OC4v4) generally performed well, but significantly over-estimated chl- a where inorganic suspended sediment was present. The algorithm is only applicable to chl- a values up to 64 mg m -3 , which was less than chl- a at the centre of the bloom. A novel algorithm for chl- a , which first estimates the inherent optical properties of the water, was applied to the SeaWiFS measurements but failed on over 90% of the pixels, perhaps because SeaWiFS is under-estimating water reflectance at the extreme blue end of the visible spectrum. [ABSTRACT FROM AUTHOR]

• BiNP/SPGE with CTAB shows highly sensitivity and separation for tin and lead detection. • BiNP/SPGE on PAD can be combined with portable potentiostat for the first time. • BiNP/SPGE exhibits an alternative tool for simple, portable and low-cost sensors. • Tin and lead were evaluated in canned food samples using BiNP/SPGE on PAD with CTAB. Due to similar properties in the electroanalysis of tin (Sn(II)) and lead (Pb(II)), the voltammograms of tin and lead overlap and it is difficult to simultaneously determine these two metals. Herein, we develop a simple fabricated sensor based on a bismuth nanoparticle-modified screen-printed graphene electrode (BiNP/SPGE) on a paper-based analytical device (PAD) for the simultaneous determination of Sn(II) and Pb(II) and combine it with a portable potentiostat. To overcome crossing interference, the use of hexadecyltrimethylammonium bromide (CTAB) can provide improved separation and enhanced sensitivity for Sn(II) and Pb(II) detection in oxalic acid as a supporting electrolyte while using square-wave anodic stripping voltammetry. Under optimal conditions, the linear range of both metals was determined to be 10–250 ng mL−1, and the calculated limit of detection (3SD/slope) was 0.26 ng mL−1 and 0.44 ng mL−1 for Sn(II) and Pb(II), respectively. This sensor was also applied to simultaneously determine Sn(II) and Pb(II) in canned food samples. The results obtained from the portable potentiostat were similar to the results obtained by a standard method. Therefore, the proposed device can be further improved for the realization of a rapid on-site detector for Sn(II) and Pb(II) detection in real samples. [ABSTRACT FROM AUTHOR]

• In this paper, proper amount of Ag nanoparticles was added into TiO 2 nanoparticles as sensing film, which could increase hydrophilicity and absorption ability of the sensing film. • The enhancement effect of Ag on humidity performance of the sensors was better than lots of most reports. • This high-sensitivity humidity sensor proposed in this work could enable the nondestructive detection of wet paper and has potential applications in the preservation of ancient manuscripts, historical calligraphies and paintings. In this paper, a capacitive-type humidity sensor based on TiO 2 /Ag nanoparticle composites film was fabricated on interdigital electrodes. Experimental results showed that a small amount of Ag nanoparticles mixed with TiO 2 nanoparticles could greatly improve the sensor sensitivity. Compared with pure TiO 2 sample, the improved capacitance variation of sensor raised more than two orders of magnitude. The reduction in water contact angle measurements proved that the hydrophilicity of the film had increased, and the appearance of Warburg impedance at 11% RH in the complex impedance spectra plot indicated that adding Ag improved the absorption ability of composite film. This high-sensitive humidity sensor proposed in this work could enable the nondestructive detection of wet paper and had potential applications in the preservation of ancient manuscripts, historical calligraphies and paintings. [ABSTRACT FROM AUTHOR]

Paper-based sensors fabricated using the pencil-on-paper method are expected to find wide usage in many fields owing to their low cost and high reproducibility. Here, hydrogen (H2) detection was realized by applying palladium (Pd) nanoparticles (NPs) to electronic circuits printed on paper using a metal mask and a pencil. We confirmed that multilayered graphene was produced by the pencil, and then characterized Pd NPs were added to the pencil marks. To evaluate the gas-sensing ability of the sensor, its sensitivities and reaction rates in the presence and absence of H2 were measured. In addition, sensing tests performed over a wide range of H2 concentrations confirmed that the sensor had a detection limit as low as 1 ppm. Furthermore, the sensor reacted within approximately 50 s at all H2 concentrations tested. The recovery time of the sensor was 32 s at 1 ppm and 78 s at 1000 ppm. Sensing tests were also performed using Pd NPs of different sizes to elucidate the relationship between the sensing rate and catalyst size. The experimental results confirmed the possibility of fabricating paper-based gas sensors with a superior sensing capability and response rate. [ABSTRACT FROM AUTHOR]

Paper‐based superomniphobic surfaces are of great interest because paper is flexible, inexpensive, lightweight, breathable, and recyclable. Prior reports on paper‐based superomniphobic surfaces have failed to demonstrate high mobility with low surface tension liquids. In order to overcome this issue, in this work, superomniphobic papers are developed through growth of nanofilaments on inherent microfibers of papers without noticeably altering their microscale features (i.e., diameter and distance of the microfibers). These superomniphobic papers display very low roll‐off angle, indicative of ultra‐high droplet mobility, even with low surface tension liquids. Here, a facile method is also developed to control the motion and adhesion of the droplets on the superomniphobic paper. Utilizing such liquid mobility in a controlled manner on these superomniphobic papers, a simple on‐paper pH sensor is fabricated. It is anticipated that this on‐paper, simple, and rapid detection methodology can also be extended to the colorimetric sensing of protein and chemical assays. Further, these superomniphobic papers have potential applications in water–oil separation and enhanced weight‐bearing capacity. [ABSTRACT FROM AUTHOR]

The article reports on the 2008 Institute of Electrical and Electronics Engineers (IEEE) Radar Conference held in Rome, Italy in 2008. The technical program covered issues in radar theory and applications and aspects of radar systems for civilian, defense applications, and technology. Also highlighted were the space-time-adaptive-processing (STAP), waveform design, and sensors. It describes 10 conference papers that delve in topics such as multiple input multiple output radar systems and the European effort on radar imaging.

A polarization independent refractive index (RI) sensor with a RI sensitivity of 50 nm/RIU is demonstrated. The proposed RI sensor simply consists of a liquid crystal (LC) polymeric polarization grating film and one glass substrate. The wavelength shift over the refractive index of surrounding medium is investigated through anisotropic rigorous coupled‐wave analysis. Such a LC‐based polarization independent RI sensor not only enables the usage of an unpolarized light source but also manifests a high sensitivity, offering great potential for the integration with display systems. [ABSTRACT FROM AUTHOR]

We have developed a nanomesh based on skin sensors that can detect physiological signals such as electrocardiogram (ECG), pressure, and acoustic detection. Nanomesh sensors have high gas permeability and softness. Owing to the high gas permeability, the nanomesh sensor did not cause inflammation when the sensor was attached to the skin for a week. Furthermore, we developed a wireless ECG monitoring system by combining a nanomesh sensor and a textile‐based wireless module. [ABSTRACT FROM AUTHOR]

Solution‐processed organic photodetectors (OPDs) have witnessed great progress in the past few years. With silicon‐like performance achieved, OPDs enable new medical imaging applications by offering cost‐effective light detection over large area. Herein, we illustrate the compelling advantages of high spatial and temporal resolution OPD arrays for medical X‐ray detectors and wearable pulse oximeters. [ABSTRACT FROM AUTHOR]

Novel multiple emitting amphiphilic conjugated polythiophene‐coated CdTe quantum dots for picogram level determination of the 2,4,6‐trinitrophenol (TNP) explosive are developed. Four biocompatible sensors, cationic polythiophene nanohybrids (CPTQDs), nonionic polythiophene nanohybrids (NPTQDs), anionic polythiophene nanohybrids (APTQDs), and thiophene copolymer nanohybrids (TCPQDs), are designed using an in situ polymerization method, which shows highly enhanced fluorescence intensity and quantum yield (up to 78%). All sensors are investigated for nitroexplosive detection to provide a remarkable fluorescence quenching for TNP and the quenching efficiency reached 96% in the case of TCPQDs. The fluorescence of the sensors are quenched by TNP through inner filter effect, electrostatic, π−π, and hydrogen bonding interactions. Under optimal conditions, the detection limits of CPTQDs, NPTQDs, APTQDs, and TCPQDs are 2.56, 7.23, 4.12, and 0.56 × 10−9m, respectively, within 60 s. More importantly, portable, cost effective, and simple to use paper strips and chitosan film are successfully applied to visually detect as little as 2.29 pg of TNP. The possibility of utilizing a smartphone with a color‐scanning APP in the determination of TNP is also established. Moreover, the practical application of the developed sensors for TNP detection in tap and river water samples is described with satisfactory recoveries of 98.02−107.50%. Amphiphilic conjugated polythiophene‐coated CdTe quantum dots with enhanced biocompatibility, fluorescence intensity, and quantum yield are developed for the selective detection of nitroexplosives. The applicability of the method is extended using a portable and cost‐effective chitosan film and a paper‐based sensor coupled with smartphone. This work reveals unique opportunities for detection of nitroexplosives in national security and environment protection. [ABSTRACT FROM AUTHOR]

Detecting antibodies in blood is as simple as it can get. In their Communication on page 15369 ff., D. Citterio, M. Merkx et al. integrate antibody‐targeting bioluminescent sensing proteins and other essential assay components into a microfluidic paper‐based analytical device. A drop of blood, a digital camera, and twenty minutes are all that is required to detect the presence and the concentration of multiple antibodies in whole blood based on the color of the emitted light. [ABSTRACT FROM AUTHOR]

This paper sets out a simple and affordable method for the manufacture of a water sensor involving drawing marks on paper using a flexible pencil. The sensor indicates flexible endurance variations upon exposure to water or a drying surface. It can be employed for the detection of water substances in ethanol. In addition, an experiment suggests the usefulness of the sensor for the sensing of breath. This shows the immense potential applications of the sensor for wearable and also health-inspecting electronic gadgetry. [ABSTRACT FROM AUTHOR]

The ability to manipulate semiconductor surfaces and interfaces has gained significant attention in the past few years, in particular to design novel routes for the development of sensors and new materials, like intelligent tissues, for bio-physics applications. In this paper, we review some recent results on the atomic manipulation of cubic silicon carbide (SiC) surfaces, as obtained by ab initio simulations, and compare them with the available experimental data. The main focus will be the study of the interaction and adsorption mechanism of simple molecules on SiC surfaces. SiC, and in particular the cubic polytype, is a wide-gap semiconductor, that for its inertness and transparency has been and still is considered a leading candidate material for biocompatible devices. [ABSTRACT FROM AUTHOR]

To determine allergen beta-lactoglobulin (β-LG) in foods, a method by a coffee-ring effect (CRE)-based paper sensor chip combined with a smartphone has been developed. The strategy was based on the principle of fluorescence quenching by the quantum dot-aptamer-graphene oxide (QD-Apt-GO) and where the degree of quenching was inversely proportional to the concentration of β-LG. First, the prepared β-LG solution was added to the QD-Apt fluorescent probe solution followed by an appropriate amount of GO. After the reaction, a certain amount of the mixture was dispensed onto the detection zone of the sensor chip, resulting in the spread of the analyte solution by evaporation-driven flow. The QD-Apt and the QD-Apt-β-LG in the mixed solution formed a visible fluorescent coffee-ring. For signal quantitation, an image of the coffee-ring was taken by a smartphone and imported into self-programmed software for analysis. The quantitative results for β-LG were acquired rapidly based on the magnitude of the generated fluorescent coffee-ring. The limit of detection (LOD) for β-LG was 0.048 mg L-1 and the linear range for the optimized assay was 0.39–1000 mg L-1. The method was validated for analysis of real food samples and the results were consistent with those of a commercial ELISA assay kit. The smartphone-based assay provides a simple, economic, compact, and visual detection platform for the determination of β-LG in foods. [Display omitted] • The area of pattern formed by coffee-ring effect on paper was utilized for visual determination of β-LG. • For signal quantitation, a special self-programmed software was developed for image acquisition and analysis. • The limit of detection of the optimized assay for β-LG was 0.048 mg L-1 and the linear range was 0.39–1000 mg L-1. • The assay was validated for analysis of real food samples. • Paper-based sensor chip with a smartphone for β-LG was carried out in a simple, economic, compact, and visual way. [ABSTRACT FROM AUTHOR]

Abstract: The (CR–LR) difference technique, based on the CR-39 and LR 115 detectors, for the determination of implanted 210Po in glass after deposition of short-lived radon progeny, was analyzed in details in this paper. The sensitivities of both detectors were calculated using the Monte Carlo method with V functions particularly derived in our previous works for the detectors used in the present experiments. The dependency of the sensitivity ratio on the removed layer of both detectors was determined and verified experimentally. The simulated sensitivity ratios correlate well with the experimental ones. A major finding of the present work is that the sensitivity ratio between the CR-39 and LR 115 detectors depends only weakly on the ratio between the 238U and 232Th concentrations in the glass samples. This is crucial for the application of the (CR–LR) difference technique for retrospective radon exposure assessments, since measurements of the 238U and 232Th concentrations in the relatively small real-life glass samples will make the retrospective radon exposure assessments impractical. [Copyright &y& Elsevier]

We apply a photolithographic patterning process to integrate a green phosphorescent organic light emitting diode (OLED) with a polymer‐based organic photodetector (OPD) side‐by‐side with resolution up to 635 ppi. The characteristics of OLED and OPD before and after patterning are investigated. The crosstalk between OLED and OPD subpixels and the linearity of the integrated OPD under different luminance are also studied. The results indicate that photolithography enabled integration is an encouraging route of organic and hybrid electronics (OHEs) manufacturing. [ABSTRACT FROM AUTHOR]

In this paper, we discovered that ZnFe2O4 magnetic nanoparticles (MNPs) possess intrinsic peroxidase-like activity. ZnFe2O4 MNPs exhibit several advantages such as high catalytic efficiency, good stability, monodispersion, and rapid separation over other peroxidase nanomimetics and horseradish peroxidase (HRP). ZnFe2O4 MNPs were used as a colorimetric biosensor for the detection of urine glucose. This method is simple, inexpensive, highly sensitive, and selective for glucose detection using glucose oxidase (GOx) and ZnFe2O4 MNPs with a linear range from 1.25 × 10-6 to 1.875 × 10-5 mol L-1 with a detection limit of 3.0 × 10-7 mol L-1. The color change observable by the naked eyes based on the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is the principle for the sensing of urine glucose level. [ABSTRACT FROM AUTHOR]

The present work describes the behaviour of nanoporous structure on two coated papers for determining their suitability for relative humidity measurement. We found that the paper with smaller pore size was better in terms of response and relative humidity range. The nanoporous inorganic thin film with high surface to volume ratio is better to detect the presence of water molecules in the environment. The hydrophilic nature of the surface coating is thus found more active compared to cellulosic paper for sensing water vapour. Prototype sensors made by us responded to the whole range of 15%− 92% RH by combining the resistance and capacitance variations of the interdigitated electrode. The resistance variations provided better response over the range of 15%− 55% RH whereas capacitance variation was better in 55%− 92% RH. The novelty of the present work is using nanocoated papers which are low cost and bio-degradable for field applications. • The present work describes the behaviour of nanoporous structure on two coated papers for determining the relative humidity measurement in the interval of 15–92%. • Prototype sensor made by us responded to the whole range of 15%− 92% RH by combining the resistance and capacitance variations of the interdigitated electrode. • The paper with smaller pore size is found better in terms of response and relative humidity range. • The novelty of the present work is using nanocoated papers which are low cost, and bio-degradable for field applications. [ABSTRACT FROM AUTHOR]

• AuNPs based ink were synthesized and formulated with three varying [Au] of 300, 600 and 1200 ppm from USP. • Rheological, flow and wetting behavior of these inks were analyzed to find out the favorable one for inkjet printing. • Furthermore, it was characterized for size, shape, purity and optimum sintering conditions. The functionality of an effective metal NPs based ink in inkjet printing depends on its ability to achieve high mass concentration as well as suitable rheological properties for stable printability. In this work, AuNPs synthesized by USP were successfully formulated in inks of varying [Au] using PVP40 as stabilizer and DI water as solvent. The influence of the increasing [Au] on the rheological, flow and wetting behavior were investigated for requisite printable characteristics. Thermo-physical characterization was carried out on the optimized concentrated AuNPs ink using TGA, DLS, SEM and EDX techniques. [ABSTRACT FROM AUTHOR]

We combine a near‐infrared (NIR) sensitive organic photodetector with a high‐resolution 508 ppi oxide TFT backplane to create a large‐area thin NIR detector. Using a NIR light source the detector is capable of imaging the (pattern of) veins under the skin in reflection, leading to improved biometric authentication. [ABSTRACT FROM AUTHOR]

This paper described the development of a small and low cost biosensor consisting of a smartphone-based electrochemical biosensor device and a paper-based biosensor. The device harvested power from the smartphone and transferred data through audio jack. We designed CMOS circuits including a power supply circuit, a potentiostat, and a ΔΣ modulator. The fabrication of a paper-based biosensor was simple: the three electrodes were directly drawn on chromatography paper using a carbon pencil. The paper-based biosensor was low cost, disposable, portable and friendly to the environment. The sensing system was designed to perform the chronoamperometry measurement, and the glucose concentration in a liquid specimen was detected. Results showed that the sensing system was capable of measuring the glucose concentration as precisely as expensive equipments. [ABSTRACT FROM AUTHOR]

Paper electronics represents a newly raised concept that includes various types of electronic devices and circuits on paper. In this work, the authors report multigate oxide‐based homojunction electric‐double‐layer thin‐film transistors (TFTs) with cellulose nanofibers electrolyte film as the gate dielectrics on paper substrate. These flexible TFTs exhibit high performance with a high ON/OFF ratio of 107 and a high mobility of around 26 cm2 V−1 s−1. Resistor‐loaded inverters are demonstrated both in a bottom‐gate mode and an in‐plane‐gate mode. Logic AND operation is realized in a device with two in‐plane gates. Significantly, the universal logic NAND is experimentally demonstrated using a one transistor/one resistor structure by combining NOT and AND logics together. The paper‐based TFT devices are very interesting for emerging areas such as disposable paper electronics and sensors. [ABSTRACT FROM AUTHOR]

With the increasing concerns of food safety and environmental protection, it is desirable to develop reliable, effective, and portable sensors for detection of organophosphorus pesticides (OPs). Here, a cascade reaction system integrated with threaded 3D microfluidic paper analytical device (3D μPAD) was firstly developed for background-free and visual detection of OPs in agricultural samples. Butyrylcholinesterase (BChE) hydrolyzed acetylcholine into thiocholine (TCh), which reduced MnO 2 nanosheets into Mn2+. With addition of OPs, BChE activity was irreversibly inhibited, and the generation of TCh and the reduction of MnO 2 nanosheets were prevented. Then the remaining MnO 2 nanosheets oxidized o -phenylenediamine into 2,3-diaminophenazine with yellow-emission fluorescence, which quenched the fluorescence intensity of red-emission carbon dots (RCDs) via inner-filter effect. Based on above mechanism, a ratiometric fluorescent system was established for OPs detection. Threaded 3D μPAD consisted of 4 layers, which allowed to load and/or add reagents to trigger the cascade reaction system for OPs detection. The fluorescent images presented distinguishable color variations from red to yellow with dichlorvos concentrations ranging from 2.5 to 120 μg L−1, and the limit of detection was 1.0 μg L−1. In the practical samples testing, threaded 3D μPAD can eliminate background influence on fluorescent signal for OPs detection. Threaded 3D μPAD integrated with ratiometric sensing platform has merits of accuracy response, facile operation, and background-free detection, which supplies a new alternative approach for on-site pesticide detection. [ABSTRACT FROM AUTHOR]

Keywords: electrochemical treatment; laser-pyrolyzed; paper-based devices; paper-based electrodes; nitrite EN electrochemical treatment laser-pyrolyzed paper-based devices paper-based electrodes nitrite 1 1 1 01/06/23 20230102 NES 230102 B The Cover Feature b illustrates eco-friendly laser-pyrolyzed paper sensors used for nitrite determination in environmental and biological samples. Cover Feature: Modulating the Electrochemical Response of Eco-Friendly Laser-Pyrolyzed Paper Sensors Applied to Nitrite Determination (ChemElectroChem 1/2023) Electrochemical treatment, laser-pyrolyzed, paper-based devices, paper-based electrodes, nitrite. [Extracted from the article]

• Modification of cellulose paper by in situ synthesis of metal-organic framework-5. • Bonding between functional groups on cellulose paper with organic ligand. • Cellulose/MOF-5 was used in the thin film solid-phase microextraction method. • Thin film showed a good ability to extraction of selective drugs in urine samples. • The method is effective, sensitive, cost-effective and have wide LDRs and low LODs. This work, reports the successful preparation a thin film by a simple and inexpensive process for quantification of a model analytes in the urine sample using HPLC-UV. To this end, cellulose paper was employed as a substrate for the in-situ synthesis of MOF-5, to increase the resistance of the prepared film. The prepared film can be reused 26 times with no reduction in its performance. The thin film prepared by MOF-5 modified cellulose substrate was utilized in thin film microextraction (TFME) method for the extraction and preconcentration of naproxen, aspirin, tolmetin, and celecoxib. Under optimal conditions, the linear dynamic range of the target analytes was 2–500 µg L −1 with correlation coefficients (R2) ranging from 0.9961 to 0.9990. Also, the limits of detection (LODs), the limits of quantification (LOQs) and relative standard deviation (RSD%) of the proposed method for selected analytes ranged between 0.57 and 0.77 µg L −1, 1.7 to 2.3 and 3.5 % to 6.2 %, respectively. Moreover, relative recoveries varied from of 94 % to 108 %, indicating the absence of matrices effect in the proposed method. Eventually, the TFME was successfully used for the extraction of selected analytes from urine samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • We developed a VK-inspired vibration sensor using advanced 3D printing techniques. • VK structures exhibit 300% out-of-plane strain, surpassing conventional spring structures with only 25% strain. • VK structures offer shape programmability for precise frequency applications, including 2 Hz. • Achieving a sensitivity of 0.80 pF/ms−2, we successfully demonstrated a wireless structural health monitoring application. Kirigami is an ancient paper art that involves cutting slit strategies, which could provide exotic and controllable engineering properties. Especially, kirigami can be combined with bio-inspired designs to improve its mechanical behaviors. A highly sensitive 3D vibration sensor has been developed using a 3D-printed structure inspired by vorticella-kirigami (VK). VK-inspired kirigami exhibits 2D-to-3D morphing and shape-programmable properties. Specifically, the VK-inspired vibrational structure has been optimized for a frequency of 2 Hz, with high sensitivity of 0.80 pF/ms−2. Structural health monitoring (SHM) is an essential application for ensuring the safety and reliability of civil infrastructure. Therefore, the tools for widely and easily accessible monitoring systems are highly demanded, considering a monitoring system with Internet-of-Things (IoT) as a promising application in this paper. The VK-inspired vibrational sensors can detect the impact delivering from the epicenter on fragile components of the structural structures through the message queuing telemetry transport (MQTT) protocol. Moreover, it allows seamless access to real-time or saved vibration data via multiple smartphones and personal computers. These SHM technologies hold the potential to significantly enhance their adoption in safety–critical domains. [ABSTRACT FROM AUTHOR]

Using Hg2+-promoted deprotection reaction, we have developed a new fluorescent turn-on sensor 2TS based on bithiophene fluorophore for Hg2+ detection. The sensing mechanism of 2TS towards Hg2+ was strongly proved by 1H NMR, FTIR, HRMS, UV–vis and fluorescence spectra. Remarkly, 2TS towards Hg2+ in 100% aqueous solution shows high sensitivity with a low detection limit of 19 nM, superior selectivity and ultra-rapid response of 20 s during a wide sensing pH range from 4 to 10. Taking advantage of the excellent properties, the low-cost sensor 2TS -based filter paper/TLC test strips were fabricated for visual, immediate and quantitative detection of Hg2+ in water, proving its applicability towards sensitive in-situ and on-site detection. Meanwhile, 2TS showed high analytical performance for Hg2+ detection in water, seafood as well as human urine samples. Moreover, thanks to the good water solubility, negligible cytotoxicity, good biocompatibility and cell-membrane permeability, 2TS was further applied to effectively image Hg2+ in live cells. Furthermore, the developed sensor 2TS acted as good fluorescent display material for Hg2+ with obvious color change. Unlabelled Image • A new turn-on fluorescent sensor 2TS for Hg2+ in 100% aqueous solution was developed. • 2TS features good selectivity, ultra-sensitivity, ultra-rapid response towards Hg2+ in a wide sensing pH range. • 2TS was used to detect Hg2+ in water, seafood, human urine, test strips and living cells. • 2TS was used as fluorescent display material for conveniently detecting Hg2+. [ABSTRACT FROM AUTHOR]