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Quantitative oxygen detection is of great importance in biological fields, complex environments, and chemical process engineering. Due to the high sensitivity and rapid response of long-lived phosp...

We utilized a seeded growth method to synthesize SiO2@Ag NPs with tunable plasmonic resonance peak to investigate the effect of spectral overlap between the SiO2@Ag plasmonic resonance spectrum and the PtTFPP‐based oxygen sensors’ absorbance spectra on luminescence enhancement and performance optimization. An organic silicate was used as the matrix. Oxygen‐sensors were produced by directly casting the mixture of NPs and dyes with silicate gels onto glass slides. Oxygen‐induced spectral response of the PtTFPP was obtained as the analytical signal. Our results show that when the plasmonic resonance spectrum of SiO2@Ag has a maximum wavelength overlap with the absorbance spectra of dyes, the Stern‐Volmer slopes were enhanced by almost an order of magnitude. At 21% O2, the Stern‐Volmer plot achieved a maximum seven‐fold increase over the oxygen sensor without the metal‐enhanced luminescence. Our results also show that 10% wt NPs is the optimal amount for the PtTFPP‐SiO2@Ag based oxygen sensors that can eliminate self‐quenching and the NRET process. These data confirm that the spectral overlap between the dyes and noble metal NPs and how to eliminate self‐quenching and the NRET process are vital to high‐sensitive oxygen sensors. We have also shown that our fabrication process of these oxygen sensors is repeatable.

Chemical sensors are measurement devices that convert a chemical or physical property of a specific analyte into a measurable signal, whose magnitude is normally proportional to the concentration of the analyte [...]

Optical oxygen sensors based on photoluminescence quenching have gained increasing attention as a superior method for continuous monitoring of oxygen in a growing number of applications. A simple and low-cost fabrication technique was developed to produce sensor arrays capable of two-dimensional oxygen tension measurement. Sensor patches were printed on polyvinylidene chloride film using an oxygen-sensitive ink cocktail, prepared by immobilizing Pt(II) mesotetra(pentafluorophenyl)porphine (PtTFPP) in monodispersed polystyrene microparticles. The dispersion media of the ink cocktail, high molecular weight polyvinyl pyrrolidone suspended in 50% ethanol (v/v in water), allowed adhesion promotion and compatibility with most common polymeric substrates. Ink phosphorescence intensity was found to vary primarily with fluorophore concentration and to a lesser extent with polystyrene particle size. The sensor performance was investigated as a function of oxygen concentrations employing two different techniques: a multi-frequency phase fluorometer and smart phone-based image acquisition. The printed sensor patch showed fast and repetitive response over 0-21% oxygen concentrations with high linearity (with R(2) >0.99) in a Stern-Volmer plot, and sensitivity of I(0)/I(21) >1.55. The optical sensor response on a surface was investigated further using two-dimensional images which were captured and analyzed under different oxygen environment. Printed sensor patch along with imaging read-out technique make an ideal platform for early detection of surface wounds associated with tissue oxygen.

In Ukraine today there are more than 6000 boiler plants with a heating capacity of up to 1 Gcal/h with an efficiency of about 70 %, requiring replacement or modernization, 40 % of boilers are operated with an efficiency of less than 82 %, about 11000 boilers with a capacity of 100 kW to 1 MW have been in operation for over 20 years. Although the part of these boilers in the municipal heat power system of Ukraine does not exceed 14 %, the projected savings in natural fuel in these boilers is more than 130 million cubic meters per year. Thus, increasing the efficiency of the fuel combustion process in small and medium power boilers is an urgent task at the present time. The article presents the results of creating a method and hardware that implements it, to increase the speed and reliability of monitoring the process of fuel combustion in boiler units based on measuring the concentration of residual oxygen in exhaust gases. The developed method is implemented by stepwise correction of the ratio of the air-fuel mixture entering to the furnace of the boiler for combustion, according to feedback signals from a broadband oxygen sensor manufactured by Bosch, located in the outgoing channel. The air-fuel ratio control with automatic adjustment of the blower fan speed depending on the amount of fossil fuel supplied for combustion ensures low-toxic combustion of fuel with low emissions of nitrogen oxides and carbon monoxide, and high efficiency. Additional use of a variable frequency drive in the combustion control system allows to reduce energy consumption by 30-40 %, eliminate starting currents and motor overloads, reduce mechanical wear of equipment, increase the service life of contact switching equipment. In general, the developed fuel combustion control system allows to optimize the fuel combustion mode, taking into account the actual conditions, operating modes of the boiler unit and fuel characteristics; to reduce specific fuel consumption by at least 10%; to reduce the level of emissions of nitrogen oxides up to 40 % and carbon monoxide up to 50 %; to increase the efficiency by at least 5 %; qualitatively to simplify the work of the boiler maintenance personnel.

In an oxygen consumption calorimeter system for measuring heat release rate, the CO/CO2 analyzer and the O2 analyzer for chemical species analysis of the sampling gas are the main factors that increase the construction cost of the system. In this experimental study, a low-cost device with performance similar to that of the existing high-cost device was developed. To evaluate the contribution of the CO/CO2 analyzer to the measurement of the heat release rate, the performance of unsteady and steady-state conditions depending on whether CO/CO2 was measured for diffusion flames with various fire growth rates was examined. As a result, it was confirmed that when only the O2 concentration was considered, the heat release rate could be measured accurately. Based on these results, the measurement performance of a low-cost O2 analyzer manufactured using an oxygen sensor for healthcare was verified. As a result of the verification of the low-cost O2 analyzer for diffusion flames with various fire growth rates, it was confirmed that the relative error was within 10% for unsteady and steady-state fire sources and can be used to measure the heat release rate.

There is a strong demand for reliable oxygen sensors in the fields of fitness tracking, health monitoring, and medical diagnostics. Recently, oxygen-sensing materials based on phosphorescence quenching by oxygen have attracted interest due to their high sensitivity, rapid response, and suitability for directly imaging oxygen distribution on large tissue areas. Here we tested different compositions of metalloporphyrins and their support matrices and identified optimal materials that can be applied to oxygen-sensing devices. Our results showed that a pivaloyl-terminated metalloporphyrin embedded in poly(propyl methacrylate) (PPMA) exhibits the highest porphyrin emission brightness and oxygen-dependent phosphorescence intensity changes can be easily visualized even by eye under ambient light. In vivo studies revealed that our PPMA-based, highly breathable oxygen-sensing films can be used to non-invasively detect changes in tissue oxygenation in a rabbit model, a promising step for integration into wearable devices. In addition, it was found that an alkyne-terminated metalloporphyrin embedded in tetraethyl orthosilicate (TEOS) shows the most rapid response time. The detailed composition exploration and material characterization described in this study provides a good resource towards developing more versatile oxygen-sensing devices.

Fast response rate is a desirable character of gas sensors to monitor kinds of environments. In order to improve the response and recovery rate of YSZ-based electrochemical oxygen sensors, the laser ablation method was used to modify surface of YSZ substrates, and the effect of triple phase boundary (TPB) was studied. Results have shown that the increment of the TPB density can substantially improve the response rate, especially at a relative low working temperature (500 °C), and the max increment that is 70% was realized. Meanwhile, the sensor exhibited good selectivity toward interferences of reducing gases at this relative low working temperature. The results had provided a convenient and steerable way to improve the response, recovery rate, and electrochemical catalytic activity of YSZ-based electrochemical devices at medium and low working temperature.

Irrespective of the change in kind of energy to renewables there are many processes in which combustion of conventional fuels and biofuel are necessary. For cement and glass production, paper fabrication and air traffic it is absolutely essential to control the combustion processes by intelligent sensors in order to maximize the efficiency and to minimize the emission of harmful substances such as NOx and CO. Mainly oxygen sensors based on solid electrolytes and calorimetric sensors using the heat formation by catalytic combustion of CO and hydrocarbons with two resistance temperature detectors (RTD) are utilized. Recently, tunable diode laser spectroscopy (TDLS) became attractive in chemical plants. Several analytical companies are offering in-situ or extractive laser analyzers for combustion gases.

During the operation of internal combustion engines the air-fuel ratio (A/F) is an important parameter which affects fuel consumption and pollutant emissions. The automotive oxygen sensor (Lambda) measures the quantity of residual oxygen in the combustion gases. Sensor degradation in time due to the exposure to high temperatures causes a distortion in controlling the A/F with the increase in gas emissions. In this paper an experimental stand is designed to test oxygen sensor degradation in laboratory condition. Four oxygen sensors were tested function of temperature and time recording their variation in resistance and voltage. The results showed similar values in the curves for all sensors tested.

Multisensor detectors have merits of low cost, compact size, and capability of supplying accurate and reliable information otherwise hard to obtain by any single sensors. They are therefore highly desired in various applications. Despite the advantages and needs, they face great challenges in technique especially when integrating sensors with different sensing principles. To bridge the gap between the demand and technique, we here demonstrated an integration of electrochemical and colorimetric sensors with a webcam readout for multiple gas detection. Designed with two parallel gas channels but independent sensor cells, the dual-sensor detector could simultaneously detect each gas from their gas mixture by analysis of the group photo of the two sensors. Using Ag electro-dissolution as reporter, the bipolar electrochemical sensor achieved quantitative analysis for the first time thanks to application of pulse voltage. The sacrificed Ag layer used in the bipolar electrochemical (EC) sensor was recycled from CD, which further decreased the sensor cost and supplied a new way of CD recycling. The EC O2 sensor response, edge displacement of Ag layer due to electrochemical dissolution, has a linear relationship with O2 concentration ranging from 0 to 30% and has good selectivity to common oxidative gases. The colorimetric NO2 sensor linearly responded to NO2 concentrations ranging from 0 to 230 ppb with low detection limit of 10 ppb, good selectivity, and humidity tolerance. This integration method could be extended to integrating other gas sensors.

In this paper, we report the scalable, high sensitivity, fast response, and low operating temperature Cerium oxide (CeO2) thin film-based oxygen sensors by optimizing CeO2 film thickness. CeO2 thin films of thickness ranging from 90 to 340 nm have been deposited at 400°C using radio frequency (RF) magnetron sputtering on Al2O3 substrates. Ellipsometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize the CeO2 films for their thickness, structural, compositional/chemical, and surface morphology properties. Gas sensors have been fabricated using CeO2 film as a sensing material and tested in an oxygen gas environment. CeO2 film with an optimum thickness of 260 nm has shown high sensitivity (12.6) and fast response time (≤10 s) along with fast recovery time (15 s) at a low operating temperature of 400°C. To the best of our knowledge, these are the best values reported till date for undoped CeO2 thin film-based oxygen sensors. Furthermore, from the sensor’s response, it was observed that there was no drifting from the baseline. This superior performance of CeO2 thin film-based oxygen sensor may be attributed to the combination of three factors, i.e., 1) high surface energy and reactivity due to the presence of (200) oriented CeO2 plane; 2) low resistance due to better crystallinity; and 3) perfect stoichiometry with required roughness.

The method of fuel quality control is considered, which is based on the using of the oxygen sensor (without sensors of incomplete fuel combustion products). An algorithm for the electric drive of a fan is proposed, which is based on a step changing in the rotation speed. The choice of broadband oxygen sensor as a basis for the development of a fuel combustion control system is determined. In the course of experimental studies, the possibility of reconstructing the boiler by replacing a burner with an installed control system was demonstrated. The commissioning works were carried out with the installed system, the optimum operating conditions of the boiler were determined (with the formation of CO in the flue gases at a minimum level

Luminescent oxygen sensor composed of platinum-porphyrin and a gas-permeable polymer binder was applied as an optical crack sensor paint for infrastructure. The sensor paints were designed as a three-layered structure in which the luminescent oxygen sensor layer was sandwiched between oxygen barrier layers. The sensor paints emitted intense luminescence under UV light irradiation, and the luminescence was efficiently quenched when a new crack formed on the concrete surface. Microcracks, which were

We present a sensor system to monitor the uptake of oxygen by mammalian cells as a direct indicator for the metabolism under consideration of the requirements for the usage in biolabs. That includes reliable oxygen sensing as well as a small footprint of the setup without sophisticated external equipment, the usage of compatible materials and the suitability for a high degree of integration and automation. These requirements are fulfilled by a system that consists of a microfluidic chip with an integrated oxygen-sensitive phosphorescent film, heater and temperature sensor, external optical read-out and 3D-printed holders and housing. The chip with the closed microfluidic chamber is made by clean-room technologies out of silicon and glass. An excitation LED and a small and low-cost Raspberry Pi camera are used to measure the phosphorescent signal. With this system, the concentration of dissolved oxygen can be determined with an accuracy of ±0.8% (air) for oxygen concentrations between 0 and 26% (air) and at any temperature between 23 and 41 °C. To demonstrate the capabilities, the oxygen consumption rates of HaCaT-cells (human keratinocyte cell line) are determined at different temperatures.

A freestanding, miniaturized electrochemical oxygen sensor for biomedical implantation has been microfabricated and characterized. The sensor is fabricated on a flexible and biocompatible polyimide substrate using lithographic techniques and singulated with an excimer laser. The sensor consists of a round-shaped planar sensing portion (diameter: 2.4 mm and thickness: $180~\mu \text{m}$ ) and metal lines and contact pads for connection with external analytical tools. The sensing portion is comprised of three electrodes (working, counter, and reference electrodes), an electrolyte reservoir filled with liquid electrolyte, and a semipermeable membrane for oxygen introduction. The electrodes are patterned using a single layer of gold without the adhesion layer to eliminate any multilayer metallic structure in the sensing region. Both polydimethylsiloxane and fluorinated ethylene propylene semipermeable membranes are characterized. The fabricated sensor demonstrated an oxygen response of −14 nA/atm.% and good linearity (correlation coefficient exceeding 0.99). This device can potentially be incorporated into physiological applications, including monitoring oxygen tension in biomedical-related applications over semi-chronic time periods. [2019-0004]

Research in wearable electronics has paved the way for next-generation technology, sought to create point-of-care biosensors that combine chemical sensing on a biocompatible platform with a broad range of applications in human health monitoring. Despite significant progress, the microspatial mechanical mismatch and fluid-impermeable interface presented between skin and the electronics create adscititious problems in device lamination, conformality, and long-term monitoring. Herein, we engineered a skin-inspired, deterministically patterned, electrochemical biosensor that can be fully integrated with the curvilinear surface of the human body, while mechanically adapting to the natural stresses applied to the skin and allowing the mass transfer of gas and fluids. In particular, we developed mechanically-compliant lattice-structured biosensors for the continuous evaluation of lactate and oxygen. Systematic studies of the sensor performance were evaluated with variations in polymeric membranes and its ability to withstand commonplace harsh, multiaxial stresses.

Polymeric microfibers, particularly the fluorinated copolymers’ fibers, are promising functional materials for photoelectric devices, sensing, and energy storage due to their various surface characteristics. However, to obtain the high fluorine content copolymer-based fibers with considerable uniformity is likely to be especially challenging, which seriously debilitates their applications in sensor devices. Herein, for the first time, we presented a high fluorine content platinum porphyrin-grafted poly(isobutyl methacrylate-co-dodecafluoroheptyl methacrylate) copolymers (PtTFPP-p(IBM-co-DFHMA)) microfibrous thin-films used as optical oxygen sensors. The porous thin-film frameworks were formed of uniform microfibers, which afforded an exceptional improvement in sensitivity and exhibited 584% higher sensitivity than the solid sensing film owing to the large specific surface area, porous structures and oxygen diffusion enhancement by fluorine elements. Additionally, the remarkable emission intensity-changing characteristic of the microfiber sensing film under various air pressures facilitates convenient visualization of pressure distributions on film surface. The characteristics are particularly important for the computational fluid dynamics simulations in various sensing fields such as unsteady flow visualization and unsteady pressure measurements, etc. Owing to its attractive advantages and versatile performance, fluorine-containing copolymers fibers are expected to provide a new strategy for the rational design of high performance gas sensor devices.

This work proposes the oxygen sensing by an Electrostatic Charge Plasma (E-CP) based Rectangular Gate All Around NWFET (Nanowire Field Effect Transistor), RGAANFET. We have used Silver as the gate metal to due to its reactivity towards the gas and IGZO as the material for channel. The gas sensing has been done by studying the variations (due to the presence of gas) in the different parameters of the RGAANFET. Gas presence has been simulated by the variation of the work function of the metal gate. We have also tried to record the effect over sensitivity due to various factors like dielectric and distinct lengths of channel. We have made the device more efficient than the last proposed devices.

Vacuum packaging (VP) is used to reduce exposure of retail meat samples to ambient oxygen (O2) and preserve their quality. A simple sensor system produced from commercial components is described, which allows for non-destructive monitoring of the O2 concentration in VP raw meat samples. Disposable O2 sensor inserts were produced by spotting small aliquots of the cocktail of the Pt–benzoporphyrin dye and polystyrene in ethyl acetate onto pieces of a PVDF membrane and allowing them to air-dry. These sensor dots were placed on top of the beef cuts and vacuum-packed. A handheld reader, FirestinGO2, was used to read nondestructively the sensor phase shift signals (dphi°) and relate them to the O2 levels in packs (kPa or %). The system was validated under industrial settings at a meat processing plant to monitor O2 in VP meat over nine weeks of shelf life storage. The dphi° readings from individual batch-calibrated sensors were converted into the O2 concentration by applying the following calibration equation: O2 (%) = 0.034 * dphi°2 − 3.413 * dphi° + 85.02. In the VP meat samples, the O2 levels were seen to range between 0.12% and 0.27%, with the sensor dphi signals ranging from 44.03° to 56.02°. The DIY sensor system demonstrated ease of use on-site, fast measurement time, high sample throughput, low cost and flexibility.

During a first-in-humans clinical trial investigating electron paramagnetic resonance tumor oximetry, a patient injected with the particulate oxygen sensor Printex ink was found to have unexpected fluorodeoxyglucose (FDG) uptake in a dermal nodule via positron emission tomography (PET). This nodule co-localized with the Printex ink injection; biopsy of the area, due to concern for malignancy, revealed findings consistent with ink and an associated inflammatory reaction. Investigations were subsequently performed to assess the impact of oxygen sensors on FDG-PET/CT imaging. A retrospective analysis of three clinical tumor oximetry trials involving two oxygen sensors (charcoal particulates and LiNc-BuO microcrystals) in 22 patients was performed to evaluate FDG imaging characteristics. The impact of clinically used oxygen sensors (carbon black, charcoal particulates, LiNc-BuO microcrystals) on FDG-PET/CT imaging after implantation in rat muscle (n = 12) was investigated. The retrospective review revealed no other patients with FDG avidity associated with particulate sensors. The preclinical investigation found no injected oxygen sensor whose mean standard uptake values differed significantly from sham injections. The risk of a false-positive FDG-PET/CT scan due to oxygen sensors appears low. However, in the right clinical context the potential exists that an associated inflammatory reaction may confound interpretation.

Oxygen is crucial for normal tissue function and repair. We have developed a toolkit of optical oxygen sensors that can be made into a wide range of materials and form factors for biomedical sensing applications.

Fuel cells (2021). doi:10.1002/fuce.202100034, Published by Wiley-VCH, Weinheim

We report an oxygen sensor based on laser photothermal spectroscopy in a hollow-core fiber with double transmission (i.e., visible and near infrared) bands. With a 4.3-cm-long hollow- core fiber as the gas cell, we demonstrated oxygen detection down to 1800 ppm.

Oxygen concentration is an essential parameter in in vitro cell cultures as it affects cell viability, cellular activity, cell differentiation, and can be a measure for cellular response. Organ-on-chip (OoC) devices provide an in vitro cell culture method, aiming to mimic the in vivo situation better than conventional cell culture methods. Oxygen control in these OoC devices is very meaningful especially for organs with inherently large oxygen concentration gradients, such as the gut. Here, we show a versatile fabrication method for optical oxygen sensor patches based on platinum tetrakis (pentafluorophenyl) porphyrin (PtTFPP) in polystyrene (PS). The PtTFPP/PS sensors show a linear Stern Volmer calibration plot. The proposed fabrication method allows abundant design freedom regarding both the sensor patches (size and shape) and integration (site and number of patches) in a typical two-channel OoC device.

In most optical-based oxygen sensors, fluorescent quenching is used as the sensing principle. Intensity and lifetime are two known measurement techniques that are employed to quantify the measured parameter. The lifetime measurement technique has superior features such as little or no sensitivity to changes in the optical path, degradation of the film or photo-bleaching. In this study, we conducted an experiment to analyze the performance of both the intensity and lifetime measurement techniques of a platinum-porphyrin fluorescent film, the sensing material, under different concentrations of oxygen. A prototype that deploys an analog front-end, a light emitting diode driver, and a power management block is implemented on a printed circuit board with commercial off-the-shelf components. The system resolves changes in oxygen pressure from 0.5 mmHg to 500 mmHg with a power consumption of 132 mW. This system could be potentially used to measure the concentration of oxygen diffused through the skin, also known as transcutaneous measurement of oxygen. These measurements are key to developing more sophisticated read-out circuits for reliable and sensitive medical purpose transcutaneous oxygen sensing.

In this work it is reported about the development and characterization of a microwave interdigital capacitor (IDC). The IDC structure was realized in microstrip line technology and its surface was functionalized by screen printing a titanium-dioxide (TiO 2 ) layer on the electrodes and the sensing properties towards O 2 have been evaluated. Electrical characterization was carried out in a frequency range spanning from 1.5 GHz to 3.5 GHz. The sensor response was evaluated at different binary gas mixtures O 2 /N 2 by means of an Agilent 8753ES Vector Network Analyzer (VNA).

We present a solution-processed flexible organic photodiode (f-OPD) with a bulk heterojunction (BHJ) structure based on a blend of poly (3-hexylthiophene-2,5-diyl) and 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 (P3HT:PCBM). We used Cs2CO3-doped polyethyleneimine ethoxylated (d-PEIE) as the electron transport layer (ETL) material, which significantly improved the electron injection properties of the f-OPD. Compared with f-OPDs with conventional ETL materials such as Cs2CO3, the external quantum efficiency (EQE) of the d-PEIE-based f-OPD was highly improved. Analytical results showed that the d-PEIE reduced the work function of the cathode, thereby facilitating the efficiency of electron injection from the active layer (AL) to the cathode of the f-OPD. In addition, after 10,000 cycles of tensile bending at a bending radius of 5 mm, the normalized ID variation (ID/ID0) in the d-PEIE-based f-OPD remained above 90%, indicating an excellent device bending stability. Finally, f-OPD-based luminescent oxygen (O2) sensors were successfully fabricated consisting of a photoluminescent O2 sensing film, a light source, and an f-OPD. The O2 sensors based on d-PEIE-based f-OPDs showed the highest photocurrent and O2 sensitivity in relation to the O2 concentration compared with O2 sensors based on f-OPDs with conventional ETL materials.

Automotive industry targets such as complying with emission legislations and increasing fuel economy, require the improvement of air-fuel ratio control systems. Oxygen sensors are a crucial part of these control systems and regulations oblige monitoring of their performance and detecting sensor-related faults. The primary purpose of this paper is to develop a methodology for precise and accurate monitoring and diagnosis of oxygen sensors to meet legislations and performance targets while the required calibration effort is reduced. Input parameters with the highest correlation factors were selected to be utilized in different system identification methodologies to statistically determine the most fitting model. In the end, a NARX model with two hidden layers and eight neurons in each hidden layer with standard deviation and mean threshold values was determined to be the optimum design to detect if the oxygen sensor was functioning or faulty.

Additive manufacturing has gained a lot of interest in recent years to create customized reactors and equipment for milli- and micro flow applications. This work presents the development of 3D printed stainless steel reactors for the oxidation of Grignard reagents in flow. In our first approach a 3D printed micro CSTR-cascade was designed as a tool to get more insight in the reaction kinetics. Novel optical sensors were integrated inline in the cascade to monitor the oxygen consumption in real time. Based on the obtained experimental data and CFD simulations, a customized 3D printed split and recombine reactor was designed especially for the needs of the reaction.

Oxygen concentration in living organisms is one of the important vital indicators in emergency care and bedside medical settings. However, the oximetry method has limitations: the measurement site is limited to the tissue containing blood and the absolute value of oxygen concentration cannot be measured. To overcome these limitations, in this work, we develop a new oxygen sensor that can directly measure the oxygen particle pressure (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$p\text{O}_{2}$ \end{document}) on the surface of the body and organs. A light emitting diode (LED) and a photodiode (PD) were embedded in a dimethylpolysiloxane substrate mixed with carbon nanotubes. The effectiveness of the device was evaluated using calibration, bending strain tests, time and frequency response, and finally in vivo assessments. The results reveal that the calibration experiment of the fabricated oxygen sensor device showed high sensitivity. The carbon nanotube electrode has a sufficient bending resistance and does not affect the response characteristics of the LED and PD, that is, it does not affect the oxygen measurement. In vivo assessment shows that the developed patch-type flexible oxygen sensor can accurately measure \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$p\text{O}_{2}$ \end{document} by attaching it to tissues or organs having irregularities or curved surfaces and actual measurements on rat liver surface demonstrated its feasibility., We present a new oxygen sensor that can directly measure the oxygen particle pressure (pO2) on the surface of the body and organs. In vivo assessment shows that the developed patch-type flexible oxygen sensor can accurately measure pO2 with high sensitivity on tissues or organs with irregularities or curved surfaces.

Nanoporous material-based sensors promise easier integration into portable devices. Here, we use a nanoporous layer (∼130 nm thick) fabricated on a cover glass as a planar waveguide and integrated sensing surface. A combination of custom-built planar waveguiding experiments and the Zemax ray tracing model confirmed that the nanoporous surface produced an increased in-plane waveguide signal output in backscattering mode. Also, by addition of a fluorophore (coumarin 6) on the surface, the nanoporous glass showed increased interactions between the dye and in-plane waveguided light, resulting in 4–6× higher emission. Utilizing the nanoporous glass as an integrated chemical and mechanical surface, we report a fluorescent planar waveguide-based oxygen sensor that is operational in backscattering mode. We showed an 11× improvement in the sensing signal upon using an appropriate filter and a ∼2× overall improvement for the nanoporous glass over plain glass in oxygen sensing. The Stern–Volmer (SV) plot confirmed a...

We present a new concept for a wearable oxygen (O2) sensor for transcutaneous O2 pressure (tcpO2) monitoring by combining the technologies of luminescent gas sensing and wearable devices. O2 monitoring has been exhaustively studied given its central role in diagnosing various diseases. The ability to quantify the physiological distribution and real-time dynamics of O2 from the subcellular to the macroscopic level is required to fully understand mechanisms associated with both normal physiological and pathological conditions. Despite its profound biological and clinical importance, few effective methods exist for noninvasively quantifying O2 in a physiological setting. The wearable sensor developed here consists of three components: a luminescent sensing film attached onto skin by a carbon tape, an organic light-emitting diode (OLED) as a light source, and an organic photodiode (OPD) as a light detector. All the components are solution-processable and integrated on a plane in a bandage-like configuration. To verify the performance, tcpO2 variations by pressure-induced occlusion were measured in the lower arm and a thumb by the wearable sensor, and the results were comparable to those measured by a commercial instrument. In addition to its flexibility, other features of this sensor render it a potential low-cost solution for the simultaneous monitoring of tcpO2 in any part of a body.

Semiconductors, based on their unique properties, are widely used in various fields such as in sensors, information and energy technologies, which are usually contact with metallic substances. Among them, oxygen vacancy semiconductors have a wide range of applications such as oxygen sensors, transparent electrodes, and oxygen separation membranes. Herein, the effect of oxygen vacancy semiconductor on facilitating the dense oxide layer formation at its metal interface was demonstrated, which might have a profound effect on many related areas. Corrosion of metal not only causes tremendous economic loss, but also leads to structural failure that brings about catastrophic consequences to human society and environment. In this manuscript, black TiO2 (BT) nanowires, a model of oxygen vacancy semiconductor, were prepared by chemical reduction of white TiO2 (WT) nanowires with NaBH4 and served as an additive in epoxy coatings to protect the metal substrates. The experimental results demonstrate that coatings containing BT nanowires exhibit superior ability to ordinary TiO2 nanowires in the formation of dense oxide layer at the steel/coating interface. Finally, the experimental results were discussed and the mechanism was proposed.

Sensitivity enhancement of optical oxygen sensors is crucial for the characterization of nearly anoxic systems and oxygen quantification in trace amounts. In this work, for the first time we presented the introduction of silver nanowires (AgNWs) as a sensitivity booster for optical oxygen sensors based on AgNWs–palladium octaethylporphine–poly(methyl methacrylate) (AgNWs@PdOEP–PMMA) microfiber mats prepared by electrospinning. Herein, a series of sensing microfiber mats with different loading ratios of high aspect ratio AgNWs were fabricated, and the corresponding sensitivity enhancement was systematically investigated. With increasing incorporated ratios, the AgNWs@PdOEP–PMMA-sensing microfiber mats exhibited a swift response (approx. 1.8 s) and a dramatic sensitivity enhancement (by 243% for the range of oxygen concentration 0−10% and 235% for the range of oxygen concentration 0–100%) when compared to the pure PdOEP–PMMA microfiber mat. Additionally, the as-prepared sensing films were experimentally confirmed to be highly photostable and reproducible. The advantages of AgNW-induced sensitivity enhancement could be useful for the rational design and realization of revolutionary highly sensitive sensors and expected to be readily applicable to many other high-performance gas sensor devices.

As the ceramic substrate materials in automobile oxygen sensor, 5YSZ/Al2O3matrix composite ceramic with different amount of silica are prepared by ball-milling,tape casting and sintering.They are investigated for their microstructure and mechanical properties.The microstructure of the sample is analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX).Fracture strength is measured by ring-on-ring method. It is found that adding 1 wt.% SiO2into 5YSZ/Al2O3matrix can improve the strength of composite ceramics.

The Oxygen Analyzer is a tool for measuring the oxygen content in a gas exhaust system. The Oxygen analyzer is used in various fields including the fields of industry and health. In the health sector, the Oxygen Analyzer is used to measure oxygen content in Continuous Positive Airway Pressure (CPAP), anesthetic machines, ventilator machines, or oxygen cylinders. In this study the researchers made an Oxygen Analyzer that can read oxygen levels 21% 100% with a reading range per digit. This study uses an oxygen sensor that serves to detect oxygen levels which is set with an Arduino Uno microcontroller. The testing is carried out directly on a ventilator as a comparison tool. The method of data analysis in this study uses descriptive analysis. In this study the tool created was able to detect the value of oxygen levels in the range of 21% - 100% with an average error of 0.01%.

We report a novel, simple and cheap generator–collector electrode system, employing platinum leaves, with micron-sized pores and typically 100–300 nm thickness, sandwiched with a porous track etch membrane spacer with typically 30 nm diameter pores. The electrode assembly is sealed into a polymer lamination pouch with one side 2 mm diameter exposed to electrolyte solution. The generator electrode with sweeping potential (top or bottom electrode) shows transient current with high capacitive current component. The collector electrode with fixed potential shows well-defined steady state current response at low potential sweep rates. The fabricated device shows good performance in monitoring both 1,1′-ferrocenedimethanol oxidation and proton reduction redox processes. Oxygen sensor signals are assigned to a lowering of the steady state proton reduction current.

Oxygen (O2) sensors are needed for monitoring environment and human health. O2 sensing at low temperature is required, but studies are lacking. Here we report, for the first time, that the performance of a field effect transistor (FET)-type O2 sensor operating at 25 °C was improved greatly by a physisorption sensing mechanism. The sensing material was platinum-doped indium oxide (Pt-In2O3) nanoparticles formed by an inkjet printer. The FET-type sensor showed excellent repeatability under a physisorption mechanism and showed much better sensing performance than a resistor-type sensor fabricated on the same wafer at 25 °C. The sensitivity of the sensor increased with increasing Pt concentration up to ∼10% and decreased with further increasing Pt concentration. When the sensing temperature reached 140 °C, the sensing mechanism of the sensor changed from physisorption to chemisorption. Interestingly, the pulse pre-bias before the read bias affected chemisorption but had no effect on physisorption.

Luminescence-quenching based optical oxygen sensors have wide applications in many fields, which have already replaced almost 40% of the commercial market share dominated previously by the Clark oxygen electrode. The majority of optical oxygen sensors are based on lifetime measurement, which are precise, but are relatively expensive, and require high-speed electronics and detecting circuits. Alternatively, oxygen concentration can be measured via a luminescence intensity change, which is a referenced approach according to the Stern-Volmer equation. However, luminescence intensity based measurement tends to be highly influenced by background light. At a given sensor composition, different instrumentation setups, sensor surface roughnesses and thicknesses, and environmental light will result in significantly different calibration curves and sensitivities. This makes luminescence-intensity based optical sensors almost impossible to use practically, because each sensor needs to be recalibrated before use, and the calibration curve each time is quite different. We have solved this problem by introducing a new background-subtraction strategy. After background subtraction, oxygen sensors with different probe concentrations, instrumentation setups, surface roughnesses, supporting matrixes, and at different temperatures present identical calibration curves. This could greatly reduce the calibration task during practical use. Combined with the advantages of low price and a simple optical configuration, the new method will significantly promote wider applications of optical oxygen sensors.

A fully integrated dissolved oxygen (DO) sensor was fabricated using laser induced graphene (LIG). The LIG was patterned on polyimide (Kapton) film using CO2 laser followed by the electrodeposition of colloidal platinum to form the electroactive sensing area. The sensing area was insulated in an oxygen gas permeable membrane for selective detection of DO. The fabricated sensor demonstrated excellent catalytic activity towards the reduction of oxygen with a sensitivity of 246.66 µA/mMcm2 over a linear detection range of 30 µM to 400 µM. The sensor exhibited a limit of detection (LOD) of 2.4 µM DO and fast response time of 2 s. The LIG-based DO sensor also exhibited good selectivity and stability. The sensor was further evaluated in a cell culture system to monitor DO to maintain cell culture viability. The DO sensor showed good performance in detecting oxygen in fresh medium (82.2 µM), at 80% cell confluency (102.37 µM), and at 100% confluency (93.52 µM). The performance of the DO sensor offers great promise for detecting dissolve oxygen in cell culture systems for biomedical and environmental applications.

A self-powered flexible oxygen gas sensor has been developed for intelligent food packaging, which provides users with information on quality and safety of packaged food during storage and transport. Unlike most conventional oxygen sensors for intelligent packaging, this sensor based on an electrochemical battery requires no external power sources for oxygen sensing. The self-powered flexible oxygen sensor was composed of three layers: a silver-deposited oriented polypropylene film (cathode), a zinc sheet (anode), and an adhesive gel electrolyte. This film-type sensor was flexible, robust, and lightweight. This self-powered sensor generated the output voltage, which was linearly proportional to the oxygen gas concentration in the range of 0–21% (R2 = 0.999) with a sensitivity of 18 mV/% O2 and a good repeatability. The oxygen gas concentrations measured with this sensor were in good agreement with those with an expensive oxygen gas analyzer. Due to its good features and performance, it is expected that the self-powered flexible oxygen sensor will be commercially applied to intelligent food packaging for healthier and safer foods.

Low temperature co-fired ceramic (LTCC) electronic packaging materials are applied for the advantages of their mechanical durability, low cost, flexibility of the layered manufacturing, and capability to integrate both electronic and microfluidic functions in a single LTCC module. Clark-type oxygen sensors are electrochemical devices that are widely used for sensing dissolved oxygen in biological applications. In this paper, a Clark-type oxygen sensor has been developed using the LTCC thick-film technique instead of the traditional silicone/glass micromachining, and it consisted of an LTCC substrate with three electrodes (working electrode, counter electrode, and Ag/AgCl reference electrode), a polydimethylsiloxane (PDMS) oxygen permeable membrane and a PDMS reservoir. The fabricated Ag/AgCl reference electrode demonstrated high density with longtime stability. Cyclic voltammetry and chronoamperometry were measured to evaluate the electrochemical properties of the LTCC-based Clark-type oxygen sensor. The reduction current had a linear relationship with oxygen concentration. Meanwhile, the LTCC-based Clark-type oxygen sensor exhibited comparative performances, including low residual current

In this study, an oxygen monitoring system was demonstrated for sensitive oxygen detection. The system is based on tunable diode laser absorption spectroscopy (TDLAS) and wavelength modulation spectroscopy (WMS). Stable 2nd-harmonic signals of oxygen were detected by measuring the oxygen P9 absorption line at 764.38 nm. In the detection, a cubic diffuse integrating cavity was employed as a gas absorption cell to increase the optical path length and achieve a higher sensitivity. In addition, to perform automatic gas concentration measurements, a data recording and analyzing program based on the National Instruments LabVIEW software platform was developed. An uncertainty of 0.05% and a detection sensitivity of 350 ppmv were obtained using this system.

While fluorescence-based fiber optic sensors for measuring both pH and oxygen concentration (O2) are well known, current sensors are often limited by their response time and drift, which limits the use of existing fiber optic sensors of this type in wider applications, for example in physiology and other fields. Several new fiber optical sensors have been developed and optimized, with respect to key features such as tip shape and coating layer thickness. In this work, preliminary results on the performance of a suite of pH sensors with fast response times, < 3 second and oxygen sensors (O2) with response times < 0.2 second. The sensors have been calibrated and their performance analyzed using the Henderson–Hasselbalch equation (pH) and classic Lehrer-model (O2).

Continuous monitoring of regional tissue oxygenation (RTO) can provide therapeutic guidance for critical care patients. Current technologies for RTO assessment require tethered, wired connections or batteries, creating problems related to implantation and chronic use due to their large volume. Recently, ultrasound (US) has been demonstrated as an efficient way to wirelessly power and communicate with implantable devices deep in tissue, enabling their miniaturization [1], [2]. Here, we present a fully implantable, wireless, battery-free, real-time sensor system for deep tissue oxygen (0 2 ) monitoring. The system combines a luminescence sensor with US technology, achieving competitive or better O 2 resolution, the lowest power consumption and the smallest volume (4.5mm3) of any system previously demonstrated [3]–[5].