scholarly journals Electrochemical multi-analyte point-of-care perspiration sensors using on-chip three-dimensional graphene electrodes

2020 ◽  
Author(s):  
Meike Bauer ◽  
Lukas Wunderlich ◽  
Florian Weinzierl ◽  
Yongjiu Lei ◽  
Axel Duerkop ◽  
...  
Keyword(s):  
Response Time ◽  
Large Scale ◽  
Electrochemical Impedance ◽  
Point Of Care ◽  
Three Dimensional ◽  
Reference Electrode ◽  
Amperometric Detection ◽  
Fast Response ◽  
Electrochemical Sensing ◽  
Electron Mediator

Abstract Multi-analyte sensing using exclusively laser-induced graphene (LIG)-based planar electrode systems was developed for sweat analysis. LIG provides 3D structures of graphene, can be manufactured easier than any other carbon electrode also on large scale, and in form of electrodes: hence, it is predestinated for affordable, wearable point-of-care sensors. Here, it is demonstrated that LIG facilitates all three electrochemical sensing strategies (voltammetry, potentiometry, impedance) in a multi-analyte system for sweat analysis. A potentiometric potassium-ion-selective electrode in combination with an electrodeposited Ag/AgCl reference electrode (RE) enabled the detection of potassium ions in the entire physiologically relevant range (1 to 500 mM) with a fast response time, unaffected by the presence of main interfering ions and sweat-collecting materials. A kidney-shaped interdigitated LIG electrode enabled the determination of the overall electrolyte concentration by electrochemical impedance spectroscopy at a fixed frequency. Enzyme-based strategies with amperometric detection share a common RE and were realized with Prussian blue as electron mediator and biocompatible chitosan for enzyme immobilization and protection of the electrode. Using glucose and lactate oxidases, lower limits of detection of 13.7 ± 0.5 μM for glucose and 28 ± 3 μM for lactate were obtained, respectively. The sensor showed a good performance at different pH, with sweat-collecting tissues, on a model skin system and furthermore in synthetic sweat as well as in artificial tear fluid. Response time for each analytical cycle totals 75 s, and hence allows a quasi-continuous and simultaneous monitoring of all analytes. This multi-analyte all-LIG system is therefore a practical, versatile, and most simple strategy for point-of-care applications and has the potential to outcompete standard screen-printed electrodes.

scholarly journals The Development of Fast Response Aerodynamic Probes for Flow Measurements in Turbomachinery

1994 ◽  
Author(s):  
Roger W. Ainsworth ◽  
John L. Allen ◽  
J. Julian M. Batt
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Flow Direction ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Fast Response ◽  
Rotor Blades ◽  
Small Scale ◽  
Hot Wire ◽  
Flow Measurements

The advent of a new generation of transient rotating turbine simulation facilities, where engine values of Reynolds and Mach number are matched simultaneously together with the relevant rotational parameters for dimensional similitude (Dunn et al [1988], Epstein et al [1984]. Ainsworth et al [1988]), has provided the stimulus for developing improved instrumentation for investigating the aerodynamic flows in these stages. Much useful work has been conducted in the past using hot-wire and laser anemometers. However, hot-wire anemometers are prone to breakage in the high pressure flows required for correct Reynolds numbers, Furthermore some laser techniques require a longer runtime than these transient facilites permit, and generally yield velocity information only, giving no data on loss production. Advances in semiconductor aerodynamic probes are beginning to fulfil this perceived need. This paper describes advances made in the design, construction, and testing of two and three dimensional fast response aerodynamic probes, where semiconductor pressure sensors are mounted directly on the surface of the probes, using techniques which have previously been successfully used on the surface of rotor blades (Ainsworth, Dietz and Nunn [1991]). These are to be used to measure Mach number and flow direction in compressible unsteady flow regimes. In the first section, a brief review is made of the sensor and associated technology which has been developed to permit a flexible design of fast response aerodynamic probe. Following this, an extensive programme of testing large scale aerodynamic models of candidate geometries for suitable semiconductor scale probes is described, and the results of these discussed. The conclusions of these experiments, conducted for turbine representative mean and unsteady flows, yielded new information for optimising the design of the small scale semiconductor probes, in terms of probe geometry, sensor placement, and aerodynamic performance. Details are given of a range of wedge and pyramid semiconductor probes constructed, and the procedures used in calibrating and making measurements with them. Differences in performance are discussed, allowing the experimenter to choose an appropriate probe for the particular measurement required. Finally, the application of prototype semiconductor probes in a transient rotor experiment at HP turbine representative conditions is described, and the data so obtained is compared with (PD solutions of the unsteady viscous flow-field.

An Experimental Investigation of the Flow Through an Axial-Flow Pump

1995 ◽  
Vol 117 (3) ◽  
pp. 485-490 ◽  
Author(s):  
W. C. Zierke ◽  
W. A. Straka ◽  
P. D. Taylor
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Axial Flow ◽  
Fast Response ◽  
Complex Flow ◽  
Penn State ◽  
Response Pressure ◽  
Axial Flow Pump ◽  
Scale Experiment ◽  
High Reynolds

The high Reynolds number pump (HIREP) facility at ARL Penn State has been used to perform a low-speed, large-scale experiment of the incompressible flow of water through a two-blade-row turbomachine. The objectives of this experiment were to provide a database for comparison with three-dimensional, turbulent flow computations, to evaluate engineering models, and to improve our physical understanding of many of the phenomena involved in this complex flow field. This summary paper briefly describes the experimental facility, as well as the experimental techniques—such as flow visualization, static-pressure measurements, laser Doppler velocimetry, and both slow- and fast-response pressure probes. Then, proceeding from the inlet to the exit of the pump, the paper presents highlights of experimental measurements and data analysis, giving examples of measured physical phenomena such as endwall boundary layers, separation regions, wakes, and secondary vortical structures. In conclusion, this paper provides a synopsis of a well-controlled, larger scope experiment that should prove helpful to those who wish to use the database.

A Semi-Active, High-Torque, Magnetorheological Fluid Limited Slip Differential Clutch

2006 ◽  
Vol 128 (5) ◽  
pp. 604-610 ◽  
Author(s):  
Barkan Kavlicoglu ◽  
Faramarz Gordaninejad ◽  
Cahit Evrensel ◽  
Alan Fuchs ◽  
George Korol
Keyword(s):  
Response Time ◽  
Three Dimensional ◽  
Fast Response ◽  
Design Development ◽  
Element Analysis ◽  
Mr Fluid ◽  
Bingham Plastic ◽  
Mr Fluids ◽  
Torque Transmission ◽  
And Performance

The design, development, and performance characterization of a magnetorheological (MR) fluid clutch for automotive limited slip differential (LSD) applications is presented in this study. The controllability of MR fluids provides an adjustable torque transmission and slippage for the LSD application. Three-dimensional electromagnetic finite element analysis (FEA) is performed to optimize the magnetic circuit and clutch design. Based on the results obtained from the FEA, the theoretical torque transfer capacity of the clutch is predicted utilizing Bingham-Plastic constitutive model. The clutch is characterized at different velocities and electromagnet electric input currents. Both the torque transfer capacity and the response time of the clutch were examined. It was demonstrated that the proposed MR fluid LSD clutch is capable of transferring controllable high torques with a fast response time.

scholarly journals A Fast-Response Automated Gas Equilibrator (FaRAGE) for continuous in situ measurement of CH<sub>4</sub> and CO<sub>2</sub> dissolved in water

2020 ◽  
Vol 24 (7) ◽  
pp. 3871-3880 ◽  
Author(s):  
Shangbin Xiao ◽  
Liu Liu ◽  
Wei Wang ◽  
Andreas Lorke ◽  
Jason Woodhouse ◽  
...  
Keyword(s):  
Response Time ◽  
Greenhouse Gas ◽  
Three Dimensional ◽  
Fast Response ◽  
In Situ Measurement ◽  
Inland Waters ◽  
Gas Analyzer ◽  
Potential Applications ◽  
Carbon Dioxide Co2

Abstract. Biogenic greenhouse gas emissions, e.g., of methane (CH4) and carbon dioxide (CO2) from inland waters, contribute substantially to global warming. In aquatic systems, dissolved greenhouse gases are highly heterogeneous in both space and time. To better understand the biological and physical processes that affect sources and sinks of both CH4 and CO2, their dissolved concentrations need to be measured with high spatial and temporal resolution. To achieve this goal, we developed the Fast-Response Automated Gas Equilibrator (FaRAGE) for real-time in situ measurement of dissolved CH4 and CO2 concentrations at the water surface and in the water column. FaRAGE can achieve an exceptionally short response time (t95 %=12 s when including the response time of the gas analyzer) while retaining an equilibration ratio of 62.6 % and a measurement accuracy of 0.5 % for CH4. A similar performance was observed for dissolved CO2 (t95 %=10 s, equilibration ratio 67.1 %). An equilibration ratio as high as 91.8 % can be reached at the cost of a slightly increased response time (16 s). The FaRAGE is capable of continuously measuring dissolved CO2 and CH4 concentrations in the nM-to-sub mM (10−9–10−3 mol L−1) range with a detection limit of sub-nM (10−10 mol L−1), when coupling with a cavity ring-down greenhouse gas analyzer (Picarro GasScouter). FaRAGE allows for the possibility of mapping dissolved concentration in a “quasi” three-dimensional manner in lakes and provides an inexpensive alternative to other commercial gas equilibrators. It is simple to operate and suitable for continuous monitoring with a strong tolerance for suspended particles. While the FaRAGE is developed for inland waters, it can be also applied to ocean waters by tuning the gas–water mixing ratio. The FaRAGE is easily adapted to suit other gas analyzers expanding the range of potential applications, including nitrous oxide and isotopic composition of the gases.

scholarly journals A Fast-response automated gas equilibrator (FaRAGE) for continuous in situ measurement of methane dissolved in water

2020 ◽  
Author(s):  
Shangbin Xiao ◽  
Liu Liu ◽  
Wei Wang ◽  
Andreas Lorke ◽  
Jason Woodhouse ◽  
...  
Keyword(s):  
Response Time ◽  
Three Dimensional ◽  
Fast Response ◽  
In Situ Measurement ◽  
Gas Analyzer ◽  
Biogenic Methane ◽  
Lakes And Reservoirs ◽  
Ch4 Concentration ◽  
Dissolved Ch4 Concentration

Abstract. Biogenic methane (CH4) emissions from inland waters contribute substantially to global warming. In aquatic systems, CH4 dissolved in freshwater lakes and reservoirs is highly heterogeneous both in space and time. To better understand the biological and physical processes that affect sources and sinks of CH4 in lakes and reservoirs, dissolved CH4 needs to be measured with a highest temporal resolution. To achieve this goal, we developed the Fast-Response Automated Gas Equilibrator (FaRAGE) for real-time in situ measurement of dissolved CH4 concentration at the water surface and in the water column. FaRAGE can achieve an exceptionally short response time (t95 % = 12 s when including the response time of the gas analyzer) while retaining an equilibration ratio of 63 % and a measurement accuracy of 0.5 %. An equilibration ratio as high as 91.8 % can be reached at the cost of a slightly increased response time (16 s). The FaRAGE is capable of continuously measuring dissolved CH4 concentrations in the nM-to-mM (10−9–10−3 mol L−1) range with a detection limit of sub-nM (10−10 mol L−1), when coupled with a cavity ring-down greenhouse gas analyzer (Picarro GasScouter). It enables the possibility of mapping dissolved CH4 concentration in a quasi three-dimensional manner in lakes. The FaRAGE is simple to operate, inexpensive, and suitable for continuous monitoring with a strong tolerance to suspended particles. The easy adaptability to other gas analyzers such as Ultra-portable Los Gatos and stable isotopic gas analyzer (Picarro G2132-i) also provides the potential for many further applications, e.g. measuring dissolved 13δC-CH4 and CO2.

The Development of Fast Response Aerodynamic Probes for Flow Measurements in Turbomachinery

1995 ◽  
Vol 117 (4) ◽  
pp. 625-634 ◽  
Author(s):  
R. W. Ainsworth ◽  
J. L. Allen ◽  
J. J. M. Batt
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Flow Direction ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Fast Response ◽  
Rotor Blades ◽  
Small Scale ◽  
Hot Wire ◽  
Flow Measurements

The advent of a new generation of transient rotating turbine simulation facilities, where engine values of Reynolds and Mach number are matched simultaneously together with the relevant rotational parameters for dimensional similitude (Dunn et al., 1988; Epstein and Guenette, 1984; Ainsworth et al., 1988), has provided the stimulus for developing improved instrumentation for investigating the aerodynamic flows in these stages. Much useful work has been conducted in the past using hot-wire and laser anemometers. However, hot-wire anemometers are prone to breakage in the high-pressure flows required for correct Reynolds numbers. Furthermore, some laser techniques require a longer run-time than these transient facilities permit, and generally yield velocity information only, giving no data on loss production. Advances in semiconductor aerodynamic probes are beginning to fulfill this perceived need. This paper describes advances made in the design, construction, and testing of two and three-dimensional fast response aerodynamic probes, where semiconductor pressure sensors are mounted directly on the surface of the probes, using techniques that have previously been successfully used on the surface of rotor blades (Ainsworth et al., 1991). These are to be used to measure Mach number and flow direction in compressible unsteady flow regimes. In the first section, a brief review is made of the sensor and associated technology that has been developed to permit a flexible design of fast response aerodynamic probe. Following this, an extensive program of testing large-scale aerodynamic models of candidate geometries for suitable semiconductor scale probes is described, and the results of these discussed. The conclusions of these experiments, conducted for turbine representative mean and unsteady flows, yielded new information for optimizing the design of the small-scale semiconductor probes, in terms of probe geometry, sensor placement, and aerodynamic performance. Details are given of a range of wedge and pyramid semiconductor probes constructed, and the procedures used in calibrating and making measurements with them. Differences in performance are discussed, allowing the experimenter to choose an appropriate probe for the particular measurement required. Finally, the application of prototype semiconductor probes in a transient rotor experiment at HP turbine representative conditions is described, and the data so obtained are compared with CFD solutions of the unsteady viscous flow-field.

scholarly journals Smart Integrated Sensor for Multiple Detections of Glucose and L-Lactate Using On-Chip Electrochemical System

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Tomoyuki Yamazaki ◽  
Takaaki Ikeda ◽  
Byounghyun Lim ◽  
Koichi Okumura ◽  
Makoto Ishida ◽  
...  
Keyword(s):  
Point Of Care ◽  
Reference Electrode ◽  
Electrochemical Sensing ◽  
Quantitative Detection ◽  
Enzymatic Reactions ◽  
Single Chip ◽  
Lactate Oxidase ◽  
Integrated Sensor ◽  
System L ◽  
On Chip

Multiple sensor electrodes, a supplementary electrode, a reference electrode, and signal-processing circuits were integrated on a single chip to develop a chip-shaped electrochemical sensing system. L-lactate and glucose were measured using on-chip working electrodes modified by polyion complex to immobilize lactate oxidase and glucose oxidase, respectively. Cyclic voltammetry measurements were conducted using an on-chip potentiostat. Selective and quantitative detection of glucose and L-lactate and the interference behavior were studied. Hydrogen peroxide generated by enzymatic reactions was detected by an increase in anodic oxidation current. Reaction currents at +0.7 V versus Ag/AgCl were used to obtain calibration plots. The measured dynamic ranges for L-lactate and glucose were 0.2–1.0 mM and 2.0–8.0 mM, respectively. The sensitivities were 65 nA/mM and 15 nA/mM, respectively, using a working electrode of 0.5 mm2. The 3σdetection limit was 0.19 mM and 1.1 mM, respectively. We have achieved multiple biomaterial detections on a circuit-equipped single chip. This integrated electrochemical sensor chip could be the best candidate for realizing point-of-care testing due to its portability and potential for mass production.

scholarly journals On-Chip Glucose Detection Based on Glucose Oxidase Encapsulated on a Platinum Modified Gold Microband Electrode

2021 ◽  
Author(s):  
Julia Madden ◽  
Colm Barrett ◽  
Fathima Laffir ◽  
Michael Thompson ◽  
Paul Galvin ◽  
...  
Keyword(s):  
Glucose Oxidase ◽  
Glucose Sensor ◽  
Electrochemical Impedance ◽  
Reference Electrode ◽  
Linear Sweep Voltammetry ◽  
Fast Response ◽  
Small Sample ◽  
Ease Of Use ◽  
Glucose Detection ◽  
Serum Samples

We report a two-step electrodeposition process incorporating glucose oxidase onto a platinum- modified gold microband electrode with an o-phenylenediamine and ß-cyclodextrin mixture. The bare microband electrodes were fabricated on silicon using standard microfabrication methods i.e. lithography and etching techniques. The two-step electrode modification process was characterized using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The enzymatic based microband biosensor exhibited a linear response to glucose from 2.5-15 mM using both linear sweep voltammetry and chronoamperometric measurements in buffer based solutions. The resulting miniaturized glucose sensor presented a number of advantages such as ease of use, fast response time, measuring within physiologically relevant glucose concentrations in addition to sensing in small sample volumes without the need for an external counter and reference electrode. The biosensor performance was tested in 30 µl volumes of undiluted fetal bovine serum. Whilst a reduction in signal was evident within 100 % serum samples, the sensor achieved linear glucose detection with increasing glucose concentrations (2-12 mM).

scholarly journals On the fly EIS tracking of rechargeable alkaline Zn-MnO2 batteries for large-scale use

2020 ◽  
Author(s):  
Joshua Gallaway
Keyword(s):  
Large Scale ◽  
Electrochemical Impedance ◽  
Cell Model ◽  
Porous Electrode ◽  
Reference Electrode ◽  
Cost Effective ◽  
Capacitive Coupling ◽  
Electrode Placement ◽  
Alkaline Batteries ◽  
Minimum Number

This talk will discuss electrochemical impedance spectroscopy (EIS) tracking of aqueous alkaline Zn-MnO2 cells cycled at 20% depth of discharge (DOD) based on cathode capacity. Shallow cycled alkaline batteries have previously been reported as cost effective and safe options for large-scale electrical storage. Periodically collected EIS data was used to fit a full battery model based on Voigt elements, and fitted parameters were tracked over time. These were used as a real-time diagnostic to assess performance and predict future performance in advance of any degradation of the cell voltage.The cell model was based on individual electrode models developed previously by Donne and co-workers for γ-MnO2 and Hampson and McNeil for Zn. Two prismatic cell builds were compared using electrodes fabricated by two different commercial sources with identical compositions. Both cell performance and EIS response were distinctly different between the electrode sources. The model provided an acceptable fit of the experimental data in both cases, as shown in Figure 1. The parameters of the model corresponded to physical phenomena, allowing an analysis of the performance difference despite the fact that all electrode fabrication variables could not be known unless provided by the commercial sources.The combined anode and cathode interfacial models were incorporated into a transmission line porous electrode, shown in Figure 2. Each anode + cathode fit involved a combined 15 parameters, which was the minimum number of parameters that would fit data for all cells in all states of charge. Performance analysis was accomplished by comparing a) the individual parameters, b) lumped parameters such as the RC time constants and RLC Q factors, and c) features of the cycling potential such as the discharge end voltage (DEV). Use of a reference electrode with EIS has been shown to be highly dependent on electrode placement. Battery EIS also faces a challenge in that electrodes may have similar capacity, while ideally the counter electrode should be non-limiting. We will address these factors and discuss steps taken to obtain repeatable data free of inductive loops caused by capacitive coupling with current collectors and electrode tabs.

scholarly journals Label free, electric field mediated ultrasensitive electrochemical point-of-care device for CEA detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Chakraborty ◽  
A. Das ◽  
N. Mandal ◽  
N. Samanta ◽  
N. Das ◽  
...  
Keyword(s):  
Electric Field ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Zno Nanorods ◽  
Hybrid Nanostructures ◽  
Electrochemical Sensing ◽  
Label Free ◽  
Electron Transfer Rate

AbstractDeveloping point-of-care (PoC) diagnostic platforms for carcinoembryonic antigen detection is essential. However, thefew implementations of transferring the signal amplification strategies in electrochemical sensing on paper-based platforms are not satisfactory in terms of detection limit (LOD). In the quest for pushing down LOD, majority of the research has been targeted towards development of improved nanostructured substrates for entrapping more analyte molecules and augmenting the electron transfer rate to the working electrode. But, such approaches have reached saturation. This paper focuses on enhancing the mass transport of the analyte towards the sensor surface through the application of an electric field, in graphene-ZnO nanorods heterostructure. These hybrid nanostructures have been deposited on flexible polyethylene terephthalate substrates with screen printed electrodes for PoC application. The ZnO nanorods have been functionalized with aptamers and the working sensor has been integrated with smartphone interfaced indigenously developed low cost potentiostat. The performance of the system, requiring only 50 µl analyte has been evaluated using electrochemical impedance spectroscopy and validated against commercially available ELISA kit. Limit of detection of 1 fg/ml in human serum with 6.5% coefficient of variation has been demonstrated, which is more than three orders of magnitude lower than the existing attempts on PoC device.

Sign in / Sign up

Export Citation Format

Share Document