Rapid Measurement of Room Temperature Ionic Liquid Electrochemical Gas Sensor using Transient Double Potential Amperometry (original) (raw)

Miniaturized planar room temperature ionic liquid electrochemical gas sensor for rapid multiple gas pollutants monitoring

Sensors and Actuators B: Chemical, 2017

The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.

A Novel Amperometric O2 Gas Sensor Based on Supported Room-Temperature Ionic Liquid Porous Polyethylene Membrane-Coated Electrodes

Electroanalysis, 2004

A novel solid-state amperometric O 2 gas sensor based on the supported 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF 4) porous polyethylene membrane-coated electrodes has been proposed with its characterization. By electrochemical impedance technique, the ionic conductivity of the supported EMIBF 4 membrane was estimated to be ca. 0.6 S m À1 , indicating that the supported EMIBF 4 membrane (the thickness: 50 mm) can be used as a solid state ionic conductor at room temperature. The cyclic voltammograms obtained for the one-electron redox reaction of O 2 / O 2 À. (O 2 À. : superoxide ion) couple at high scan rates (> 100 mV s À1) showed a couple of usual redox peaks, while at low scan rates (< 30 mV s À1) S-shaped steady-state voltammograms similar to those obtained by rotating disk voltammetry were obtained. These results were explained on the basis of the mass transport of O 2 at the supported EMIBF 4 membrane-coated electrode system. The transient and steady-state reduction currents for the reduction of O 2 to O 2 À. as well as the transient oxidation current for the reoxidation of O 2 À. to O 2 , which were obtained by potentialstep chronoamperometry, could be used to measure the change of O 2 concentration in O 2-N 2 mixed gas stream. The present O 2 gas sensor demonstrated a wide detection range, a high sensitivity and an excellent reproducibility.

Towards improving the robustness of electrochemical gas sensors: impact of PMMA addition on the sensing of oxygen in an ionic liquid

The electrochemical reduction of oxygen (O 2) has been studied on commercially-available integrated Pt thin-film electrodes (TFEs). Chemically reversible (but electrochemically quasi-reversible) cyclic voltammetry was observed in the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 2 mim][NTf 2 ]), showing superior behaviour of TFEs compared to screen-printed electrodes for oxygen sensing. As a step towards the preparation of robust gas sensors, the RTIL was mechanically stabilised on the TFE surface by the addition of poly(methyl methacrylate) (PMMA). At a PMMA concentration in the RTIL of ca. 50% mass, electrolyte flow was not evident. O 2 reduction peak currents were found to decrease systematically with increasing PMMA content, reflecting the higher viscosity of the electrolyte medium. Linear calibration graphs were obtained for 0–100% vol. oxygen at all PMMA–RTIL mixtures studied. The sensitivities decreased as [PMMA] increased, but the limits of detection were relatively unchanged. Mechanical stability of the sensors was tested in different orientations (flat, upside down, sideways) with both the neat RTIL and 50% mass electrolyte. Whilst the electrochemical responses were dramatically changed for the neat RTIL, the responses in the PMMA– RTIL mixture were independent of electrode orientation. Additionally, the oxygen response in the PMMA–RTIL mixture was less affected by atmospheric impurities and moisture, compared to the neat RTIL. This suggests that these low-cost miniaturised devices can successfully be used for oxygen sensing applications in field situations, especially where portability is essential.

Amperometric Gas Detection Using Room Temperature Ionic Liquid Solvents

2010

The electrochemistry of various gases, including oxygen, carbon dioxide, hydrogen, ammonia, hydrogen sulfide, sulfur dioxide and nitrogen dioxide, in room temperature ionic liquids (RTILs) is reviewed. The application of RTILs to gas sensor design and development is highlighted. http://link.aip.org/link/ECSTF8/v33/i7/p473/s1

CMOS Monolithic Electrochemical Gas Sensor Microsystem Using Room Temperature Ionic Liquid

IEEE Sensors Journal, 2018

The growing demand for personal healthcare monitoring requires a challenging combination of performance, size, power, and cost that is difficult to achieve with existing gas sensor technologies. This paper presents a new CMOS monolithic gas sensor microsystem that meets these requirements through a unique combination of electrochemical readout circuits, post-CMOS planar electrodes, and room temperature ionic liquid (RTIL) sensing materials. The architecture and design of the CMOS-RTIL-based monolithic gas sensor are described. The monolithic device occupies less than 0.5 mm 2 per sensing channel and incorporates electrochemical biasing and readout functions with only 1.4 mW of power consumption. Oxygen was tested as an example gas, and results show that the microsystem demonstrates a highly linear response (R 2 = 0.995) over a 0-21% oxygen concentration range, with a limit of detection of 0.06% and a 1 s response time. Monolithic integration reduces manufacturing cost and is demonstrated to improve limits of detection by a factor of five compared to a hybrid implementation. The combined characteristics of this device offer an ideal platform for portable/wearable gas sensing in applications such as air pollutant monitoring.

Electrochemical Sensing of Oxygen Gas in Ionic Liquids

The work presented in this thesis aimed to investigate the potentiality of screen printed electrodes (SPEs), when used in conjunction with non-volatile room temperature ionic liquids (RTILs), for the amperometric sensing of gases. O 2 was selected as the model gas for these studies. Cyclic voltammetry (CV) and amperometry techniques were employed for these investigations. Experiments were conducted with an inert background atmosphere of N 2 gas.

Methane-oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

The Analyst, 2014

Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample mat...

?-Sensors: A new concept for advanced solid-state ionic gas sensors

Applied Physics A Solids and Surfaces, 1992

A new principle of solid state electrochemical sensors based on the kinetics of controlled chemical reactions of the gas with the electroactive species of a solid electrolyte is presented and demonstrated for the measurement of CO2 partial pressures. The reaction may be for many gases modified by the formation of intermediate product phases.