Toward Membrane-Free Amperometric Gas Sensors: A Microelectrode Array Approach

Abstract

Room temperature ionic liquids (RTILs) have been applied to a microelectrode array and been demonstrated to form effective, membrane-free amperometric gas sensors. Determining the RTIL [P(6,6,6,14)][FAP] as the most appropriate choice for extended use, the amperometric quantification of oxygen has been demonstrated. The response of the sensor was quantified by both cyclic voltammetry and chronoamperometry. A range of O(2) contents (2-13% v/v) and RTIL layer thicknesses (from ca. 6 to 125 mum) have been investigated. The combination of microelectrode array and RTIL, as well as the absence of membrane and volatile solvent, results in an elegant, easy to calibrate gas sensor with potential utility in standard and nonstandard conditions.

Oxygen reduction voltammetry on platinum macrodisk and screen-printed electrodes in ionic liquids: Reaction of the electrogenerated superoxide species with compounds used in the paste of Pt screen-printed electrodes?

“…Voltammetry for O 2 reduction has been widely reported in the literature in some (but not all) of these RTILs on glassy carbon (GC)/Au/Pt macro-, [22,25,26] Pt/Au/GC micro- [15,23,27,28] and Au microarray [29] electrodes, with similar voltammetric wave shapes to those observed in Figure 3. Table 2 shows the peak-to-peak separations (ΔE pp ) for the O 2 /O 2 -redox couple presented in Figure 3.…”

Room Temperature Ionic Liquids As Useful Overlayers for Estimating Food Quality from Their Odor Analysis by Quartz Crystal Microbalance Measurements

“…Thus, sensors designed to generate current responses and exploiting both gas permeable membranes 12,13 and membrane-free devices were developed, these last based on either solid polymer electrolytes (SPEs) [14][15][16] or room temperature ionic liquids (RTILs). [17][18][19][20][21][22][23] Unfortunately, these sensors provides responses for specific classes of VOCs alone, while flavors come out almost always from the contribution of different volatile species.…”

“…To achieve retention of volatile compounds, overlayers consisting of GC stationary phases displaying adsorption properties, 30 supramolecular compounds, 31 organic polymers, 32 biomolecules 33 or room temperature ionic liquids (RTILs) [17][18][19][20][21][22][23]28,29 have been employed. Among these, RTILs appear to be particularly attractive for their good thermal and electrical conductivity, negligible vapor pressure and ability to dissolve several compounds, thanks to their amphiphilic character which can be tuned by tailoring suitably their cations and anions.…”

Robust and versatile ionic liquid microarrays achieved by microcontact printing

“…ILs have been regarded as ideal candidate electrolytes for replacing aqueous/organic solvent electrolytes in commercial gas sensors, which are prone to drying out and sensor failure, and for the development of membranefree gas sensors ( Supplementary Fig. 15a,b) 8,32 . However, current IL-based gas sensors suffer from one intrinsic drawback, namely the high viscosity of ILs 32 .…”

“…For example, Hozumi et al 7 have utilized ILs in photolithography as a medium for smart visualization of submicron-scale structures. Huang et al 8 applied ILs as electrolytes and developed a membrane-free amperometric gas sensor which can operate in extreme conditions such as high temperature and pressure. Dubois et al 2 have fabricated IL droplets (300 nl) on a chip surface using Eppendorf micropipettes, and they demonstrated that efficient organic synthesis can be achieved inside the stable IL-droplet reactors 9 .…”