Reversible Optical Sensor Strip for Oxygen

Abstract

Oxygen sensors have attracted great attention in recent years because of their extensive applications in oceanography, meteorology, biology, environmental science, and life science.[1] Up to now, many oxygen sensors based on pressure, electrochemistry, and photochemistry have been made for accurate quantitative determinations.[1] However, sophisticated scientific instruments with complicated data-collecting and -processing systems are required, and thus the high costs and the requirement for a professional operator severely limit their usage. Following the first report of a novel luminescence-based colorimetric oxygen sensor with a "traffic light" response, [2] a new approach has been available for colorimetric oxygen determination without the need for additional measuring instruments. However, the complicated relationship between apparent color and oxygen concentration makes quantitative determination difficult without the assistance of intricate data processing. Furthermore, several disadvantages, including low resolution, high cost, the lack of simultaneous excitation at a single wavelength, and not fully achieving diverse color change according to different usage, limit the application of this approach.Herein, we report the development of a novel optical sensor strip for oxygen based on cadmium telluride (CdTe) quantum dots (QDs) and [meso-tetrakis(pentafluorophenyl)-porphyrinato]platinum(II) (PtF 20 TPP), which achieves colorimetric oxygen determination with precise, distinct, and tunable color. An additional advantage of this oxygen sensor is that the strip is reversible in its response and, therefore, can be used many times. Figure 1 shows a diagram and scanning electron microscopy (SEM) image of the reversible optical sensor strip for oxygen. PtF 20 TPP (l em,max = 648 nm, red), [3] which was chosen as the oxygen-sensing probe, was embedded in an organically modified silica (ormosil) matrix [4] and is indicated by "A" in the SEM image. To facilitate colorimetric oxygen determination, a layer of background color "B" was then designed underneath the oxygen-sensing layer. To achieve a diverse change in color, quantitative oxygen determination, and simultaneous excitation at a single wavelength, the materials for the background color were critical.Many inorganic QDs have a narrow and symmetric photoluminescence, which is color-tunable by simply controlling the size, a wide excitation wavelength, and are cheap, and were therefore one of the best choices. Water-soluble CdTe QDs are ideal fluorophores because of their unique optical properties and ease of scale-up, [5] and have been widely used as a consummate toner for multicolor sensing and encoding. [6] To embed the water-soluble CdTe QDs [7] under the oxygensensing layer, but to avoid the aggregation of QDs and their solution into the water during oxygen determination, a modification of Murases method [8] was developed. Tetraethoxysilane (TEOS; 1.0 %, v/v) in a solution of (3-aminopropyl)trimethoxysilane (APTMS) in methanol was introduced during the prepa...

Tuning the Emission Colour of Triphenylamine‐Capped Cyclometallated Platinum(II) Complexes and Their Application in Luminescent Oxygen Sensing and Organic Light‐Emitting Diodes

“…[20][21][22][23][24][25]32,33] Luminescent O 2 sensing is based on the quenching effect of O 2 on the phosphorescence emission of the complexes. [21,[34][35][36][37][38] To address the drawbacks of emission-intensity-based O 2 sensing, lifetime-based sensing or ratiometric sensing is desired. [21][22][23][24] Lifetime-based O 2 sensing requires phosphorescent dyes with longer luminescent lifetimes.…”

Planar Oxygen Sensors for Non Invasive Imaging in Experimental Biology

“…This is not possible if using even high-tech standard consumer cameras which allow ratiometric calibration schemes at best. However, beside the restriction of transparent sensors ratiometric imaging has proved to be also an excellent solution for measuring analyte contents of a sample quantitatively and two dimensionally (Wang et al, 2008). Then, it depends on the sample target and analytical problem if the possibility of miniaturisation and mobility overcompensates the restriction.…”

Extended detection range for an optical enzymatic glucose sensor coupling with a novel data-processing method

“…The glucose sensor consisted of an oxygen sensing layer and a glucose oxidase layer, and was prepared layer by layer based on our previous description [17][18][19].…”