Chemiluminescence chemical sensors

Nowadays all over the world considerable attention is focused on development of chemical sensors for the detection of various organic compounds in solutions and gas phase. One of the possible sensor types for organic compounds in solutions detection is optochemotronic sensor - device of liquid-phase optoelectronics that utilize effect of electrogenerated chemiluminescence. In order to enhance selectivity and broaden the range of detected substances the modification of working electrode of optochemotronic cell with organic films is used. Composition and deposition technique of modifying films considerably influence on electrochemical and physical processes in the sensor. 

From a general point of view, a chemical sensor is a device capable of continuously monitoring the concentration of an analyte. The two main classes are electrochemical sensors and optical chemical sensors. The latter are based on the measurement of changes in an optical quantity refractive index, light scattering, reflectance, absorbance, fluorescence, chemiluminescence, etc. For remote sensing, an optical fiber is used, and the optical sensor is then called an optode because of... 

Sensing Volume. The sensing volume of a sensor is the volume where the air is actually monitored. The sensing volume is the reaction chamber of a flame photometric detector or a chemiluminescence device, the field of view of an open-path sensor, or the White cell of a reduced-pressure optical system. The residence time of the sample within the sensing volume ultimately limits the temporal resolution of most chemical sensors. 

Hofmann, O., Miller, P, SuUivan, P., Jones, T.S., deMello, J.C., Bradley, D.D.C., and deMello, A.J., Thin-film organic photodiodes as integrated detectors for microscale chemiluminescence assays. Sensors and Actuators B—Chemical, 106, 878-884, 2005. 

Known measuring techniques comprise local physical methods (hydrophones, thermoacoustic sensors, aluminum foil erosion, optical sound pressure and velocity sensors, radiation pressure scale, laser-Doppler anemometry), local chemical methods (Weissler reaction, chemiluminescence, electrochemical sensors), global chemical methods (model reactions), and sonoluminiscence (single-bubble sonoluminescence SBSL, multibubble sonoluminescence MBSL). 

Here, the product species NO2 is produced in an excited electronic state and emits light in the visible-near IR region. It has been found that the intensity of the chemiluminescence is proportional to the concentration of NO in the ppm- ppb range. Thus, the reaction shown in Equation [32] can be used as the basis for the development of a chemical sensor for NO. The detection of NO is important because nitric oxide is a chief environmental pollutant, and also because NO plays an Important role in human biology. 

Chemiluminescence sensors utilize chemicals that generate photons, e.g. 

Here A and B are non-luminescence molecules. The C is the excited state of the product C. Often these reactions involve oxidation reactions and the presence of a catalyst. Both chemical and biochemical reactions could generate the photon. The intensity of the photons are collected through optical fibers and measured with a photon detector. The most successful chemiluminescence sensor for the detection of the hydrogen peroxide [13] is based on luminol using ferricyanide as catalyst... 

Figure 3.35 — Flow-through chemiluminescence sensor with immobilized luminol. (Reproduced from [244] with permission of the American Chemical Society).

Therefore, this sensor integrates a biochemical and a chemical reaction with a prior separation (dialysis) and chemiluminescence detection. The process involves the following steps (a) dialysis of the enzyme (6) enzymatic oxidation of the reagent (c) derivatization of hydrogen peroxide and d) detection of the chemiluminescence produced. Such an original approach offers several advantages over similar methodologies, namely ... 

Fig. 1 Chemical interaction mechanisms, basic components of the optical sensor instrumentation and their operation. Mechanisms direct measurement of chemical compounds that exhibit spectroscopic properties (1 A) and measurement of light originating from a chemical or a biological reaction in chemiluminescent or bioluminescent phenomena (IB) 2 optodes based on the interaction of indicators and labels with light, which are immobilized in a support and sensors that modify the intrinsic physical or chemical properties of a waveguide (refractive index, phase, etc.) as a result of the presence of the analyte (3A), a recognition element (35), an intermediate analyte (3C) or an indicator (3D)...

Application of chemiluminescence to chemical analysis has been developing since the latter half of the 1950s. This method has many advantages, e.g., high sensitivity, good selectivity, linearity in a wide concentration range, and quick response. It has also been used for the measurement of air pollutants. This method, however, requires a supply of reactants to produce luminescent species through chemical reaction. This is a difficult point for the application of this method to gas sensors. 

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