Absorbance-Based Integrated Devices

Despite the fact that direct absorbance/transmittance measurements are well established in analytical chemistry owing to the simplicity of the instrumentation and their broad applicability and versatility towards a large number of analytes, most of the reported miniaturized optical devices are based on the measurement of variations of the real part of the refractive index, such as SPR sensors [84,109-111] or interferometric sensors [94,112]. 

The most significant reported absorbance-based miniaturized devices are detailed next. 

---

Mogensen, K.B., Petersen, N., Htibner, J., Kutter, J., In-plane UV absorbance detection in silicon-based electrophoresis devices using monolithically integrated optical waveguides. Micro Total Analysis Systems, Proceedings 5th ytTAS Symposium, Monterey, CA, Oct. 21-25, 2001 Kluwer Academic Publishers, Dordrecht, the Netherlands, 2001, 280-282. 

To detail DSSC technologies, Fig. 18.1 illustrates the modus operandi of DSSCs. Initially, light is absorbed by a dye, which is anchored to the surface of either n- or p-type semiconductor mesoporous electrodes. Importantly, the possibility of integrating both types of electrodes into single DSSCs has evoked the potential of developing tandem DSSCs, which feature better overall device performances compared to just n-or p-type based DSSCs [19-26]. Briefly, n-type DSSCs, such as TiOz or ZnO mesoporous films, are deposited on top of indium-tin oxide (ITO) or fluorine-doped tin oxide (FTO) substrates and constitute the photoanodes. Here, charge separation takes place at the dye/electrode interface by means of electron injection from the photoexcited dye into the conduction band (cb) of the semiconductor [27,28]. A different mechanism governs p-type DSSCs, which are mainly based on NiO electrodes on ITO and/or FTO substrates... 

---