All-ceramic analytical microsystems with monolithically integrated optical detection microflow cells

All-ceramic microfluidic platforms with integrated optical microflow cells, fabricated using the low-temperature co-fired ceramics (LTCC) technology, are presented. The fabrication procedure described allows the construction of hermetically sealed monolithic microfluidic platforms, with homogeneous surface chemistry and physical properties. Therefore, the presented procedure eliminates the problems related to properties mismatch of the different construction materials used up to now to integrate transparent windows in the ceramic platforms. LTCC sheets, used as optical windows, were optically characterized in terms of transmittance according to their thickness in the UV–Vis–NIR regions. The influence of optical microflow cells parameters, such as optical path length, diameter, and window thickness, on sensitivity and detection limit, were investigated using the colorimetric complex [Fe(phen)3]2+ formed between Fe(II) and 1,10-phenanthroline. Detection limit as low as 8 ppb of Fe(II) was obtained. The results open the possibility of using optical detection within the traditional application fields of LTCC technology, such as high-temperature or organic solvents applications, while using a simple fabrication procedure suitable for low-cost mass production.