Microfluidic arrangement with an integrated micro-spot array for the characterization of pH and solvent polarity

Micro-spot arrays with different pH and polarity sensitive fluorescence dyes were prepared using a piezo dispensing head. A polyethylene glycol matrix was used to immobilize the dyes covalently. The polymer matrix was cross-linked to ensure stable dye bonding and for controlling the swelling and permeability of the thin film. Analytical experiments were carried out in the fluidic phase with specially developed micro-fluidic and CCD imaging optical set-up. As a result, different solvents and solutions could be distinguished for their pH and polarity using fluorescence digital imaging. After calibration, a quantitative determination of the solution composition was also possible. The chemo-chips were tested against different solvent species leading to confirmation of the applicability of the developed spot array for the reproducible recognition of different liquid types focusing on polarity and pH as parameters.