A miniaturized amperometric CO2 sensor based on dissociation of copper complexes

A novel miniaturized amperometric carbon dioxide sensor with fabrication compatibility to most modern MEMS production techniques and with a miniaturization potential down to 100 μm has been developed. The electrochemical detection concept is based on a pH-dependent dissociation of copper complexes. The pH change of an electrolyte solution occurring due a variation of the pCO2 results in a variation of the concentration of free copper ions. In the presence of chloride, the copper ions can be reduced by a quasi-reversible reaction path. The reduction current is taken as measurement signal for the carbon dioxide concentration of an analyte. With the introduction of good-buffer substances as non-volatile ligands for the formation of the copper complexes, a reversible and highly stable chemical system is achieved to allow a radical miniaturization.