The invention relates to a device for the measurement of hydrogen peroxide and optionally other biomarkers in a gaseous mixture, and in particular to a microfabricated device. The device comprises hydrogen peroxide capturing means and an electromechanical sensor comprising a sensing element in direct contact with the capturing means. The device further comprises means to measure the potential of the sensing element and/or the current through it as a result of a changing hydrogen peroxide concentration in the gaseous mixture. The device also comprises cooling/heating means for cooling and/or heating the capturing means. The device is preferably applied for online measurement of the hydrogen peroxide content in exhaled air.