Abstract
A method for measuring free radical comprises providing a sensor including a substrate and a conductive polymer layer, wherein the conductive polymer layer is configured on the substrate and made of conductive polymer; applying a liquid sample with free radical to the sensor so that the conductive polymer layer is covered with the liquid sample and the conductivity of the conductive polymer layer is lowered due to oxidation of the conductive polymer by free radical; and calculating the concentration of the free radical in the liquid sample based on the conductivity change rate of the conductive polymer before and after the liquid sample is applied to the conductive polymer. The present invention has advantages including low cost, small size, and ease of operation, which make it a good candidate for detecting hydroxyl radicals for oxidative stress studies.