Abstract: A sensor for the detection of chemical messengers is described herein. In particular a sensor for the detection of catecholamines, for example dopamine, epinephrine or norepinephrine, is reported. Catecholamines play pivotal roles as neurotransmitters and hormones in the human body. An electrode for detecting a catecholamine comprising a conducting or semi-conducting substrate, and a polymer comprising polyethylenedioxythiophene on said substrate is disclosed. The polymer is doped with a cyclodextrin macrocycle. Suitable cyclodextrin macrocycles include anionic cyclodextrin macrocycles, for example sulfonated ?-cyclodextrins (CDs). Also, disclosed in sensor capable of selectively detecting a catecholamine in the presence of ascorbic acid (ascorbate).