One big analytical challenge is the detection of levodopa within human blood serum. The drug levodopa is the gold standard in the treatment of Parkinson's disease. Up to now, monitoring of levodopa blood levels has not really been implemented, due to time-consuming and complex laboratory methods like liquid chromatographymass spectrometry. Nonetheless, measuring levodopa blood levels can be a crucial step to get the best treatment for an individual patient and decrease the risk of levodopa-induced side effects like dyskinesias. Dyskinesias exhibit a direct correlation with the levodopa plasma concentration and are absent within a precise therapeutic window. The complex milieu present in human blood demands high selectivity and high sensitivity sensors to obtain accurate and reliable measurements. Simultaneously, for a final device one needs to consider requirements for on-site monitoring of patients.