Herein, we present the large scale fabrication of carbon nanotubes (CNT) electrodes supported on flexible polymeric sheets by subsequent multilayer inkjet printing of a silver layer for electrical connection, CNT layers as active electrode material and an insulation layer to define a stand-alone CNT active electrode area with high accuracy. Optical and electrochemical characterization using several redox mediators demonstrates the reproducibility of the electrode surfaces and their functionality even with a single inkjet printed CNT layer. These electrodes are targeted to the clinical sector for the determination of the antioxidant power (AOP) of biologically relevant fluids by pseudo-titration voltammetry. As a proof-of-concept, the AOP of ascorbic acid solutions and biological samples such as erythrocyte concentrates (ECs) from different blood donors were determined demonstrating the potential use of the presented CNT sensors on ECs for blood transfusion purposes and the clinical sector.