Introduction. About 90% of blood serotonin is stored in secretory granules of platelets and is released by exocytosis. Serotonin is a biogenic amine and the mechanisms for its accumulation in secretory granules and exocytosis are similar to some neurotransmitters. As it is an electroactive molecule, its release can be detected via amperometry. Thus, platelets are an easily accessible human cell model to study exocytosis. Methods. We have optimized boron-doped diamond (BDD) on multielectrode array (MEA) systems that allow the detection of amperometric recordings from the quantum release of serotonin from human platelets. Exocytotic events are detected as transient oxidation currents. Our initial experiments were carried out with microelectrode devices on silicone matrices (BDD-on-silicon MEAs)¹. We introduce here a new transparent material which allows microscopy observations: a BDD-on-quartz MEA. Results. BDD-on-quartz MEA devices exhibit excellent electrochemical properties similar to BDD-on-silicon MEAs¹. We present the amperometric data obtained from unloaded platelets and after loading the platelets with 10 µM serotonin for 2 h, as well as a comparative study of the quantum and kinetic characteristics of amperometrical spikes obtained with both MEA chips. Conclusions. We demonstrate the effectiveness of BDD-on-quartz MEAs as biosensors for the amperometrical measurement of serotonin exocytosis from human platelets. References. ¹ González Brito, R; Montenegro, P; Méndez, A; Carabelli, V; Tomagra, G; Shabgahi, R.E.; Pasquarelli, A.; Borges, R. Multielectrode Arrays as a Means to Study Exocytosis in Human Platelets. Biosensors 2023, 13, 86. https://doi.org/10.3390/bios13010086.