Among the different application fields of biosensor, the biomedical sector attracts a special attention due to the countless needs to monitor disease-related parameters and parameters associated with the maintenance of health. Nowadays, biomedical systems should be miniaturisable, at low cost and easy to use in order to allow patient self-monitoring. Si photodiodes have the great advantage with respect to traditional detection systems of being highly miniaturisable, integratable and inexpensive. Hence, they are the best candidates for portable applications. For these reasons, an optical system based on silicon photomultipliers (SiPMs) for biomedical applications was developed.