Organic Electrochemical Transistors (OECTs) represent a very promising technology for biosensing applications, and flexible wearable electronics is surely a fertile field for OECTs-based devices. The purpose of this thesis project is to improve and optimize an OECT-based sensor for a flexible wearable device, able to detect the glucose level in the patient’s sweat in a non-invasive way. In fact, the glucose concentration in sweat varies depending on the health conditions of the patient, particularly for diabetic ones. OECTs are widely exploited in this sector due to the significant amplification and capability of transduction of the signal, the low operating voltages and the biocompatibility.