In this PhD project, scanning electrochemical microscopy (SECM) will be applied in the development of biosensors. The aim of this project is to create fast, sensitive, inexpensive and reusable biological sensors, using SECM as a signal transducer. When the signal transducer is an electrode on which a detectable substance is immobilized, it blocks the charge transfer to the electrode. The SECM uses ultramicroelectrode as a probe, which scans the surface close to the immobilized material at some distance. Nowadays the new biosensors’ research methods are developing in the world using SECM. In this project, new, innovative research methods will be applied: SECM redox competition mode and SECM local electrochemical impedance.