The impact of RF radiation on the living constitutes a controversial topic, whereas wireless applications continue to grow drastically and our daily environment is surrounded of electromagnetic fields. In order to evaluate the potential impact of RF radiations even with severe RF exposures, it is important to conduct experiments with a very well controlled dosimetry and with calibrated RF exposure systems. In this paper, a miniature RF applicator, which enables to apply controlled electromagnetic fields radiation on micro-tissues, is introduced. An experimental method based on thermal measurements has been developed in such a micro-device to define the Specific Absorption Rate applied to micro-tissues depending on the applied power and the thermal increment in steady state. Due to miniature configuration of the applicator, a large range of SAR may be achieved in moderate thermal conditions.