Device for thermal treatment of tissue comprising a plurality of surfaces of implantable electrode (37-43, 71-81), at least one thermal sensor (55-61) for measuring temperature in or near at least one of said surfaces electrode (37-43, 71-81), at least one tissue heating element (32, 34) for heating the tissue, a current generator (50, 53), measuring means for measuring the value of an electrical property (52) between selectable pairs of said electrode surfaces (37-43, 71-81), and a control system (17) for controlling said heating elements of the tissue, current generating and measuring device, characterized in that a laser source (13, 15) for providing power to said heating element of tissue (32, 34)； and said device comprises memory (54) for storing measured values of these measures electrical properties over a period of time and software to process the stored measured values to determine a calculated value of the electrical property between at least one selectable pair of electrodes and to disable said heating elements tissue when said calculated value of the electrical property keeps changing for a predetermined period of time.Dispositivo para el tratamiento térmico del tejido que comprende una pluralidad de superficies de electrodo implantables (37-43, 71-81), al menos un sensor térmico (55-61) para medir temperaturas en o cerca de al menos una de dichas superficies de electrodo (37-43, 71-81), al menos un elemento de calentamiento del tejido (32, 34) para calentar el tejido, un generador de corriente (50, 53), medios de medición para medir el valor de una propiedad eléctrica (52) entre pares seleccionables de dichas superficies de electrodos (37-43, 71-81), y un sistema de control (17) para controlar dichos elementos de calentamiento del tejido, generador de corriente y dispositivo de medición, caracterizado por que una fuente láser (13, 15) para proporcionar energía a dicho elemento de calentamiento del tejido (32, 34)； y dicho dispositivo comprende memor
