coupling the gel however does not completely resolve the problem or compensate for poor or improper electrode skin contact rf energy coupled to the skin induces an electric current that heats the skin the current is dependent on the skin impedance which is a function of the quality of the rf electrode contact with the skin fig5 is an exemplary graphical illustration of the skin impedance dependency on quality of the electrodes with the skin contact the temperature measured by the sensor is dependent on the actual rate of heat exchange between the electrode and the skin and on the quality of the electrode with the skin contact proper contact between electrodes 208 and skin 212 fig2 a and 2b may be detected during the treatment by monitoring skin impedance between electrodes 208 as disclosed in the u s pat no 6 889 090 awarded to the same assignee as the present disclosure the impedance measurement is an excellent indicator of the contact quality low impedance between electrodes 208 and skin 212 fig2 a and 2b means that a firm contact between the electrode and the skin exists and accordingly the temperature sensor can follow the changes in the skin temperature sufficiently quick other known impedance monitoring methods may also be applied generally it is possible to measure the quality of the thermal.