A system for monitoring energy delivery, the system comprising: an energy supply unit for delivering energy to a target tissue region comprising a plurality of tissue layers each having varying characteristics; a treatment unit having a device body and a plurality of pairs of energy transfer elements, where the device body includes a tissue engaging surface that allows orientation of the device body on the surface of tissue, where the plurality of energy transfer elements extend from the tissue engaging surface and each include an energy transfer portion configured to apply energy during a treatment cycle of the energy supply unit; a connector (96, 610) adapted to couple the energy supply unit to the plurality of energy transfer elements; wherein the energy supply unit is arranged to deliver an initial energy to the energy transfer elements to enable identification of a tissue characteristic of a tissue layer in which the energy transfer portion of the energy transfer element is located; and a graphical user interface coupled to the energy supply unit and energy transfer element, the graphical user interface configured to display a tissue characteristic indicator associated with the tissue characteristic characterized by: a controller arranged to monitor the initial impedance of the tissue and use an algorithm including a PID (Proportional, Integral, Derivative) control to control an input voltage between a pair of energy transfer elements, wherein the controller is configured to determine a depth of the tissue layer based on the monitored impedance. an energy supply unit for delivering energy to a target tissue region comprising a plurality of tissue layers each having varying characteristics; a treatment unit having a device body and a plurality of pairs of energy transfer elements, where the device body includes a tissue engaging surface that allows orientation of the device body on the surface of tissue, where the plurality of energy transfer elements extend from the tissue engaging surface and each include an energy transfer portion configured to apply energy during a treatment cycle of the energy supply unit; a connector (96, 610) adapted to couple the energy supply unit to the plurality of energy transfer elements; wherein the energy supply unit is arranged to deliver an initial energy to the energy transfer elements to enable identification of a tissue characteristic of a tissue layer in which the energy transfer portion of the energy transfer element is located; and a graphical user interface coupled to the energy supply unit and energy transfer element, the graphical user interface configured to display a tissue characteristic indicator associated with the tissue characteristic characterized by: a controller arranged to monitor the initial impedance of the tissue and use an algorithm including a PID (Proportional, Integral, Derivative) control to control an input voltage between a pair of energy transfer elements, wherein the controller is configured to determine a depth of the tissue layer based on the monitored impedance. a controller arranged to monitor the initial impedance of the tissue and use an algorithm including a PID (Proportional, Integral, Derivative) control to control an input voltage between a pair of energy transfer elements, wherein the controller is configured to determine a depth of the tissue layer based on the monitored impedance.