An apparatus for applying an alternating electric field to a subject's body, the apparatus comprising: a plurality of capacitively-coupled electrode elements, each of the electrode elements having a dielectric layer; a support configured to hold the electrode elements so that the dielectric layer of each of the electrode elements can be positioned in contact with the subject's body; and an electrical conductor; a plurality of temperature sensors, wherein each of the temperature sensors is positioned to sense a temperature at a respective one of the electrode elements and generate a respective signal indicative of the sensed temperature; a plurality of electrically-controlled switches, wherein each of the switches is configured, depending on a state of a respective control input, either to allow current to flow between the electrical conductor and the respective one of the electrode elements or prevent current from flowing between the electrical conductor and the respective one of the electrode elements; and a controller configured to control the state of the control input of each of the switches, wherein the controller is configured to accept, from each of the temperature sensors, the respective signal indicative of the sensed temperature, determine, based on the accepted signals, duty cycles at which the electrode elements are to be driven, and periodically toggle the state of the control inputs of the switches that correspond to the respective electrode elements at the determined duty cycles in order to drive the electrode elements at the determined duty cycles and periodically prevent current from flowing between the electrical conductor and the respective electrode elements. a plurality of capacitively-coupled electrode elements, each of the electrode elements having a dielectric layer; a support configured to hold the electrode elements so that the dielectric layer of each of the electrode elements can be positioned in contact with the subject's body; and an electrical conductor; a plurality of temperature sensors, wherein each of the temperature sensors is positioned to sense a temperature at a respective one of the electrode elements and generate a respective signal indicative of the sensed temperature; a plurality of electrically-controlled switches, wherein each of the switches is configured, depending on a state of a respective control input, either to allow current to flow between the electrical conductor and the respective one of the electrode elements or prevent current from flowing between the electrical conductor and the respective one of the electrode elements; and a controller configured to control the state of the control input of each of the switches, wherein the controller is configured to accept, from each of the temperature sensors, the respective signal indicative of the sensed temperature, determine, based on the accepted signals, duty cycles at which the electrode elements are to be driven, and periodically toggle the state of the control inputs of the switches that correspond to the respective electrode elements at the determined duty cycles in order to drive the electrode elements at the determined duty cycles and periodically prevent current from flowing between the electrical conductor and the respective electrode elements.