An apparatus for use together with an AC signal generator for imposing electric fields through a target region in a subject's body, the apparatus comprising: a transducer array comprising: a plurality of capacitively-coupled electrode elements configured for placement against the subject's body; a substrate configured to hold the electrode elements against the subject's body; and a plurality of temperature sensors positioned to sense temperatures at respective ones of the electrode elements; a cable with multiple conductors and having a proximal end and a distal end, wherein the cable includes a first conductor that permits AC current to flow between the proximal end of the cable and the distal end of the cable, and a data path configured to carry digital data from the distal end of the cable to the proximal end of the cable; a module mounted directly or through intervening components to the distal end of the cable, wherein the module includes a distal circuit comprising: an analog multiplexer having an analog output and a plurality of selectable analog inputs, wherein each of the analog inputs is operatively connected to a respective one of the temperature sensors; an analog-to-digital converter configured to digitize signals from the analog output of the analog multiplexer; and a controller configured to sequentially select each of the analog inputs of the analog multiplexer, sequentially obtain, from the analog-to-digital converter, a plurality of temperature readings, each of the temperature readings corresponding to a respective one of the temperature sensors, and transmit digital data corresponding to the temperature readings; and a connector connecting the transducer array to the module, whereby the first conductor in the cable is connected to the transducer array and the temperature sensors are connected to the analog multiplexer. a transducer array comprising: a plurality of capacitively-coupled electrode elements configured for placement against the subject's body; a substrate configured to hold the electrode elements against the subject's body; and a plurality of temperature sensors positioned to sense temperatures at respective ones of the electrode elements; a plurality of capacitively-coupled electrode elements configured for placement against the subject's body; a substrate configured to hold the electrode elements against the subject's body; and a plurality of temperature sensors positioned to sense temperatures at respective ones of the electrode elements; a cable with multiple conductors and having a proximal end and a distal end, wherein the cable includes a first conductor that permits AC current to flow between the proximal end of the cable and the distal end of the cable, and a data path configured to carry digital data from the distal end of the cable to the proximal end of the cable; a module mounted directly or through intervening components to the distal end of the cable, wherein the module includes a distal circuit comprising: an analog multiplexer having an analog output and a plurality of selectable analog inputs, wherein each of the analog inputs is operatively connected to a respective one of the temperature sensors; an analog-to-digital converter configured to digitize signals from the analog output of the analog multiplexer; and a controller configured to sequentially select each of the analog inputs of the analog multiplexer, sequentially obtain, from the analog-to-digital converter, a plurality of temperature readings, each of the temperature readings corresponding to a respective one of the temperature sensors, and transmit digital data corresponding to the temperature readings; and an analog multiplexer having an analog output and a plurality of selectable analog inputs, wherein each of the analog inputs is operatively connected to a respective one of the temperature sensors; an analog-to-digital converter configured to digitize signals from the analog output of the analog multiplexer; and a controller configured to sequentially select each of the analog inputs of the analog multiplexer, sequentially obtain, from the analog-to-digital converter, a plurality of temperature readings, each of the temperature readings corresponding to a respective one of the temperature sensors, and transmit digital data corresponding to the temperature readings; and a connector connecting the transducer array to the module, whereby the first conductor in the cable is connected to the transducer array and the temperature sensors are connected to the analog multiplexer.