The STF consists of 9 independently heated thermal zones and two guard zones. The guard zones purpose is to thermally isolate the other zones to prevent any un-measurable heat loss. The test and guard zones are controlled via temperature measurements from
thermistors. Additionally, each thermal zone has sweat control through evenly distributed fluid ports on it’s surface. The foot is split into two halves to facilitate insertion into footwear. There is a guard located on the top of each of the two foot sections.