BI TAD®, or Transdermal Alcohol Detector, continuously monitors for alcohol consumption through a noninvasive skin sensor worn on a client’s ankle. TAD also includes radio frequency monitoring capabilities so clients can be monitored for curfews and alcohol use with the same device. If a client drinks alcohol while wearing a TAD ankle bracelet, the sensor detects a “drinking event” via sensible perspiration (sweat) and insensible perspiration (vapor) emitted through the skin.