The history of ingestible medical devices dates back more than fifty years to the introduction of the Heidelberg pH Diagnostic System by Heidelberg Medical. Used primarily by gastroenterologists and nutritionists, the system is designed to measure the pH levels of the stomach, duodenum and small intestine. This information can be used to diagnose a number of conditions such as acid reflux, ulcers, and achlorhydria (a lack of stomach acid). The capsule, 8mm x 21mm, or about the size of a standard vitamin pill, is battery powered and transmits data through a radio frequency back to a recording system. Prior to the introduction of this technology, patients would need to endure the unpleasant experience of being intubated with a stomach tube in order to properly diagnose stomach or intestinal issues. In addition to that benefit, the capsule could continue to relay information after it leaves the stomach and enters the intestines, which was past the point that a tube could safely reach. The Heidelberg and CorTemp systems were designed to measure and record two different things, but in many ways were created for the same purpose; to increase the accuracy of the recorded data, and to do it in a way that greatly improves the experience for the patient.