Tadpole endoscope: a wireless micro robot fish for examining the entire gastrointestinal (GI) tract

Abstract

Cancers of the gastrointestinal (GI) tract, including oesophagus cancer, stomach cancer and colon cancer, rank as the second most prevalent among all types of cancers in the world and the first in Hong Kong. The traditional method of diagnosing cancers in the GI tract requires three procedures: oesophagus cancer and stomach cancer can be diagnosed using gastroscopy; intestinal cancer can be diagnosed using capsule endoscopy; and colorectal cancer can be diagnosed using colonoscopy. These separate procedures are not only expensive but also exert a great deal of stress on the human body (both gastroscopy and colonoscopy require anaesthesia). Clearly, a simple, reliable and non-invasive diagnosis procedure for the GI tract would be a major breakthrough. This paper introduces an innovative capsule endoscope, called the Tadpole Endoscope (TE), which it mimics the tadpole in the nature and adopts a thunniform swimming mode. A simplified model is derived to illustrate the propulsion principle. The TE is a type of active locomotion capsule endoscope; it is like a micro-robot fish and can propel itself along the GI tract, especially in the stomach. Through the ex vivo tests, the maximum swimming speed can reach 12.5 mm/s and the minimum turning radius is 25 mm in the stomach.