Wireless Surgical Capsule Robots for the Gastrointestinal Tract: Towards small scale therapeutic functions without on-board computation

Capsule robots provide an alternative route of entry to the gastrointestinal tract with minimal discomfort to patients. There are many examples of therapeutic capsules, but a gap exists in their capability in carrying out complex surgical functions such as manipulation in a suitable capsule size. There are two major factors for that limit the size of capsules; small scale actuators and on-board computation and communication required to control them. Controlling soft actuation wirelessly with an on-board pneumatic source of pressure could help with miniaturisation of efficient small scale actuators due to their scalability. An untethered robotic capsule that can provide volumetric expansion using a chemical reaction without on-board electronic components was designed along with a theoretical model for predicting the inflation behaviour. The expansion is based on the reaction between chemicals that are safe for ingestion, operated with thermal input provided by alternating magnetic fields from outside the body. Additionally, a new amplifier design that can deliver power to simple receiver circuits in parallel was presented. This allows the control of a wireless capsule that can use the electrical power for applications such as heating a target location, powering small motors bidirectionally and turn on LEDs without the use of a microcontroller. The design was tested for up to 6 addressable components, and an analysis on the limitations of this approach has been carried out. An example design of a capsule robot capable of anchoring itself to the intestinal tissues, use its manipulator arm to target a specific location and heat the location to patch wounds, or destroy pathogens or cancer cells was presented. Together, the wireless soft actuator and the wireless powering method should benefit further miniaturisation of therapeutic capsule robots capable of more complex in-vivo surgical functionality.