Micro-, and milli-scale robots have emerged as next generation of intelligent technology for minimal invasive diagnosis and treatment. One example is ingestible capsule endoscope, which is a type of medical robot designated for diagnosis and treatment of diseases in the digestive tract, such as gastrointestinal bleeding, in inflammatory bowel disease, and celiac disease. Unlike traditional upper gastrointestinal endoscopes and colonoscopes, which cause drastic discomfort when inserted form mouth or rectum of a patient, the non-precedent small envelope size of the ingestible capsule endoscope will allow for minimal invasive interventions.Recent minimal invasive interventions call for robots that work as tiny “surgeons" or drug delivery “vehicles" to achieve inner body diagnostic, surgical, and therapeutic practices, without any trauma or discomfort. A robot with such an application typically contains a miniature camera, LED light sources, an on-board battery, a microcontroller, and a wireless transmitter, while advanced robots may also incorporate multiple sensors, robotic actuators, and even surgical end-effectors.One issue in traditional medical robots is their large body sizes, which make them hard to swallow. Another issue is a lack of control methods for the robots during their working procedure. This problem may even aggravate when a robot becomes lodged in a digestive tract rather than leaving the body in a bowel movement within several days. According to previous discussion, it is beneficial to have a design of a robot, that is small and controllable, for minimal invasive interventions. However, these two objectives are contradictory as the robot size is also required to be large enough during its working procedure for good controllability. In addition, a robot body should be lightweight for low energy cost in motivation, and high-stiffness for desired shape maintenance. A robot for minimal invasive interventions that satisfies these design requirements, to the best of authors’ knowledge, is currently unavailable.To fill the aforementioned technical gap, this paper presents a design of an innovative milli-scale deployable tensegrity microrobot for minimal invasive interventions. The robot is made of a deployable tensegrity structure integrated by self-stress. The tensegrity structure is free-standing, and can maintain its desired shape without complex joints or mechanisms, which are commonly seen in umbrella- or origami-shape deployable structures. The stowage size of the robot is small for easy swallow. After deployment, the tensegrity body of the robot displays lightweight and high stiffness and good controllability. Active control in reconfiguration of the tensegrity body can lower the chance of retention in the small bowel. The robot is also energy-efficient, as it is self-deployable by structure member stored potential energy, and is motivated by remote magnetic actuation. A battery smaller than that used in traditional robots for minimal invasive interventions can be attached to this robot, since no internal power is needed for deployment and locomotion. Such a modification will yield a robot with even smaller stowed size and lighter body weight.

A Deployable Tensegrity Microrobot for Minimal Invasive Interventions

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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