Page 39 - Flexible Robotics in Medicine

22 Chapter 2

modifications to the pattern of cutting to enable the robot to achieve discontinuous
phase transitions, which enabled the robot to advance even faster than using uniform
and continuous propagation.

2.2.2 Actuation

The common types of actuation are pneumatic, hydraulic, mechanical, thermal, and
magnetic. Materials used in soft robotics need to have a controllable response to external
stimuli since many applications. The material also needs to allow the soft robot to adapt to
the physiological environment and navigate through a morphology that is not uniform or
constant in applications such as endoscopy. A balance between these two requirements
remains a challenge for research in soft and continuum actuation technologies [11,26 37].

The actuation method that this project will investigate is pneumatics. Pneumatics
accommodates the deformity of the origami-based design from its flat layout into its 3D
structure and vice versa. Pneumatics is also one of the accessible and versatile forms of
actuation, making it suitable for the task of this project to design a soft robot prototype.
Furthermore, the soft robot here is for colonoscopic procedures that use air insufflation to
distend the lumen of the colon for more natural advancement during the colonoscopy
examination. Thus studying its effects as an actuation method will be helpful for future
studies involving the application of soft robots for colonoscopy.

2.2.3 Colonoscopy and anatomical models

Colonoscopy procedures require a certain level of proficiency to be able to succeed in a full
inspection, which is often measured by the successful cecal intubation rate. The difficulty
of intubation arises from the complexity of the anatomy of the colon. For example, the
colon has compliant walls and a tortuous nature, which makes it prone to looping [12].
Additionally in segments like the sigmoid colon, the insertion length of the colonoscope
varies considerably, 10 35 cm in length where physicians have to be able to judge and
adapt to the different lengths [13]. The difficulty in achieving successful colonoscopy is
evident when the physician is not adequately trained or experienced in using colonoscopy
techniques [14]. Another factor is the changing colon anatomy from changing position and
orientation of the subject and different compressions and pelvic motions. Compressive
effects can be more significant than the effects of gravity [12]. The position and orientation
of the subject affect the colon since it is mobile and not planar in its position within the
body, as well as the high variability of different segments of the colon [15]. The variability
in diameter is not just present between segments, but there are variations in distal and
proximal measurements within the segments [12]. Even with proficient users of the
colonoscope, there are inherent difficulties for the physician to examine the colon because