Page 48 - Flexible Robotics in Medicine

Prototyping soft origami quad-bellows robots from single-bellows characterization 31

The sections from the anal verge to the middle of the descending colon were chosen for
their difficulty during a typical colonoscopy so that the experiments conducted could be
more representative [14]. The challenging areas for these segments are the junctions
because the bends are tough to navigate with existing colonoscopy equipment, and there
is typically a struggle finding the balance between sufficient stiffness for easy navigation
and sufficient flexibility for maneuvering around bends. The difficulties faced during
colonoscopy include the need to succeed in navigating through the rectosigmoid and
sigmoidodescending junctions, as well as sigmoid colon without causing loop formation
or iatrogenic perforation.
For focused experimentation, we create two components modeled after the geometries of
the more complex segments of the colon during the procedure. The components included a
straight segment scaled after the sigmoid colon, which is the area with the smallest
diameter in the colon, as well as a curved segment modeled after the rectosigmoid junction,
which has an acute bend and is one of the challenging segments of the colonoscopy
procedure. The components were fabricated using the PCL material and cast using a
silicone equivalent model of a colon available in the lab as reference.

2.4 Results and discussion

2.4.1 Actuation of the individual bellows unit

Actuation of the paper-based prototypes using individual octagonal bellows is to study
the differences between the types of materials. Fig. 2.7 shows the resting state of the
silicone-coated 9 mm paper prototype, followed by its deflation and inflation through
manual operation of a syringe. The deflation was unable to achieve full and planar
deflation, as the frontal edge collapsed more than the further edge. This probably arose

Figure 2.7
Actuation of 9 mm diameter paper prototype, showing deflection along the centerline upon
inflation.