Page 50 - Flexible Robotics in Medicine

Prototyping soft origami quad-bellows robots from single-bellows characterization 33

Referring back to Fig. 2.5, which shows the different prototypes created using the different
materials, the cardboard prototype was not able to produce successful actuation. This can be
attributed to a variety of factors. Firstly, the thicker material made it increasingly difficult
to fold the flat origami pattern into a geometrically uniform 3D structure despite the
etching, which was supposed to crease and allow for easier folding. Thus the cardboard
prototype required several attempts to successfully achieve a straight and uniform prototype
without tearing the material during the folding process. Etching also caused flaking along
the edges during the folding process, and this greatly affected the quality of the silicone
coating of the surface.

2.4.2 Borescope through colon model components

We verify the ability of the design and dimensions of the soft robot by carrying a
borescope. Two bellows units were attached to each side of an 8 mm tip borescope before
the assembled prototype was pushed through both the scaled colon model components.
Fig. 2.9 shows the successful passing of the assembled prototype through the scaled model
to succeed in navigating through a model of the sigmoid colon. It also shows that the
assembled robot was able to pass through the bent component of the rectosigmoid junction.

Fig. 2.10 shows the inner surface of the bent component of the scaled colon model that was
cast using the silicone equivalent model available in the lab. The lumen was not perfectly
circular as it was intentionally shaped in a way to simulate the uneven surface of the inner
colon walls as well as the narrow bend of the rectosigmoid junction that is known to be
challenging to navigate through. An observation made through the experiments resonated
with the discussion point mentioned earlier in a study regarding the inability of the
endoscopic view to be fully representative of the colon geometry [16]. Also, the soft robot

Figure 2.9
Borescope through bent component and a straight component of the colon model made from
Plastimake.