Page 52 - Flexible Robotics in Medicine

Prototyping soft origami quad-bellows robots from single-bellows characterization 35

actuation process based on the programmed sequence of inflation and deflation patterns.
The long-term aim is achieving successful navigation through the compliant and
tortuous colon using a combination of rectilinear locomotion for end-effector
advancement and concertina locomotion for curved trajectory advancement. Automation
of the actuation method will eliminate inconsistencies and errors arising from manual
handling of the multiple syringes required to inflate and deflate different units of the
soft robot individually.

Another possibility besides pneumatic actuation is to consider utilizing a magnetic type of
actuation. This form of actuation would be beneficial to the application of colonoscopy,
as it adds the element of rotation that the existing design and gaits chosen are unable to
achieve using pneumatic actuation. Since the rectilinear and concertina gaits tend to be
dependent on the resting surface that it is moving along as well as advancing in a planar
manner, the added rotation element from magnetic actuation would be useful. Varying 3D
colon anatomy results from the position and orientation changes of the patient as well as
compression or insufflation of the colon during the procedure. Preliminary ideas on the
study of implementing magnetic actuation would be to attach different types of magnets to
specific folds of the bellow and explore the ideal strength and placement of the magnets
that can best propel the robot forward. The origami pattern of the soft robot design could
also be modified to introduce a twisting or rotational element so that the robot could
achieve torsion during the expansion from flat layout to 3D structure to further aid its
forward advancement.

2.5 Conclusion

This project investigated soft robotic origami design that can potentially be useful in
transluminal applications. We explored the effects of different thicknesses of paper-based
materials folded in the form of a simple octagonal bellows design. The different materials
exhibited different advantages and disadvantages regarding their strength, successful
actuation, and miniaturization. Standard 80 gsm paper proved to be the most versatile of
the paper-based materials tested due to its creasing precision, inflation length achieved,
and ability to be miniaturized successfully into a 9 mm prototype that could pass through
bent and straight colon segment models. However, the increasing thickness of material
resulted in less deflection along the centerline, and hence a more accurate straight path
was achieved.
The quad-bellows prototype involves four 9 mm bellows units with space in between for
the inclusion of a scope. This project achieved successful navigation of an 8 mm borescope
through a model of the sigmoid colon segment, which is the narrowest segment of the
colon. However, more work is needed to ensure that the size of the soft robot can meet the