Page 120 - Flexible Robotics in Medicine

106 Chapter 5

Figure 5.1
In vivo MOJO schematic.

structure, joint positions, equipment channel, lumen, and perforations used for the entry of
the support wires. The CAD rendering of MOJO shows perforations at its side for the
threading of actuating cables. It has two equipment channels within its lumen and two
perforations used for the entry of the support wires.
The objective of this project is to create a device with multibending using origami
techniques for the purpose of performing a tracheostomy. Inspiration was from the article
“Programmable Origami Strings”. However, this mechanism involves actuation at the tail
device by clamping the two sides of the elements together and using the rigidity of the
material to propagate this closing force throughout the whole device. This actuation
mechanism will not work with the project because it requires significant mechanical
strength at the head of the device to curve the drilling wire 90 degrees with a small radius
of curvature of about 6 mm. The 90-degree curve is significant because the device needs to
bend the drilling wire perpendicular to the trachea so that it can drill through the trachea for
tracheostomy. Furthermore, the device needs to fit into a trachea, which results in long and
relatively thin elements. Thus the elements will not be very rigid, and force propagation
will decay rapidly, causing the tip to have an insufficient closing force to bend the drilling
wire fully.

Thus an actuation method that can provide equal actuation through all the elements is
needed.