Figure 1. Diagram detailing components of an endoscope.

These modern endoscopes can be expensive and thus are reused from patient to patient after being disinfected. Unfortunately, as these instruments are complex, they are exceedingly difficult to disinfect. This has led to the spreading of a bacterial “superbug” that has infected and claimed the lives of many patients at the UCLA hospital. The portions of the endoscope that provided the most issues and that are the focus of this project are the bending section and insertion tube of the modern day endoscope.

The motivation behind this project is to solve the disinfecting issue from a unique perspective; instead of perfecting the cleaning process, the problem can be avoided entirely by making the endoscope disposable. Thus, the current proposal for the project is to design, build, test, and document a mechanically operated endoscope that is disposable and primarily manufactured by 3-D printing.

Final Design

As the purpose of our project was to demonstrate feasibility of 3-D printing for the production of a disposable endoscope, the final design was identified as a minimal example to demonstrate the capabilities. This design is composed of three distinct segments: an actuated tip segment with 2 degrees-of-freedom (DOF), several passive (non-actuated) segments following the tip, and the actuation technology. The completed endoscope can be seen below in Figure 2.

Figure 2. Final completed endoscope design.

The endoscope was actuated through the use of Bowden cycles (popularly referred to as bicycle cables), which applies tension to a side of the tip of the endoscope, thereby reducing the length of wire through that side which results in a curvature of the scope. This can be seen below in Figure 3.

Figure 3. Actuated tip of the endoscope.

All three components are connected using ball joints and the final length of the endoscope can be customized depending on the number of passive followers used. Each of the components was 3D printed using a Objet 350 Connex 3 printer using the materials Tango Black Plus and VeroClear. The material composition of the actuated tip and the passive follower comprise of a mixture of Tango Black Plus and VeroClear. Tango Black Plus is a soft rubber like material, and VeroClear is a rigid clear plastic material. The passive followers composition results in a shore value of A70 to allow for bending of each section, but reducing the amount of buckling of each section. The actuated tips composition results in a shore value of A40 to allow for maximum bending. The ball joint sections of each component are printed using VeroClear in order to have the ball joints to snap together.

Results

Through the course of our work, we aimed to demonstrate the feasibility of 3D-printing for the sake of producing a disposable endoscope. This required demonstrating that the endoscope was able to turn 180 degrees and look back at itself. The other important consideration was that the endoscope would not produce surfaces stresses greater than the body's physical capacity for stress.The remaining requirements were satisfied without complication.

For the sake of demonstrating the capacity of the endoscope to turn 180 degrees, we were able to isolate a single actuated element to demonstrate that it was able to turn a full 180 degrees as can be seen in Figure 3. This demonstrated the capacity of the endoscope to satisfy the requirement that the endoscope be able to turn a complete 180 degrees.