Inspecting 2 mm laser cut components for defects before assembly

Author: Ariadna Ramirez | Major: Mechanical Engineering | Semester: Fall 2024

Minimally invasive surgeries have transformed healthcare offering faster recovery times, shorter hospital stays, and reduced risks in many cases compared to traditional open surgeries. But despite these advancements, the tools surgeons rely on still fall short when it comes to addressing certain complex cases. For endovascular surgeries—procedures performed within blood vessels—the limitations of existing technology can mean life-saving treatment remains out of reach for some patients.

Currently, surgeons use guidewires and catheters to navigate the vascular system. These tools work together, with the guidewire creating a pathway for the catheter to follow. However, this approach has a major drawback: limited range of motion. Blood vessels are intricate and uniquely structured, and when surgery is needed in a hard-to-reach area, these tools can present difficulties in navigating the twists and turns.

Soft robotics offers a groundbreaking solution. By designing millimeter-scale soft robots with tendon-driven movement, we can vastly improve dexterity and enable access to challenging anatomical structures for example. These tiny robots have the potential to revolutionize minimally invasive procedures by increasing precision, delivering treatments directly, and making surgeries safer and more accessible.

However, creating such precise robots at this scale isn’t easy. My work this semester focused on tackling these challenges, from low-cost manufacturing methods to hands-on prototyping.

Before research, the biggest hurdle I faced was actually putting myself out there in the professional field. While I could work out the complex mathematical computations necessary, I lacked many practical skills making me hesitant to approach a professor about research. After taking Dr. Shou’s Introduction to Materials class, he extended the invitation to check out his lab. It was during the tour of his lab that he introduced a concept for this project that immediately piqued my interest.

Coming into university, I was fascinated by the field of bioastronautics because while I could not see myself going to space, I wanted to be involved in providing better ways to protect the astronauts during and after long flights. However, one does not simply go from finishing high school to literal rocket science which left me with no clue on what to research as an undergraduate. The millimeter scale robot concept immediately caught my interest because of the challenge of constructing at a miniature scale. Ironically, while I liked miniature structures, I would come to realize I had largely underestimated the difficulties I would face.

From the get-go, I struggled to find the optimal settings required to laser cut the 2-mm circle components that were the backbone of the robot. Too much power and the acrylic sheet that I used would melt or even be eviscerated in certain cases. Too little power, and it would not cut through. Along with power settings, work speed works in tandem to determine the speed at which the laser head moves across the material being cut. The settings that I eventually used for a couple of the prototypes were 65% power with 60% work speed. It took me 37 tests and an additional 10 repetitions to get to that point which already was much longer than I expected.

While assembling the robot was my favorite part of prototyping, it was very difficult to do so by hand. Tendon-driven actuation meant that I needed to thread very thin tubes through those 2-mm parts to serve as channels for the even thinner wire threaded through those tubes. Paired with shaky hands, it could take up to 2 hours to simply align the pieces of the robot before fixing them in place. For this reason, my aim for the second semester of work into this project is to explore avenues that would streamline the assembly process and cut down on the time needed to assemble each robot.

For this project, Dr. Shou provided me with a lot of freedom to experiment and design, giving me feedback on every step of the process and the results I shared with him. Additionally, I was assisted by a couple of PhD students who taught me the ropes of using slicing software for 3D printing, different types of laser cutters, and how to document experiment results in an efficient manner. As mentioned before, my future plans in this project include shortening the time required to build each robot and designing a maze of sorts that would be similar to the intricate pathways of blood vessels to test each design.

My long-term plans include the goals of presenting the results of this research at an upcoming conference and submitting a paper alongside it. With my graduation date coming up in May 2026, I hope to build a good resume and learn more about my interests in order to have full confidence in my future graduate school applications.