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Vacuum Table upgrade to CNC Mill (Ongoing)

During my work as a postdoctoral research fellow at Haverford College myself and an undergraduate research student have set out to find a way to gently cut cylinders from sheets of polyurethane in a way that preserves the material’s optical properties. This process is not trivial, other research groups have attempted to make a similar process work with mixed success. None the less, after a summer of diligent effort the student researcher handed off a working process that simply needed refinement. I designed an all-in-one version of the initial process which incorporated a vacuum table with a clamping bracket work holding solution and shop-vac assisted cylinder collection apparatus. This set-up bolts directly onto the existing hardware of the mill and includes a high accuracy zeroing solution to protect the cutting tool. Ongoing work on this problem includes working with a skilled lathe expert to create custom tools out of hardened steel with key design adjustments to a commercial tool that didn’t quite fit our needs.

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Composite Imaging Robot

Another facet of my postdoctoral work includes the development of a robot that takes an array of images we can stitch together into a single cohesive high resolution image. The technique is inspired by astrophysical composite images. Our application uses an Instron testing frame to compress a quasi-2D granular sample (cylinders stacked between glass plates). The Instron has its own control software but also allows for signaling using serial communications via an arduino uno so that the imaging portion of the set-up can be synchronized with the testing frame. The imaging apparatus consists of a 2D gantry that moves a camera equipped with a linear actuator. The action of the polarizer attached to the linear actuator allows the camera to take images with and without a polarizer at each position. A python program controls the gantry, camera, actuator, and communicates with the arduino. The video above shows a portion of an image capture sequence.

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Force Transduction Apparatus

My first project as a graduate student in Joey Paulsen’s lab at SU was centered around the force of indentation of ultra-thin polymer films floating on a water bath. We wanted to measure this force over a large range of indentation and found the commercially available force sensors unhelpful in the range of forces we needed to resolve. Thankfully a colleague of Joey’s from UMass Amherst was able to share the designs of an apparatus they used to do the only other study of this particular system. I contacted the engineering department to get trained up on safely using machine shop mills and lathes so I could make my own. Using aluminum I made the transduction appartatus, on the far left as well as the shim and indentation probe on the bottom left of the middle image below. I used thermoplastic to make the hooked probe on the upper left of the middle image which allowed us to study the mirror case where the film is indented from below. I used a capacitive sensor, a modified trigger button assembly, and data acquisition card to synchronize the triggering of video, force data, and positional data. This apparatus was featured in Timounay et al. PRX 2020 and Ripp et al. Soft Matter 2021 as well as my dissertation: Buckling Patterns and Mechanics of Thin Interfacial Polymer Films 2021 available via SURFACE at SU.