CAD Modeling & Simulations
Adobe Illustrator
Iterative Prototyping
Material Selection
Heat Transfer
Patent Search

Team

Erik Furton, Jonathan Toth, Nathan Young & Christy Zhang, team leader

Sponsor

Hu “Tiger” Tao, BIBIE Lab

Faculty Advisors

Brian Korgel & Thomas Krueger

This was my senior design project for Mechanical Engineering at The University of Texas at Austin.

January - May 2018

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temperature- controlled microscope stage

Nanolithography uses an atomic force microscope (AFM) and has a variety of biomedical and electrical applications, but the properties of some materials are dependent on temperature. Existing heated AFM stages are designed to fit specific microscopes and cost around $8000. We created a $10 stage (plus temperature controller and sensor) that is retrofitted to an existing AFM and controllable for accurate measurement of samples on a nanometer scale.

Concept Generation, Prototyping, Testing & Iteration

Out biggest challenge in developing a heated microscope stage was minimizing thermal drift in readings, which is a combination of thermal expansion and testing conditions that can’t be accounted for. We also wanted a uniform temperature distribution across the surface of the stage. This meant that a combination of conductive and insulating materials and stage geometry would be critical to our design.

We created three prototypes to iterate on based on testing. The first validated our model and proved that it would provide a uniform temperature distribution. The second allowed us to compare sensor and sample temperatures and measure settling time and steady state fluctuations at different temperature set points. Our sponsor was able to conduct a set of experiments with this prototype to image a known specimen. This prototype succeeded at imaging up to 70ºC, which we discovered was a limit for the AFM measurement components.

Solution & Lessons

We designed our final prototype to be as thin as possible with two wood frames that are stacked together to hold a aluminum plate and a heater.

Our prototype cost us a total of $5.20 for materials. If this design were to be manufactured, there would be costs associated with machining, but both wood and aluminum are relatively cheap, and the design is simple to machine.

This project taught me to challenge standards. Upon discovering that wood had the properties we needed for our project, we, along with our sponsors and mentors, were skeptical. Wood is not typically a material used for precise measuring devices due to its irregularities from sample to sample and its tendency to deform under humidity. Despite the concern, we felt that wood could be an acceptable material since all AFM testing is done in an isolated room where humidity isn’t a concern and mass production of the stage wasn’t needed. Testing showed us that our stage sufficiently fulfilled the requirements and constraints for this project.