January 1, 2019.
We study the behavior of the liquid-solid-vapor contact line of water held in a narrow gap between two plates. A syringe pump injects and withdraws a constant, small volume of the water, driving the contact line back and forth repeatedly and changing its shape. We take photos of the contact line after each cycle. Comparing subsequent images to each other, we find that after several cycles the contact line reaches one of two steady states: a reversible steady state, where the shape is not changing, or a fluctuating steady state, where the shape continues to change slightly. Experiments on acrylic plates show a fluctuating steady state at higher volumes, while experiments on glass plates become reversible even at high volumes. This behavior motivated the search for return point memory in the contact line on glass plates. On glass, we train the contact line with a certain volume to reach a steady state, which we show is erased by larger volumes but not smaller volumes. This suggests memory exists, and that the trained volume can be stored as information in the contact line.
Nathan C. Keim
California Polytechnic State University (Cal Poly SLO)
The 2019 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (http:://www chevron com), the National Science Foundation through the Robert Noyce Program under Grant 1836335 and 1340110 the California State University Office of the Chancellor, and California Polytechnic State University in partnership with the National Science Foundation Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the funders. This work was supported by NSF grant DMR-1708870.