The pagoda instability (PI) on soluble fibers

TL;DR

This paper introduces the pagoda instability (PI), a new phenomenon observed when soluble fibers are immersed in liquid, involving spontaneous contact line instability and shape optimization due to dissolution and wetting effects.

Contribution

It proposes a criterion for PI, analyzes the competition between interface energy and chemical potential, and demonstrates how optimized fiber shapes reduce capillary effects in AFM measurements.

Findings

PI causes spontaneous contact line instability.

Optimized fiber shapes exhibit low adhesion force.

Using optimized fibers reduces capillary influence by 70%.

Abstract

This paper presents a new kind of instability when inserting a soluble fiber into liquid. After wetting and dissolving the fiber by the liquid, the moving contact line (MCL) spontaneously loses stability. Because the sculpted shape from fiber looks like a Chinese pagoda, we name this instability as pagoda instability (PI). Coupling of dissolution and wetting leads to other special phenomena, i.e. dissolving-induced jet flow, and optimizes the fiber shape, etc. We propose a criterion of PI and show the competition between interface energy and chemical potential deduce the MCL motion and PI. A phase diagram is used to summary the final shapes of fibers. By conducting atomic force microscope (AFM) measurement, we find the fiber with optimized-shape has the characteristics of low adhesion force. Using the optimized-fiber can decrease the 70% influence of capillary force for AFM measurement in humid environment.