# Comparison of the lateral retention forces on sessile, pendant, and inverted sessile drops

## TL;DR

This study experimentally compares the lateral retention forces on sessile, pendant, and inverted sessile drops, revealing that the retention force depends on the drop's placement and deposition history, with inverted drops often exhibiting larger forces.

## Contribution

It provides new experimental insights into how the retention force varies with drop configuration and history, highlighting factors influencing adhesion beyond static placement.

## Key findings

- Pendant drops have smaller retention forces than sessile drops.
- Inverted sessile drops often have larger retention forces than sessile drops.
- Drop deposition history affects shape, contact angles, and retention force.

## Abstract

We compare the lateral retention forces on sessile drops (which are drops that are placed on top of a solid surface), pendant drops (which are drops that are placed on the underside of the surface), and inverted sessile drops (which are drops that are first placed on top and then on the underside of the surface by flipping the surface). We have found experimentally that the retention force on a truly pendant drop is always smaller than that on a sessile drop. However, the retention force on an inverted sessile drop is comparable to, and usually larger than, that on a sessile drop. Thus, the retention force on a drop depends not only on whether it is placed on top or on bottom of a surface, but also on the history of drop deposition, since such history affects the width, the shape and the contact angles of the drop.