Fig. 5.

Diagram of an agarose bead immersed in ASL. The diagram shows the force due to surface tension and the capillary forces acting on the bead, and the parameters relevant to Eq. (3). Where R is the radius of the agarose bead, γ is the surface tension of ASL, δ is the height of the ASL layer in the trachea, z ₀ is the meniscus depth of the ASL due to the capillary effect of liquid around the agarose bead, θ is the contact angle between the ASL and the agarose. Our analysis shows that under our experimental conditions, the net effect of gravity and surface tension push the beads against the epithelium without causing significant tissue displacement