Micropipette aspiration

In a membrane-mechanics experiment, a narrow glass pipette applies a controlled pressure difference and draws a tongue of membrane into its opening. Imaging the aspirated length and vesicle geometry estimates the change in apparent membrane area. At low tension, much of that change can flatten thermal undulations; at higher tension it can measure actual area dilation. For ideal spherical caps with pipette radius $R_p$ and vesicle radius $R_v>R_p$, the Young–Laplace equation gives $\Delta p=2\sigma (1/R_p-1/R_v)$. Bending at the rim, adhesion and a membrane-associated cytoskeleton can require corrections to this simple geometric inference.