Table 1.

List of GUV mechanical properties and their definition.

Mechanical Property	Definition
Young’s modulus	A physical quantity that measures the general stiffness of elastic solids. Generally not a quantity used to characterize GUVs.
Bending rigidity	Physical quantity that measures resistance of an elastic material to changing its curvature. Membrane bending rigidity is one of the commonly measured GUV physical quantities.
Area expansion modulus/stretching modulus	Under tensile stress, an elastic material can expand to failure. Area expansion modulus measures the resistance of an object to expand/stretch under load. In GUVs, area expansion modulus measures how GUV bilayers withstand area expansion.
Membrane tension	Membrane tension is a state property measuring the force per area acting on a membrane cross-section. For GUVs, different approaches can be used to either measure membrane tension of GUV bilayer at an unperturbed state or to modulate membrane tension.
Viscoelasticity	Like most biological materials, GUVs exhibit both elastic and viscous properties. Viscoelasticity measures time dependent behavior of a material by measuring loss modulus from the relaxation curve during loading and unloading phases of the material.
Area compressibility modulus	This is the same as area expansion modulus when the load is compressive
Deformability	In GUVs, deformation modes are often elliptical. Deformability measures how much elliptically deformed GUVs deviate from a unit circle by calculating the ratio of major axis to minor axis.