  Measuring the mechanical properties of cells and tissues often involves
indentation with a sphere, or compression between two plates. Previously,
different theoretical approaches have been developed to retrieve material
parameters (e.g. elastic modulus) or state variables (e.g. pressure) from such
experiments. Here, we extend previous theoretical work on indentation of a
spherical pressurized shell by a point force to cover indentation by a
spherical probe or a plate. We provide formulae that enable the modulus or
pressure to be deduced from experimental results with realistic contact
geometries, giving different results that are applicable depending on pressure
level. We expect our results to be broadly useful when investigating
biomechanics or mechanobiology of cells and tissues.
