The measurement of the kinetics of lipid phase transitions: a volume-perturbation kinetic calorimeter.

A volume-perturbation kinetic calorimeter to be used to study membrane phase transitions in lipid vesicles has been developed. In this instrument, the voltage-dependent extension of a stack of piezoelectric crystals is used to force the solution being studied to undergo a small adiabatic bidirectional volume change. This volume change induces a shift in the equilibrium position of the lipid gel to liquid-crystalline transition. The time course of the relaxation to the new equilibrium position is then monitored by observing the induced temperature and pressure changes as a function of time.