The scientific objective of Archimedes is to weigh the vacuum, i.e. to investigate the role of the interaction of vacuum fluctuations with the force of gravity, using a high sensitivity balance. It will measure the small weight variations induced in two high-temperature superconductors that have the property of "trapping" or "expelling" vacuum energy when their temperatures are greater or lower than their critical temperatures (thermal modulation). Only the radiative heat exchange mechanism must be used to remove or add thermal energy to the sample as it must be isolated from any external interaction that could prevent the reversibility of the thermodynamic transformation or generate a spurious force on the sample. A cryogenic prototype at liquid nitrogen temperature is being optimised for performing thermal modulation with the help of a FEM analysis. The characterisation of different high-temperature superconductors is also an important study to be explored. The most recent results will be presented.