# Power/energy density of an actuator

What is the meaning of power/energy density of an actuator?

Context: As a novel kind of actuator, the dielectric elastomer ( DE ) demonstrates high-strain response [ 1 ] , high energy densities ( seventy times higher than conventional electromagnetic actuators ) [ 2 ] , and high energy conversion ef ﬁ ciencies ( 60% – 90% [ 3 ]) .

For example, if your actuator is made from $$2kg$$ of DE and delivers $$5W$$ worth of power, then the power density is $$5/2=2.5W/kg$$
Again, the DE actuator is $$5W$$ in output, and it has a volume of $$0.02m^3$$, the its power density will be $$5/0.02=250W/m^3$$