Table 5. Comparison of the Properties between Natural Muscles and Artificial Actuators.³⁰

Actuators	Strain	Actuation Pressure	Density	Efficiency	Speed (fast AND slow)
Natural Muscle	●	●	●	●	●
Electromagnetic	●	●	○	●	○
Piezoelectric	○	●	◐	●	●
Shape Memory Alloy	◐	●	◐	○	○
Magnetostrictive	○	●	○	●	○
Electrostatic	●	○	●	●	●
Dielectric Elastomer	●	●	●	●	●

○ = Poor ◐ = Fair ● = Good