Degradation test of the actuator
The circular-type actuator was placed on actinomycetes (Oki, Dr.
Actinomycete)-mixed soil in an oven (Yamato Scientific, ADP 300C) at 60
°C. The oven had a small hole that allowed air to flow in, which kept
the actinomycete active. The soil was collected on the campus of the
University of Electro-Communications.