Nitinol actuation voltage and durability tests were done with the same setup. Pre-stretched Nitinol wire was fixed one end to a monkey bar, the other to a force sensor. Powerstat (Staco Energy Products Co. Type 3PN1010, Miamisburg, Ohio, USA) was used to deliver power. The on/off operations were performed by hands, which can be inconsistent between repeats. The actual on/off can be interpreted from the force/time graph.