Experimental setup (a) with a silicone chamber (b). The right and left edges of the silicone chamber were grasped with a holding block and plate, and we inserted cylindrical pins into the four holes of the chamber to transmit a force from the connecting plates to the chamber. The chamber was stretched by moving the pair of pulse stages with a controller. The acrylic block kept the silicone membrane flat. A surfactant added to the water in the dish reduced the friction significantly between the acrylic block and the silicone membrane when stretching.