The motor is 80 mm × 25 mm in size and weights about 3 g. It generates up to about 0.1 N · m of rotational force (corresponding to a bending force of a little finger) and the maximum operating angle reached 90 degrees. The motor is filled with acetone which is evaporated by a printed heater. When heating is stopped, the gas turns into liquid, and the motor returns to its original form. The results are part of the Kawahara ERATO project devoted on delicate and powerless IoT infrastructures, https://www.jst.go.jp/erato/en/research_areas/ongoing/15663117.html

JST news release, May 26, 2017