Robots run on alcohol

Traditionally, the "muscles" of small robots worked with external power sources or batteries. In the latter case, this increased the weight and size of the robot considerably. The best batteries have an energy density of around 1,8 megajoules per kilogram. This is a fraction of what is made from animal fat, around 38 MJ / kg. The methanol-powered muscles used by RoBeetle can reach an energy level of up to 20 MJ / kg through catalytic combustion.

The methanol stored in the fuel tank triggers an energy-releasing chemical reaction that causes the robot's composite muscles to contract into a programmed shape. This enables the microrobot to move like a beetle. The robot can move and carries an object weighing 230 milligrams on its back - 2,6 times more than RoBeetle alone or 1,3 times more than RoBeetle and a full fuel tank.
The robot's builders are conducting further research to improve the RoBeetle's performance by using other fuel sources, including propane, which has an energy density of 50 MJ / kg. The researchers also plan to develop a flying version of the RoBeetle with funding from DARPA, the research division of the US Department of Defense. - We want to create the first fully autonomous flying robot, "says Perez-Arancibia.

Source: New Scientist, fot. Yang et al., Sci. Robot. 5, eaba0015 (2020)