Alternate Alternative Fuel for Robots of the Future

In what seems like the perfect solution to everything (or an episode of What Could Possibly Go Wrong?!), a pair of prototypes hint at a future in which robots eat bugs for fuel. Forget charging batteries or docking in your very own R2D2 — these autonomous, self-feeding droids could easily run along happily without us. The secret lies in two developments, both of which mimic the Venus flytrap’s prey-catching method:

Recreating this method means finding materials that can not only detect the presence of an insect but also close on it quickly. At Seoul National University in South Korea, Seung-Won Kim and colleagues have done this using shape memory materials. These switch between two stable shapes when subjected to force, heat or an electric current.
The team used two different materials – a clamshell-shaped piece of carbon fibre that acts as the leaves, connected by a shape-memory metal spring. The weight of an insect on the spring makes it contract sharply, pulling the leaves together and enveloping the prey. Opening the trap once more is just a matter of applying a current to the spring.
Mohsen Shahinpoor at the University of Maine in Orono took a different approach. His robot flytrap uses artificial muscles made of polymer membranes coated with gold electrodes. A current travelling through the membrane makes it bend in one direction – and when the polarity is reversed it moves the other way.
Bending the material also produces a voltage, which Shahinpoor has utilised to create sensors. When a bug lands, the tiny voltage it generates triggers a larger power source to apply opposite charges to the leaves, making them attract one another and closing the trap (Bioinspiration and Biomimetics, DOI: 10.1088/1748-3182/6/4/046004).
“We should be able to benefit enormously from these flytrap technologies,” says Ioannis Ieropoulos of the Bristol Robotics Lab in the UK. He and colleagues previously developed Ecobot, a robot that can digest insects, food scraps and sewage to power itself. Ecobot uses bacteria to break down a fly’s exoskeleton in a reaction that liberates electrons into a circuit, generating electricity.

It’s an interesting premise, the bug-eating robot. I’d personally never thought of feeding a machine anything other than electricity (or sunlight for the solar-powered variety).
If you built a robot, which fuel source would you design it to run on?

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