In the finished device, described in the online 16 January Nature Materials, the heart muscles contract rhythmically to drive the machine, drawing energy from the glucose in the solution around them.
"I'll send you my material about the heart in Egyptian afterlife," announced a friend as we took a walk.
I had always considered my thoughts as something abstract, but they weren't; they were as material as the heart beating in my chest.
The department has argued that plutonium, the material at the heart of nuclear bombs, deteriorates over time, and thus the hollow plutonium spheres at the heart of the bombs, the "pits," have to be replaced.
The plan was to have both countries build factories that could mix uranium with plutonium, the material at the heart of nuclear bombs, to be burned as fuel for civilian reactors.
If that is not possible, then obtaining a relatively pure form of the fissionable material at the heart of a nuclear weapon is a more complicated possibility that would require building the rest of the weapon.
The scientific and technical know-how to build a bomb is useless without sufficient quantities of highly enriched uranium or plutonium, the "fissile material" at the heart of an atomic weapon.
When particles crash into the semiconducting material at the heart of their detector, they heat it by tiny amounts, which it records.The trouble is that any particle can play this game.
The Guardian's judges chose this winner for its "impressive attempt to source a material at the heart of their products' sustainability, using circular economy thinking and taking a zero waste approach".
Contrast material in the heart and vessels will appear green in the images.
