Previous “microrockets” have been fuelled by hydrogen peroxide, which disagrees with the human stomach. But this one can get the little motors zooming around at a speedy clip with a tiny bubble propelling it.
Wei Gao, Aysegul Uygun and Joseph Wang at the University of California, San Diego, published their work in a recent issue of the Journal of the American Chemical Society. They say their microrockets, which are shaped like tiny tubes 10 micrometres long with diameters of 2-5 micrometres, could be used for targeted drug delivery, nanoimaging or for the monitoring of industrial processes. They’re made of polyaniline (aka PANI), lined with a thin layer of zinc on the inner surface. When immersed in any highly acidic solution, the zinc loses electrons and gives off hydrogen bubbles, which means the minimotors self-propelled.
The lower the pH of the solution, the faster the minirocket will go. They reached a maximum of 1050 micrometres per second, and the scientists say the pH range in the human stomach would create a zippy environment for their device, which can keep going for between 10 seconds and two minutes.
Video: American Chemical Society