Researchers at University of California, San Diego have developed a propulsion system for navigation of small capsules through highly acidic environments without requiring any internal power source.
The scientists foresee the swallowable devices powered by the zinc-based motor used for drug delivery and for sensing the internal environment for medical applications.
From the study abstract:
Tubular polyaniline (PANI)/Zn microrockets are described that display effective autonomous motion in extreme acidic environments, without any additional chemical fuel. These acid-driven hydrogen-bubble-propelled microrockets have been electrosynthesized using the conical polycarbonate template. The effective propulsion in acidic media reflects the continuous thrust of hydrogen bubbles generated by the spontaneous redox reaction occurring at the inner Zn surface. The propulsion characteristics of PANI/Zn microrockets in different acids and in human serum are described. The observed speed–pH dependence holds promise for sensitive pH measurements in extreme acidic environments. The new microrockets display an ultrafast propulsion (as high as 100 body lengths/s) along with attractive capabilities including guided movement and directed cargo transport. Such acid-driven microtubular rockets offer considerable potential for diverse biomedical and industrial applications.
Abstract in Journal of the American Chemical Society: Hydrogen-Bubble-Propelled Zinc-Based Microrockets in Strongly Acidic Media