Research of pH gradient on swimming bacteria control

Micro-robots have wide application prospects on biomedicine, aerospace, etc., and driving technique is critical in researching micro-robot and also the bottleneck in micro-robot development. In this paper, it is proposed that pH gradient generated by electrolysis is used for driving bacteria colonies so as to propel the micro-robot, based on the character of free swimming of flagellar bacterium in liquid and tending to swim toward optimal pH area. First, distribution of pH value near electrode surface was measured with micro pH electrode, which approved the validity of forming pH gradient through electrolysis. Another experiment was then designed to measure pH distribution in solution using a universal pH indicator by acquiring images using a color CCD camera, which can be used for measurement in micro device of driving bacteria. Modeling of pH gradient formation was analyzed to give guidance for further pH gradient control so as to apply pH gradient in driving bacteria colonies.