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pH-taxis of biohybrid microsystems




The last decade has seen an increasing number of studies developing bacteria and other cell-integrated biohybrid microsystems. However, the highly stochastic motion of these microsystems severely limits their potential use. Here, we present a method that exploits the pH sensing of flagellated bacteria to realize robust drift control of multi-bacteria propelled microrobots. Under three specifically configured pH gradients, we demonstrate that the microrobots exhibit both unidirectional and bidirectional pH-tactic behaviors, which are also observed in free-swimming bacteria. From trajectory analysis, we find that the swimming direction and speed biases are two major factors that contribute to their tactic drift motion. The motion analysis of microrobots also sheds light on the propulsion dynamics of the flagellated bacteria as bioactuators. It is expected that similar driving mechanisms are shared among pH-taxis, chemotaxis, and thermotaxis. By identifying the mechanism that drives the tactic behavior of bacteria-propelled microsystems, this study opens up an avenue towards improving the control of biohybrid microsystems. Furthermore, assuming that it is possible to tune the preferred pH of bioactuators by genetic engineering, these biohybrid microsystems could potentially be applied to sense the pH gradient induced by cancerous cells in stagnant fluids inside human body and realize targeted drug delivery.

Author(s): Zhuang, Jiang and Carlsen, Rika Wright and Sitti, Metin
Journal: Scientific reports
Volume: 5
Year: 2015
Month: June
Day: 15
Publisher: Nature Publishing Group

Department(s): Physical Intelligence
Research Project(s): Bacteria-propelled bio-hybrid microswimmers
Bibtex Type: Article (article)

DOI: 10.1038/srep11403


  title = {pH-taxis of biohybrid microsystems},
  author = {Zhuang, Jiang and Carlsen, Rika Wright and Sitti, Metin},
  journal = {Scientific reports},
  volume = {5},
  publisher = {Nature Publishing Group},
  month = jun,
  year = {2015},
  month_numeric = {6}