Development of bacteria-actuated microrobots using the surface modification of microstructures

Microrobots are useful for application in various fields. However, they have limitations with respect to their actuators and motilities. In this study, we fabricated the two types of flagellated bacteria-actuated microrobots using the flagellated bacteria Serratia marcescens and Salmonella typhimurium that could be utilized as microactuators. First, we fabricated the Serratia marcescens-actuated microrobot, where we adopted the selective bacteria adhering on the surface of SU-8 microcubes through the selective coating with bovine serum albumin. Many number of Serratia marcescens attached on bovine serum albumin-uncoated side of SU-8 microcubes. The average velocity of the selective Serratia marcescens-attached SU-8 microcubes was increased more than two times from SU-8 microcubes with a nominal Serratia marcescens attachments. Second, we fabricated the Salmonella typhimurium-actuated microrobots that have a selective bacteria patterning on the surface of polystyrene microbeads using bovine serum albumin. Similarly, the average velocity of the selective Salmonella typhimurium patterned polystyrene microbeads was 5 folds faster than that of the polystyrene microbeads where the bacteria were attached on the whole surface of the microbeads. Consequently, the experimental results mean that the flagellated bacteria could be utilized as microactuators for microrobots and the selective patterning of the bacteria could enhance the velocity of the bacteria-actuated microrobots.