E. coli cells in plaza zones normally are in random
motions with no permanent routines. The trace of bacteria have been tracked and
recorded by Image J. Hence, the routines of E. coli cells are visualized, and
the speed of their movements can be measured as well. According to the
statistics, the swimming speed of E. coli is in the range from 19.15 um/s to
35.39 um/s, and the average speed of E. coli cell in microfluidics are 23.37
um/s. In addition, it is found that a number of E. coli have the tendency to
swim until they reach the wall of PDMS, and then the bacteria will continue
moving along the planar as the Figure1 and Figure2
showed. This is related with the flagella of the E. coli cells. As Ramia et al.
has concluded in the model of hydro-dynamism, the movement of bacteria in
aqueous medium can be benefited from the propulsion generated during the
process when it is closed to the surface and move along with planar.
Figure 1
Figure 2
The second pattern in study is the parallel track that
has been mentioned in previous section. Eight parallel tracks with different
width connecting with the plaza zone have been provided to the E. coli cells.
The motions of E. coli in this pattern can be divided into three stages,
entering the tracks, moving inside the tracks, and exiting the tracks. According
to the observation results, the movements of entering the tracks from the plaza
zone and exiting the tracks to the plaza zone are similar. The average speed of
entering the channels from the plaza is 26.69 um/s, and the average speed of
exiting the channels to the plaza is 25.51 um/s. Moreover, when considering the
routines of entering the channel, as the Figure 3 has
presented, it can be seen that three traces of three E. coli cells entering the
channel from the plaza at the same time are generally in a line along with the
same orientation that parallel to the channels. There is a little number of E.
coli turning a right angle immediately after coming in or out of the channels
from or to the plaza.
Figure 3
