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Free keywords:
Abt. Dietrich; Forschungsgruppe Sanchez; smart nano-bio devices;
Abstract:
We demonstrate the closed-loop motion control of
self-propelled microjets inside a fluidic microchannel. The motion
control of the microjets is achieved in hydrogen peroxide solution
with time-varying flow rates, under the influence of the controlled
magnetic fields and the self-propulsion force. Magnetic dipole mo-
ment of the microjets is characterized using the
U-turn
and the
rotating field
techniques. The characterized magnetic dipole mo-
ment has an average of 1.4
×
10
−
13
A.m
2
at magnetic field, linear
velocity, and boundary frequency of 2 mT, 100
μ
m/s, and 25 rad/s,
respectively. We implement a closed-loop control system that is
based on the characterized magnetic dipole moment of the mi-
crojets. This closed-loop control system positions the microjets by
directing the magnetic field lines toward the reference position.
Experiments are done using a magnetic system and a fluidic mi-
crochannel with a width of 500
μ
m. In the absence of a fluid flow,
our control system positions the microjets at an average velocity
and within an average region-of-convergence (ROC) of 119
μ
m/s
and 390
μ
m, respectively. As a representative case, we observe that
our control system positions the microjets at an average velocity
and within an average ROC of 90
μ
m/s and 600
μ
m and 120
μ
m/s
and 600
μ
m when a flow rate of 2.5
μ
l/min is applied against and
along the direction of the microjets, respectively. Furthermore, the
average velocity and ROC are determined throughout the flow
range (0 to 7.5
μ
l/min) to characterize the motion of the microjets
inside the microchannel
