The recent advancements in nanoscale 3D printing and microfabrication techniques have reinvigorated research on microrobotics and nanomachines . However, precise  control of the robot motion and navigation on biological environments have remained challenging to date. This work presents the first demonstration of magnetic microscale rocker robot (microrocker bot) capable of bidirectional movement on flat as well as biological surfaces, when actuated by a single compact electromagnet . The 100um by 113um by 36um robot was 3D printed via two-photon lithography and subsequently coated with a nickel (Ni) thin film. When actuated by an externally applied magnetic sawtooth field, the robot demonstrated stick-slip motion enabled by its rockers. The controllable bidirectional motion is enabled by adjusting the DC offset of the waveform, which tilts the robot and biases it towards either forward or backward motion . The microrocker bots are further equipped with sharp  tips that can get engagedvia application of DC-only or low frequency magnetic fields. This novel control method offers an attractive solution to replace the multiple bulky coils traditionally used for magnetic actuation and control, as well as allows for a more flexible and simple approach towards microrobotics motion control. When the frequency and offset of the  sawtooth waveform are optimized, the robot travels up to 87ums (0.87 body length per second) forward and backward with minor deviance from linear trajectories. Finally, to prove the robot's capabilities in direct contact with biological environments , we demonstrate the microbot 's ability to traverse forward and backward on the surface of a Dracaena Fragrans (corn plant), as well as upend on its mechanical tip.
The recent advancements in nanoscale 3D printing and microfabrication techniques have reinvigorated research on microrobots . However, precise motion control of the microrobots on biological environments using compact actuation setups remains challenging to date. This work presents a novel control mechanism and contact design that enables bidirectional steering via biasing the neutral position of the microrobot. Equipped with rockers to contact the substrate, the microrobot, hence microrocker bot, is capable of well-controlled forward and backward movement on flat and non-flat biological surfaces . The 100um by 113um by 36um robots were 3D printed via two-photon lithography and subsequently deposited with nickel thin films. Under a relatively small static magnetic field, the microrocker bot tilts either forward or backward to align the thin film magnetization direction with the magnetic field lines. When combined with an oscillating magnetic field, the robot undergoes stick-slip motion in the predisposed direction, dictated by the neutral position tilt . The microrocker bots are further equipped with sharp mechanical tips that can be selectively engaged. When the frequency and offset of the actuation sawtooth waveform are optimized, the robot travels up to 100um/s (1 body length per second) forward and backward showing very linear trajectories. Finally, to prove the functionality of the microrocker bots in direct contact with biological surfaces , we demonstrate the robot 's ability to traverse forward and backward on the surface of a Dracaena Fragrans leaf, and upend/engage on its mechanical tip.
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microrobotics and nanomachines
microrobots
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motion
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robot motion and navigation
microrobots
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have remained
using compact actuation setups remains
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the first demonstration of magnetic microscale rocker robot (microrocker bot) capable of bidirectional
a novel control mechanism and contact design that enables bidirectional steering via biasing the neutral position of the microrobot. Equipped with rockers to contact the substrate, the microrobot, hence microrocker bot, is capable of well-controlled forward and backward
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as well as biological surfaces, when actuated by a single compact electromagnet
and non-flat biological surfaces
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robot was
robots were
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coated with a nickel (Ni) thin film. When actuated by an externally applied magnetic sawtooth
deposited with nickel thin films. Under a relatively small static magnetic field, the microrocker bot tilts either forward or backward to align the thin film magnetization direction with the magnetic field lines. When combined with an oscillating magnetic
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demonstrated
undergoes
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enabled by its rockers. The controllable bidirectional motion is enabled by adjusting the DC offset of the waveform, which tilts the robot and biases it towards either forward or backward motion
in the predisposed direction, dictated by the neutral position tilt
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mechanical
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get engagedvia application of DC-only or low frequency magnetic fields. This novel control method offers an attractive solution to replace the multiple bulky coils traditionally used for magnetic actuation and control, as well as allows for a more flexible and simple approach towards microrobotics motion control.
be selectively engaged.
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actuation
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87ums (0.87
100um/s (1
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with minor deviance from
showing very
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robot's capabilities
functionality of the microrocker bots
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environments
surfaces
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microbot
robot
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(corn plant), as well as upend
leaf, and upend/engage