Magnetically actuated gearbox for the wireless control of millimeter-scale robots

Area of Science:

• Robotics
• Micro-mechanics
• Magnetic Actuation

Background:

• Miniature magnetic actuators have limited force and torque, restricting the performance of millimeter-scale robots.
• Existing magnetic actuators struggle to provide sufficient power for complex robotic functions like locomotion and manipulation.

Purpose of the Study:

• To develop a magnetically actuated gearbox for wireless millirobots to overcome the limitations of miniature magnetic actuators.
• To enhance the force, speed, and functionality of millimeter-scale robots through improved actuation.

Main Methods:

• Fabrication of a 3-millimeter magnetic gearbox using microgears (down to 270 micrometers) made from aluminum-filled epoxy resins via casting.
• Actuation of the gearbox using an external rotating magnetic field (≤ 6.8 millitesla) applied to an attached magnetic disk.
• Characterization of torque output, power density, and transmission efficiency in air and viscous liquids across various frequencies (1–40 Hz).

Main Results:

• The gearbox achieves a maximum torque of 0.182 millinewton meters at 40 Hz, with torque and power densities of 12.15 μNm/mm³ and 8.93 μW/mm³, respectively.
• Transmission efficiency in air ranges from 25.1% to 29.2%, decreasing in viscous liquids.
• Demonstrated integration with functional modules to achieve peristaltic crawling, tunable jumping, object clamping, needle-puncture sampling, and liquid handling.

Conclusions:

• The developed miniature magnetic gearbox significantly enhances the force and functionality of millimeter-scale robots.
• Wireless actuation and integration capabilities enable a wide range of advanced robotic applications, from locomotion to sampling and manipulation.
• This innovation addresses key limitations in miniature magnetic actuation, paving the way for more capable micro-robots.