Using Magnetic Fields to Control Elastic Sheets

Scientific Achievement

Rotating magnetic fields can drive 2D elastic sheets, made of magnetic particles, to expand, contract, or twist.

Sheets in a tight-rotating magnetic field.

Sheets in a wide-rotating magnetic field.

Left:  Dependence of a sheet’s total energy on the twisting   angle of its boundaries (2α) in a tight-rotating field.

Right:    Sheet symmetry dependence on field strength (|γ|)   and boundary separation (L/L_o) in a wide-rotating   magnetic fields. 

Significance and Impact

Understanding the effects of dynamic magnetic fields on the shape and symmetry of elastic sheets advances the design of autonomous, soft microrobots.

Research Details

• Forces on sheet boundaries can be manipulated by changing the angle of rotating magnetic fields above and below a critical value, θ^∗.
• Changing magnetic field strength,|γ|, in fields rotating below a critical angle can enhance or resist torque on sheet boundaries.
• Rotating magnetic fields above a critical angle can induce spontaneous symmetry breaking

Work Performed at Northwestern University