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CBES: Center for Bio-Inspired Energy Science

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 tight-rotating magnetic field.

 

Sheets in a wide-rotating magnetic field

 

Sheets in a wide-rotating magnetic field.

Lower, left: Dependence of a sheet’s total energy on the twisting  angle of its boundaries (2𝛼) in a tight-rotating field. Lower, right:   Sheet symmetry dependence on field strength (|𝛾|)  and boundary separation (𝐿/𝐿_𝑜) in a wide-rotating  magnetic fields.

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

 

Actuation of Magnetoelastic Membranes in Precessing Magnetic Fields
Brisbois, CA; Tasinkevych, M.; Vázquez-Montejo, P.; Olvera de la Cruz, M.
Proceedings of the National Academy of Sciences, 2019, 116, 2500-2505

Work Performed at Northwestern University