Template‐Assisted Electroforming of Fully Semi‐Hard‐Magnetic Helical Microactuators

• Published in: Advanced engineering materials Vol. 20; no. 9
• Main Authors: Chatzipirpiridis, George, de Marco, Carmela, Pellicer, Eva, Ergeneman, Olgaç, Sort, Jordi, Nelson, Bradley J., Pané, Salvador
• Format: Journal Article
• Language: English
• Published: 01.09.2018
• Subjects: electroforming; hard‐magnetism; magnetic manipulation; microrobotics
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.201800179

The authors report on the fabrication of semi‐hard‐magnetic microhelices using template‐assisted electroforming. The method consists of electrodepositing a material on a sacrificial mandrel on which a pattern has been previously written. To electroform the helical microswimmers, a helical template on a polymer‐coated metallic mandrel is created using a laser, which precisely ablates the polymer coating and exposes the mandrel surface. Subsequently, the semi‐hard‐magnetic material is electrodeposited in the trenches produced by the laser. In this investigation, the helical structures are obtained from an electrolyte, which enables the production of hard‐magnetic CoPt alloys. The authors also show that electroformed semi‐hard‐magnetic helical microswimmers can propel in viscous environments such as silicon oil in three dimensions and against gravity. Their manufacturing approach can be used for the fabrication of more complex architectures for a wide range of applications and can be potentially extended to any electroplatable material. Semi‐hard‐magnetic cobalt‐platinum microhelices are fabricated using template‐assisted electroforming. The method consists of electrodepositing a material on a sacrificial mandrel on which a pattern has been previously written. By pre‐magnetizing the helices perpendicularly to their long axis, the microdevices can swim by corkscrew motion under rotating magnetic fields. Propulsion in a viscous environment in three dimensions and against gravity is demonstrated.