Microscale sensors and transducers based on magnetic forces can be used to provide wireless, contamination-free interaction with micro- and nanoenvironments. However, integration of magnetic components with typical microfabrication processes can be challenging. Here we show the creation and characterization of polymer micromagnets that can be utilized in microelectromechanical systems (MEMS), microfluidics, microassembly and microrobotics applications. These magnets can be patterned using standard UV lithography, are inexpensive to manufacture, and require limited equipment to produce. We demonstrate the creation of polymer micromagnets with 3 µm feature resolution and greater than 10:1 aspect ratio, the controlled movement of freestanding structures using contact-free applied magnetic fields, and the fabrication of novel ‘hybrid’ magnetic microstructures with controlled heterogeneity of magnetic properties.
It is important to fabricate biocompatible and chemical-resistant microstructures that can be powered and controlled without a tether in fluid environment for applications when contamination must be avoided, like cell manipulation, and applications where connecting the power source to the actuator would be cumbersome, like targeted delivery of chemicals. In this work, a novel fabrication method was described to encapsulate magnetic composite into pure SU-8 structures, enabling the truly microscale ferromagnetic microrobots biocompatible and chemical resistant. The microrobots were developed using the simple multilayer photolithography that allows us to mass produce and were actuated contact-free by external magnetic field to complete micromanipulations of micro-objects. The microrobots were actuated moving along a preplanned path to transport a glass microsphere object at an approximately average speed of 1.1 mm/sec and can be operated to rotate, aim at targets and collect objects.
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