Wafer-scale Micromagnet fabrication using RIE and Dry Bonding for MEMS Applications

Microscale detectors and actuators utilizing magnetic forces have the potential to facilitate wireless and contamination-free interaction with small-scale and nano environments. Nevertheless, incorporating magnetic components into conventional microfabrication methods may pose difficulties. Here, we demonstrate the fabrication and characterization of microscale patterned permanent magnets, which can be suitable for utilization in microelectromechanical systems (MEMS), microfluidics, microtransport, and energy harvesting applications. A 2'' silicon wafer is employed to create the patterned grooves via standard photolithography and reactive ion etching (RIE) system, subsequently filled with Neodymium-iron-boron micropowder (~5 μm) to facilitate the batch fabrication of 100 μm thick micromagnets. To assess its field strength, we integrate the micromagnet into a microfluidic device and conduct magnetic particle microtrapping and manipulation experiments. Before integration, the effective gap and magnet thickness is investigated using FEM simulations to generate a high magnetic field gradient, resulting in a high magnetic force (200 -600 pN).