Abstract
There is an overgrowing interest in the synthesis of high performance micro magnets due to their wide application areas in MEMS, microfluidics, and micro-robotics. In addition, they possess great potential to become a model system for the development of next-generation hard magnets. In this study, NdFeB/Fe hybrid micro-magnets have been synthesized by a photolithography technique. NdFeB micro and Fe nano powders in the form of nano-thin flakes have been synthesized by one step surfactant assisted planetary ball milling. The fabricated nano-thin flakes with different lateral sizes have been obtained by varying the milling time. Room temperature coercivities of up to 3.1 kOe for NdFeB has been achieved after milling for 8 h. Photoresist and powders of NdFeB and Fe have been mixed at various powder-to-resist ratios. SU-8 has been chosen as the photoresist due to its resistance to chemicals and its suitability to be utilized in MEMS technology. Micro islands of SU-8/NdFeB/Fe have been prepared according to the manufacturer’s recommendations for pure SU-8. The hybrid micromagnets in pillar form have been successfully produced. The evolution of magnetic, structural and microstructural properties of these micro magnets will be reported. Successful fabrication of hybrid micro-magnets using the methodology prescribed in this work can pave the way for the development of next-generation MEMS.
Highlights
High performance nano and micro magnets are the key parts of MEMS,1 microfluidics2 and robotic swimmers used in wide range of applications from computer to biomedical industry
It has been observed that the coercivity increases by increasing the milling time and the maximum room temperature coercivity of 3.1 kOe has been reached after 6 hours of ball milling. [Figure 1] Coercivity increase is attributed to grain size refinement fewer defects are expected per particle
Powders milled for 6 h has been used for further experiments due to the better morphology observed in the synthesized flakes
Summary
High performance nano and micro magnets are the key parts of MEMS, microfluidics and robotic swimmers used in wide range of applications from computer to biomedical industry. In common practice, magnetic materials are incorporated into MEMS and other applications via physical/chemical vapor deposition, ergo in thin film form. this morphology hinders with the magnetic properties of the material. Magnetic materials are incorporated into MEMS and other applications via physical/chemical vapor deposition, ergo in thin film form.. Magnetic materials are incorporated into MEMS and other applications via physical/chemical vapor deposition, ergo in thin film form.5–8 This morphology hinders with the magnetic properties of the material. Another method to incorporate magnetic materials is loading them into curable polymers This method is preferable since developed powders of ferromagnetic alloys with best magnetic properties for permanent magnet production could be used, ergo better magnetic performance could be achieved for applications. NdFeB powder, in the form of nano thick and laterally micron sized flakes, and Fe nanoparticles (∼20 nm) was mixed with the photosensitive resist, SU8, to synthesize NdFeB/Fe loaded micro magnets by photolithography technique. Successful compatibleness of SU8 with nano and micro particles has been shown. SU8 has been chosen for its rigidness, biocompatibility and resistant to chemicals.
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