Micro-additive manufacturing technologies of three-dimensional MEMS

Conventional microfabrication processes have been well established, but their capabilities are generally limited simple and 2D extruded geometries. Additive manufacturing allows the ability to manufacture true 3D complex geometries, rapid design for manufacturing, mass customisation, materials savings, and high precision which have triggered the increased interest in manufacturing microelectromechanical systems (MEMS). This paper consolidates MEMS manufacturing's recent advancements, including both conventional and additive manufacturing technologies, their working principles, and practical capabilities. The paper also discusses in detail the use of additive manufacturing in several MEMS areas such as in microelectronics, circuitry, microfluidics, lab on a chip, packaging, and structural MEMS. Furthermore, the potentials and limitations of additive manufacturing are investigated with regards to the MEMS requirements. Finally, the technology outlook and improvements are discussed. This study showed that additive manufacturing has offered a promising future for the fabrication of microelectromechanical systems, especially using high resolution techniques such as microstereolithography, materials jetting, and materials extrusion. On the other hand, current challenges such as materials requirements, equipment innovation, fabricating of in vivo devices for biomedical applications, inherited defects and poor surface finish, adhesion to substrates, and productivity are areas that requires further study to increase the uptake by the MEMS community.