Unformatted text preview: ransformers, and magnetic actuators.
Presently, micro-inductors are fabricated as ‘spirals’ or ‘square
spirals’ in 2-D layouts, as shown below: [Fig. 8.9 from ‘Foundations of
MEMS’, Chang Liu] © N. Dechev, University of Victoria 7 2D Spiral Micro-inductors
2-D micro-inductors, such as the one shown in Fig. 8.9(a) are
simple to fabricate. However, they are not too effective due to
their spiral shape, and the relatively low magnetic permeability of
air or free space.
To improve their performance in creating a strong magnetic field,
the magnetic cores have been fabricated at their center, as shown
below: [Fig. 8.9 from ‘Foundations of
MEMS’, Chang Liu] However, the resulting improvements are marginal. © N. Dechev, University of Victoria 8 2D Spiral Micro-inductors
An even bigger problem with ‘in-plane’ micro-inductors is their
poor efficiency, or ‘quality factor’ since they are fabricated inplane with the substrate.
By being in-plane with the substrate, the magnetic flux must pass
through the silicon substrate, which is conductive, yet has a high
resistance. Eddy currents will form in the substrate, and degrade
the performance of the device. © N. Dechev, University of Victoria 9 3D Micro-inductors
In order to avoid the problems with 2D in-plane micro-inductors,
researchers are attempting to construct 3D micro-inductors with
magnetic cores, and without cores.
The primary motivation is to minimize the amount of magnetic
flux that must pass through the substrate. © N. Dechev, University of Victoria [Fig. 8.11 from ‘Foundations of
MEMS’, Chang Liu] 10 Monolithic Fabrication of 3D Micro-inductors
The micro-inductors shown below are fabricated using surface
micromachining, or similar thin-film fabrication technologies. Micromachined, 3D micro-inductors [Microfabrica.com] HARM fabricated, 3D micro-inductors [KAIST] © N. Dechev, University of Victoria 11 Case Study 8.2: Self-Assembly of 3D Micro-inductors
CASE 8.2. Magnetic Beam Actuation: (Self Assembly of
Here, a powerful electromagnet is used to create an...
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