Magnetic interactions provide outstanding performances for powerful integrated micro-actuators. This paper explains how magnetic interactions involving permanent magnets, currents, and various magnetic materials remain very effective and even improve as dimensions are reduced. The technological problems that have slowed the development of magnetic micro-actuators and systems (MAGMAS) are progressively being solved. As long as materials scientists continue to develop better thick-film patterned permanent magnets compatible with microsystem technologies, MAGMAS will have a promising future.

Scanning Hall probe microscopy has been used for the quantitative measurement of the z-component (out-of-plane) of the stray magnetic fields produced by Nd–Fe–B hard magnetic films patterned at the micron scale using both topographic and thermomagnetic methods. Peak-to-peak field values in the range 20–120 mT have been measured at scan heights of 25–30 μm above the samples. Quantitative comparison between calculated and measured field profiles gives nondestructive access to the micromagnets’ internal magnetic structure. In the case of topographically patterned films the average value of remanent magnetization is extracted; in the case of thermomagnetically patterned films the depth of magnetization reversal is estimated. The measured field profiles are used to derive the spatial variation in the field and field gradient values at distances in the range 0.1–10 μm above the micromagnet arrays. These length-scales are relevant to the application of the micromagnet arrays for lab-on-chip applications (trapping and confinement of magnetic particles). Very large field and field gradient values as high as 1.1 T and 4.1×106 T/m, respectively, are estimated.

In this paper, harvesters coupling magnetostrictive and piezoelectric materials are investigated. The energy conversion of quasi-static magnetic field variations into electricity is detailed. Experimental results are exposed for two macroscopic demonstrators based on the rotation of a permanent magnet. These composite/hybrid devices use both piezoelectric and magnetostrictive (amorphous FeSiB ribbon or bulk Terfenol-D) materials. A quasi-static (or ultra-low frequency) harvester is constructed with exploitable output voltage, even in quasi-static mode. Integrated micro-harvesters using sub-micron multilayers of active materials on Si have been built and are currently being characterized.

Open-circuit direct piezoelectric coefficients g31 of bi-axially stretched PVDF and chiral PLLA are reported. This measure is decisive for sensor, generator and energy harvesting applications. We use an in-situ method with contactless voltage measurement during a conventional tensile-test, greatly improving measurement precision (error less than 10%).