Integrated flux concentrator improves CMOS magnetotransistors

Fully integrated magnetically actuated micromachined relays

“…After verifying that the NiFe cores are not saturated during device operation, all of the following magnetic simulations were performed assuming linear material properties with an effective permeability for permalloy. A permeability for permalloy represents the lower values reported in the literature [21]. Fig.…”

“…2-D infinite boundary elements were incorporated to model an infinite extension of the air above and below the actual microrelay structure. Initial simulations were based on the nonlinear material properties of the permalloy films as measured with a vibrating sample magnetometer [21], [22]. After verifying that the NiFe cores are not saturated during device operation, all of the following magnetic simulations were performed assuming linear material properties with an effective permeability for permalloy.…”

Magnetic field amplification by slender cuboid-shaped magnetic concentrators with a single gap

“…Planar magnetic concentrators of related geometry with a single gap have been shown to considerably improve the resolution of CMOS magnetotransistors [4,5] and CMOS Hall devices [1,6,7]. Recently, a cuboid-shaped planar magnetic concentrator with two narrow gaps and a micromechanical resonator were integrated into a highly sensitive resonant magnetic microsensor with frequency output [8,9].…”

“…Thick magnetic concentrators have been produced at the wafer level by electroplating permalloy (NiFe) layers [4,5] and by attaching amorphous soft-magnetic ribbons onto pre-processed wafers [1,7,10]. In the first case, structuring of the concentrator shape and gap were achieved by photolithography preceding the electroplating.…”

Hybrid magnetometers for unshielded operation : combining hall sensors with superconducting flux concentrators

“…Because all four sensors are identical, operation in a bridge setup cancels temperature influences. Figure 1.3a) shows two rectangular plates, this is an often applied approach but there are also examples where the plates are tapered towards the gap focusing the flux even more [45]. The main drawback is the hysteresis of the device due to complete or partially saturated magnetization.…”