A miniaturized force sensor based on hair-like flexible magnetized cylinders deposited over a giant magnetoresistive sensor

The detection of low-magnitude forces (under 1mN) is essential in applications that require either a very high sensitivity and resolution acquisition (e.g. detection of microfluidic flows) or very high reliability and control (e.g. biomedical or humanoid robotics). In this work, we present a bio-inspired ciliary force sensor consisting in an array of magnetized, flexible quasi-elastic pillars deposited over a magnetoresistive GMR sensor. The GMR sensor stack (Ta 10/NiFe 28/CoFe 25/Cu 26/CoFe 23/MnIr 80/Ta 30, thickness in Å) was deposited at INESC-MN by ion beam and patterned in series array of 120 elements with 60 x 3 μm
²
, over a total area of 3 x 3 mm
²
, resulting in a sensitivity of 22.5 Ω Oe
^-1
.