A resonant magnetic field microsensor with a high quality factor at atmospheric pressure has been designed, fabricated and tested. This microsensor does not require vacuum packaging to operate efficiently and presents a compact and simple geometrical configuration of silicon. This geometry permits us to decrease the size of the structure and facilities its fabrication and operation. It is constructed of a seesaw plate (400 × 150 × 15 μm 3 ), two torsional beams (60 × 40 × 15 μm 3 ), four flexural beams (130 × 12 × 15 μm 3 ) and a Wheatstone bridge with four p-type piezoresistors. The resonant device exploits the Lorentz force principle and operates at its first resonant frequency (136.52 kHz). A sinusoidal excitation current of 22.0 mA with a frequency of 136.52 kHz and magnetic fields from 1 to 400 G are considered. The mechanical response of the microsensor is modeled with the finite element method (FEM). The structure of the microsensor registered a maximum von Mises stress of 53.8 MPa between the flexural and the torsional beams. Additionally, a maximum deflection (372.5 nm) is obtained at the extreme end of the plate. The proposed microsensor has the maximum magnetic sensitivity of 40.3 μV G −1 (magnetic fields <70 G), theoretical root-mean square (rms) noise voltage of 57.48 nV Hz −1/2 , theoretical resolution of 1.43 mG Hz −1/2 and power consumption less than 10.0 mW.
Titanium aluminum nitride coatings were fabricated by a d.c. magnetron sputtering system from a Ti-Al (60/40wt%) target. Coatings were deposited on steel substrates, at a substrate temperature of 250 • C and a bias voltage of-80 V. The nitrogen flow was varied from 1•5-6 sccm and the Ar flow was kept constant at 20 sccm. The morphology and microstructure of the coatings were analysed by X-ray diffraction and scanning electron microscopy. The results of X-ray diffraction showed the presence of two cubic crystalline phases, TiN and AlN, which were confirmed by X-ray photoelectron spectroscopy. The Vicker hardness was obtained by the effective model of indentation. It was observed that the hardness of the coatings decreases from 22•8-9•5 GPa with an increased nitrogen content from 1•5-4•5 sccm. Subsequently, the hardness increased to 22•1 GPa by increasing nitrogen to 6 sccm. The behavior of hardness with grain size variation is consistent with the Hall-Peth relationship. The high value in the hardness of the coatings is mainly attributed to small grain sizes and the compressive stress present.
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