A magnetic nanocomposite has been implemented as artificial hair on a giant magnetoimpedance (GMI) thin-film sensor for flow sensing. The 500 μm long and 100 μm in diameter pillars are composed of iron nanowires incorporated in polydimethylsiloxane (PDMS). The nanowires' length and diameter are 6 μm and 35 nm, respectively. Upon fluid flow, the pillars are deflected, causing a change in the magnetic field at the GMI element and a corresponding change in impedance. The permanent magnetic behavior of the nanowires in combination with the GMI sensor and the high elasticity of the PDMS pillars result in a high-performance flow sensor with low power consumption and potential for remote detection. No additional magnetic field is required to magnetize the nanowires or bias the sensor, which simplifies miniaturization and integration in microsystems. At a power consumption of 31.6 μW, air flow rates up to 190 mm s(-1) can be detected with a sensitivity of 24 mΩ (mm)(-1) s and a resolution of 0.56 mm s(-1) while the range for water flow is up to 7.8 mm s(-1) with a sensitivity of 0.9 Ω (mm)(-1) s and a resolution of 15 μm s(-1). When power consumption is reduced to as low as 80 nW a high resolution of 32 μm s(-1) is still maintained.
Magnetic field sensors are an integral part of many industrial and biomedical applications, and their utilization continues to grow at a high rate. The development is driven both by new use cases and demand like internet of things as well as by new technologies and capabilities like flexible and stretchable devices. Magnetic field sensors exploit different physical principles for their operation, resulting in different specifications with respect to sensitivity, linearity, field range, power consumption, costs etc. In this review, we will focus on solid state magnetic field sensors that enable miniaturization and are suitable for integrated approaches to satisfy the needs of growing application areas like biosensors, ubiquitous sensor networks, wearables, smart things etc. Such applications require a high sensitivity, low power consumption, flexible substrates and miniaturization. Hence, the sensor types covered in this review are Hall Effect, Giant Magnetoresistance, Tunnel Magnetoresistance, Anisotropic Magnetoresistance and Giant Magnetoimpedance.
Ru nanoparticles supported on carbon nanotubes showed efficient reactivity for hydrogenolysis of aqueous glycerol solution to produce glycols of 1,2-propanediol and ethylene glycol. The glycerol conversion along with the product selectivity depended essentially on the mean size of Ru nanoparticles. The Ru mean size around 5 nm showed the highest yield of glycols. The results indicated that the hydrogenolysis of glycerol catalyzed by the supported Ru nanoparticles might be structure-sensitive.
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