We operated a Hall sensor using energy harvested from a magnetic wire. A battery-less sensor is expected to be a key device for the internet of things (IoT). Magnetization reversal in magnetic wires with bistable magnetization states induces a pulse voltage in a pickup coil. The amplitude of the voltage is independent of the applied field frequency, down to zero. This fast magnetization reversal is accompanied by a large Barkhausen jump, which has been known as the Wiegand effect. Electricity generation using this effect, obtained with twisted FeCoV magnetic wires, was studied. The energy obtained as a single pulse voltage was 600 nJ. The Hall sensor was operated with this pulse voltage. The pulse power of 0.88 V/1.3 mA was applied to the Hall sensor. The Hall voltage was proportional to the sensing magnetic field of 50-300 mT.Index Terms-Battery-less sensor, energy harvesting, FeCoV wire, Hall sensor, Wiegand effect, Wiegand pulse.

Implantable medical devices are utilized in the human body for maintaining good health. As these devices are becoming increasingly functionalized, supplying power to them has become very important. Instead of batteries, technologies for wireless power supplies are being developed, such as inductive coupling or piezoelectric elements. However, we propose the use of magnetic wires for this purpose. Inside these wires, a fast magnetization reversal, called a "large Barkhausen jump," occurs due to an applied magnetic field. This reversal induces a large pulse voltage in pick-up coils, which is called a "Wiegand pulse." By applying this pulse as an electric source, a higher electric power is expected compared with the conventional method using a sinusoidal excitation field. A wire core coil was prepared, and open-circuit voltage was measured. In addition, DC voltage and electric power were measured by connecting the wire core coil to a rectifier. The experimental results confirmed the superiority of using a Wiegand pulse at an applied magnetic field intensity of 60 Oe and a frequency of lower than 10 kHz.

A fast magnetization reversal accompanied by a large Barkhausen jump in a magnetic wire is utilized in speed sensors, rotation sensors, and other applications. This magnetization reversal induces a pulse voltage in a pick-up coil, which can also be applied for electricity generation as an energy-harvesting element. Dependence of the output voltage on the position of the pick-up coil indicated a fast magnetization reversal by a domain wall propagation. An excitation method for a vibration-type electricity-generating element using a single magnet was optimized by changing the magnet size. The output voltage obtained from the FeCoV wire depended on the amplitude of vibration of an excitation magnet. In order to minimize the vibration amplitude of an excitation magnet required for generating the output voltage, a field distribution from magnets of various sizes was calculated. It was found that just a 0.6 mm-movement of an NdFeB magnet was sufficient to generate the output voltage.

We operated a Hall sensor using energy harvested from a magnetic wire. A battery-less sensor is expected to be a key device for the internet of things (IoT). Magnetization reversal in magnetic wires with bistable magnetization states induces a pulse voltage in a pickup coil. The amplitude of the voltage is independent of the applied field frequency, down to zero. This fast magnetization reversal is accompanied by a large Barkhausen jump, which has been known as the Wiegand effect. Electricity generation using this effect, obtained with twisted FeCoV magnetic wires, was studied. The energy obtained as a single pulse voltage was 600 nJ. The Hall sensor was operated with this pulse voltage. The pulse power of 0.88 V/1.3 mA was applied to the Hall sensor. The Hall voltage was proportional to the sensing magnetic field of 50-300 mT.