What is a magnetic bead?
The magnetic bead is called a ferrite bead filter and is an ultra-small magnetic component that has been introduced in recent years. It is made by sintering a ferrite material (or amorphous alloy) with a wire at a high temperature. Magnetic particle is a much smaller magnetic material than magnetic beads, but its properties are quite different from magnetic beads. Below I will take you to appreciate the charm of magnetic beads!
The main features of the magnetic beads:
- Magnetic beads have the characteristics of high frequency loss, high resistivity and high magnetic permeability, and can suppress noise interference in an extremely wide frequency band. By connecting the magnetic beadsin series in the path of the signal or power supply, the series mode noise interference can be effectively suppressed.
- The magnetic beads can be equivalent to a series circuit of inductance and resistance, and the equivalent inductance and equivalent resistance are proportional to the length of the magnetic beads. In the DC or low frequency band, the magnetic beads exhibit a very low inductive reactance and do not affect the signal transmission on the data line or signal line.
- A magnetic bead is measured by the impedance it produces at a certain frequency, and its unit is Q, not H.
- Magnetic beads have an absorption effect on high-frequency components, and are therefore also referred to as absorption filters. In contrast, the role of the common mode inductor in the EMI filter is to reflect electromagnetic interference back to the signal source, which is a reflective filter.
- Magnetic beads are devices that convert high-frequency energy into eddy currents and dissipate them in the form of heat. For short, energy-consuming devices, the eddy current loss is proportional to the square of the noise frequency. The common inductor is an energy storage component, referred to as an energy storage component. The magnetic bead has a maximum operating frequency of 1 GHz, and the operating frequency of the inductor generally does not exceed 50 MHz.
- Magnetic beads can suppress the generation of switching noise. It is an active suppression of high frequency interference. This is because the magnetic beads are connected to the main circuit (the output circuit) that generates the spikes, and the inductance is used to reduce the rate of rise of the spike current, so it is called “active suppression type”. The electromagnetic interference filter can only passively suppress interference, so it is called “passive suppression type”, which is the fundamental difference between the two.
- It is allowed to use a plurality of magnetic beads in series or in parallel. Usually, the beads should be installed close to the source of the interference.
- Magnetic beads can be used not only in high-frequency switching power supplies, electronic measuring instruments, and various circuits with strict requirements on noise, but also in digital home appliances such as mobile phones, DVDs, and digital video cameras. Chip beads eliminate RF interference in the transmission line. In electromagnetic compatibility (EMC) design, magnetic beads are a kind of magnetic component commonly used to suppress high frequency electromagnetic interference.
Several important applications of magnetic beads
- “Universal” immunomagnetic beads
Immunomagnetic beads are a new immunological technique developed in recent years. It combines the unique advantages of curing reagents with the high specificity of immunological reactions. It is based on immunology and penetrates into various fields such as pathology, physiology, pharmacology, microbiology, biochemistry and molecular genetics. It is in immunoassay and cell separation. Biomacromolecule purification and molecular biology have been widely used. Immunomagnetic beads can be mainly used in the following aspects:
- Cell separation.
- Purification of biological macromolecules.
- The application of molecular biology.
- Application in nanopore DNA sequencing
Since 1996, the use of nanopores as sensors to analyze DNA sequences has become a hot research area. The principle of the method is that when the DNA molecule passes through the nanopore, local clogging of the nanopore is caused, thereby realizing the change of the ionic current of the vias, and the information of the transwell DNA sequence is obtained by the change of the ionic current. However, in order to overcome the entropy resistance of DNA, in order to drive DNA, it is necessary to apply a large current, which will cause the DNA to pass through too fast, which will reduce the temporal and spatial resolution of DNA vias and increase the noise. Therefore, reducing DNA via velocity is a key technology for achieving nanopore determination of DNA sequences. Tests have shown that DNA can be slowed down by attaching DNA to well-beaded beads or magnetic beads and controlling the beads by light or magnetic enthalpy.
- Refuge for insomnia patients
You certainly can’t think of a small magnetic bead that will bring good news to patients with insomnia. The magnetic bead acupoint method is simple to operate, stimulates by ear acupuncture, regulates the corresponding organ function, and plays a role of conditioning and health care. It is a non-invasive, non-adverse-response, safe, non-medical and traditional Chinese medicine health care measure. The majority of patients hospitalized in the chest are elderly. Compared with the application of sedative and hypnotic drugs, the magnetic bead acupoint method is safer and has no side effects. It is an effective drug replacement therapy, which promotes sleep and rehabilitation of patients and improves patients. The quality of life has given full play to the advantages of traditional Chinese medicine nursing technology.