Due to the particularity of medical equipment's application scenarios (directly related to human life and health), the strong magnets used in them have extremely strict performance requirements. These requirements cover magnetic performance, stability and reliability, mechanical performance, biocompatibility and other aspects. Only by meeting these requirements can strong magnets ensure the safety and effectiveness of medical equipment in clinical applications.

First of all, in terms of magnetic performance, strong magnets for medical equipment need to have high magnetic flux density and good magnetic field uniformity. Magnetic flux density is the core index to measure the strength of the magnetic field. For example, in high-field MRI equipment, the magnetic flux density of the main magnetic field needs to reach 3.0T or higher, which requires the strong magnet to have excellent magnetic energy product. The magnetic energy product is an important index to measure the magnetic performance of permanent magnets, and the higher the magnetic energy product, the stronger the magnetic field generated by the magnet under the same volume. Rare-earth permanent magnets such as neodymium-iron-boron have high magnetic energy products, which can meet the requirements of high-field medical equipment.

Magnetic field uniformity is another key magnetic performance index, especially for MRI equipment. The uniformity of the main magnetic field directly affects the quality of the MRI image. If the magnetic field is uneven, the resonance frequency of hydrogen nuclei in different regions of the human body will be inconsistent, resulting in image distortion and artifacts, which will affect the accuracy of diagnosis. Therefore, the strong magnets used in MRI equipment need to have extremely high magnetic field uniformity, usually requiring the uniformity error to be within a few parts per million (ppm) in the imaging area. To achieve this requirement, in addition to selecting high-quality magnetic materials, it is also necessary to carry out precise design and processing of the magnet, and use shimming technology (such as passive shimming and active shimming) to adjust the magnetic field.

Secondly, in terms of stability and reliability, strong magnets for medical equipment need to have long-term magnetic stability and environmental stability. Long-term magnetic stability means that the magnetic performance of the magnet does not decay significantly during long-term use. For example, the service life of MRI equipment is usually 10-15 years, and the strong magnet in it needs to maintain stable magnetic field intensity and uniformity during this period. This requires the magnetic material to have good coercivity (the ability to resist demagnetization). Rare-earth permanent magnets have high coercivity, which can effectively prevent demagnetization caused by external factors.

Environmental stability requires that the strong magnet can maintain stable performance under different environmental conditions (such as temperature, humidity, vibration, etc.). Temperature is an important factor affecting the magnetic performance of permanent magnets. For example, the magnetic performance of neodymium-iron-boron magnets is sensitive to temperature. When the temperature rises, the magnetic flux density will decrease. Therefore, the strong magnets used in medical equipment need to have good high-temperature resistance, and the working temperature range should meet the requirements of clinical use. At the same time, the magnet needs to be protected against moisture and corrosion to prevent the magnetic material from being oxidized and corroded in the humid medical environment, which will affect its performance. In addition, medical equipment may be subject to vibration during transportation and use, so the strong magnet also needs to have certain vibration resistance to avoid damage or performance degradation caused by vibration.

Thirdly, in terms of mechanical performance, strong magnets for medical equipment need to have sufficient mechanical strength and toughness. Strong magnets, especially rare-earth permanent magnets, are usually brittle and easy to break under external force. In the process of assembly, transportation and use of medical equipment, the magnet may be subjected to impact, extrusion and other forces. Therefore, the magnet needs to be processed and modified (such as surface coating, encapsulation) to improve its mechanical strength. At the same time, the magnet's size and shape accuracy also need to meet strict requirements to ensure that it can be accurately assembled with other components of the medical equipment.

Finally, in terms of biocompatibility, if the strong magnet is in direct or indirect contact with the human body (such as magnetic surgical instruments, implanted magnetic components), it must have good biocompatibility. Biocompatibility means that the magnet does not cause toxic and side effects, allergies, inflammation and other adverse reactions to the human body. This requires the selection of non-toxic and harmless magnetic materials and surface treatment materials, and the magnet needs to pass a series of biocompatibility tests (such as cytotoxicity test, skin irritation test, implantation test) in accordance with relevant medical standards.

In summary, the performance requirements of strong magnets for medical equipment are comprehensive and strict. These requirements are the key to ensuring the safety, effectiveness and reliability of medical equipment. With the continuous development of medical technology, the performance requirements of strong magnets will become higher and higher, which will promote the continuous progress of magnetic material technology and processing technology.