A magnet specified for a wearable or implantable device cannot be qualified by a material name or a “medical-grade” label alone. The device’s intended use, patient contact, enclosure, magnetic field and operating environment all matter. This guide is a starting checklist for design and purchasing teams preparing a magnet specification. It does not establish that a particular magnet or finished device is approved for medical use.
Start with the finished device
For a body-contacting device, the FDA describes biological evaluation as a risk-based assessment of the final finished device, including processing and sterilization where applicable. A coating specified on a drawing does not, by itself, establish biocompatibility. The device manufacturer should define the contact type and duration, select the evaluation plan, and confirm the required evidence for its market and intended use. See the FDA’s guidance on ISO 10993-1.
Tell a component supplier whether the magnet is fully enclosed, may contact skin, or is intended to sit inside an implant. Those are different design questions. If an implantable application is proposed, define the finished enclosure and its validation requirements before choosing a bare magnet or surface finish.
Specify the field where the device uses it
“Strong magnet” is not a measurable acceptance criterion. A useful drawing or RFQ states the field or force needed at the actual working gap, the measurement position, the direction of magnetization, and the surrounding parts that may change the result. A sensor magnet, retention feature and small actuator can require different field profiles even when they use similar magnet sizes.
Include the available space, finished dimensions and tolerances, operating temperature range, and any mating steel or magnetic components. If the design uses more than one magnet, show the pole arrangement and assembly orientation. Agree on a practical inspection method before treating a nominal grade as the entire specification. Our micro magnets and custom magnets pages outline component options.
Separate material choice from device qualification
NdFeB and SmCo are possible permanent-magnet materials, but their suitability depends on the required field, temperature, geometry and environment. NdFeB also needs corrosion protection suited to the design. A coating or encapsulation system should be selected and tested as part of the finished device, especially where moisture ingress, cleaning, sterilization or long service life is relevant. No coating name alone is a guarantee of a sealed or biocompatible device.
When comparing suppliers, request the material grade, dimensional inspection method, magnetization direction, coating specification and any documentation the project needs. Ask for evidence tied to the proposed part and process instead of assuming that generic catalogue data represents your finished assembly.
Assess magnetic interference and MRI exposure
Magnetic fields can affect some implanted electronic devices. The FDA reports that certain consumer electronics with strong magnets can trigger a magnet mode in some implanted devices and change their operation. Its six-inch precaution applies to those consumer electronics and patients; it is not a universal safe-distance rule for a new medical-device design. Device teams must assess interference for their own geometry and use conditions. Read the FDA magnetic-interference notice.
Do not infer MRI compatibility from the magnet material or from a supplier’s component description. The FDA explains that implanted devices need an established MR Safe or MR Conditional status, with conditions of use where applicable. MRI safety and labeling belong to the finished device evaluation. See the FDA’s MRI benefits and risks guidance.
Information to include in an RFQ
- Drawing or CAD file with finished dimensions, tolerances and any enclosure.
- Target field or force at a stated working gap and measurement point.
- Magnetization direction, pole layout and mating components.
- Operating temperature, moisture, cleaning and sterilization exposure, if applicable.
- Intended body contact, duration and the device team’s required documentation.
- Quantity, inspection criteria and any part-specific traceability requirements.
Magnetstek can review the component drawing, material and magnetization options, and the inspection information needed for a quotation. The device manufacturer remains responsible for finished-device testing, clinical claims, regulatory submissions and approval. Send your drawing for a specification review.
