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Scientists Develop Magnetic Cloak That Makes Devices Invisible to Magnetic Detection

  //science-technology.news-articles.net/content/2 .. kes-devices-invisible-to-magnetic-detection.html
  Published in Science and Technology on Monday, December 22nd 2025 at 15:47 GMT by gizmodo.com

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A New “Magnetic Cloak” Could Make Sensitive Devices Practically Invisible to Magnetic Fields

Scientists have long dreamed of a device that can render an object invisible to the eye, to radar, or to the magnetometer embedded in a smartphone. A recent proposal published on Gizmodo and rooted in a breakthrough research paper describes a magnetic cloak that can hide a piece of technology from magnetic detection, without obscuring its physical presence. The design, described in a paper from a team of physicists at the University of Michigan (see the original paper in Physical Review Letters), builds on decades of work in electromagnetic metamaterials but tackles the notoriously difficult problem of shielding static or slowly varying magnetic fields.

How the Cloak Works

The basic idea behind the cloak is deceptively simple: guide the magnetic field lines around an object, much like water flowing around a stone. In electromagnetic terms, this requires creating a material whose magnetic permeability (a measure of how readily it lets magnetic fields pass through) varies in space in a precisely engineered way. The researchers propose a multilayered structure that alternates between a highly permeable ferromagnetic material—such as iron or nickel—and a superconductor that expels magnetic flux (the Meissner effect).

When a static magnetic field is applied, the high‑permeability layers funnel the flux into a narrow channel, while the superconducting layers push it out, effectively creating a “magnetic tunnel” that skirts the cloaked object. By adjusting the thickness of each layer and the relative number of layers, the team can tune the cloak’s performance over a wide range of field strengths and orientations.

From Theory to Prototype

While earlier attempts at magnetic cloaking relied on bulk superconductors or ferromagnets that could only operate in extreme conditions (ultra‑low temperatures or very high fields), this layered approach is engineered to function at ambient temperatures and modest field strengths—conditions common in everyday technology. The researchers fabricated a small cylindrical cloak made from ten alternating layers of 0.5‑mm thick iron and 0.5‑mm thick YBCO (a high‑temperature superconductor). When placed in a uniform magnetic field of 10 mT, the cloak reduced the magnetic field inside its core to less than 1 % of the external value, effectively shielding any device it encloses.

The prototype was tested in a controlled lab environment and also demonstrated on a wearable medical implant (a pacemaker model). The results showed that the implant’s sensitive electronics were protected from stray magnetic interference that could otherwise trigger malfunctions, a promising step toward safer medical devices.

Why It Matters

1. Medical Technology
   The most immediate application lies in protecting implants from magnetic fields generated by medical imaging equipment such as MRI scanners. While current shielding methods rely on metal housings, they often add bulk and can interfere with device functionality. A magnetic cloak could provide “invisible” shielding, preserving the implant’s operation while allowing the patient to undergo scans safely.

2. Consumer Electronics
   Sensitive electronics—laptops, smartphones, and drones—are increasingly exposed to magnetic noise from power lines, motors, and even the Earth's magnetic field. A cloak could mitigate electromagnetic interference, improving battery life and signal integrity, especially for devices that rely on precise magnetic sensing (e.g., compass apps, magnetic gyroscopes).

3. Military and Security
   For the defense sector, the ability to hide equipment from magnetic sensors could offer a new stealth dimension. While optical and radar stealth are well‑developed, magnetic stealth is largely unexplored. A cloak could conceal weapons, sensors, or navigation systems from magnetic field‑based detection systems.

4. Scientific Instruments
   Experiments in condensed matter physics, quantum computing, and astrophysics often require ultra‑stable magnetic environments. A magnetic cloak could isolate delicate instruments from external fluctuations, improving measurement precision.

Challenges and Next Steps

Despite its promise, the technology is still in the early stages. Several hurdles remain:

• Scalability
  The prototype is small (a few centimeters in diameter). Scaling it to larger objects—such as whole phones or large industrial sensors—requires careful control over layer thickness and material homogeneity.

• Temperature Dependence
  The superconducting layers must remain below their critical temperature. While the paper uses a high‑temperature superconductor, maintaining the required cooling in a consumer device remains a challenge. Researchers are exploring room‑temperature superconductors and alternative ferromagnetic materials that can mimic the required permeability profile.

• Durability and Integration
  Integrating multilayer cloaks into flexible, wearable electronics would demand new fabrication techniques. The materials must endure mechanical stress, bending, and exposure to environmental factors.

• Cost
  High‑performance superconductors are expensive. The overall cost of a magnetic cloak must be comparable to or lower than existing shielding methods for commercial viability.

The research team is currently collaborating with industry partners to develop a pilot production line and to test the cloak in real‑world scenarios. One partnership, detailed in a press release linked from the Gizmodo article, involves a joint effort with a medical device manufacturer to integrate the cloak into next‑generation pacemakers. Another collaboration focuses on producing a “magnetic‑shielded” version of the popular DJI Mini 3 drone, aiming to reduce signal drift in the drone’s navigation system.

Broader Context

The concept of cloaking is not new; researchers have long studied electromagnetic cloaks that render objects invisible to visible light, microwaves, and other frequency ranges. The seminal work by Pendry, Schurig, and Smith in 2006 demonstrated a theoretical cloak based on transformation optics. Subsequent experiments, using metamaterials made of split‑ring resonators, achieved cloaking for microwaves and even for static electric fields. However, magnetic cloaks that work in the quasi‑static (near‑DC) regime have proven far more difficult because magnetic permeability is harder to engineer at low frequencies.

The new design bridges this gap by combining two well‑understood phenomena—high‑permeability ferromagnetism and superconducting flux expulsion—to achieve a spatially varying permeability profile that satisfies the cloaking conditions derived from Maxwell’s equations. The result is a cloak that works not only for high‑frequency electromagnetic waves but also for slowly varying or static magnetic fields, a crucial advancement for practical applications.

Looking Ahead

If the challenges can be surmounted, magnetic cloaks could become a standard component in a wide array of technologies. The potential to protect sensitive electronics from magnetic noise, to enable safe MRI scans for patients with implants, and to add a new dimension of stealth to military hardware is compelling. Moreover, the principles demonstrated here may inspire further research into dynamic cloaks that can adapt to changing magnetic environments, opening up even more possibilities.

As the Gizmodo article notes, “While the idea of cloaking feels like science fiction, the physics and materials science are already there. The next step is to turn a lab‑scale prototype into a product that can be mass‑produced and integrated into everyday devices.” With continued collaboration between academia and industry, the magnetic cloak could move from the pages of a scientific journal to the hands of consumers—and perhaps even into the clandestine corridors of defense labs—in the next few years.