Magnetic-field sensors can be placed virtually anywhere, including inside living bodies, because magnetic fields pass through biological tissue without being blocked [1, 2].
This capability allows for the development of diagnostic and monitoring tools that can operate within the human body without the interference caused by skin or bone. Because magnetic fields are not impeded by organic matter, sensors can detect activity from deep within an organism.
Science journalist Ed Yong said that magnetic fields permeate living matter. "So they just go through my body, and they're not impeded by skin or bone or anything like that," Yong said. "And so a sensor that detects a magnetic field could be absolutely anywhere" [1].
The utility of these sensors extends beyond biological applications. They are also being deployed in space-based platforms to measure the magnetic field of the Earth [3]. For example, the MagQuest competition announced its final phase in 2026 [3].
While these sensors can be placed externally or internally, they are often designed to detect the extremely weak magnetic fields generated by the human body. These fields occur as electric currents flow through the brain, heart, and other tissues [2]. To achieve the necessary precision, some technologies utilize fluxgate sensors. These tools harness magnetic saturation to provide scientific-grade accuracy and stability that exceeds ordinary inductive detection [4].
The ability to place sensors in diverse environments—from the interior of a human organ to the vacuum of space—stems from the fundamental physics of magnetism. Unlike light or certain types of radiation, magnetic fields do not collide with or be absorbed by the dense materials of the human anatomy [1].
“Magnetic fields permeate living matter.”
The ability to deploy sensors that are unimpeded by biological tissue suggests a future where internal health monitoring could be non-invasive or minimally invasive. By leveraging the fact that magnetic fields ignore the barriers of skin and bone, medical technology can move toward real-time, high-precision tracking of electrical activity in the brain and heart without requiring the sensors to be physically adjacent to the organ.
