Tiny Diamond Compass Peers Inside Batteries ⚡ экспресс
A mini diamond quantum magnetometer with a head diameter of 6 mm and sensitivity of 91 pT/√Hz (2 kHz bandwidth) operates in an unshielded environment by solving the fluorescence collection problem. This is achieved using a multi-core optical fiber bundle that separates excitation and collection channels, along with a custom micro-objective with a high numerical aperture. A compact FPGA unit handles microwave control, synchronous detection, and resonance tracking, ensuring stability during imaging. Its capabilities were demonstrated by mapping the magnetic field of a commercial lithium-ion battery, reconstructing depth-resolved current maps. The combination of sensitivity and probe geometry opens new avenues for measurements in confined volumes, particularly in battery technology.
Ordinary magnetic sensors lose sensitivity as they shrink. But scientists turned a tiny diamond into a light-based compass. Unlike jewelry diamonds, what matters here isn't purity but artificially created defects — these are what turn the crystal into a compass. Under a laser beam, these defects start glowing, but a magnetic field sharply quenches the glow. That's how the diamond reveals the field's direction and strength.
The secret to its clarity lies in a fiber-optic bundle of many glass threads. One thread carries the beam to the diamond, while others collect the returning light, eliminating interference. This entire optical setup, along with the diamond, fits inside a 6-mm tip — thinner than a pencil.
The sensor is so sensitive it picks up fields millions of times weaker than Earth's, and it needs no bulky shielding. They brought it close to a working lithium-ion battery and, through spectroscopic measurements, mapped the internal currents.
This technology will be useful for checking microchips, implants, and even studying living tissues.
🎯 These sensors are already being tested to record nerve impulses: they sense the ultra-weak magnetic fields that neurons create.
🎬 This device is like a tricorder from Star Trek — a portable scanner that sees the internal structure of objects.