A collaborative Chinese-German team has created LeMaMa, a novel magnetic sensor capable of detecting incredibly faint magnetic signals. This table-top device, operating at room temperature, can measure fields a billion times weaker than Earth’s magnetic field. LeMaMa uses a “floating compass” design, suspending a magnetic needle to minimize friction and maximize sensitivity. By precisely tracking minuscule deflections of the needle, researchers can detect magnetic fields down to the femtotesla level. This breakthrough significantly enhances the capabilities for detecting elusive dark matter particles. The technology also holds potential applications beyond dark matter research, including geological surveys and biomedical sensing. The success of LeMaMa marks a substantial advancement in magnetic field detection technology.