Flex-PCB-Based Multilayered LED Quantum Sensor (FleQS) Utilizing NV Centers in Randomly Oriented Microdiamonds With Novel Orientation Determination

We present a quantum magnetometer based on a flexible printed circuit (FPC) board with a streamlined and automated assembly design. By employing a foldable design, the system achieves advanced miniaturization and integration, along with the capability to form a multilayered structure for direct optical path generation. The sensor head, measuring (3.4×2.9×2) mm3 , is combined with sidearms and a FPC connector which can extend the length as required (here 32 mm). The device demonstrates a sensitivity of 70 nT/(Hz)1/2 and a theoretical shot-noise-limited sensitivity (SNLS) of 11.73 nT/(Hz)1/2 . This design is fully compatible with automated production processes, facilitating efficient and cost-effective manufacturing. With a power consumption of approximately 0.1 W , which is mainly caused by the light-emitting diode (LED), the foldable sensor is well-suited for a wide range of applications, from handheld devices to stationary systems. A novel approach for automated orientation determination facilitates the usage of randomly oriented, 150- μ m sized, low-cost microdiamonds, further streamlining the fabrication process. Therefore, the sensor presented here offers a step further from the laboratory into the concrete application of quantum sensors based on nitrogen-vacancy (NV) centers.