Flex-PCB Based Multi-Layered 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 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)mm 3 , is combined with sidearms and a flexible printed circuit (FPC) connector which can extend the length as required (here 32 mm). The device demonstrates a sensitivity of 70nT/ √ Hz and a theoretical shot-noise-limited sensitivity of 11.73nT/ √ Hz. 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 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 μm 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 NV centers.