Wafer-Level Micro Alkali Vapor Cells with Anti-Relaxation Coating Compatible with MEMS Packaging for Chip-Scale Atomic Magnetometers

Compared with superconducting quantum interference devices, chip-scale atomic magnetometers using the wafer-level micro alkali vapor cells can be used more conveniently in the applications of geophysical mapping, health care and remote monitoring. Drastic wall collisions and decreased polarization lifetime are the main barriers for the performance of the chip-scale atomic magnetometers. In this study, OTS organic films coated on the inner surface of the micro vapor cells were used to suppress wall collisions and improve polarization lifetime of the alkali atoms in the micro cells. First of all, the fabrication process of wafer-level micro OTS coated vapor cells is introduced, the process is based on anodic bonding technology. Then the prepared wafer-level micro OTS coated vapor cells have been characterized by the water-contact angle test and measured in the micro-machined spin-exchange relaxation free(SERF) atomic magnetometers. Results show that the OTS coating is effective after anodic bonding from the water contact angle test. Results also indicate that the spin exchange relaxation free atomic magnetometer using the micro OTS-coated vapor cell can operate successfully.