Highly Sensitive Pressure Sensor Based on h-BN/Graphene/h-BN Heterojunction and Cu–Sn Solid–Liquid Interdiffusion Bonding

Graphene with atomic layer thickness has excellent mechanical properties and provides tremendous potential for developing high-performance pressure sensors. However, bare graphene is sensitive to humidity, and oxygen in the air also significantly affects the stability of graphene pressure sensor. In this work, a highly sensitive pressure sensor was fabricated through the MEMS process and nanofilm transferring. The graphene sensing element is entirely isolated from the external environment by the initial protection of h-BN, followed by the secondary protection of Cu–Sn solid–liquid interdiffusion bonding. After the static test, an average sensitivity of $2.9\times10$ ⁻⁴ kPa ⁻¹ was achieved over a pressure range from −80 to 0 kPa. Also, it exhibited excellent repeatability and minimal hysteresis. As graphene pressure sensor was exposed to ambient air for 30 days, the relative resistance change was just 2.3%. The resistance of graphene pressure sensor can also keep stable even if the device was stored in a high-temperature or high-humidity environment. Thus, this work provides a promising approach for the practical application of high-performance graphene pressure sensors.