Design of zinc oxide-based surface acoustic wave sensors using a graphene electrode

Continuous monitoring of skin moisture by using a wearable moisture sensor consisting of the materials that have no risk of skin sensitization, such as zinc oxide (ZnO), is essential to optimize the healing process in wound care. Here we tackled the investigation of the optimum electrode for ZnO-based surface acoustic wave (SAW) sensors to achieve this goal. Al and Au electrodes commonly used were compared with a graphene electrode by simulation in terms of the frequency characteristics of the SAW device. Graphene and Al showed the same tendency in frequency characteristics as the 0 thickness electrode (ideal electrode). Since graphene is suitable for flexible devices due to its stretchability and for the long-term stability due to its chemical innerness, it was concluded that graphene is more suitable than the conventional Al and Au electrodes for flexible SAW sensor devices.