A flexible lightweight self-powered wireless metal detector enabled by triboelectric discharge effect

Traditional metal detectors are relatively expensive, bulky, and inflexible, and they require an external power source; all of this limits their usage. Here, we present a self-powered wireless metal detector enabled by the triboelectric discharge effect, inductive coupling, and a signal modulation strategy. The device can convert mechanical triggers into wireless electromagnetic waves that contain information on nearby metals. Based on this strategy, we fabricated two prototypes with different sizes and different trigger modes, thus showing the capabilities and scalability for metal detection under different scenarios. In addition, because of the differences in the waveforms of the electromagnetic (EM) waves triggered by different types of metal, the device can also recognize the type of metal with the assistance of a trained machine learning model.