Fig. 2. Design and characterization of TEB scanner.
(A) Single-electrode TENG-based sensor with a central ellipse (contact separation–based single-electrode mode) for palm interaction to monitor biometric information and eight protruded digitated electrodes (sliding-based single-electrode mode) for finger sweep to record control information. (B) TEB scanner features an Al electrode sandwiched by a bottom polyethylene terephthalate (PET) layer for insulation and a top polytetrafluoroethylene (PTFE) layer as the triboelectric material, rendering low cost and ease of fabrication. (C) Self-generated Ebio spectrum under repeated human palm interaction. (D) Zoom-in of (C) to show the successful recording of palm characteristics with four characteristic states, namely, “partial touch,” “half touch,” “full touch,” and “release.” (E) Self-generated Econtrol spectrum when a finger sweeps across eight digitated electrodes. The resultant control signals are three-digit binary signals. “Start” corresponds to the moment when the finger touches the central ellipse and “End” corresponds to the moment when the finger sweeps across the outermost electrode bar.