that are provided to driver unit 36 to cause in-plane movement of (part of) the robot 38. Computing device 34 may also determine the potential ratio VEZ/VEV, which indicates the position of the user’s finger F along the I D sensor 12. Computing device 34 may track the position as a function of time, and translate this into command signals that are provided to driver unit 36 to cause out-of-plane movement (e.g., movement in a vertical direction or rotation) of (part of) the robot 38. Referring now to Figure 4, some alternative embodiments of triboelectric sensors are shown. I n each of the sensors of Figure 4, a single electrode is provided as a grid structure in or on a substrate. Grating structures of the grid are configured to generate different characteristic signals in different respective directions when an object, such as a user’s finger, is slid across the substrate and traverses the grid. The grid structure itself is therefore used to output the signal. The embodiments depicted in Figure 4 each provide a triboelectric nanogenerator (TENG) with a single electrode output using a patterned grid or grating design for multi-directional 2D and 3D sensing and controlling. Advantageously, embodiments provide a device in which one electrode can realise multi-directional sensing and controlling based on the output peaks of the generated signal, which is not dependent on the absolute magnitude of the output signal, therefore being robust to different use scenarios and different users. For example, directional sensing can be based on the number, relative positions and/or relative amplitudes of the peaks in the signal. The device according to example embodiments comprises an electrode grid design with different grating structures (e.g., different number of grating elements, different width of grating elements, etc.) disposed along different directions and configured into e.g. a square, polygon or circle shape for multi-direction sensing and controlling. I n these embodiments, all the grating structures are connected together and operate under triboelectric based sliding single electrode mode.