I n certain embodiments, the at least one electrode comprises at least one pair of electrodes, respective electrodes of the pair being located at opposite sides of the substrate; and wherein : the at least one grid structure comprises a spacing structure, said spacing structure comprising a plurality of raised portions, the raised portions having a constant height, such that transport of the object along the surface of the substrate generates a separation of charges between the substrate surface and the object surface when the object encounters one of said raised portions, and such that motion parameters of the object are derivable from the ratio of electric potentials of said pair of electrodes. I n certain embodiments, the triboelectric sensor may comprise two pairs of electrodes, wherein a first pair of electrodes is arranged opposite each other along a first direction, and a second pair of electrodes is arranged opposite each other along a second direction that is orthogonal to the first direction. Advantageously, the provision of a grid structure with a plurality of constant- height raised portions, in conjunction with one or more pairs of opposed electrodes, enables accurate measurement of continuous motion of an object sliding across the surface of the substrate. This is because the sliding motion of the object is interrupted by the raised portions at positions that are known due to the design of the grid structure. The separation of charge between the object and the substrate due to such interruptions manifests as a time-varying voltage signal that can be used to infer the motion of the object. Additionally, by using the ratio of the electric potentials to infer the motion parameters, the results are made independent of the absolute magnitudes of the output at the respective electrodes. I n certain embodiments, the at least one grid structure comprises a first electrode grid formed on the substrate and configured to function as an output electrode of a first triboelectric nanogenerator operating under sliding single electrode mode; wherein the first electrode grid comprises a plurality of different The spacing structure may be formed from a resin material, for example.