finger and the silicone rubber. HPE is conductive and the current through HPE reflects the changes in the external electric field. Figures 2(b) and 2(c), respectively, show the open circuit voltage and short circuit current of HPE- silicone rubber device when a user’s finger is tapped against the substrate 24. As mentioned above, 2D and I D triboelectric sensors 10 and 12 may be used as part of a triboelectric control system, such as the system 30 shown in Figure 3. The outputs of the electrodes E1-E4 of sensor 10 and electrodes - 2’ of sensor 12 may be connected to a detection unit 32 for measurement and pre- processing of signals from the sensors 10, 12. Specifically, analog signals from respective electrodes E1-E4 and - 2’ may be captured by a signal acquisition module 32a of the detection unit 32. A filtering and amplifying module 32b may receive the acquired signals from the signal acquisition module 32a, and perform certain signal processing operations, such as applying a low-pass filter to remove noise, followed by amplification of the filtered signal. The filtered and amplified signals are then fed to ADC 32c, and may be output to an external computing device 34 for analysis. I n some embodiments, the detection unit 32 may have on-board processing capability for analysis of the output signals from ADC 32c. Computing device 34 is in communication with a driver unit 36 for a machine such as a robot 38. The driver unit 36 is configured to receive command signals from computing device 34 to cause motion of one or more components of robot 38. In one example, the robot 38 under control is an industrial robot of KUKA AG, with a corresponding KSP600 driver that may be used to control different motors of the robot 38 to make it perform different movements. Computing device 34 receives the processed signals from the respective electrodes, and determines the potential ratios V / V and VEA/VE2 for the 2D sensor 10. These potential ratios indicate the position of the user’s finger F on the surface 20a of the sensor 10, i.e. the (x,y) coordinates in the plane of the sensor 10. Accordingly, by tracking the (x,y) position as a function of time, computing device 34 can infer motion parameters of the user’s finger such as speed and direction of movement, and translate these into command signals