The present study discusses the testing of proper materials to be used as friction surface such as polymeric textiles and strings to be applied in the double-channel bidirectional direct current triboelectric nanogenerator (BDC-TENG). The BDC-TENG will be used as self-powered sensor in the application of electronic skin (e-skin). Textiles and strings of polymethyl methacrylate (PMMA) and polyamide (PA) as well as aluminium (Al) and copper (Cu) films were chosen as friction surfaces sliding on polytetrafluoroethylene (PTFE) film in order to generate feedback signal by triboelectrification.   Based on the experimental results, it was observed that fibrous PMMA textile of 0.8 mm thickness recorded the highest voltage values when slid on PTFE film that adhered to an elastic substrate. While PA textile of 0.4 mm thick showed reasonable voltage values. Voltage increased with increasing the applied load. PMMA strings displayed lower values than that observed for textiles. Besides, Al and Cu film showed the lowest voltage values. It was found that the thickness of the textile affects the value of the generated voltage. It can be recommended that the values of voltage produced by the proposed BDC-TENG can be developed by applying fibrous PMMA textile sliding on PTFE films adhered to soft substrate.