Fig. 1

Introduction of the method. a Energy flow chart of TENG system. b The V–Q plot at σ = 50 μC m⁻², showing the positive (“+”) part as the non-breakdown area and negative (“−”) part as the breakdown area. c Circuit of the universal method, with TENG2 being the power source and TENG1 being the target device. d Process flow chart of the universal method