Fig. 4: Response characteristics of TPTS under different load directions and locations.

a The initial state of triboelectric sensing unit 1, and the angle α between the external load and the horizontal line. b The state of sensing unit 1 at the angle α = 0^∘, and the open-circuit voltage and short-circuit current responding to the external load. c The state of sensing unit 1 at the angle α = 22. 5^∘, and the open-circuit voltage and short-circuit current responding to the external load. d The state of sensing unit 1 at the angle α = 45^∘, and the open-circuit voltage and short-circuit current responding to the external load. e The state of sensing unit 1 at the angle α = 67. 5^∘, and the open-circuit voltage and short-circuit current responding to the external load. f The state of sensing unit 1 at the angle α = 90^∘, and the open-circuit voltage and short-circuit current responding to the external load. g The open circuit voltage for sensing unit 1 responding to stimuli at different positions under the conditions of F = 3 N, f = 0.8 Hz, and α = 90^∘. h The open circuit voltage for sensing unit 5 responding to stimuli at different positions under the conditions of F = 3 N, f = 0.8 Hz, and α = 90^∘. (i) The open circuit voltage responding to flexible covers with different curvatures under the conditions of F = 3 N, f = 0.8 Hz, and α = 90^∘.