Fig. 1

Schematic and experiment photos of triboelectric plasma. a Schemes of an atmospheric-pressure non-equilibrium plasma jets (APNP-J) directly driven by two serial freestanding rotary triboelectric nanogenerators (FR-TENGs). To enhance the output voltage, two FR-TENGs are mounted face to face with the same phase and the electrodes are connected in series. Each FR-TENG is composed of not only a stator coated by copper foil which is evenly divided into 12 sector as two electrodes, but also a rotator fixed of 6 fluorinated ethylene propylene (FEP) films with the other edge free on each side. The rotator has to rotate in clockwise at this point of view. The diameters of rotator and capillary are Ø295 mm and Ø0.88 mm, respectively. b As a low-temperature plasma, APNP-J can contact skin of human finger for biomedicine applications (scale bar, 10 mm). c Schematic of a patterned electrode dielectric barrier discharge (DBD) plasma source. The inset shows a photo of device (scale bar, 30 mm). d A luminescence photograph of patterned electrode directly driven by TENG (scale bar, 10 mm). 10 s exposure, no Photoshop (NIKON D700 @ 70 mm, ISO 1000, f/3.5). e Schematics of four stages in one full electric cycle at the two sector-electrodes connected with a DBD device. Blue arrow shows the velocity direction of the FEP film. There are theoretically two main discharge processes in one full cycle, in the opposite current directions