Fig. 1. (Color online) (a) Schematic illustration of the fabrication process of porous PDMS TENG device. (b) Schematic illustration of structure of porous PDMS TENG device. SEM images of porous PDMS thin film from (c) cross-sectional view and (d) top view. SEM images of (e) PEDOT:PSS electrode (f) PEDOT:PSS/Porous PDMS interface. (g) Photograph of fabricated porous PDMS TENG.

Fig. 2. (Color online) (a) SEM image of porous PDMS structure examined in EDX (b) structural formula of polydimethylsiloxane (PDMS) and polystyrene (PS). Energy dispersive X-ray analysis (EDX) images of (c) carbon element and (d) silicon element of porous PDMS structure. SEM images of porous PDMS structure (e) after compressive pressure (f) before compressive pressure. (g) Photograph of the stretching test setup. (h) Resistance change of the screen-printed PEDOT:PSS electrode under various levels of applied strain.

Fig. 3. (Color online) Charge generation mechanism of the porous PDMS TENG under external compressive force.

Fig. 4. (Color online) (a) Schematic illustrations of porous PDMS TENG (top) and non-porous PDMS TENG (bottom). (b) Output voltage and (c) output current of porous PDMS and non-porous PDMS TENG at loading force and frequency of 100 N, 0.8 Hz.

Fig. 5. (Color online) Loading force and frequency response of porous PDMS TENG. (a) Output voltage and (b) output current response under different loading forces at same loading frequency of 0.8 Hz. (c) Output voltage and (d) output current response under different loading frequencies at same loading force of 100 N.