Fig. 4: Power generation performance of the IENG under different surrounding conditions.

a–c Power generation performance of the IENGs under different light intensities. d–f Power generation performance of the IENGs in different liquids. g–i Power generation performance of the IENGs under different wind speeds. The lengths, widths and heights were 20 mm, 20 mm and 20 mm, respectively. The error bars represent standard deviations.