The Internet of Things is widely applied in our daily live, such as smart sensing and recognition technologies, which contains thousands of sensors. Replacement of batteries for sensors is a difficult task and disposal of batteries may contaminate soil and water. By combining freestanding sliding mode triboelectric nanogenerator (FS-TENG) and electrically tunable liquid lens (ETULL) made of environmentally friendly materials, we develop a self-powered electrowetting optical switch (EOS) for wireless sensing networks.