Milk-based triboelectric nanogenerator on paper for harvesting energy from human body motion

In recent years, the triboelectric nanogenerator (TENG) has been demonstrated as a renewable power source by converting ambient energy into remarkable electrical output. In this study, milk film was investigated as a novel triboelectric material, and the results revealed that it occupies a top-level positive position in the triboelectric series owing to its strong ability of losing electrons during the triboelectrification process. A friction process based on sandpaper was introduced to increase the surface roughness of polytetrafluoroethylene (PTFE) tape to enhance the output performance of the proposed milk-based paper TENG (MP-TENG). The approximate values of the short-circuit current (I-SC), open-circuit voltage (V-OC), and output power density reached 93 mu A, 392 V, and 583.75 mu W/cm(2), respectively. To increase the output performance, a lozenge stacked MP-TENG was designed and fabricated, and enhanced output was achieved. The proposed MP-TENGs are capable of providing three working patterns corresponding to human body movements. The working patterns 1, 2, and 3 can harvest energy produced by foot movement, arm motion, and lumber motion, respectively. The motion state of the human body, such as walking, running, or jumping, can be detected. Additionally, the MP-TENG can be used to test the protein content of milk. The generated electrical output of an MP-TENG with a size of 5 cm x 5 cm is capable of directly powering 82 blue high-power LEDs with a working voltage of 3.4 V. This paper proposes a potential light-weight, flexible, and wearable electronic device for energy harvesting and food quality detection.