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Jan et al. Soft Sci 2024;4:10 https://dx.doi.org/10.20517/ss.2023.54 Page 9 of 12

Figure 5. Monitoring motion and energy harvesting. (A) Optical images of E-TENG sensors attached to the human wrist (top) and index
finger (bottom) for motion detection; (B) Voltage output signal of wrist movement (extension and flexion); (C) Voltage output signal of
finger bending angles of 30°, 60°, and 90°; (D) Demonstration of energy harvesting from walking and jogging motions; (E) Voltage
output signal of walking motion at step frequency of 1.1 Hz. Stepping down and up produces the positive and negative peaks (inset); (F)
Voltage output signal of jogging motion at step frequency of 1.9 Hz. E-TENG: Encapsulated-triboelectric nanogenerator.

powered E-TENG sensor generated a voltage signal of approximately 2 V. Moreover, the E-TENG sensor
can serve as an energy harvesting device simultaneously. E-TENG was further tested for the detection of
bending movements of the index finger at approximately 30°, 60°, and 90° angles, respectively [Figure 5C].
These bending movements of the finger can be clearly traced by the distinctive voltage signals of
approximately 0.188, 0.889, and 1.99 V for 30°, 60°, and 90° angles, respectively.

Moreover, everyday physical activities, such as walking and jogging, can serve as valuable energy sources for
the E-TENG sensor. In Figure 5D, we demonstrate using the E-TENG sensor for energy harvesting during
walking and jogging motions. To capture these motions, individuals stepped onto the E-TENG sensor. The
voltage signals produced during these activities [Figure 5E and F] can be easily distinguished based on their
amplitudes and frequencies. When stepping down on the floor, the E-TENG sensor was compressed,
resulting in positive voltage signals, while stepping up released the sensor, generating negative voltage
[Figure 5E, inset]. This behavior aligns with the working mechanism illustrated in Figure 2A. Notably, the
E-TENG generated maximum peak-to-peak voltages of 18.3 and 57.4 V during walking and jogging
activities, respectively. Simultaneously, the frequencies of walking and jogging were recorded at 1.1 and
1.9 Hz, respectively. Given their high power density and superior sensitivity in a broad pressure range,
E-TENGs demonstrate significant potential for applications such as human motion monitoring, tactile
sensing, and harvesting the waste energy from daily life physical activities.