Fig. 4: Comprehensive reliability tests of the developed DC-ThEG.

a Resistance change ratios of the fabricated DC-ThEG in the bending state for various radii from 5cm to 1.5cm, shown in the inset in (a), along the long-axis direction (A–A′) and the short-axis direction (B–B′), shown in the inset in (b). The fabricated device can be bent to a radius of 3 cm in both directions while the resistance remains almost constant. b Resistance change ratios and output voltages (ΔT = 50 °C) of the developed DC-ThEG at different bending cycles in both the A–A′ and B–B′ directions, which were remarkably stable even after 1000 bending cycles. c Similar to other traditional ThEGs, the resistance of this DC-ThEG increases as the temperature increases, but it is worth mentioning that the increase is linear and stays at a relatively low level with a less than 1% increase per 6 °C. d The repeatability of the developed DC-ThEG was tested by 100-cycle heating, which revealed that its resistance and output performance remained steady. In brief, as one of most important factors of sustainable power sources for wearable electronics applications, the reliability and repeatability of the proposed DC-ThEG were proven