## 3 Results
### Thermal Performance Evaluation of the ENMH  
The surface temperature of the ENMH before and after voltage application was measured using infrared thermal imaging (Figure 4a). At 0 V, the surface displayed a uniform temperature distribution ranging from 21.2 \({}^{\circ}\)C to 24.9 \({}^{\circ}\)C, with no observable heating. Upon application of 1 V, the central region exhibited a rapid temperature rise, while the overall surface maintained a uniform thermal profile. The maximum temperature reached 124.1 \({}^{\circ}\)C. These results indicate that the ENMH enables effective localized heating under low driving voltage while preserving uniform thermal distribution. The heating performance of the ENMH was further assessed by incrementally applying voltage from 0.0 V to 1.0 V in 0.1 V steps (Figure 4b). Each voltage was held for 30 s, and the surface temperature was recorded in real time at the central measurement region. The temperature increased in a stepwise manner, with each voltage increment producing a stable and gradual rise. The temperature profile closely followed the programmed voltage input. Average surface temperatures at 0.2 V, 0.4 V, 0.6 V, 0.8 V, and 1.0 V were 28.4 \({}^{\circ}\)C, 44.7 \({}^{\circ}\)C, 68.4 \({}^{\circ}\)C, 96.2 \({}^{\circ}\)C, and 124.0 \({}^{\circ}\)C, respectively, corresponding to an average increase of approximately 13.3 \({}^{\circ}\)C per step. After removing the 1.0 V input, the temperature rapidly returned to baseline. In contrast, the ENMH(-BSA step) exhibited markedly lower thermal performance under identical conditions. Although a similar stair-like increase was observed, the maximum temperature achieved was only about 73.0 \({}^{\circ}\)C at 1.0 V (Figure S5). To evaluate the long-term thermal stability of the ENMH, the surface temperature response was monitored under continuous operation at a constant applied voltage of 0.6 V for 2 h (Figure 4c). Upon voltage application, the ENMH rapidly reached approximately 79 \({}^{\circ}\)C, and maintained a stable average temperature of around 80.9 \({}^{\circ}\)C throughout the 2 h period. The temperature fluctuation remained within \(\pm\)1-2 \({}^{\circ}\)C over the entire duration, and the temperature drift rate was as low as \(-\)1.8 \({}^{\circ}\)C/h. No signs of thermal degradation, delamination, or overshooting were observed during the test. After the power was turned off, the temperature quickly returned to its initial value. Thermal repeatability and response characteristics were assessed using repeated ON/OFF voltage cycles at 10 s intervals under a constant 0.6 V input (Figure 4d). In each cycle, the surface temperature increased rapidly from approximately 29 \({}^{\circ}\)C to a peak of 77.1 \({}^{\circ}\)C upon voltage application and returned to baseline upon voltage removal. The heating-up time--defined as the time required for the temperature to rise from 10% to 90% of the total increase--was approximately 4.7 s. The cooling-down time--corresponding to the drop from 90% to 10%--was about 3.4 s. These results confirm that the ENMH exhibits excellent thermal responsiveness and reproducibility, with consistent heating and cooling behavior across all cycles. In contrast, the ENMH(-BSA step) sample was tested at the same applied voltage of 0.6 V with repeated ON/OFF cycles at 10 s intervals (Figure S5). Upon voltage application, the surface temperature increased from approximately 26.5 \({}^{\circ}\)C to 35.5 \({}^{\circ}\)C and returned to the baseline after the power was turned off. The heating and cooling times were calculated to be about 7.8 s and 6.4 s, respectively. Although the maximum temperature was lower, the thermal response was slower than that of the ENMH sample, indicating a reduced heating efficiency. Figure 4: Thermal performance evaluation of the ENMH. (**a**) Infrared thermal images of the heater before and after applying 1 V. (**b**) Temperature response of the heater under incremental voltage steps (increasing by 0.1 V every 30 s).