## 4 Conclusions and Future Perspectives  
Inspired by honeycomb, a self-powered sensor for downhole applications is proposed in this research. The designed H-TENG can measure the vibration frequency in the drill string from 0 to 11 Hz and the amplitude from 5 to 25 mm. Errors in measuring vibration frequency and amplitude are fewer than 5% and 6%, respectively. When the vibration frequency is 11 Hz, a single H-TENG's output voltage is 12 V. Furthermore, any H-TENG can be utilized as an independent vibration sensor, which means that even if one of the H-TENGs are damaged, the other H-TENGs can continue to function, resulting in high reliability. In terms of self-powered performance, the maximum output power is 1.57 uW at a frequency of 11 Hz and a resistor of 107 \(\Omega\) when multiple H-TENGs are used in combination. H-TENG can light up to twelve LEDs in real-time, proving that the sensor can power other downhole instruments.  
The H-TENG has the following advantages. Firstly, the H-TENG can realize self-powered sensing, it has a wide measurement range, high measurement accuracy, good high-temperature resistance, and its output voltage fluctuation is still very small after repeated work. Secondly, the H-TENG is composed of multiple sensing units, and the internal structure of each unit is consistent, so when one of the sensing units fails, the other units can still be used normally without affecting the measurement function of H-TENG. Thirdly, the combination of multiple sensing units can effectively improve the overall output power of H-TENG, which also makes it possible for H-TENG to supply power to other micro-power devices in the downhole environment.  
However, although H-TENG satisfies the fundamental requirements, there are still two things that need to be enhanced. One is that the amplitude measurement error is currently slightly larger, which will cause the small gap between the output voltage produced by different amplitudes to introduce errors. The other is that H-TENG has limited power generation, but in the future, it is possible to increase power generation by changing nanomaterials and perfecting the structure of H-TENG.  
**Author Contributions:** Validation, Y.F.; Writing--original draft, G.P.; Writing--review & editing, Y.F. and C.W.; Project administration, C.W. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by the CNPC Innovation Found (2022 DQ02-0309); the Scientific research project of Shaanxi Coal Industry and Chemical Industry Group Co., Ltd. (KCY)Y-2023-ZD-02 and 2023-TD-ZD003-003); and the National Key R&D Program of China (2023 YFC2907502).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
Figure 6: H-TENG power generation tests. (**a**) Capacitor charging curve; (**b**) a picture depicting the LEDs being lit in real-time by output power.  
Data Availability Statement: The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
Conflicts of Interest: Author [PERSON] was employed by the company Tiandi Science & Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare that this study received funding from Shaanxi Coal Industry and Chemical Industry Group Co., Ltd. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.