# Research on Hybrid Vibration Sensor for Measuring Downhole Drilling Tool Vibrational Frequencies
## 4 Conclusions  
In this research, a hybrid downlink vibration sensor (HDV-TENG) based on electromagnetic-piezoelectric-triboelectric-triboelectric nanogenators is developed, which can realize the measurement of vibration frequency and the collection of vibration energy. The frequency measurement bandwidth is 0 to 200k Hz, using the principles of triboelectric nanogenators and piezoelectric nanogenators to measure low frequency of 0 to 10 Hz and medium-high frequency of 10 to 200k Hz vibrations, respectively; the corresponding measurement errors are less than 5% and 8%, which meet the downhole accuracy requirements and solve the limitation of small measurement frequency bandwidth of friction nanogenators in downhole vibration measurement. At the same time, the power generation performance of the sensor is explored. The maximum load power of TENG is 447.8 nW when the frequency is f = 10 Hz and the load is 10\({}^{8}\)\(\Omega\); the maximum load power of PENG  
Figure 12: Stability test results: (**a**) voltage decay ratios of TENG (f = 10 Hz) and PENG (f = 1k Hz) at different temperatures; (**b**) TENG (f = 10 Hz) and PENG (f = 1k Hz) at different temperatures Peak power attenuation ratio; (**c**) voltage attenuation ratio of TENG (f = 10 Hz) and PENG (f = 1k Hz) under different humidity; (**d**) peak power attenuation of TENG (f = 10 Hz) and PENG (f = 1k Hz) under different humidity ratio; (**e**) voltage decay curves of TENG (f = 10 Hz) and PENG (f = 1k Hz) under different vibration cycles; (**f**) voltage decay curves of EMG (f = 1k Hz) under different vibration cycles. is 5347 nW when the frequency is 1k Hz and the load is \(10^{8}\)\(\Omega\); the peak load power of EMG is 3.04 mW when the frequency is 1k Hz and the load is 100 \(\Omega\). The sensor's output signal, after rectification, can simultaneously illuminate eight LED lights. In addition, the influence of downhole temperature and humidity changes on the performance of the sensor was explored. The experiments show that the HDV-TENG can still work normally at 440 K (high temperature) and 90% RH humidity, which has good anti-interference and reliability. The innovation of HDV-TENG is that it overcomes the limitation that the triboelectric nanogenerator itself can only measure low frequencies. Combined with the characteristics of piezoelectric ceramics suitable for high-frequency vibration measurement, the use of magnetic levitation technology to achieve nonfaulty measurement of low-frequency to medium-high-frequency vibration has high measurement reliability and accuracy. At the same time, HDV-TENG can withstand high temperatures and high humidity and is suitable for complex downhole working conditions. In addition, HDV-TENG combines triboelectric power generation, piezoelectric effect, and electromagnetic power generation, and introduces a self-powered mode, which improves energy utilization efficiency and drilling efficiency. However, at present, the HDV-TENG still has some limitations. At present, the output power of the self-powered sensor is still limited and unstable, so it is difficult to directly supply power to other components. Therefore, it is necessary to further study the output power of the sensor and deal with the alternating current (AC) output. Validation, J.L. and Y.F. ; writing--original draft, G.P. ; methodology, C.W. ; writing--review and editing, J.L., Y.F. and C.W. ; project administration, C.W. All authors have read and agreed to the published version of the manuscript. This work was supported by CNPC Innovation Found (2022 DQ02-0309); Scientific research project of Shaanxi Coal Industry and Chemical Industry Group Co., Ltd. (KCYY-2023-ZD-02 and 2023-TD-ZD003-003); National Key R&D Program of China (2023 YFC2907502). Not applicable. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy. Author [PERSON] was employed by the company Shaanxi Schaanxi Coal Caojiantan Mining Co., Ltd.