# Research on Hybrid Vibration Sensor for Measuring Downhole Drilling Tool Vibrational Frequencies
## 1 Introduction  
The drilling process is one of the key methods used to bore holes from the surface to extract various underground resources [1, 2]. Throughout the drilling operation, the drill string tends to undergo nonlinear vibrations [3]. These vibrational patterns encapsulate significant drilling condition data, pivotal for mitigating drilling incidents, fine-tuning drilling parameters, and enhancing drilling velocity [4, 5]. At present, there are mature measurement-while-drilling systems (MWD, LWD) used in drilling operations to measure the vibration of drill strings [6, 7], as well as strain gauges [8], high-speed cameras [9], surface measurement and deep learning [10, 11], dynamic model optimization [12, 13], and other methods that have achieved good results in measuring vibration in the simulateddownhole environment. Some scholars choose to install the measuring device on the surface to measure the vibration information of drilling tools [14]. Although numerous methods exist for measuring downhole vibrations, significant challenges persist under actual operational conditions. Traditional vibration measuring systems rely on cable or battery power sources, which can impede construction efficiency and increase costs related to tool processing, installation, and frequent drilling. Meanwhile, due to limitations in installation methods and size requirements, measurement approaches applicable in simulated environments often fall short of meeting downhole operational demands. Furthermore, indirect surface measurement methods are prone to cumulative errors due to the influence of the formation medium. Hence, there is an urgent need to develop a vibration sensor tailored for downhole conditions that also optimizes power supply methods.  
The emergence of triboelectric nanogenators (TENGs) in 2012 opened avenues for self-powered sensing and the harvesting and recycling micro-nanoenergy, offering a new dimension to the measurement and utilization of drilling tool vibrations [15]. Through extensive scholarly research, the principles of triboelectric nanoenergy generation have significantly evolved, particularly in the realms of energy harvesting and sensing [16; 17]. In the field of energy collection, the principle of triboelectric nanoenergy generation has realized the collection of blue energy [18; 19; 20], mechanical energy [21; 22; 23], human motion energy [24; 25; 26], etc. In the field of sensing, research achievements such as speed sensing [27; 28], pressure sensing [29; 30], motion detection [31; 32], and wearable devices [33; 34; 35] have been achieved; the power supply mode realizes self-sensing and self-power supply. Meanwhile, certain scholars have undertaken initial explorations into applying triboelectric nanoenergy generation in downhole drilling [36; 37; 38]. However, several challenges persist, notably the limited bandwidth of vibration measurement confined to low frequencies and inadequate power supply. The utilization of piezoelectric nanogenators (PENGs) in the field of high-frequency vibration monitoring, as well as electromagnetic power generation (EMG) in the field of energy harvesting, provides references for addressing the aforementioned issues [39; 40]. Based on this, this research proposes a hybrid downhole vibration sensor (HDV-TENG) based on triboelectric nanogenators, which can realize the vibration frequency measurement from the low-frequency to high-frequency band in a self-powered manner. The sensor addresses the narrow frequency measurement range issue of conventional TENG-based vibration sensors. It not only achieves automatic force vibration sensing but also collects downhole vibration energy, providing power for other micropower devices. It offers a new solution to the power supply problem of downhole equipment and is undoubtedly more suitable for use in drilling conditions.