A self-powered vibration sensor for downhole drilling tools based on hybrid electromagnetic-triboelectric nanogenerator.

The vibration of downhole drilling tools is important to the drilling process, which needs to be measured in real time. Here, a self-powered vibration sensor for downhole drilling tools based on a hybrid electromagnetic-triboelectric nanogenerator is proposed in this research. The sensor has high reliability because the triboelectric nanogenerator (TENG) and the electromagnetic generator (EMG) parts of the sensor can be used as vibration sensors alone, and it may also supply power to other micro-power measurements while drilling instruments when the TENG and the EMG are used in parallel to increase the output power. Test results show that for the TENG part, the maximum output voltage, current, and power are 14 V, 5.2 µA, and 3.2 µW, respectively, with a 1 MΩ resistance in series, and for the EMG part, they are 1.22 V, 33 µA, and 21.8 mW, respectively, with a 10 Ω resistance in series. Further tests show that the measurement range of both the TENG and EMG is 0-11 Hz, the measurement error of both is less than ±5%, and both can work normally in the temperature range of less than 250 °C. In addition, this research also builds a wireless vibration data transmission system based on the sensor, which shows the potential for use in the wireless sensing field.