Bio-inspired vibrational wireless underground communication system

The internet of the underground things (IoUT) is an emerging field that concerns connected underground sensing nodes and can find applications in various fields such as geotechnical engineering, precision agriculture, and search and rescue operations. The complex underground environment and multiphase nature of the soil pose challenges to wireless underground communication. Most existing studies on wireless underground communication focus on the use of electromagnetic waves. However, as a highly lossy material for electromagnetic waves, soil can limit the range and reliability of data transmission. Inspired by subterranean animals that rely on vibrations or seismic waves for underground communication, the prototype system developed in this study is based on vibration. This system includes a bio-inspired vibrating source, a micro-electromechanical system (MEMS) accelerometer, a micro-controller, and a set of algorithms for encoding and decoding information. Specifically, the mole rats-inspired source is small in size, low in cost, and energy-efficient. An on-off-keying decoding algorithm enhanced with an error-correction algorithm is found to be robust in transmitting textual and imaginary information. With the current design, a maximum transmission bit rate of 16–17 bits per second and a transmission distance of 80 cm can be achieved. The bit error ratio is as low as 0.1%, demonstrating the robustness of the algorithms. The performance of the developed system shows that seismic waves produced by vibration can be used as an information carrier and can potentially be implemented in the IoUT.