Design and development of a variable ultrasonic frequency generator for rodents repellent

Rodent is one of the major stored pests in Bangladesh, which causes a huge problem in the food sector. They substantially harm to crops and other valuable items on a large scale. Chemically rodent repellents already exist, but because of their toxicity and high price, they are not recommended for use in food storage. The aim of the study was to develop an electronic rodent-repelling circuit that is capable of generating variable ultrasonic frequencies. These frequencies cause discomfort for pests including rats, and nocturnal insects, which affects their aural senses. A device was successfully designed and constructed by microcontroller, printed circuit board, passive infrared sensor, liquid crystal display, Relay module, and other relative components. The device was vigorously tested in Precision Lab, Bangladesh Agricultural University. Laboratory tests were conducted to evaluate the device's repellent efficacy, considering factors such as range, coverage area, power consumption, and durability. The device functioned as it detected the presence of rodents and then released frequency by the positive signal for 30 s. The device generated ultrasonic signals within the range of 20–125 kHz and detected signals from any live substances up to 4.5 m with an error of a maximum of ±0.428 %. The frequency range of rodent hearing is approximately 20 Hz to 300 kHz, with the greatest sensitivity between 30 and 70 kHz, affecting their aural senses and causing discomfort. Therefore, the developed ultrasonic rodent-repellent circuit can be a practical and sustainable solution for repelling stored rodents, which mitigates storage losses caused by rodent infestations.