Novosibirsk State Technical University (NSTU) has developed a device that makes it possible to determine the moisture content of grain crops using a low-error measurement method.
Yegor Chikulaev, a fourth-year student at the Faculty of Automation and Computer Engineering at NSTU-NETI, has created a portable moisture meter that allows determining grain moisture using a dielectrometric method based on the dependence of the dielectric constant of a material on its moisture content.
A special feature of the development is accuracy: the device provides an absolute measurement error of no more than ± 0.5%, a typical value of ± 0.25%. Such indicators were achieved due to the design of the capacitive sensor and optimal circuit design solutions.
According to the developer, the improved version of the system consists of a reference and a working generator. The initial frequency of the oscillator is practically independent of the device's movements in space and weakly depends on the external electromagnetic environment due to shielding and an electronic frequency tuning mechanism for calibrating the device before each measurement. The microcontroller manages all processes and stores calibration values.
The analog part of the device is implemented mainly on domestic electronic components. The analog and digital systems are powered by a galvanic cell with a voltage of 9V type 6LR61, and software specially developed for the moisture meter allows fast data processing.
"The system's operating frequency is 20 MHz and was chosen experimentally as the optimal value between a sufficient resolution level of the resulting device and the operating range for the selected circuitry. This solution allows you to measure humidity at the level of tenths of a percent," said Egor Chikulaev.
The device does not require special laboratory conditions and special skills: it is enough to turn on the device, put the sample in a capacitive sensor, screw on the lid, select the type of grain crop and wait for the result on the screen of the device itself. Testing has confirmed the effectiveness of the device. In future, according to the developer, it is planned to improve the hardware and software for collecting statistics on grain crops.
Also, within the framework of the Bioengineering youth integration laboratory at NSTU-NETI, a system for analyzing soil gases is being developed.