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The paper analyzes the hardware implementation of the rapid method of bioimpedance spectrometry for assessing the degree of berry ripeness. This method is based on the measurement of electrophysical parameters of biological tissues of berries given that the permeability of cell membranes changes during ripening. When creating a portable device for rapid assessment of the degree of berry ripeness, the research results described below were used. After the onset of maturation, when there is an increase in the content of dry soluble substances, there is also an increase in the informative indicator- the coefficient of dispersion of tissue polarization, defined as the ratio of the modules of electrical impedances measured at two frequencies. When berries reach ripeness suitable for harvesting, its increase significantly slows down and stabilizes. The device allows the operator to record this process and determine the optimal timing for harvesting. The operation principle of the device is as follows. The berry is placed in the impedance sensor, made in the form of a clothespin, and contacts with its electrodes. Regulated by the microcontroller, electric current from two sources of sinusoidal current with different frequencies is alternately set between the electrodes in a berry. When the current flows, the voltage across the electrodes is proportional to the magnitude of the berry tissue impedance module. Next, the voltage of each frequency is converted to codes and alternately sent to the microcontroller, which calculates their ratio - the coefficient of dispersion of berry tissue polarization. The result of the calculation is displayed on the screen of the alpha-numeric indicator. Before the beginning of berry maturation, an operator monitors the change in the dispersion coefficient of the berry tissue polarization with the help of the device at intervals of 2-3 days. When its increase stops, the berry is considered to have reached ripeness suitable for harvesting. |
