Nondestructive In Situ Measurement Method for Kernel Moisture Content in Corn Ear

Abstract

Moisture content is an important factor in corn breeding and cultivation. A corn breed with low moisture at harvest is beneficial for mechanical operations, reduces drying and storage costs after harvesting and, thus, reduces energy consumption. Nondestructive measurement of kernel moisture in an intact corn ear allows us to select corn varieties with seeds that have high dehydration speeds in the mature period. We designed a sensor using a ring electrode pair for nondestructive measurement of the kernel moisture in a corn ear based on a high-frequency detection circuit. Through experiments using the effective scope of the electrodes’ electric field, we confirmed that the moisture in the corn cob has little effect on corn kernel moisture measurement. Before the sensor was applied in practice, we investigated temperature and conductivity effects on the output impedance. Results showed that the temperature was linearly related to the output impedance (both real and imaginary parts) of the measurement electrodes and the detection circuit’s output voltage. However, the conductivity has a non-monotonic dependence on the output impedance (both real and imaginary parts) of the measurement electrodes and the output voltage of the high-frequency detection circuit. Therefore, we reduced the effect of conductivity on the measurement results through measurement frequency selection. Corn moisture measurement results showed a quadric regression between corn ear moisture and the imaginary part of the output impedance, and there is also a quadric regression between corn kernel moisture and the high-frequency detection circuit output voltage at 100 MHz. In this study, two corn breeds were measured using our sensor and gave R2 values for the quadric regression equation of 0.7853 and 0.8496.

A Comprehensive Review of Portable Microwave Sensors for Grains and Mineral Materials Moisture Content Monitoring

“…Measuring the amplitude and phase of the reflected voltage signal is another technique. The MC monitoring in [3], [4], [21], [37], [38], [42], and [43] was accomplished through measuring the input impedance. It should be noted that measuring impedance is also possible through S-parameters measurement.…”

“…The MC is calculated by MC = (Ww-Wd)/(Ww-Wc) [3], [5] where Ww, Wd, and Wc are the weight of sample under test (SUT), dried SUT, and container weight without SUT, respectively. The MC indicates the amount of water that exists in the SUT.…”

Determination of Equilibrium Moisture Content in Trade Distribution

“…Therefore, non-destructive detection of maize moisture content is recommended in farm level. There are several nondestructive detection methods could be applied at farm level, including using used ring electrode pair as sensors (Zhang et al, 2016), 555 integrated circuit timer (Klomklao et al, 2017), microcontroller (Oktavianty&Wildian, 2016) and web based capacitive (Savero et al, 2018). Preventive action could be controlled when the moisture content already known at farm level.…”

Developing an Online Measurement Device Based on Resistance Sensor for Measurement of Single Grain Moisture Content in Drying Process

“…In the last few decades, researchers have done some work on the measurement of moisture content of agricultural products using the following methods: Optical [ 5 , 6 ], Nuclear [ 7 ], Hygrometric [ 8 ], and Dielectric methods [ 9 , 10 , 11 ], which describe the moisture content of a batch of grains based on the assumption of the uniform distribution of moisture. However, owing to the change of drying parameters, environmental conditions, material properties and differences in drying technique, the moisture content of the grains to be tested in the testing instrument chamber is often nonuniform [ 12 , 13 , 14 ].…”