Determining the Freshness of Living Tissue Using an Accurate and Sensitive Microwave Sensor

In the following manuscript, an original microwave sensor is planned to detect the meat's dielectric changes, as a type of tissue. The presented sensor is created in the model of a microstrip structure and consists of U-shaped, meander, and waterfall parts. If a liquid sample is located on the sensor at the sensing location, it can measure permittivity changes. For this, a resonance is formed in the free-load sensor at 3.2 GHz frequency then when the sample touches the sensor, according to the amount of relative dielectric changes of the desired sample, the sensor resonance frequency is shifted. To determine the sensitivity of the proposed sensor, water–methanol solution samples are used and as a result, its Q-factor and sensitivity are 5346 and 2.36%, respectively. Then, three samples of sheep, fish, and chicken meats are measured by the proposed sensor, and with time, the measurement is repeated, and the results are analyzed. With this method, the freshness of the meat is evaluated. It is possible to use the proposed sensor in the food production industry and can determine the exact postmortem time of all types of meat with high speed and accuracy.