Characterization of Multilayer Capacitive Sensor for Water Content Detection Application in Seaweed Drying Process Using Fast Fourier Transform (FFT) Algorithm

Abstract

The moisture content of seaweed during the drying process is one of the factors determining the quality of seaweed. Therefore, measuring the percentage of water content in seaweed during the drying process is very important to note. A multilayer capacitive sensor for water content detection application in seaweed drying process using the Fast Fourier Transform (FFT) algorithm has been successfully built and characterized. The sensor is made from a Cu PCB substrate in the form of a potential ladder pattern with dimensions of 5 x 5 cm. The PCB substrate is then coated with several layers of NiFe and Cu forming layers using electro deposition technique. The research method consists of making the sensor, calibrating the sensor using the gravimetric method, and performing two measurement schemes, namely measuring changes in the ADC value of the sensor as a representation of the seaweed moisture content value and measuring changes in the frequency value of the sensor as a representation of the moisture content value using FFT algorithm. The results showed that the sensor characteristics in the form of sensor slope of 18.866 ADC value / (%) water content with an intercept of 68.248 ADC value. So that the sensor will experience a decrease in ADC value changes by 18.866 every 1% increase or decrease in water content. For the coefficient of determination R2 of 0.91618 which indicates that the sensor has approached the reading of the water content value with good precision. Based on the measurement results of the seaweed water content value also shows that by using FFT algorithm, the reading of the seaweed water content value can be represented by the frequency value of the sensor well. This research contributes to the development of innovative sensor technology in measuring moisture content during the seaweed drying process.