Interdigital capacitance sensing of moisture content in rubber wood

• Published in: Computers and electronics in agriculture 2017-11, Vol.142, p.545-551
• Main Authors: Chetpattananondh, Pakamas, Thongpull, Kittikhun, Chetpattananondh, Kanadit
• Format: Article
• Language: English
• Subjects: Capacitive sensor; Interdigital sensor; Printed circuit board; Wood moisture content
• ISSN: 0168-1699; 1872-7107
• DOI: 10.1016/j.compag.2017.11.016

•We propose an interdigital capacitive sensor for moisture content in rubber wood.•The performance of the sensor is 2% accuracy error and 0.98% precision error, respectively.•An effective capacitance was measured in rubber wood within a range from 6 to 70% of the moisture content.•The constructed sensor has linear sensitivity and better accuracy at very low moisture content.•This sensor does not damage the surface of rubber wood since their electrode contact is non-penetrating. A low-cost, repeatability, and linearity interdigital capacitive transducer is proposed with an explanation of experimental results. The probe is in the form of a printed circuit board (PCB) with configuration of two interpenetrating comb electrodes, which is different from the configuration of the moisture content sensors available in the market and literature. The moisture contents of the tested rubber wood samples were in the range of 6–70%. The change in capacitance of sensing probe due to the change of moisture content inside rubber wood was detected by the modified bridge circuit. The performance of this sensor is 2% accuracy error with 0.98% precision error.