A capacitance sensor has been designed to investigate the correlation between wood capacitance value, Janka hardness rating and density. The sensor was developed based on parallel plates using copper as the electrodes. Capacitance values were measured using CV-circuit, 20 Vp-p, 2.5 MHz. Five wood specimens from forest plantation that is rubber tree (Hevea brasiliensis), blackboard tree (Alstonia sp.), pine (Pinus mercusii), sengon (Paraserianthes falcataria), and fast growing teak (Tectona grandis) were tested. Each specimen was measured in tangential and radial directions under 0% moisture content conditions. The designed sensor was capable to distinguish the capacitance values in tangential and radial directions. The measurement results showed that wood capacitance value has a good relation with wood's hardness and density.
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