Experimental investigation of delignified woods for sustainable piezoelectric energy harvesting

Wood is a renewable and biodegradable material with intrinsic piezoelectricity originating from cellulose microfibrils and dipolar domains, making it attractive for sustainable energy harvesting. This study investigates the piezoelectric performance of two wood species -Balsa, and Pine- enhanced through a chemical delignification process. The treatment removed 27.05% lignin from Balsa and 39.19% from Pine. SEM observations demonstrated lignin removal–induced porosity and inter-fiber gap expansion, which enhanced compressibility and stress transfer within cellulose-dominated piezoelectric regions. These structural changes improved compressibility and enhanced voltage response. Under a 1 kg load, treated Balsa generated up to 300.52 mV, significantly higher than its untreated counterpart (2.3 mV) as well as treated Pine produced 254.56 mV also showing considerable improvements. Beyond voltage measurements, the electromechanical behavior was quantitatively characterized by deriving the piezoelectric charge coefficient (d₃₃) and charge density using standard piezoelectric relations. The calculated d₃₃ values were 0.0448 pC/N for Balsa and 0.0253 pC/N for Pine , with corresponding charge densities of 4.88 × 10⁻¹ ¹ C/m² and 2.53 × 10⁻¹ ¹ C/m² . The results demonstrate that delignified wood is an effective, eco-friendly energy-harvesting material, addressing a key literature gap through comparative species analysis and highlighting its potential for self-powered sensors and sustainable building technologies.