Jianguo Sun - Wood based energy harvesters

Increased depletion of fossil fuels and severe environmental pollution have motivated considerable efforts to find alternative and more sustainable energy sources. Mechanical energy exists in various forms, including sound waves and human movements, which can be harvested from the surrounding environment by means of piezoelectric nanogenerators. Many materials have been utilized to fabricate piezoelectric nanogenerators, however many of these materials, such as PZT, are brittle ceramics that contain toxic elements (lead). Wood is one of the most abundant natural resources on Earth, and it is renewable, lightweight, biocompatible, and biodegradable. Thanks to the uniaxial orientation and monoclinic symmetry of crystalline cellulose fibrils, wood does behave as a piezoelectric material. However, due to the low piezoelectric constant (previously reported to be approximately 1/20 of that of quartz) and poor deformability of natural wood, limited progress has been made in the past decades for its application in piezoelectric devices. Jianguo tries to increase the piezoelectricity of wood by various methods, such as delignification, making the displacement of cellulose crystal easier under a minute load resulting in a significant increase of electrical output.