MADISON, WI - Semiconductor chips made almost entirely of wood have been developed by research teams at the University of Wisconsin-Madison and the Madison-based U.S. Department of Agriculture Forest Products Laboratory (FPL).

Published in late May by the journal Nature Communications, the research paper details replacing the substrate of the computer chip with cellulose nanofibril (CNF), a flexible, biodegradable material made from wood. "Now the chips are so safe you can put them in the forest and fungus will degrade it. They become as safe as fertilizer," said research team leader and UW-Madison electrical and computer engineering professor Zhenqiang "Jack" Ma.

Working with Shaogin “Sarah” Gong, UW-Madison professor of biomedical engineering, FPL project leader Zhiyong Cai’s group resolved the issues of surface smoothness and thermal expansion by using an epoxy coating on the surface of the CNF. "You don't want it to expand or shrink too much. Wood is a natural hydroscopic material and could attract moisture from the air and expand," Cai said. "With an epoxy coating on the surface of the CNF, we solved both the surface smoothness and the moisture barrier."

Gong also noted that CNF has a low thermal expansion coefficient, compared to other polymers.

The paper was also co-authored by Yei Hwan Jung and Tzu-Hsuan Chang, UW-Madison Department of Electrical and Computer Engineering.

Information obtained from John Steeno, University of Wisconsin, Engineering External Relations Office, Madison, WI