Jae Joon Kim1 Linden Allison1 Trisha Andrew1

1, University of Massachusetts Amherst, Amherst, Massachusetts, United States

The leaves of certain plants, such as banana, pothos, and palm, are readily and cheaply available and possess amazing mechanical robustness, to the extent that they are used as eco-friendly, disposable food containers and other household wares in many countries. In theory, these plant leaves can also act as rugged, cheap, lightweight and flexible substrates for biocompatible and biodegradable organic electronic devices. However, the surfaces of these leaves are textured and nonplanar, and the leaves themselves are degraded by heating and/or various chemical treatments. Therefore, the typical fabrication methods currently used to create polymer devices cannot reliably produce leaf-based electronic technologies. Here, we describe our efforts to grow functional, high-performing electrode arrays and electrochemical transistors on various plant leaves using reactive vapor deposition (RVD). RVD is a nascent vapor coating technique in which a conjugated polymer film is formed in situ upon the mixing of separately-introduced oxidant and monomer vapors inside a specially-designed reaction chamber. RVD reliably and conformally creates conjugated polymer films on a diverse range of substrates, irrespective of surface chemistry or roughness/topography. Banana, pothos and palm leaves can be uniformly and conformally coated with highly-conductive conjugated polymer films using our custom reaction chamber while remaining unaltered and undamaged. Further, the electronic polymer coatings retain the unique, hierarchical native structure of each leaf, leading to electronically-active films that display intriguing mesoscale architectures. The performance of selected electrochemical transistors created on various plant leaves will be discussed.