RUI: Leaf as a Biodegradable Material for Electronic Components

As the global household income continues to rise and the overall cost of electronic components continues to fall, a record number of electronic devices are produced every year to satisfy the demand. However, the usable lifetime of these devices has also fallen as consumers are enticed by newer versions of devices that arrive on the market every few years and built-in obsolescence from manufacturers takes effect.

This has resulted in the generation of a record amount of electronic waste (e-waste) every year. Most of the e-waste is discarded in landfills which results in environmental pollution. Some e-waste is sent for recycling in the developing world where workers are protected by sub-par health and safety regulations if any.

The problem appears to grow only worse as the amount of e-waste is projected to increase to new levels. One way to help address the issue to some extent is to develop electronic devices from materials that are biologically sourced and biodegradable so that these devices can be discarded with minimal environmental impact. This NSF project aims to develop leaf-based electronic devices as an environmentally friendly alternative to conventional electronics with a short lifespan.

Leaves are abundant and are available in various textures and morphology. The investigators will study the intrinsic charge transport mechanism within leaves and the charge transport mechanism through the conducting polymers introduced in the leaves. By using this knowledge and taking advantage of the various architecture of the leaves, the investigators plan to develop various electronic devices for harvesting residual energy, storing energy, and sensing the surrounding environment such as ion contents within leaves or in solutions exposed to the leaves.

The work to be carried out by the investigators will lay the groundwork for ultimately developing an integrated system of leaf-based self-powered environmental sensors. The PI will mentor a team of undergraduate students which will include members of underrepresented groups to carry out the research and fulfill proposed project goals. In addition, the PI will integrate knowledge gained from the research in a university-wide seminar course that the PI recently developed which focuses on the civilizational consequences of the discoveries in electronics.

In a world with an ever-increasing amount of electronic waste, growing applications for use-and-throw electronics, and significantly limited recycling mechanisms for such waste, there is a need to develop biodegradable electronics that minimize environmental impact during fabrication as well as after they are discarded. Leaves are readily available biological materials rich in morphological diversity and therefore could be an environmentally friendly cost-effective alternative as active materials, substrates, or enclosures.

The investigators will study electron and ion transport mechanisms in leaves, both in their naturally occurring state and when conducting polymers have been introduced. By using this knowledge and taking advantage of the leaf architecture, the investigators will develop electronic devices such as triboelectric nanogenerators (TENGs) for residual energy harvesting, supercapacitors for storing the energy, transistors and logic gates for environmental sensing, and resistive switching mechanism based in-vivo monitoring of hydration level in plants.

The proposed work would not only help expand knowledge in the field of “green electronics” but also help explore the potential for developing electronics integrated within living systems and generate ideas for bio-inspired electronics.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.