Printability and Electrical Response of Biopigments on Paper

Natural organic materials are relevant for the eco-design of biodegradable electronic devices and their powering elements (batteries). Printing natural organic materials on paper offers the possibility to compost electronic devices. Printed paper electronics enable to alleviate the accumulation of Electrical and Electronic Equipment Waste (E-waste) which has harmful effects on human health and the environment¹.<br/>Sepia melanin is one of the natural forms of Eumelanin (the black-brown member of the melanin family of biopigments). It is extracted from <i>Sepia Officinalis</i> natural ink. Melanins are ubiquitous in nature; they are key to diverse bio-functions in fauna and flora. Sepia melanin is mainly constituted of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid monomers that, after steps of hierarchical development, brings about a material featuring nanometric granular structure. Recently, printed films including Sepia showed predominant electronic transport^2-3.<br/>We focus on the printability on paper and electrical response of the <i>Sepia Officinalis</i> natural ink. <i>Kromekote</i> paper substrates are pre-patterned by flexographic printing with a silver-based aqueous ink, to generate electrode pairs (interelectrode distance about 100 µm). The interface between the ink and the paper is studied considering: (i) paper rugosity, porosity, and air permeability, (ii) ink rheology and wettability, (iii) tensile, rigidity, tear and burst tests, on paper before and after printing. The current-voltage (I-V) and potentiostatic (I-t) characteristics were carried out for applied electrical biases ranging between 0.1 V and 10 V and different voltage sweeping rates (1 - 500 mV/s), in controlled atmosphere (dry, wet, and ambient conditions). Preliminary results show that the conductivity and stability of the devices are remarkable. Work is in progress to discover the chemical composition of the biosynthesized Sepia. Our efforts pave the way towards greener and more sustainable electronics.<br/><b><u>References:</u></b><br/>[1] V. Forti, C. P. Baldé, R. Kuehr, G. Bel, <i>The Global E-waste Monitor 2020. Quantities, flows, and the circular economy potential</i>, United Nation University, 2020<br/>[2] A. Camus, M. Reali, M. Rozel, M. Zhuldybina, F. Soavi, C. Santato, <i>High conductivity Sepia melanin ink films for environmentally benign printed electronics</i>, Proc Natl Acad Sci U S A. 2022 Aug 9;119(32):e2200058119. doi: 10.1073/pnas.2200058119. Epub 2022 Aug 1. PMID: 35914170; PMCID: PMC9371694.<br/>[3] M. Reali and C. Santato, in <i>Handbook of Nanoengineering, Quantum Science and Nanotechnology</i>, ed. S. E. Lyshevski, CRC Press, 1st edn., 2019, pp. 101–113