Application of Agave Silk Fibers in Sustainable and Flexible Electronics

Developing novel biodegradable substrates for electronics is crucial for reducing e-waste, minimizing environmental impact, and promoting sustainable resource use. Here, for the first time, we report the use of Agave silk fibers (ASFs) in sustainable and flexible electronics. Morphological characterization was carried out on the obtained ASFs-based substrate, showing an average thickness of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$83 \mu \mathrm{m}$</tex> and an average roughness (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$R_{a}$</tex>) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.6 \mu \mathrm{m}$</tex>, with the silk fibers composing the substrate having an average length and width of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$243.8 \mu \mathrm{m}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$26.2 \mu \mathrm{m}$</tex> respectively. Biodegradability tests showed that the substrate fully degraded after 2 days and 7 hours in water. As a proof of concept, a copperbased resistance temperature detector (RTD) was fabricated and thermally characterized. The electrical characterization showed a sensitivity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.26 \%{ }^{\circ} \mathrm{C}^{-1}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.24 \%{ }^{\circ} \mathrm{C}^{-1}$</tex> during heating and cooling, respectively. To evaluate the repeatability of the sensors, 10 cycles of heating (55° C) and cooling (25° C) were carried out, showing stable behavior for 7 h. To confirm the mechanical stability of the device, bending tests were performed, showing a stable resistance of the RTD at different bending radii.