From Biobased Materials to Flexible Functional Devices: An Interdisciplinary Innovative Experiment Design for Materials Science and Engineering Students

Abstract To bridge the gap between materials synthesis and intelligent systems engineering, this article presents an interdisciplinary innovative experiment based on fully biobased flexible functional devices for undergraduate materials science and engineering students. Students prepare a flexible substrate through latex compounding and acid coprecipitation, using interfacial hydrogen bonding between plant-derived lignin and natural rubber latex to suppress lignin self-aggregation. Direct laser writing is then introduced, in which the photothermal effect of a CO2 laser beam converts the insulating lignin in situ into conductive, porous laser-induced graphene (LIG). On this platform, students construct and evaluate five types of functional devices: resistive strain and pressure sensors evaluated using a universal testing machine and digital multimeters; a serpentine temperature sensor that exploits polymer thermal expansion; a capacitive humidity sensor based on a graphene oxide/NaOH dielectric film, characterized across saturated salt solutions using an LCR meter; and an electrothermal Joule heating actuator evaluated using a DC power supply and an infrared thermal camera. Finally, students collect real-time resistance signals from their self-fabricated knee-joint strain sensors and use a deep-learning model for human motion recognition with over 97% accuracy. Implemented across two consecutive semesters with 58 students, this experiment helps students develop a systematic “Materials–Devices–Data–Applications” engineering perspective in green electronics.