Microgravity Synthesis of Laser-Induced Graphene

Emerging aerospace technologies manufactured for microgravity environments require materials with unique structure-property-processing relationships, which drive important considerations for the in-space design and manufacture of components and devices for the future of space flight. These materials, processes, and systems are needed to enable long term habitation and space exploration objectives. For example, the current approach to the problem of failed sensors and devices is the use of spares. However, spare parts are typically manufactured on earth and are associated with significant payload costs and storage requirements. Additive manufacturing in a microgravity environment could provide substantial benefits by lowering fabrication costs, time to deployment, and custom fabrication, therefore enabling devices and sensors to be deployed at a large scale. The emergence of novel materials offers a more sustainable approach for on-demand materials synthesis and device design and manufacture. In this study we demonstrate the fabrication of laser-induced graphene (LIG) during zero gravity. LIG is a graphitic material synthesized using a 445-nm laser patterned onto a polyimide substrate. We demonstrate the effect of the intensity of the incident beam on the morphology and properties of the material in comparison to LIG synthesized terrestrially. Raman analyses show the synthesized material is defect rich and there is a high level of disorder within the LIG structure under varying power conditions at zero gravity. Our results suggest the elimination of gravity-driven phenomena such as convection play a key role in controlling the morphology of the material, and the fundamental role of laser fluence and thermal expansion in LIG synthesis as it relates to the crystallinity, porosity, and microstructure of the material.