Their paper on these new measuring tools, “Colloidal Photonic Crystal Strain Sensor Integrated with Deformable Graphene Phototransducer,” was published as the frontispiece of the leading materials journal Advanced Functional Materials.
Other optical strain sensors provide a good indication of strain, but accurate quantification of strain requires additional equipment, adding bulk and reducing efficiency. With Snapp and Nam’s coupling of technologies, not only do the strain sensors provide a visual indication of deformation, but they have an electrically quantified readout provided by the graphene transducer. The combination of these two provides a sensor with greater sensitivity, making the hybrid a vast elevation of the strain sensors made with each individual component.
“If you are photonic crystal person now we are offering you the possibility of an integrated, electrical readout,” Nam said. “If you are a graphene sensor person we’re telling you we can enhance your sensitivity by 100 times.”
There are countless possible applications for the improved strain sensors, but a specific use that Snapp has been focusing on utilizes the sensors in a space based structural health monitoring system for NASA. The thinness of the graphene would allow for the strain sensors to be placed on the structure of spacecraft so that it could be monitored for cracks or deformation. In this configuration, the sensor would change color if any damage occurred offering a visual alert and astronaut to electrically probe the sensor and get a specific measurement on the amount of strain the craft experienced. Additionally for NASA, the sensors could be used for astronaut physical health monitoring. The absence of trained physicians on long journeys could be replaced with monitoring of physical exertion using the strain sensors.
Moving forward for this research group, they hope to improve the sensors by enhancing the electrical readout and making the sensors self-powered. Snapp’s current work surrounds solving these problems and he will move onto a career as a NASA scientist once he completes his PhD program.