20 Minutes With Olivia Graeve
Rachel Fowler, Managing Editor | TLT 20 Minutes February 2017
This University of California, San Diego professor explains the triboluminescence phenomenon and speculates on its underlying causes.
Roller coasters are one of the applications for triboluminescent sensors.
© Can Stock Photo / jabiru
OLIVIA GRAEVE - The Quick File
Professor Olivia Graeve joined the University of California (UC), San Diego in 2012 and is currently professor in the department of mechanical and aerospace engineering, director of the CaliBaja Center for Resilient Materials and Systems and faculty director of the IDEA Engineering Student Center. Graeve holds a doctorate in materials science and engineering from the University of California, Davis, and a bachelor’s degree in structural engineering from UC San Diego.
Her area of research focuses on fundamental studies of the synthesis and processing of nanostructured materials, including ceramic and metallic nanomaterials and amorphous/nanocrystalline composites for both structural and functional applications, with a special emphasis on electromagnetic multifunctional materials for sensors and energy applications. She has been involved in many activities related to the recruitment and retention of women and Hispanic students in science and engineering and has received several prestigious awards including:
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The National Science Foundation CAREER Award
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The 2006 Hispanic Educator of the Year Award by the Society of Hispanic Professional Engineers
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The 2010 Karl Schwartzwalder Professional Achievement in Ceramic Engineering Award by the American Ceramic Society
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The 2012 B.J. Harrington Lectureship by McGill University
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The 2011 Society of Hispanic Professional Engineers Jaime Oaxaca Award
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Outstanding Engineering Educator by the San Diego Chapter of the California Society of Professional Engineers (2015)
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Alumna of the Year by Southwestern College (2015).
Recently she has been named into the Tijuana Walk of Fame (2014) and the Mexican Academy of Engineering (2016).
Olivia Graeve
TLT: What is the triboluminescence phenomenon? What is a triboluminescent material?
Graeve: The triboluminescence phenomenon occurs when a material is fracturing—a crack propagates through the material—and as its moving across the material, it emits light. A triboluminescent material is, of course, a material that exhibits this type of behavior.
TLT: What are the underlying mechanisms responsible for triboluminescence?
Graeve: That’s actually a matter of controversy. The reason for this behavior is not clear. It may vary depending on the type of material.
One theory is the stress that forms in the region at the tip of the crack causes the electrons in the atoms in that location to jump to higher energy states. As the electrons come back to their ground state, they emit visible light.
TLT: What is a triboluminescent sensor? How is this material being synthesized?
Graeve: A triboluminescent sensor is a sensor that can detect the signal from the light given off by the material as it brakes. For example, you could design a paint that contains some of this material in it. Then you would paint a bridge with this paint and be able to detect if there are active and moving cracks in a civil infrastructure like this bridge.
TLT: How can damage in a civil structure be detected using a triboluminescent sensor?
Graeve: You would need to have the sensors in place in the structure (e.g., in the form of a paint). The process is one where, as the material is emitting light, you need to have some kind of recording system that allows you to see when that emission is happening. It could be some kind of video recording or camera system on a bridge, for example, which is not a difficult thing to do since most bridges nowadays have cameras on them already.
TLT: What are the cost savings (e.g., downtime) or prohibitive costs arising from fatal accidents?
Graeve: We are in the stage where we are doing fundamental studies on this.
TLT: What is the cutting edge in development and commercialization?
Graeve: This is still at the fundamental science stages of development.
TLT: Other than civil structures, what are the other potential applications for triboluminescent sensors?
Graeve: Roller coasters.
TLT: What are the main challenges for these applications?
Graeve: The main challenge with these materials is the light emission that they give off is faint. So we are at the fundamental science stages of development of these materials and that is really the one parameter that needs to improve. Emission needs to be brighter so cameras can have an easier time in seeing and recording the light emission. At the fundamental material level, the emission is still too weak to be really useful.
You can reach Olivia Graeve at ograeve@ucsd.edu.