This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The humble amino acid glycine—the simplest of all amino acids—is everywhere. The human body produces it, and it helps make up our skin, bones and ligaments.
It's found in meats like beef and has even been discovered in comets returned from outer space. Now, Stanford researchers are considering how glycine might enable the engineering of next-generation materials, like bioelectronics and environmental sensors, that could biodegrade when their job is done. A new paper in Advanced Functional Materials introduces a novel material designed by a team at the School of Engineering that addresses stubborn hurdles on the path toward glycine-based, electrified medical devices.
"Glycine is really interesting because it's so abundant," said Vivian Feig, an assistant professor of mechanical engineering in the School of Engineering and senior author of the paper. "We know how to process it, our bodies know how to break it down, and it's cheap and really accessible." Feig's lab focuses on developing dynamic functional materials for biomedical use, such as novel materials that break down over time in the body or can be introduced via minimally invasive methods. "When we are making new materials, we think about the entire functional lifetime for a device, as well as practical constraints about how it will be deployed," said Feig.
"We try to use very well-established and safe building blocks combined with innovative approaches for engineering the material in order to give familiar materials exceptional or novel properties to open up use cases that haven't existed before." This work is part of their investigations into leveraging glycine's piezoelectric properties—its ability to produce energy from mechanical stress. Piezoelectric devices are used in household products like smoke alarms and watches, environmental monitors and medical devices used for ultrasound imaging or as diagnostic sensors. Scientists already understood that glycine could make an exceptionally good piezoelectric material.
But it also has important drawbacks: When it comes in contact with water, it disintegrates within seconds, and the crystalline form the material naturally prefers is not piezoelectric at all. "Nature and our bodies can dispose of it. But how do we harness its potential?" said Feig.
"We had to solve a lot of different problems." The researchers came up with various solutions for glycine's faults. First, to keep glycine in a desirable piezoelectric form, Feig and her co-authors created a novel engineering process that applies an electric field as glycine crystallizes under nanoconfinement. This process isolates particles in exceedingly small spaces and, in this case, aligns glycine crystals by polarity, allowing them to keep their piezoelectric properties.
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