Eggshells -- nature's ceramic material

UC San Diego engineers investigate why eggshells are so strong

Think breaking an egg is easy? Try holding it sideways between your hands and pressing it, you'll find that it's almost impossible to break. That's what Eric Nicholas Hahn, a UC San Diego Ph.D. alumnus from the Department of Materials Science and Engineering, demonstrates in the video below:

Hahn was part of a team of researchers led by mechanical engineering professor Marc Meyers that investigated what makes eggshells so strong. Their findings were published last week in Journal of the Royal Society Interface.

The function of the eggshell is to protect the embryo from the environment, but it cannot be too strong otherwise the chick would not be able to break out and hatch. It is made of calcium carbonate, an important biomineral, which is different from hydroxyapatite, the mineral component of bone.

In the study, eggs of different sizes, from quail to ostrich, were tested on their strength using an electromechanical system that compressed the eggs between two pieces of rubber. When an egg is compressed in this way, tensile stresses develop radially in the shell. It is only when this radial tensile stress reaches a critical level, equal to the tensile strength of calcium carbonate, that the egg breaks.

Eric Nicholas Hahn, the first author of the study.

Chicken eggs were found to have a compressive strength of 100 lbs, whereas ostrich eggs gave values of more than 1000 lbs. Size and shell thickness were the most important factors in determining shell strength. The strength of eggshells decreases with increasing size and thus thickness, but the force required to break the egg increases because the stress (force/area) is less.

"This paper revealed, for the first time, the mechanism by which the eggs break when subjected to axial compression. It is not the compression by my hands that breaks the egg, but the tension generated radially,” Meyers said.

Meyers was interested in this topic since he was a child growing up in Brazil. He added, "We would like to check the universality of our equations by testing eggs of all kinds of birds. There are a variety of interesting birds that we did not test because their eggs are difficult to come by: penguins, eagles, dinosaur..."

Source: The Royal Society Publishing Blog

Full paper: "Nature's technical ceramic: the avian eggshell."

Apply to the Student Travel Fund

Do you need money to travel to your next conference, hackathon or networking event? Apply to the Student Travel Fund! Originally made possible by generous donations from the 2013 graduating senior class in conjunction with the annual Ring Ceremony, the fund helps cover costs for undergraduate student travel to conferences and competitions.

Taylor used the funds to travel to a conference.

Yale University, where SplashCon was held

"I am on the TESC Outreach Committee and was given the opportunity with my co-lead to be in charge of Splash -  a one-day marathon of classes in a variety of subjects that is open to all students in grades 9-12 - this year," said Taylor. "Universities such as Yale, Harvard and MIT put it on. I applied to the student travel fund to attend SplashCon, a conference that teaches universities how to run the event. I gained so much valuable information! I will apply what I learned in the workshops, like marketing tips, how to create a timeline for the event, and how to utilize the website. I also look forward to applying what I learned from listening to the other students' experiences."

Ryan used the funds to travel to a workshop in Los Angeles.

"The American Society of Civil Engineers workshop in Los Angeles gave me an opportunity to network with professionals, and interact with other students from other schools," said Ryan. "I was able to learn more about general leadership within the Society of Civil Engineers, how to go about advancing my professional career, and how to better serve the community through interaction with professionals and lectures by accomplished engineers."


Interested? You're in luck! There's a workshop January 26, 2017 in the Qualcomm Room (EBU1/Jacobs Hall). During this workshop the STF Committee will share insights about the application process, best practices for travel, and recording trip experiences. Refreshments will be provided!

Reinventing the Wheel: Former Triton Racing members invent novel public health device

What do race cars, aerospace engineering and HIV/AIDS have in common? They all played a part in the making of FluxErgy, a medical diagnostics company started by two UC San Diego aerospace engineering alumni.

Co-founders Tej Patel (BS MS, ‘12) and Ryan Revilla (BS, ’10) have similar stories – they both came to UC San Diego for aerospace engineering, and they both saw the  Triton Racing (UC San Diego’s Formula SAE team) car parked on Library Walk one day and thought, I want to work on that!

A short time later, the two found themselves working on the next iteration of Triton Racing’s competition car together, and they became fast friends.

“Triton Racing was easily the most important thing I did during my time at UC San Diego to get hands-on experience,” said Patel. “At the time, the team was only 7-8 people, so we each had the opportunity to work on every part of the car. Ryan worked on the engine, but he also helped build the chassis.”

After graduating, both were hired by a former member of the MIT Formula SAE team to build sensors for real racecars.

After living the dream working on high-end racecars for a few years, Patel began to itch to build something that could help people.

At the time, his wife (Priya Bhat Patel, BS ‘10, Physiology and Neuroscience) was working on her masters in public health, so he set out to find a way to build a point-of-care testing device.

“I approached Ryan with the idea, and between his garage and my kitchen, we built our first prototype,” said Patel.

At first, Patel and Revilla thought they’d build a low-cost PCR machine, but they knew they wanted one platform that could perform a wide array of tests, such as viral load and blood cell count. Instead, they built a general-purpose device that uses a test card with an embedded program that tells the machine what kind of unique test to run. The device works by taking various optical and electrical measurements from the function specific test card.

By adapting the design of the test card rather than the device for each type of test, the co-founders eliminated the need for multiple machines to conduct the typical assortment of laboratory analyses. With a simple workflow and small footprint, the low cost device and test card are meant for point-of-care use locally and in low-resource settings.

“Because we came into this as engineers, we took a very different approach to the assays than a biologist would,” said Patel. “We found that there were quite a few unnecessary steps in traditional assays. We found ourselves asking, ‘do we really need to do it this way?’”

Patel and Revilla attribute this approach to their time spent at the UC San Diego Jacobs School of Engineering. During that time, the Triton Racing team learned a big lesson about taking a systems level approach to building a racecar.

“The first year Ryan and I were a part of the team, we built a really complex car,” said Patel. “But because of that, we didn’t make it to the competition. We learned that you can have the fanciest, lightest wheel ever, but if the car can’t go around a turn it’s useless.”

That lesson in systems engineering has shaped the company the two built together. They have since hired six more UC San Diego graduates.

When asked what advice they have for startups, Patel and Revilla agreed that it’s best to fail early and often.

“Oftentimes, startups don’t think about scalability,” said Patel. “Our device went through nine iterations in one year in order to optimize its manufacturability.”

If you’d like to join FluxErgy’s First Access Program as a technology development partner or Beta user, please contact info@FluxErgy.com. Find out more information at www.FluxErgy.com

New solar energy "chill" spot on campus

This Friday, January 13^th, UC San Diego’s Engineers for a Sustainable World (ESW) will be showcasing their solar projects at the site of Solar Chill, a recently finished project that is open for all the community to utilize.

The site is located between the Village and ERC housing areas, directly across the street from the Rady School of Management.  The event will take place from 12-2pm and feature the students responsible for Solar Chill and more, including SolarRoller and Solar Car.

Solar Chill is an off-grid photovoltaic structure that recently finished construction and is now open for use. The system can produce 1.5kW of electricity. This generated energy flows into a battery system that feeds the lighting for the site as well as outlets built into the on-site benches. Solar Chill was created to bring solar down from rooftops tucked away out of sight and give people a chance to directly interact with solar and see its functionality. Now that the site is up and running, it is the team’s goal to spread awareness of it so that the community knows to use it. This was the first student-designed project approved to be built on the UC San Diego campus and the team hopes it will serve as an inspiration to other student teams to implement their own creations.

The Solar Chill site is open to anyone - feel free to stop by and recharge!