The multi-institution collaboration looks to link damage occurring at the cellular level in the brain with the forces and motions involved in blows to the head. This is where the Kesari group’s wearable devices come into play.

“We have Fitbits and other types of sport watches that monitor our body’s health, like how many steps we take in a day or our calories burned, so the thought was why not create a Fitbit-type device that does this for the brain’s mechanical health,” Kesari said.

Introducing the accelo-hat

Known as the accelo-hat, the accelerometer-laced helmet the team has developed is meant to take the guesswork out of brain injury. The helmet — designed and built in Kesari’s lab — uses both commercial accelerometers and sensors manufactured by the team to capture raw motion data from any movement in the head of a user so that researchers can extrapolate that data into a virtual model. Using the model, the team then recreates that motion and simulates what would happen inside the brain as a result. 

For example, the lab has recreated impacts to the brain from a person heading a soccer ball and from riding on a high-speed motorboat as it slams into the water repeatedly — a type of potential injury of increasing concern to the Navy. Those studies revealed dramatic spikes in stress applied to the brain because of these activities. The success of the accelo-hat has led the team to expand it to encompass a human-sized dummy implanted with accelerometer sensors throughout.

The system serves as a scientific tool to measure and analyze the severity of accidents too dangerous to test on humans — such as falling down stairs or surviving a plane crash. The National Institute for Aviation Research, for example, has used the accelo-hat in efforts to develop safer aircraft seats. The research involves dropping an airplane fuselage several feet to simulate a landing gear failure while human models wearing accelo-hats sit in the seats.

“We could see what happened injury wise if they changed the height of the seat or if they increased the cushioning in the back seat,” Kesari said. “Do those changes make it more safe or less safe? Those questions couldn't really be answered before, but now with the theory and algorithms that we developed, they can be.”

A cross-team effort

The accelo-hat and the mathematical theory that powers it stem from the collective expertise and dedication of the team both in the Kesari lab and via its collaborators at Brown. Each team member brings a unique skill set to the table and plays a part in a much larger effort, including developing complex algorithms to decode accelerometer data and translating raw numbers into meaningful insights about how forces impact the human body. 

Brown postdoctoral research associate Yang Wan, for instance, helped take Kesari’s initial theory of how to extract the accelerometer data from the sensors into actual experimental measurements capturing accelerations and stresses the human body experiences using the accelo-hat. The work not only involved statistical analysis and highly advanced decoding techniques, but also some boots on the ground. Wan and team members visited various Navy-supported research labs and bases to help run many of the experiments.

Beyond data interpretation, the lab’s success has also relied on partnerships with Brown researchers like Hoffman-Kim, a neuroscientist and engineer, to enhance the team’s ability to connect mechanical insights with biological realities. Hoffman-Kim’s lab creates 3D brain cell cultures, or mini-brains, that mimic real neural tissue and provide invaluable data about cellular responses to trauma.

Senior research associate Rafael González-Cruz plays a key role in this partnership, bridging the gap between engineering and neuroscience.

“Members of the Kesari lab design sensors that can detect changes in acceleration and position of the head after receiving an injury and use that to be able to determine whether the metrics compiled by these sensors are indicators of injury — I look at the biological response of these forces in actual living cells,” González-Cruz said.

To perform the injury experiments on the mini-brains, González-Cruz uses a centrifuge that rotates at fast speeds to create an enormous amount of force —which is traditionally used to separate cells by size and density. Most recently, he and Wan led a test that allowed the team to measure what happens to mini-brains when they applied different levels of sustained force. This allowed the team to measure, with precision, the cell damage not only caused by different amounts of force but the amount of damage that unfolds over longer periods of time, which mimics the effect of brain compression injuries. The information is critical for understanding how it might be possible to prevent, diagnose and treat these types of compression injuries.

For González-Cruz, the challenge of the issue and ultimate purpose of helping protect people against concussions is part of what draws him into the work and keeps him motivated. Class of 2024 graduate Hana Butler Gutiérrez, who joined the Kesari lab while she was an undergraduate and now serves as a research associate, feels the same motivation. 

One of the newest members of the lab, she works on the materials side and spends her days creating and testing silicone lattice structures designed to absorb impact. The designs are small and flexible and made to slip into protective gear like helmets that the lab designs, but are intricate and involve a lot of trial and error, especially determining which designs will best dissipate energy. 

Keeping the ultimate goal top of mind helps keep her focused, she said.

“The whole time you're thinking about how you are designing these structures for a purpose,” Gutierrez said. “You're thinking about the use that it's going to have and how you're spending all this time making something very precise for a very specific goal. Its validating and gives you a reason to continue — because while my work is sheerly mechanical, it has a place somewhere further in a much bigger project.”