Engineering news
Stanford University has been testing an airbag helmet for cyclists that has shown promise in recent drop tests conducted by a research team.
The helmet comes in a soft pocket worn around the neck. It pops up, like an airbag, around a person's head when it senses a potential collision.
Bicycling is the leading cause of sports and activity-related concussion and brain injury in the US. David Camarillo, a bioengineer and leader of the research team, believes that traditional helmets don't protect riders as well as they could.
Camarillo said: "Foam bike helmets can and have been proven to reduce the likelihood of skull fracture and other, more severe brain injury. I think many falsely believe that a bike helmet is there to protect against a concussion. That's not true.”
Mehmet Kurt, a postdoctoral scholar in the Camarillo Lab, said: "We conducted drop tests, which are typical federal tests to assess bicycle helmets, and we found that airbag helmets, with the right initial pressure, can reduce head accelerations five to six times compared to a traditional bicycle helmet.”
The drop test consisted of putting the helmets on a dummy head containing accelerometers and dropping it, neck-side up, from various heights onto a metal platform. The head form was tilted at two different angles, simulating hits to the crown and the side of the head. Researchers dropped the helmets from as low as 0.8m to as high as 2m and measured the linear acceleration of the helmet as it struck the ground.
Camarillo said that the large size of the airbag helmet compared to foam bike helmets is the likely source of its success. Being larger, it can also be softer, allowing for a more cushioned fall.
However, the cushioning also has a potential downside. In the testing, the airbag helmet was pre-inflated and the researchers maximised the pressure of the air inside the helmet before each drop in order to get these results.
Without the maximum amount of air, the airbag helmet could flatten, causing the head to hit the ground with much more force than if it were wearing a traditional foam helmet. In current versions of the airbag helmet, a chemical process triggers expansion, which does not seem to guarantee maximum air pressure.
Next steps include testing how the airbag helmet affects rotational accelerations and forces on the head during impact and how the helmet could reduce tissue-level strains in the brain. The researchers also want to investigate the flattening weakness of the helmet more closely, dropping it from greater heights and seeing how the air cushioning sustains.
The researchers also want to make the helmet smarter. Although it expands when it senses a likely impact, they want it to be able to predict the severity of the impact and compensate accordingly.
The air bag helmet is not available in the US but is sold in some European countries.
The results are published in the journal
Annals of Biomedical Engineering.