Defining impact: creating designs that are up to standard

Our competitors are quickly learning that before they can begin tinkering and programming with the components provided to them, they must understand the standards established by the medical community that both define and measure impact.

The Sudden Impact challengers hail from all corners of the world. They’re forced to navigate their countries’ standard systems for classifying injuries so diagnostics relayed are not only accurate but also uniform because coaches, trainers and athletes will rely on the data their homemade devices provide. In other words, our competitors don’t want to be put in a position where their solutions are falsely notifying users of injuries where there are none present, or missing an injury that does occur.

Head injuries and internal traumas remain two hotly debated conditions among practitioners and researchers around the world. So how do device designers define 'impact?' What does it mean and what are its limits? What is the standard, or better yet, is there even a standard? These questions and many more are forcing element14’s engineers to step outside their comfort zones as they bring their devices to life.

Cumulative concussions: a grey area

Kas Lewis, an element14 member from Canada, is taking part in the Sudden Impact challenge. For his design, Kas proposed a helmet configurable to virtually any sport that monitors for heat stroke, heart attacks and concussions. A critical differentiator to Kas’ helmet that sets it apart from previously proposed solutions is its ability to measure cumulative concussions – or repeat blows to the head. In contact sports like football, this is particularly important. One-time injuries are often thought to have lasting effects on the brain, but cumulative trauma is generally agreed to be much worse because the brain often does not have enough time to recover fully before another impact. Cases like these can have significant long-term implications on players.

Though still in the concept phase of his project, Kas has been challenged because it is “still not fully clear in the scientific community how [impact] should be measured.” Apart from traditional concussion symptoms like weakness, memory loss or headaches, and a combination of diagnostic testing like CAT scans, MRIs and X-rays, many in the medical community have admitted that research is still being conducted to help better diagnose and monitor the problem. Additionally, there is no 'magic pill' to treat cumulative concussions, thus simply monitoring for it may not be enough.

Head injury criterion

Another Sudden Impact competitor, Hendrik Lipka from Germany, is developing a solution with soccer players and skiers in mind. His device has two uses: it is a heart rate monitor to be used during training sessions as well as a helmet-mounted impact monitor to be used during active play.

Similar to Kas, to assess the effect an 'impact' can have on a player, Hendrik first looked to the biological and medical sciences for guidance. Through his research he found the 'Head Injury Criterion (HIC)', which is used to determine the effect and duration of acceleration and deceleration on the head at the moment of impact. For example, a soccer player who collides with a team member while running across the field would experience a sharp drop in acceleration. HIC has become a common scale to test the safety of personal protective gear and sports equipment like that of Hendrik’s.

The HIC formula calculates an average acceleration, pulled from an acceleration curve, during a specific window of time – typically between 3 and 36ms, though 15ms is usually the norm. A maximum value is calculated from the collective windows of time to determine the specific sensitivity of the head to a force of acceleration. Different exponents can be substituted into the formula for other parts of the body as well.

In theory, the HIC formula seems a perfect match to Hendrik’s design, but in practice all is not as it seems. Hendrik admits calculation would be easy if acceleration measurement happened in increments of one millisecond – allowing him to integrate the sum of values of a specific window of time through simple multiplication and division. Analog Devices’ ADXL series accelerometer, however, runs either 1,600 or 800 measurements per second, making accuracy more difficult. As a result, Hendrik must grapple with the challenge of programming his helmet to calculate acceleration quickly enough without compromising energy and power consumption.

Room for Reconciliation

The challenges faced by Kas, Hendrik and the other Sudden Impact participants to design technologies that are up to standard with the medical community’s definition of impact and injury are not new. The fact that there is still much debate goes to show more discussion is not only needed but imperative for finding a true solution.

Until we can reach a global consensus on how to define and measure for impact, engineers creating medical devices must consider the fluidity and flexibility of their designs once completed, anticipate changes to their designs based on medical standards that are still being determined and even create their own standards and classifications of injury based on precedent. Needless to say this is no easy task. It’s safe to assume like others before them, the Sudden Impact finalists may be forced to alter or adapt their designs accordingly. In the coming posts, we will look at the extent of that compromise and its effect on the final performance of their devices.