An alarming number of sports concussion go undetected, say experts, either because athletes fail to self-report concussion symptoms, or because sideline personnel lack the necessary training and experience to identify concussed athletes.  The best way to address the problem of under-reporting may be not to rely on the athletes themselves, game officials, or even sideline observers to call for a concussion assessment, but to use sophisticated helmet sensors to measure impacts to get around the problem altogether.