Even though a properly-fitted sports helmet is vital to avoiding brain injuries, the fitting process is still largely a subjective one. A newly designed pressure-sensitive cap, however, could objectively ensure that each athlete gets the right helmet.
Created by a team from Western Michigan University, the cap is intended to be worn against the head and beneath the helmet, during the fitting process. It incorporates 16 pressure sensors, located at different key areas of the head.
Each sensor consists of two fabric-based conductive electrodes, with a layer of a porous organic polymer (polydimethylsiloxane, or PDMS) sandwiched between them. The pores were created by heating and mixing liquid PDMS with nitric acid and sodium bicarbonate (baking soda), producing bubbles of carbon dioxide gas. When the mixture cooled and solidified, those bubbles formed into small holes.
When external pressure is applied to one of the sensors, the distance between the two electrodes decreases as the PDMS is compressed. This causes a change in the electrical capacitance of the electrodes, which can be measured by a linked computer. As a result, it's possible to quantify the amount of pressure being exerted on each sensor.
When tested on multiple volunteers wearing a helmet of the same size, the cap accurately indicated that the person with the largest head experienced the greatest amount of pressure. It is now hoped that once developed further, the technology could be used to help athletes select the right off-the-shelf helmet, and to aid in the production of custom-fit helmets.
A paper on the research, which is being led by PhD student Simin Masihi and Prof. Massood Atashbar, was recently published in the journal ACS Sensors.
Source: American Chemical Society
