There is a need for breath sampling that is more convenient for diagnostics in particular for children and the elderly. In total almost twenty percent of school children in Georgia have asthma. The ability to collect samples with minimal pressure drop and in a shorter duration without the need for cryogenic gases and complex instrumentation would make sample collection more convenient and lower the cost to administer in a clinical or research setting. Our approach is to develop a miniature sampling system that would provide efficient collection of breath condensate (water vapor and aerosolized droplets) and a preconcentrated sample of volatile organic compounds (VOC’s). Each of these samples can then be used for subsequent analysis for clinically relevant markers. The breath condensate for proteins, glutathione, glucose and hydrogen peroxide, and the VOC’s for gas chromatographic analysis. Gas chromatography is one of the most widely used chemical analysis systems in use today world-wide. It has also seen increased use in medical applications, both for breath analysis for volatile components , applied to analysis of exhaled breath for allergic asthma , for detection of markers indicating oxidative stress [3,4], in a chemometric study for cystic fibrosis , for the analysis of breath condensate  and extensively in veterinary medicine   .
Miniaturized VOC sampling systems have been investigated by a number of groups, including Sandia National Laboratories , University of Michigan  and Prof. Agah at Virginia Tech  . In the Sandia work, a micro hot-plate coated with an adsorbent film was used, but had limited capacity, due to the small area. In the work at University of Michigan a high surface area carbon powder embedded in a waffle shaped silicon heating element, resulting in very effective performance, however the packed grains introduce significant pressure drop to sample flow. The development of microfabricated pillar designs at Virginia Tech has been first systematic study of the flow in a preconcentrator to examine its effect on preconcentration factor. Their work has demonstrated high efficiencies of collection with over 1000 times preconcentration factors using a Tenex-A coating and staggered pillar array in a small area device.
Salazar-Noratto, G.E., Willett, N., Stevens, H.Y., Lin, A., Gibson, G., Guldberg, R.E., “Pre-Clinical Small Animal Model for Osteochondritis Dissecans of the Knee,” The 61st Annual Meeting of the Orthopaedic Research Society, Las Vegas, Nevada, March 28-31, 2015.