Human breath contains hundreds of volatile organic compounds (VOCs) produced both endogenously and from external environmental sources. To detect the few metabolite biomarkers of disease in the background of hundreds of other VOCs a breath analysis system must be highly dimensional, able to distinguish the signature pattern of diverse VOC biomarkers in a diverse chemical background. The metabolite biomarkers are often important at very low part per billion (ppb) concentrations. Therefore it is critical the breath analysis system sensor be very sensitive, able to detect diverse VOC biomarkers often in low single digit ppb concentration. The Metabolomx sensor has the high dimensionality and sensitivity to capture the chemical signature pattern of the complex mixture of VOC’s present in breath.
Technology Review - Metabolomx, a startup in Mountain View, California, recently completed a clinical trial that shows that its breath test can spot lung cancer with 83 percent accuracy and can also distinguish between several different types of the disease, something that usually requires a biopsy. The accuracy of the test matches what's possible with low-dose computerized tomography imaging of the lungs.
Colorimetric sensor array
At the core of the Metabolomx breath analysis system is a novel, proprietary colorimetric sensor array (CSA). The CSA is a matrix of colored chemical indicators of diverse reactivities embedded in a nanoporous sol-gel matrix. Each indicator has distinct chemical reactivity with volatile species and changes color differently upon exposure to analytes. The resulting pattern of color changes comprises a high-dimensional chemical signature pattern. The image below demonstrates the patterns produced by 10 distinct bacteria, all 10 of which were identified accurately (98.8%) in 50 blind trials. Note that even different strains of the same species cause distinct patterns.
The sensor is constructed on a simple plastic or paper like media. The sensor is inexpensive and disposable. The cost and performance easily match the requirements for a one time use medical exam. The CSA exam card used in the Metabolomx breath analysis instrument is printed on a plastic substrate, contained in a tube, through which breath can be passed. The exam card is disposable, one is used with each patient exam.
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