FIGURE 2.

Test results on volatile organic compounds (VOCs). Results for sensing three of the published VOCs identified in exhaled breath of Alzheimer's disease patients (Tisch et al. ⁴⁶ ). Concentration levels are measured in parts per billion (ppb). Test molecules are butylated hydroxytoluene (BHT), pivalic acid (2,2‐dimethylpropanoic acid), and 2,3‐dimethylheptane. All the testing procedures were done inside a sealed chamber. The resistance was monitored while injecting specific amounts of the VOC into the chamber. Clearly, the sensitivity of the BHT sensor can go well into parts per trillion range