Volatile organic compounds (VOCs) in breath are biological products of human metabolism and have been identified as potential biomarkers for diseases including lung cancer, prostate cancer, breast cancer and many other human conditions. Currently, researchers use methodologies such as gas chromatography-mass spectrometry (GC-MS), and electronic noses (e-noses) for VOC identification and detection in breath. GC-MS allows for greater sensitivity and VOC structural elucidation during analysis, but is expensive, generally nonportable, time-consuming and requires trained personnel for operation. E-nose devices utilizing metal oxide (MOx) sensors for VOC detection are highly stable and sensitive to a broad range of oxidizing or reducing gases and offer benefits such as rapid detection and portability for point of care applications. MOx sensor arrays have been previously implemented to test synthetic VOC profiles but have never been fully optimized to analyze complex samples matrices such as human breath. To optimize the sensor response to VOCs in human breath, MOx heater voltage, sensor voltage and breath exhalation time were studied. In addition, carbon dioxide monitoring was explored to determine the effects and variations of dead space breath on the sensor response. Lastly, different sensor casings including commercially fabricated and in-house fabricated housings were tested to optimize sensor performance. Optimal operating parameters have been identified and include 2V and 1.8V heater voltages for SO3 and WO3 sensor chips respectively, and 0.8V and 0.6V sensor voltages for SO3 and WO3 sensor chips respectively. Results indicated that dead space breath did not affect the sensitivity or reproducibility of the sensor array. The sensor array had optimal sensitivity when exposed to twelve exhalations over the course of a total breathing time of approximately one minute. On the other hand, the commercially fabricated housing with relatively lower volume led to increased VOC sensitivity. Experimental findings show high process efficiency and reproducibility when exhalinginto the sensing system. The current optimized setup has shown high reproducibility for intraperson analysis (relative standard deviation of sensor response=4.49%) and clear differentiation between different healthy volunteers who blew into the system. These findings help to provide a noninvasive, easy to use, and reliable diagnostic device in a point of care setting.

Optimization of metal oxide nanosensors to analyze VOC profiles in human breath

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.