Evaluation of low-cost electrochemical sensors for monitoring volatile organic compounds
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Date
2026-10-05
Authors
Παπούλιας, Αχιλλέας
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Abstract
This diploma thesis evaluates the performance and reliability of low-cost electrochemical sensors for the continuous monitoring of Total Volatile Organic Compounds (TVOCs) against a high-resolution PTR-ToF-MS reference instrument. The experimental methodology utilized a continuous flowchamber to assess sensor responses to individual, pure VOCs, as well as complex volatile mixtures emitted by common school and office supplies (e.g., whiteboard markers, liquid glues, and correction fluids).Data analysis revealed an excellent linear correlation (R2 = 0.97) between identical sensors, demonstrating hardware consistency. However, the detection capability was found to be highly compound dependent. While the sensors exhibited satisfactory dynamic tracking for compounds like ethanol, methanol, and acetaldehyde, they failed to detect highly toxic and carcinogenic aromatic hydrocarbons, such as benzene and toluene. Furthermore, absolute gas quantification was highly inaccurate. Sensors systematically overestimated real concentrations (up to 40 times) and suffered from massive baseline offsets (exceeding 800 ppb).Experiment involving everyday classroom materials confirmed that school supplies act as extremely potent indoor emission sources. Products like whiteboard markers and liquid glues emitted massive volumes of VOCs, driving the low-cost sensors to their hardware saturation limits (10,000 ppb) within minutes of active use. Toxicologically, the high-resolution PTR-ToF-MS analysis confirmed the direct release of proven human carcinogens, including formaldehyde and benzene, from these common educational-artistic supplies.In conclusion, while the sensors can track specific dynamic trends of VOCs, their reliable deployment in environmental monitoring mandates the application of advanced calibration algorithms to correct massive absolute deviations.
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Keywords
Low cost sensors, Volatile organic compounds (VOCs), Air quality, School supplies