Smartphone-based sensing system using ZnO and graphene modified electrodes for VOCs detection

• Published in: Biosensors & bioelectronics 2017-07, Vol.93, p.94-101
• Main Authors: Liu, Lei, Zhang, Diming, Zhang, Qian, Chen, Xing, Xu, Gang, Lu, Yanli, Liu, Qingjun
• Format: Article
• Language: English
• Subjects: acetone; Acetone - chemistry; biomarkers; Biomarkers - chemistry; Biosensing Techniques; biosensors; diabetes; dielectric spectroscopy; early diagnosis; Electrodes; exercise; food quality; Graphene; Graphite - chemistry; health services; Humans; Impedance measurement; Interdigital electrode; lung neoplasms; mobile telephones; quality control; Smartphone; volatile organic compounds; Volatile organic compounds (VOCs); Volatile Organic Compounds - chemistry; Volatile Organic Compounds - isolation & purification; wireless technology; zinc oxide; Zinc Oxide - chemistry
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2016.09.084

Volatile organic compounds (VOCs) detection is in high demand for clinic treatment, environment monitoring, and food quality control. Especially, VOCs from human exhaled breath can serve as significant biomarkers of some diseases, such as lung cancer and diabetes. In this study, a smartphone-based sensing system was developed for real-time VOCs monitoring using alternative current (AC) impedance measurement. The interdigital electrodes modified with zinc oxide (ZnO), graphene, and nitrocellulose were used as sensors to produce impedance responses to VOCs. The responses could be detected by a hand-held device, sent out to a smartphone by Bluetooth, and reported with concentration on an android program of the smartphone. The smartphone-based system was demonstrated to detect acetone at concentrations as low as 1.56ppm, while AC impedance spectroscopy was used to distinguish acetone from other VOCs. Finally, measurements of the exhalations from human being were carried out to obtain the concentration of acetone in exhaled breath before and after exercise. The results proved that the smartphone-based system could be applied on the detection of VOCs in real settings for healthcare diagnosis. Thus, the smartphone-based system for VOCs detection provided a convenient, portable and efficient approach to monitor VOCs in exhaled breath and possibly allowed for early diagnosis of some diseases. •A smartphone-based sensing system for VOCs detection.•Interdigital electrodes were modified with graphene and ZnO as sensors.•VOCs of acetone as low as 10−6M was detected by the smartphone-based system.•A frequency spectroscopy-based method was used to distinguish different VOCs.•The study provides a low-cost and portable and efficient approach to detect VOCs.