Emergence of graphene-derived highly functional materials has transformed chemical and biological sensing. Several novel approaches utilizing chemical modification of graphene oxide (GO) were investigated and implemented using these materials in sensor fabrication for the detection of chemical analytes such as volatile organic compounds (VOC). The detection methods rely on using functionalization of modified graphene derivatives to target select analytes and produce a quantifiable, distinguishable electrical response. In this work, an in-house hydrothermal fluorination technique to synthesize fluorinated-GO (FGO) suspension was developed. The FGO material was drop coated in its solution phase onto interdigitated electrodes to create a chemiresistive gas sensor. An ultra-low-level detection of NH3 (~>2.26 ppm) was observed by the chemiresistive sensor which was extended to detect acetone and distinguish between their individual transient responses.The sensor system is fully integrated and miniaturized making it suitable for point-of-care, continuous health monitoring applications in exhaled breath testing.iii Co-AuthorshipThe content of this scientific body of work has been developed at the Organic Sensors and Devices Laboratory at Carleton university in 2019-2021. This work has produced one published conference paper, and one special issue conference paper submission (in progress).These described FGO chemiresistive sensors were able to quantify and distinguish noticeable responses to changes in select gas concentration. The sensitivity, specificity, reliability, are all established with a low-cost synthesis fabrication process. The first conference paper describes a novel FGO chemiresistive sensor able to detect ammonia and acetone in ultra-low concentrations and its viability for point-of-care, non-invasive health monitoring. The second paper is in submission progress and pertains to the same work with a focus on the hybrid implementation of the sensor onto a custom printed circuit board (PCB) for data acquisition and production on flexible polymer substrates. This experimental work presented in this thesis with references A and B were in collaboration with the author, research supervisor Prof. Ravi Prakash, Dr. Siziwe Bebe and Bruno Gamero at the Organic sensors and devices laboratory (OSDL) at Carleton University. The graphene material was kindly provided by Brian Kennedy from KennedyLabs. Electrode patterning was carried out by the Carleton University nanofabrication team led by Mr. Rob Vandusen, with material deposition carried out with assistance Dr. Siziwe Bebe. Development of these deposition techniques was created and carried out by Dr. Siziwe Bebe and Prof. Ravi Prakash. The readout circuit was built by the author, and Bruno Gamero. Data analysis was then performed by the author. Custom PCB design was carried out by the author with the assistance of Mr. Nagui Mikhail.