Abstract
Active pulmonary tuberculosis (TB) is a death leading disease caused by a bacteria by the name of mycobacterium. TB is a life-threatening disease in most developing countries including sub-Saharan Africa countries (Nigeria, Mozambique, Zambia and South Africa). Culture and microscopy methods are still reliable techniques for pulmonary diagnoses even though every year there are millions of deaths from it, hence there is a need for a cheap, portable and more sensitive new diagnostic tool to assist the system. There is a new approach to diagnosing pulmonary TB through the detection of volatile organic compounds TB biomarkers. Based on technology and research development, currently, analytical instruments used for detection of TB biomarkers are Gas Chromatography-Mass Spectroscopy, proton mass transfer reaction- mass spectroscopy and more, unfortunately, they are expensive, require high maintenance, trained personnel, and are not portable. The failures in using analytical instruments for the detection of TB biomarkers allow the introduction in finding a portable, inexpensive and easy operation sensing device which can detect volatile organic compounds (VOCs) biomarkers. From the previous studies, Semiconductor metal oxides (SMOs), carbon materials and polymers received great attention to the gas sensor research field. Nickel oxide nanoparticles (NiO NPs), carbon nanoparticles soot (CNPs), nickel oxidecarbon nanoparticles-cellulose acetate (NiO-CNPs-CA) composite and titanium dioxide-carbon nanoparticles-cellulose acetate (TiO2-CNPs-CA) composite were synthesized and characterized using scanning electron microscopy (SEM), highresolution transmission electron microscopy (HRTEM), powder X-ray diffraction (PXRD), Fourier transform Infrared spectroscopy (FTIR), Raman spectroscopy and N2 adsorption-desorption isotherms. NiO, TiO2, CA, NiO-CA, TiO2-CA, CNPs-CA, NiOCNPs, TiO2-CNPs, NiO-CNPs-CA, TiO2-CNPs-CA room temperature gas sensors were fabricated and tested using octanal, 3-pentanone, mesitylene and 4-methyl-1- hexene known as pulmonary TB biomarkers at 25 Hz frequency and 0.5V as a voltage supplied to a gas sensing electrode. Sensitivity of the gas sensors were done by testing the prepared gas sensors in both impedance and resistance parameters and various sensors were prepared by increasing the mass ratio of SMO within the ternary composite made up of SMO (NiO and TiO2), CNPs and CA sensing materials. TiO2- CNPs-CA composite (sensor A) is the best sensor to the detection of mesitylene for viii both resistance and impedance parameters with the sensitivity of 1.662 and 1.639 Ω ppm-1 respectively and sensor TiO2-CNPs composite sensor showed to have a maximum sensitivity of 1.99 Ω ppm-1 under impedance parameter.
M.Sc. (Nanoscience)