Detection of acetone using nanostructured WO3 for diabetes mellitus monitoring applications

Abstract

Diabetes mellitus which is characterized by a high levels of blood glucose is a major source of mortality, morbidity and health costs worldwide. Major gaps exist in efforts to comprehend the burden nationally and globally, especially in developing nations, due to a lack of accurate, cheap and non-invasive data and devices for monitoring and surveillance. In Africa, type 2 diabetes mellitus represents 90% of diabetes cases. The disease mainly relies on management and monitoring. Although reliable blood glucose monitoring techniques and devices exist worldwide, the challenge is with the cost, invasiveness, and long sample preparation. Herein this study, the challenge was addressed by synthesizing WO3 materials for the detection of acetone in a simulated human breath. Acetone has been reliably confirmed to be the biomarker of diabetes mellitus. The Gas Chromatography-Mass Spectrometry (GC-MS) was employed to quantify acetone in type 2 diabetes mellitus. A statistically significant correlation (R=0.756) between blood glucose and breath acetone was observed, between blood acetoacetate and breath acetone (R=0,897), and between beta-hydroxybutyrate and breath acetone (R=0,821). Furthermore, we used semiconducting metal oxide (WO3) to investigate its selectivity, sensitivity, and response towards acetone. Semiconducting metal oxides sensor has the potential to detect volatile organic compound (VOCs) at low concentrations as low as 0.1 ppb. Other advantages of semiconducting metal oxides sensors include, facile and cheap device fabrication, portability, real-time analysis, and facile operating principle. We used two synthesis methods for fabrication of acetone sensors namely solvothermal method whereby solvent ratios were varied, and the sol-gel method where carbon nanospheres were used as a template and cobalt as a dopant. The sensor fabricated with 51:49 water: ethanol is found to demonstrate high response and good selectivity to 2 ppm level of acetone when compared with the one fabricated with pure ethanol, 18:92 (ethanol: water) and 92% water. Furthermore, the sensor could respond to low concentrations of acetone ranging from 0.5 to 4.5 ppm of acetone at 100 °C. For the sol-gel method, the 0.6 % Co-doped WO3 showed higher response and selectivity towards acetone gas from as low as 0.5 ppm at a very low operating temperature of 50 °C. Contrary, there was a very low response from other gases including toluene, NO2, NH3, CH4 and H2S operating at a similar temperature. This highlights the acetone selectivity of our 0.6 % Co-doped WO3 sample. Based on the two methods used for the synthesis of the acetone sensor, we can conclude that the Co-doped sensor shows better performance as compared to the as-prepared WO3. This is from the findings that the Co-doped WO3 can respond and select acetone concentration at 50 ◦C, which is a very low temperature in comparison to other platforms described in literature. An envisioned portable point of care diabetic device could therefore be operated at 50 ◦C in any point of care setting.