Three-dimensional ordered ZnO-Fe3O4 inverse opal gas sensor toward trace concentration acetone detection

- A specific 3DIO nanostructure ZnO-Fe3O4 was obtained which can not only lead to largely increase of the surface area, but also the interaction between ZnO and Fe3O4 could effectively increase the sensing performances.
- The effect of 3DIO structure and ZnO-Fe3O4 composite structure on response enhancement was analyzed through the comparison between samples of ZnO nanoparticles/3DIO ZnO and 3DIO ZnO/3DIO ZnO-Fe3O4 composite structure.
- The 3DIO ZnO-Fe3O4 sensor exhibited high response as 47 to 50 ppm acetone at the optimal temperature. And the detection limit as low as 100 ppb was obtained, indicating great potential in ppb-level acetone sensing application, especially for diabetes biomarker gas.

Three-dimensional inverse opal (3DIO) ZnO-Fe3O4 composite structure was prepared by a template method and the gas sensing property was investigated toward trace acetone which is an important biomarker of diabetes. The prepared 3DIO composite sensors have large surface area due to both macropores (larger than 100 nm) and mesoporous structure in skeleton, which make the inner surface accessible and provide more active sites to adsorb more oxygen species and target molecules. 3DIO ZnO-Fe3O4 composite sensor exhibits much higher response toward acetone relative to pure ZnO sensor. The optimal 3DIO sensor exhibited a detection limit as low as 100 ppb acetone and showed 40% response increase from 0.9 ppm (healthy humans) to 1.8 ppm (diabetics) which allow reliable diagnosis of diabetic patients by acetone monitoring.