Tailored Co _{1– <i>x</i>} Zn _<i>x</i> Fe ₂ O ₄ Spinel Bulk Heterojunction Composites for Acetone Detection toward Diabetes Diagnosis

Acetone has been identified as a volatile organic compound (VOC) biomarker, whose concentration in exhaled breath shows a strong correlation with diabetic status. Consequently, reliable detection of trace acetone gas is of paramount importance for diabetes diagnosis. However, acetone gas sensors still encounter specific technical challenges, such as an excessively high detection limit and insufficient sensitivity. To develop high-performance acetone sensing materials, constructing highly reactive composites has emerged as an effective approach to modulate the sensing properties of gas-sensitive materials. Herein, Co_1-<i>x</i>Zn_<i>x</i>Fe₂O₄ spinel bulk heterojunction (BHJ) composites with mixed spinel structure were efficiently synthesized via a simple one-step solvothermal process. The optimized Co_0.5Zn_0.5Fe₂O₄ sensor exhibited superior acetone-sensing performance, featuring a high response (S = 4.36 to 1 ppm acetone) and a low detection limit (S = 2.24 to 0.2 ppm acetone) at 200 °C. Significantly, the sensor could distinguish between exhaled breath samples from healthy individuals and those from simulated diabetic patients, indicating that Co_1-<i>x</i>Zn_<i>x</i>Fe₂O₄ composites represent a promising tool for noninvasive diabetes diagnosis via breath analysis.