Obesity is a global health threat on the rise, and its prevalence continues to grow. Yet suitable biomedical sensors to monitor body fat burn rates in situ, to guide physical activity or dietary interventions toward efficient weight loss, are missing. Here, we introduce a compact and inexpensive breath acetone sensor based on Si-doped WO₃ nanoparticles that can accurately follow body fat burn rates in real time. We tested this sensor on 20 volunteers during exercise and rest and measured their individual breath acetone concentrations in good agreement with benchtop proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS). During exercise, this sensor reveals clearly the onset and progression of increasing breath acetone levels that indicate intensified body fat metabolism, as validated by parallel venous blood β-hydroxybutyrate (BOHB) measurements. Most importantly, we found that the body fat metabolism was especially pronounced for most volunteers during fasting for 3 h after exercise, with strong variation between subjects, and this was displayed correctly by the sensor in real-time. As a result, this simple breath acetone sensor enables easily applicable and hand-held body fat burn monitoring for personalized and immediate feedback on workout effectiveness that can guide dieting as well.

中文翻译：

---

掺硅的WO ₃传感纳米颗粒对呼出丙酮的无创人体脂肪燃烧监测

肥胖是一种日益严重的全球性健康威胁，其患病率仍在继续增长。仍然缺少合适的生物医学传感器来原位监测人体脂肪燃烧率，以指导身体活动或饮食干预以有效减肥。在这里，我们介绍一种基于Si掺杂的WO ₃的紧凑而廉价的呼吸丙酮传感器可以实时准确追踪人体脂肪燃烧速率的纳米颗粒。我们在运动和休息期间对20位志愿者测试了该传感器，并与台式质子转移反应飞行时间质谱（PTR-TOF-MS）很好地测量了他们各自的呼吸丙酮浓度。在运动过程中，该传感器清楚地揭示了呼气中丙酮水平升高的发生和进展，表明体内脂肪代谢增强，这已通过平行静脉血β-羟基丁酸（BOHB）测量得到证实。最重要的是，我们发现大多数志愿者在运动后禁食3小时后体内脂肪代谢尤为明显，受试者之间的差异很大，并且可以通过传感器实时正确显示。因此，