Particle Technology Laboratory, Department of Mechanical and Process Engineering , ETH Zurich , CH-8092 Zurich , Switzerland.
ACS Sens. 2018 Mar 23;3(3):677-683. doi: 10.1021/acssensors.7b00976. Epub 2018 Feb 27.
Isoprene is a versatile breath marker for noninvasive monitoring of high blood cholesterol levels as well as for influenza, end-stage renal disease, muscle activity, lung cancer, and liver disease with advanced fibrosis. Its selective detection in complex human breath by portable devices (e.g., metal-oxide gas sensors), however, is still challenging. Here, we present a new filter concept based on activated alumina powder enabling fast and highly selective detection of isoprene at the ppb level and high humidity. The filter contains high surface area adsorbents that retain hydrophilic compounds (e.g., ketones, alcohols, ammonia) representing major interferants in breath while hydrophobic isoprene is not affected. As a proof-of-concept, filters of commercial activated alumina powder are combined with highly sensitive but rather nonspecific, nanostructured Pt-doped SnO sensors. This results in fast (10 s) measurement of isoprene down to 5 ppb at 90% relative humidity with outstanding selectivity (>100) to breath-relevant acetone, ammonia, ethanol, and methanol, superior to state-of-the-art isoprene sensors. Most importantly, when exposed continuously to simulated breath mixtures (four analytes) for 8 days, this filter-sensor system showed stable performance. It can be incorporated readily into a portable breath isoprene analyzer promising for simple-in-use monitoring of blood cholesterol or other patho/physiological conditions.
异戊二烯是一种多功能的呼吸标志物，可用于非侵入性监测高胆固醇血症以及流感、终末期肾病、肌肉活动、肺癌和肝纤维化等疾病。然而，通过便携式设备（例如金属氧化物气体传感器）对复杂的人体呼吸进行选择性检测仍然具有挑战性。在这里，我们提出了一种基于活性氧化铝粉末的新型过滤概念，能够在高湿度条件下快速且高度选择性地检测低至 ppb 水平的异戊二烯。该过滤器包含高表面积的吸附剂，可保留亲水性化合物（例如酮、醇、氨），这些化合物是呼吸中的主要干扰物，而疏水性的异戊二烯则不受影响。作为概念验证，我们将商业活性氧化铝粉末的过滤器与高灵敏度但特异性相对较低的纳米结构 Pt 掺杂 SnO 传感器结合使用。这使得在 90%相对湿度下，异戊二烯的快速（10 秒）测量低至 5 ppb，对与呼吸相关的丙酮、氨、乙醇和甲醇具有出色的选择性（>100），优于现有技术的异戊二烯传感器。最重要的是，当连续暴露于模拟呼吸混合物（四种分析物） 8 天时，该过滤器-传感器系统表现出稳定的性能。它可以很容易地集成到便携式呼吸异戊二烯分析仪中，有望用于简单易用的血液胆固醇或其他病理/生理状况的监测。
