Ultrasensitive detection of nitrogen oxides over a nanoporous membrane

A nitrogen oxide (NOx; x = 1, 2) optical sensor with an extremely low detection limit in the range of fractions of ppbV (0.3 ppbV for 20 s sample injection) is presented. Phenylenediamine derivatives are utilized as molecular probes in the solid state on a nanoporous membrane to produce a miniaturized and low cost sensing platform for use as a wearable personal monitor.Fil: Prabhakar, Amlendu. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Wang, Rui. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados Unido

Online sample conditioning for portable breath analyzers

Various innovative chemical sensors have been developed in recent years to sense dangerous substances in air and trace biomarkers in breath. However, in order to solve real world problems, the sensors must be equipped with efficient sample conditioning that can, e.g., control the humidity, which is discussed much less in the literature. To meet the demand, a miniaturized mouthpiece was developed for personal breath analyzers. A key function of the mouthpiece is to condition the humidity in real breath samples without changing the analyte concentrations and introducing substantial backpressure, which is achieved with optimized packing of desiccant particles. Numerical simulations were carried out to determine the performance of the mouthpiece in terms of various controllable parameters, such as the size, density, and geometry of the packing. Mouthpieces with different configurations were built and tested, and the experimental data validated the simulation findings. A mouthpiece with optimized performance reducing relative humidity from 95% (27 000 ppmV) to 29% (8000 ppmV) whereas retaining 92% nitric oxide (50 ppbV to 46 ppbV) was built and integrated into a hand-held exhaled nitric oxide sensor, and the performance of exhaled nitric oxide measurement was in good agreement with the gold standard chemiluminescence technique. Acetone, carbon dioxide, oxygen, and ammonia samples were also measured after passing through the desiccant mouthpiece using commercial sensors to examine wide applicability of this breath conditioning approach. © 2012 American Chemical Society.Fil: Prabhakar, Amlendu. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Arizona State University; Estados UnidosFil: Shan, Xiaonan. Arizona State University; Estados UnidosFil: Xian, Xiaojun. Arizona State University; Estados UnidosFil: Zhang, Lihua. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados Unido

A microfluidic-colorimetric sensor for continuous monitoring of reactive environmental chemicals

Colorimetry is a powerful sensing principle that detects a target analyte based on a reaction-induced color change. The approach can be highly sensitive and selective when a sensing material that reacts specifically with the analyte is found, but the specific reaction is usually accompanied by slow recovery and irreversibility, making continuous monitoring of air quality difficult. Consequently, colorimetry is often one-time only and single-point measurement. To overcome the difficulty, the present work reports a combined microfluidic and colorimetric approach that measures time evolution of a color gradient along a microfluidic channel via a complementary metal-oxide-semiconductor (CMOS) imager. The change of the color gradient provides continuous monitoring of the analyte concentration over many hours, and the principle and capability of the approach is demonstrated by theoretical simulation, and experimental validation with real samples.Fil: Wang, Rui. Arizona State University; Estados UnidosFil: Prabhakar, Amlendu. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Xian, Xiaojun. Arizona State University; Estados UnidosFil: Shan, Xiaonan. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados Unido

Ultrasensitive Detection of Nitrogen Oxides over a Nanoporous Membrane

A nitrogen oxide (NOx; x = 1, 2) optical sensor with an extremely low detection limit in the range of fractions of ppbV (0.3 ppbV for 20 s sample injection) is presented. Phenylenediamine derivatives are utilized as molecular probes in the solid state on a nanoporous membrane to produce a miniaturized and low cost sensing platform for use as a wearable personal monitor

Breath Acetone as Biomarker for Lipid Oxidation and Early Ketone Detection

Former ketone studies, including ketoacidosis (KAD), fasting ketosis (FK), nutritional ketosis (NK), and exercis-eaffected ketosis have brought great advances to the field of ketones. In the present work, blood, urine and breath ketone detections were evaluated systematically. We found that breath ketone (acetone) is the ketone of choice for detecting early stages of ketosis. In addition, acetone was correlated with respiratory quotient, and found to be a highly sensitive non-invasive biomarker of lipid oxidation. Furthermore, acetone was used for fast screening of ketosis or ketoacidosis in populations, and demonstrated value upon screening a population of 48 individuals, among which a type I diabetes case with early symptoms of KAD and FK case were identified.</p