Real-Time Ozone Detection Based on a Microfabricated Quartz Crystal Tuning Fork Sensor

A chemical sensor for ozone based on an array of microfabricated tuning forks is described. The tuning forks are highly sensitive and stable, with low power consumption and cost. The selective detection is based on the specific reaction of the polymer with ozone. With a mass detection limit of ∼2 pg/mm2 and response time of 1 second, the sensor coated with a polymer sensing material can detect ppb-level ozone in air. The sensor is integrated into a miniaturized wearable device containing a detection circuit, filtration, battery and wireless communication chip, which is ideal for personal and microenvironmental chemical exposure monitoring

Particle Pollution Estimation Based on Image Analysis.

Exposure to fine particles can cause various diseases, and an easily accessible method to monitor the particles can help raise public awareness and reduce harmful exposures. Here we report a method to estimate PM air pollution based on analysis of a large number of outdoor images available for Beijing, Shanghai (China) and Phoenix (US). Six image features were extracted from the images, which were used, together with other relevant data, such as the position of the sun, date, time, geographic information and weather conditions, to predict PM2.5 index. The results demonstrate that the image analysis method provides good prediction of PM2.5 indexes, and different features have different significance levels in the prediction

Hybrid separation and detection device for analysis of benzene, toluene, ethylbenzene, and xylenes in complex samples

We present a hybrid system for rapid detection and analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX). The system combines selective and sensitive sensing elements with a fast and miniaturized chromatographic separation method. The sensing elements are an array of microfabricated quartz crystal tuning forks modified with selective molecularly imprinted polymers, and the separation method uses optimized short columns. The high sensitivity and selectivity of the sensing elements together with the help of the separation provides fast detection and analysis of BTEX in real samples containing highly concentrated interfering agents without preconcentration or heating of columns. The low cost, low power consumption, and small size of the hybrid device are particularly suitable for occupational health, industrial safety, and epidemiological applications.Fil: 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: Tsow, Francis. Arizona State University; Estados UnidosFil: Wang, Rui. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados Unido

Regression results with and without humidity as a feature.

<p>Regression results with and without humidity as a feature.</p

Thermochemical Humidity Detection in Harsh or Non-Steady Environments

We present a new method of chemical quantification utilizing thermal analysis for the detection of relative humidity. By measuring the temperature change of a hydrophilically-modified temperature sensing element vs. a hydrophobically-modified reference element, the total heat from chemical interactions in the sensing element can be measured and used to calculate a change in relative humidity. We have probed the concept by assuming constant temperature streams, and having constant reference humidity (~0% in this case). The concept has been probed with the two methods presented here: (1) a thermistor-based method and (2) a thermographic method. For the first method, a hydrophilically-modified thermistor was used, and a detection range of 0–75% relative humidity was demonstrated. For the second method, a hydrophilically-modified disposable surface (sensing element) and thermal camera were used, and thermal signatures for different relative humidity were demonstrated. These new methods offer opportunities in either chemically harsh environments or in rapidly changing environments. For sensing humidity in a chemically harsh environment, a hydrophilically-modified thermistor can provide a sensing method, eliminating the exposure of metallic contacts, which can be easily corroded by the environment. On the other hand, the thermographic method can be applied with a disposable non-contact sensing element, which is a low-cost upkeep option in environments where damage or fouling is inevitable. In addition, for environments that are rapidly changing, the thermographic method could potentially provide a very rapid humidity measurement as the chemical interactions are rapid and their changes are easily quantified

PM estimation via outdoor image analysis.

<p>PM estimation via outdoor image analysis.</p

Image features variation with PM index.

<p>(a~d): Hazy images showing that the contrast of the building region decreases with the PM index, where the lower panel shows the zooming-in images of the regions marked by the red boxes. (e) The normalized features vs. PM_2.5 index plot, including ROI RMS contrast (blue), image entropy (black), and image RMS contrast (red).</p