Tae Hyun Yoon, Department of Chemistry, Hanyang University, Seoul, Korea
During the last few decades, increasing numbers of microfluidic device applications in the area of environmental monitoring and biological assays were reported, due to the ever-increasing demand for in-situ real time monitoring and high-throughput toxicological assays. In this presentation, I will give an overview on recently published studies on the applications of micro total analysis system (TAS) or Lab-on-a-chip for environmental monitoring and toxicological assessments. This presentation will also cover current status of important components of these novel platform technologies, such as fabrication methods and materials of microfluidic devices, types of detection methods (e.g., electrochemical, optical and fluorescence) and (bio)chemical sensors used for this novel approach as well as the author’s perspectives on future directions for environmental monitoring and toxicological assessments using microfluidic devices.
Hans Grimm¹, Jürgen Spielvogel¹, Markus Pesch¹ and Lothar Keck¹, ¹GRIMM AEROSOL Technik GmbH & Co. KG, 83404 Ainring, Germany
During the handling of nanomaterials there is the risk that nanoparticles are released in airborne state, and these nanoparticles might be harmful to health when inhaled by the employees. Thus, monitoring of nanoparticle concentrations is recommendable.
Therefore Grimm has developed many different methods to measure this fine”dust”
With these new and different methods we can detect limits in count and mass values for inhalable, thoracic and alveolic mass fraction in the different work place conditions.
This presentation will show examples and results obtained with these new methods.
Michael J. Sailor, Department of Chemistry and Biochemistry, University of California - San Diego, USA
Nanotechnology enables the fabrication of complex miniature devices that can be used to detect traces of chemicals in the air, in water, and in the body. However, several problems limit the fidelity of microsensors: nanostructured sensors are subject to corrosion-induced zero point drift, they can absorb molecules that interfere with detection of their targets, and they are limited in their ability to identify specific analytes. Nanostructured porous silicon possesses many properties that can be harnessed to solve these chemical detection problems. Prepared by electrochemical etching of silicon in HF-containing electrolytes, porous silicon can be used to build multi-stage nanoscale reactors: the size and shape of the pores can be used to separate molecules, enzymes can be entrapped to perform specific catalytic reactions, and the photonic properties provide highly sensitive and label-free detection.1, 2
The photoluminescence and reflective optical response of porous silicon is sensitive to chemical adsorbates, allowing the design and construction of small, low power sensors for chemical and biological compounds.3 Of particular interest are reflective systems, in which detection of chemicals or biomolecules is achieved by monitoring the change in the spectrum of light reflected from the material. This usually derives from a change in refractive index that occurs when analyte is captured in the pores or on the surface of a film. This presentation will discuss the synthesis and properties of porous Si films, microparticles, and nanoparticles, and their application to environmental separations and sensing problems.
1. Dorvee, J. R.; Sailor, M. J.; Miskelly, G. M., Digital microfluidics and delivery of molecular payloads with magnetic porous silicon chaperones. Dalton Trans. 2008, (6), 721 - 730.
2. Anglin, E. J.; Cheng, L.; Freeman, W. R.; Sailor, M. J., Porous Silicon in Drug Delivery Devices and Materials. Adv. Drug Deliv. Rev. 2008, 60, (11), 1266–1277.
3. Sailor, M. J.; Link, J. R., Smart Dust: nanostructured devices in a grain of sand. Chem. Commun. 2005, 1375-1383.
†*Sadik O. A., †Samuel N. Kikandi, †Qiong Wang, †Ailing Zhou, †Nian Du, Fenix Garcia & **Katrina Varner
†Department of Chemistry, State University of New York-Binghamton, NY, USA; **US-EPA/NERL, Characterization Research Division, Las Vegas, USA
The discovery of fullerenes in 1985 has ushered in an explosive growth in the applications of engineered nanomaterials and products. Some of the special properties that make nanomaterials useful may also cause them to pose hazards to humans and the environment. Positive cytotoxicity and genotoxicity have been reported for the water-soluble C60 aggregates (nC60), despite its low hydrophobicity. Nanomaterials also offer new possibilities for the development of novel sensing and monitoring technologies. Nanosensors can be classified under two main categories1: (1) sensors that are used to measure nanoscale properties; and (2) sensors that are themselves nanoscale or have nanoscale materials or components. The first category can enhance our understanding of the potential toxic effects of industrial pollutants. This is an area of critical interest to detection and risk assessment, as well as for monitoring of environmental exposure1,2. The second category can eventually result in lower material cost, reduced weight and power consumption3. In this presentation, the first category of sensors will be described based on ultrasensitive portable UPAC sensor for monitoring the cytotoxicity of engineered nanomaterials including fullerenes, dendrimers and metal nanoparticles. The presentation will also involve the second category of sensors focusing on the mechanism of molecular recognition, material design and characterization, sensing efficiency as well as potential application for improving environmental quality.
1. Sadik O. A.: Applications of advanced nanomaterials for environmental monitoring, Journal of Environmental Monitoring, 11, 25-26, 2009.
2. Marcells A. Omole, Isaac O. K’Owino & Omowunmi A. Sadik, Palladium Nanoparticles for Catalytic Reduction of Cr (VI) using Formic Acid, Applied Catalysis B Environmental, 76, 158-176, 2007.
3. Andreescu, D., Wanekaya A., O.A. Sadik, Wang J., “Nanostructured Polyamic Membranes as Electrode Materials,” Langmuir, 21(15), 6891-6899, 2005.
Nanomaterial Based Environmetnal Sensing
Sung Ik Yang, Department of Applied Chemistry, Kyung Hee University, Korea
Currently, nanotechnology has been received much interests since their significant implications including order-of-magnitude increases in computer efficiency, advanced pharmaceuticals, bio-compatible materials, surface coatings, catalysts, sensors, and pollution control. Nanotechnology deals with the matter at dimensions between 1 and 100 nm and involves imaging, measuring, modeling, and manipulating matter at nanoscale. Unusual physical, chemical, and biological properties of nanoscale materials can enable nanotechnology to solve the current problems including energy, medical, sensor, and environmental problems. In particular, nanotechnology is promising for chemical, environmental, and biochemical monitoring.
Carbon nanotubes, Semiconducting nanowires, and metal nanoparticles have been received intense interests due to their potential applications in real-time and on-site detection of ions, small molecules, proteins, and viruses with high sensitivity and selectivity. The unique optical properties of plasmonic nanoparticles have led to the development of label free chemical and environmental sensor since the surface plasmon resonance is sensitive to the local environment. Semiconductor nanowires and Single-walled carbon nanotube based sensors have been fabricated for the detection of small chemicals and biomolecules with high sensitivity, where the electric field is produced through the charge accumulation at the surface.
In this talk, recent results on the development of nanosensors and the application of nanostructures in the field of environmental analysis will be presented.
Alberto Vomiero, Researcher at National Council for Research (CNR) - National Institute for the Physics of Matter (INFM) SENSOR Lab, Brescia, Italy
Quasi-1D nanostructures of semiconducting metal oxides such as zinc, tin or indium oxides are presently investigated to produce an emerging class of sensing devices These materials, due to their peculiar characteristics and size effects, show novel physical properties compared to those of the bulk. Beyond the capability to control the elemental composition, control over the particle shape and size distribution is continuously pursued because many applications of nanostructures exploit the properties related to crystallographic features. The extraordinary potential of crystal engineering has been recently exploited for electronics, pigments, cosmetics, and ceramics. Semiconducting nanowires are promising also for the field of bio-nanotechnology and chemical sensing.
The deposition of metal oxide nanostructures can be obtained by evaporation/condensation technique starting from metal oxide powders. Two basic process, namely vapor-solid (VS) or vapor-liquid-solid (VLS), are recognized to drive the growth of the nanowires. The simplicity of the vapor phase condensation method with respect to the technology of silicon processing and to other top-down approaches, as well as the capability to control the thermodynamic conditions makes this approach highly promising for nanostructure fabrication. The as-synthesized oxide nanostructures are pure, structurally uniform, and single crystalline.
Metal oxide semiconductor interactions with the surrounding atmosphere are known from more than four decades; their sensing properties are based on surface reactions with gases in the atmosphere that cause a change in the semiconductor’s conductance due to charge transfer between the adsorbate and the adsorbent. We have studied the conductive property of the multi-wires sensing device in atmospheric environment, and we have performed an investigation on the sensing capability toward gases and vapors such as NO2, an oxidizing gas of great importance for air-quality monitoring in urban areas, and CO, ethanol and ammonia. The response is enhanced as the lateral dimensions of the nanowires decreases, as expected. The greatly enhanced surface/volume ratio magnifies the role of surface states - a crucial feature for gas sensitivity. The response is reproducible and the recovery of the air signal conductance is complete after the target gas removal.
Furthermore the optical properties of 1D nanostructures can change as a function of the different environments. The visible photoluminescence of tin and zinc oxide nanowires is quenched by nitrogen dioxide at ppm level in a fast (time scale order of seconds) and reversible way. Besides, the response seems highly selective toward humidity and other polluting species and it is maximized at room temperature. This feature could be interesting for application of nanowires as selective optical sensors operating at room temperature. The experimental evidences foresee the development of a new class of stable metal-oxide multiparametric gas sensors based on electrical and optical transduction mechanisms.
Exposure and Dose Relationships of Particulate Matter in The Environement
B. Gorbunov 1, R Muir1, H Gnewuch1, 1 Naneum, CEH, University of Kent, Canterbury, UK
Widely accepted metrics for monitoring air quality are based upon a fraction of airborne particle mass such as PM10, PM2.5 as these represent the fractions deposited in the human respiratory tract.
Although PM 10 levels have been steadily reducing in many countries these metrics can cause uncertainties in health risk evaluations as they take no account of the effect of deposition efficiency, due to variation of particle sizes, on the exposure – dose relationship.
This paper presents data which investigates the total aerosol identifying the mass fraction which represents the highest risk.
Exposure and dose have been evaluated using conventional OH sampling kit and a size resolving wide range aerosol sampling system (Nano-ID) at various working places and in the general environment. Nano-ID enables particle size distributions to be obtained across the entire airborne particle size range from 1 nm to 30 micro meter in diameter. Anthropomorphologically produced nanoparticles, including incidentally produced particulate matter such as lead and respirable silica and engineered nanoparticles such as CNT and nanosilver, were investigated. Mass concentration size distributions were used to determine the exposure and the accumulated dose by applying verified ICRP models to determine the aerosol size fraction representing the greatest health risk.
The total mass concentration of nanoparticles and the nanoparticle mass fraction (i.e. sizes less than 100nm) varies considerably, e.g. for lead aerosols determined at working places mass concentration ranged from 0.6 g/m3 to 50 g/m3 and the mean size from 17 nm to 300nm. The nanoparticle mass fraction of aerosols was found to vary from 10% to 80%. The proportion of total mass of particles deposited in the respiratory tract of workers varied from 0.2 to 0.7. The evaluation of health risk based upon PM10, PM2.5 and other defined respirable fractions of the particle mass does not take account of levels of particle deposition in the respiratory tract and will therefore overestimate or underestimate the health risk considerably by up to a factor of 3.5.
Ashwin A. Seshia Nanoscience Centre, Cambridge, UK
Low cost monitoring of the natural and built environment is increasingly important in a number of different applications dictated by engineering towards a more sustainable future. This includes monitoring the quality of air, water and food, optimising soil and irrigation conditions for agriculture, meteorological research and early warning systems for natural disasters, monitoring large scale built and ageing infrastructure, improving the energy efficiency of existing industrial processes and developing solutions for green technologies including carbon capture and storage. Micro- and Nanotechnologies are now beginning to provide solutions to drive these applications by enabling new platforms for low cost and minimally disruptive monitoring of the natural and built environment.
Two particular application scenarios will be described in detail. The first one involves low-power wirelessly networked sensor platforms embedded seamlessly within the environment to provide large scale and continuous time data on physical and chemical properties. These sensor nodes are being developed to operate at very low power levels to make energy scavenging possible and to transmit on local event triggers. An ongoing research project at Cambridge is examining the feasibility of deploying these wirelessly networked monitoring systems for ageing underground infrastructure. The second application involves portable and highly sensitive gas detector platforms by scaling miniature mass spectrometers and related sensor systems. These platforms can be utilised for air quality monitoring and applications involving the trace detection of toxic chemical species. In both of these applications, the dimensional scaling and system integration enabled by micro- and nanotechnology is a significant contributor towards achieving practical systems that are low cost, low power, portable and integrate high sensitivity detection.