Laboratory for Environmental Health NanoSciences (LEHNS)

Lab Director: Philip Demokritou

The LEHNS laboratory is fully equipped with systems for the generation of artificial monodisperse and polydisperse particles, as well as state-of-the-art instrumentation for the real-time measurement of the physico-chemical properties of particles from 2 nm to 20 microns. Other activities of the laboratory include the design of particle-classification techniques, such as impactors and speciation samplers, and performance evaluation of air sampling techniques. More than a dozen instruments and methods, including a number of US-patented methods, have been developed over the years for the physico-chemical and biological characterization of particles. These novel techniques have been used extensively by air pollution scientists and human exposure assessors in United States and worldwide.

Harvard Versatile Engineering Nanomaterials Generation System (VENGES): VENGES, made in house, is based on an industrially-relevant gas-phase process: Flame Spray Pyrolysis (FSP).

The Flame Spray Pyrolysis System used to generate property controlled nanoparticles

Flame aerosol technology accounts for more than 90% of the total volume and value of nanostructured particle commodities produced in the gas-phase worldwide. The advantages of this method include its precise control of the nanoparticles properties (i.e. composition, dimensions, shape, etc.), high yield (gr/h), and reproducibility. In contrast to other methods for producing nanoparticles, such as sol-gel and hydrothermal, flame aerosol technology at high-oxidation conditions generates nanoparticles free of organic residue on their surface that can interfere with the toxicity or protein adsorption. Moreover, this system offers aerosols with average aerodynamic diameter in the range of nm, which makes it ideal for true nanoparticle inhalation studies.

Scanning Mobility Particle Sizer (SMPS): A Scanning Mobility Particle Sizer (SMPS) can measure particles from 2.5 nm to 1000 nm. They employ a continuous, fast-scanning technique to provide high-resolution measurements. The particles that are investigated can be of biological or chemical nature. The instrument can be used for indoor air quality measurement, vehicle exhaust, research in bioaerosols, atmospheric studies, and toxicology testing. Our model is the SMPS 3936 from TSI.

Condensational Particle Counter (CPC): An article counter that detects and counts aerosol particles by enlarging them by using the particles to create droplets in a supersaturated gas. Our model is the WCPC 3085 from TSI.

BET surface area measurement: Brunauer–Emmett–Teller (BET) theory aims to explain the physical adsorption of gas molecules on a solid surface and serves as the basis for an important analysis technique for the measurement of the specific surface area of a material. Our instrument is the Monosorb™ by Quantacrome.

DLS particle size measurement: Dynamic light scattering (also known as photon correlation spectroscopy or quasi-elastic light scattering) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution. It can also be used to probe the behavior of complex fluids such as concentrated polymer solutions. Our instrument is the ZetaSizer Nano by Malvern.