Daren Chen, Ph.D. profile photo

Daren Chen, Ph.D.

Professor and Floyd D. Gottwald, Sr. Chair in Mechanical and Nuclear Engineering

Engineering East Hall, Room E2250, Richmond, VA, UNITED STATES

(804) 828-2828 dchen3@vcu.edu

The applications for Chen’s research are varied and include atmospheric and combustion aerosol and particulate emission control








Image for vimeo videos on Washington People -- Daren Chen


Industry Expertise

  • Research
  • Education/Learning

Areas of Expertise

Particle instrumentation and characterization Nanoparticles and nanotechnologyParticle processing (i.g. classification charging dispersion...)Drug target delivery and release controlAir pollution and indoor air quality controlSynthesis of functional particle materialsMultiphase chemical reacting flow and reactorsPowder and spray technologyFiltration and separationMicro-contamination control in semiconductor manufacture processesAtmospheric aerosol


Benjamin Y. H. Liu Award | professional

Presented by the American Association for Aerosol Research (2012).

Space Act Award | professional

Awarded by NASA.

R&D 100 Award | professional

Awarded by R&D Magazine.

Sheldon K. Friedlander Award | professional

The Sheldon K. Friedlander Award recognizes an outstanding dissertation by an individual who has earned a doctoral degree.

Smoluchowski Award | professional

Presented by GaeF (2002) for significant contribution on nanoparticle instrumentation


Kenneth T. Whitby Award | professional

Presented by AAAR (2005) in recognition of outstanding contributions to Aerosol Science and Technology


University of Minnesota



University of Minnesota



National Tsing Hua University



National Tsing Hua University



Selected Articles

Oppositely charged twin-head electrospray: a general strategy for building Janus particles with controlled structures. | Nanoscale


Because of their unique heterostructure characteristics and anisotropic surface properties, Janus particles have gained growing interest in a number of novel applications. For the first time we demonstrate a facile, but versatile and general strategy for large-scale building of Janus particles with controlled structures and chemical composition pairs by an oppositely charged twin-head electrospray. In this protocol, two different droplets electrosprayed respectively from two tip-to-tip nozzles at high voltages of opposite polarities, after solvent evaporation and precursor gelation, collide with each other and coagulate into one Janus particle because of the Coulombic attractive forces. The as-electrosprayed droplets show different transient phase states at collision depending on the kinetic parameters such as the chemical compositions of precursors, humidity, concentration of solvent vapour, etc. Thus the resultant Janus particles have various morphologies and structures controlled by the transient phase state of the eletrosprayed droplets as well as the post-heat-treatment parameters. As examples, we demonstrate here the controlled fabrication of metal oxide-metal oxide and metal oxide-metal sulphide Janus particles with solid snowman-like, hollow-bowl snowman-like, and pot-like structures. Because of their unique heterostructure and novel morphology characteristics, the as-prepared Janus particles, despite a polydispersity in size and inhomogeneity in morphology, have some important potential applications including photocatalytic hydrogen production, environment remediation, and nanomotors.

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Comparison Between the Theoretical and Experimental Performance of a Differential Mobility Analyzer with Three Monodisperse-Particle Outlets | Aerosol Science & Technology


Differential mobility analyzers (DMAs) with more than one monodisperse-particle outlet can offer a number of advantages compared to conventional single monodisperse-particle outlet designs. A generalized theoretical model and experimental measurements describing the performance of a DMA with 3 monodisperse-particle outlets have been independently reported in the literature. The objective of this article is to compare the theoretical predictions with the measurements. Resolutions determined by the theoretically predicted transfer functions for the three monodisperse-particle outlets are compared with measurements when the DMA was operated under different operating conditions. Predictions and measurements show good agreement when the DMA is operated at low sheath flow rates and for aerosol outlets relatively far from the aerosol inlet. For aerosol outlets relatively near the inlet there is evidence that the discrepancy between theoretical predictions and measurements may disappear at higher sheath flow rates, but the chances of flow disturbances in the classifier increase as well. The theory for multiple monodisperse-outlet DMAs is thus seen as successful in predicting the performance of this instrument, provided that disturbances in the flow field are avoided.

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Open Access Phytotoxicity of Metal Oxide Nanoparticles is Related to Both Dissolved Metals Ions and Adsorption of Particles on Seed Surfaces | Journal of Petroleum & Environmental Biotechnology


This study assesses the biological effects of nanoparticles (NPs) based on seed germination and root elongation tests. Lettuce, radish and cucumber seeds were incubated with various metal oxide NPs (CuO, NiO, TiO2, Fe2O3, Co3O4), of which only CuO and NiO showed deleterious impacts on the activities of all three seeds. The measured EC50 for seed germinations were: lettuce seed (NiO: 28 mg/L; CuO: 13 mg/L), radish seed (NiO: 401 mg/L; CuO: 398 mg/L), and cucumber seed (NiO: 175 mg/L; CuO: 228 mg/L). Phytotoxicity of TiO2, Fe2O3 and Co3O4 to the tested seeds was not significant, while Co3O4 NP solution (5 g/L) was shown to improve root elongation of radish seedling. Metal oxide NPs tended to adsorb on seed surfaces in the aqueous medium and released metal ions near the seeds. Therefore, metal oxide NPs had higher phytotoxicity than free metal ions of the equivalent concentrations. Further, the surface area-to-volume ratio of seeds may also affect NPs phytotoxicity, whereby small seeds (i.e., lettuce) were the most sensitive to CuO and NiO NPs in our experiments.

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