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Generation and Mixing of Subfemtoliter Aqueous Droplets on Demand



Kristian Helmerson, Jianyong N. Tang, Ana Jofre, Rani Kishore, Joseph E. Reiner, Mark E. Greene, Geoffrey M. Lowman, John Denker, Christina N. Willis, Lori Goldner


We describe a novel method of generating monodisperse sub-femtoliter aqueous droplets on demand by means of piezoelectric injection. Droplets with volumes down to 200 aL are generated by this technique. The droplets are injected into a low refractive index perfluorocarbon so that they can be optically trapped. We demonstrate the use of optical tweezers to manipulate and mix droplets. For example, using optical tweezers we bring two droplets, one containing a calcium sensitive dye and the other calcium chloride, into contact. The droplets coalesce with a resulting reaction time of about 1 ms. The monodispersity, manipulability, repeatability, small size, and fast mixing afforded by this system offer many opportunities for nanochemistry and observation of chemical reactions on a molecule-by-molecule basis.
Analytical Chemistry


droplet, droplet on demand, femtoliter, microemulsion, microreactors, perflurocarbon, optical tweezers


Helmerson, K. , Tang, J. , Jofre, A. , Kishore, R. , Reiner, J. , Greene, M. , Lowman, G. , Denker, J. , Willis, C. and Goldner, L. (2009), Generation and Mixing of Subfemtoliter Aqueous Droplets on Demand, Analytical Chemistry, [online], (Accessed July 22, 2024)


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Created August 27, 2009, Updated February 19, 2017