The dispensing well plate: a novel nanodispenser for the multiparallel delivery of liquids (DWP Part I)

This paper reports on a novel dispensing system for the massive parallel delivery of liquid volumes in the range of 50 nL. Due to the similarity of the device to conventional microwell plates used for storage of liquids, the device has been termed "dispensing well plate" (DWP). In contrast to other known microdispensers the DWP can consist of up to 1536 dispensing units in parallel all holding different reagents. The dispensing units can be arranged very closely at the pitch of conventional microwell plates (2.25 or 4.5 mm). Driven by pneumatic actuation a fixed volume of different liquids can be dispensed simultaneously and contact free into microwell plates or onto flat substrates. By this the liquid-handling in many chemical, biochemical and pharmaceutical applications-especially within high throughput screening (HTS)-can be speed up by a factor 10-100. In this paper the basic operation principle of the device is presented and experimental evidence is given of its extraordinary performance: a reproducibility of 2-5% and a homogeneity within individual droplet arrays of 1-2% has been measured as well as viscosity independent performance for liquids in the range from 1 to 5 mPas. The fabrication of DWP prototypes by different micromachining technologies based on silicon dry etching and SU-8 technology is described and various DWP prototypes with different dosage volumes are presented. (C) 2004 Elsevier B.V. All rights reserved.