Figure 1: Femtolitre delivery and mixing capabilities of MPL.
From: Femtolitre chemistry assisted by microfluidic pen lithography
(a) Schematic illustration of the two-step MPL method, showing the patterning of an array of SoF droplets (step 1), followed by precise delivery of different volumes of a solution into them (step 2). (b) Bright-field optical and corresponding confocal fluorescence microscopy images (λexc=488 nm; λem=500–575 nm) of an array of SoF droplets (droplet distance=28 μm) created by using different DT1. (c,d) DT1 dependence of d1 and of I/A measured for each droplet series. (e) Confocal fluorescence microscopy image of an array of SoF droplets (droplet distance=35 μm), in which femtolitre volumes of an H2O/glycerol solution were added at different DT2. Note that the top row corresponds to bare SoF droplets. (f) DT2 dependence of d2. (g) Dilution factor dependence of I/AN. The line represents the expected behaviour of a bulk SoF solution (assuming that the decrease in fluorescence intensity is due only to dilution). (h–j) Confocal fluorescence microscopy images (λexc=488 nm; λem=500–575 nm (h); λexc=633 nm; λem=600–785 nm (i); and superimposed previous images (j)) of an array of SoF droplets (droplet separation=28 μm), in which femtolitre volumes of a solution of Nile Blue were added at different DT2. Note that the left and right columns correspond to pure SoF and Nile Blue droplets, respectively, whereas the gradient of colours from yellow/orange to red (left to right) denotes the increase in concentration of Nile Blue relative to SoF. In (c,d,f,g) the error bars represent the s.d. of the average results obtained for all equivalent droplets in the array.
