Extended Data Fig. 1: Characterization of reagent dissolution in SCMs and control experiments.

a, Bright-field microscope images of microfluidic chips in silicon, each chip being composed of a rounded inlet (left), an SCM (middle), and a meandering channel (right) used for conveniently measuring the concentration profile of the solution exiting the SCM. b, Amaranth solutions from an SCM (left) and in a control microchannel (right) are readily visualized using the meandering channels. c, Calibration curve for quantification of the concentration of reconstituted amaranth (n = 4 for each concentration). Error bars represent standard error of the mean. d, Concentration profiles of amaranth solution reconstituted in SCMs or control microchannels (Q_in = 500 nl min⁻¹). Means of individual acquisitions are displayed with dark coloured lines and individual acquisitions with a lighter shading. Amaranth solution was inkjet spotted into SCMs at 100 ng mm⁻¹ (250-µm pitch). The reagent accumulation in the control was so strong that the amaranth solution was diluted ×30 before deposition to keep the absorbance signal in the dynamic range of the camera. The concentration profile from control experiments shown in Fig. 2d is scaled up from this diluted signal.