A new and simple method to prepare the monodisperse microbeads was developed for soluble polymers.Using a microchannel

we generated the uniform droplets by pushing the dispersed phase into the continuous phase and then solidified them by solvent-evaporation or gelation to obtain the PLA and sodium alginate microbeads.The microchannel was fabricated in our lab

and all of the materials were commercially produced.By using a frequency-modulation oscillator to help evaporation

the droplets can be solidified within 2 h

and especially the surface of the microbeads was smooth

and small pores with diameter of 1～2 μm were well-dispersed.By controlling the flow rates of the continuous phase conveniently

we could adjust the sizes of the microbeads.The diameters of the microbeads decreased from 460 μm to 342 μm when we increased the flow rates from 100 μL/min to 900 μL/min

and the lowest coefficients of variance of the microbeads was 2.16%.Also we studied the effect of the different continuous phases on the size of the microbeads

and it was believed that the size of the microbeads can be controlled by using different surfactants or mixing them in the continuous phase.