Ultra-monodisperse droplet formation using PMMA microchannels

integrated with low-pulsation electrolysis micropumps

Xiaoping Li, Ding Li, Xiaocheng Liu and Honglong Chang*

Ministry of Education Key Laboratory of Micro/Nano Systems for Aerospace, School of Mechanical

Engineering, Northwestern Polytechnical University, Xi’an 710072, P. R. China

*Corresponding author. E-mail address: changhl@nwpu.edu.cn

Fig. S1. The time of electrodes delamination at different current: (A) before electrolysis, (B)

30min@200μA, (C) 8min@600μA and (D) 5min@1000μA. The output flow rates become

unstable after a period of time due to the electrodes delamination. However, the test results

show that the EMP can work stably at least five minutes before the electrodes are degraded.

Therefore, this EMP-based method can still be used to generate droplets in the application

without the requirements for a long duration.

Movie S1. The visualized fluid-fluid interface movements using 0.1% (w/v) methyl orange

solution and 0.1% (w/v) methylene blue solution in a microfluidic comparator region during

the pulsations test. The tested driving units are syringe pumps at flow rate of 1 μL min-1,

electrolysis micropump (EMP) with rectangular electrodes at current of 150 μA and EMP

with interdigital electrodes at current of 150 μA, respectively.

Movie S2. Generated dripping droplets by EMPs and syringe pumps as well as alternating

droplets by EMPs. The current ratio of EMPS and flow rate ratio of syringe pumps are all at a

ratio of 1:1 while the current and flow rate of disperse phase I d and Qd are fixed at 200 μA

and the corresponding value of 1.54 μL min-1, respectively.