A pressure pump (On-Chip Droplet Generator, On-chip Biotechnologies, JAPAN) was used to in-121 troduce the solutions into the microfluidic device through PTFE tubes (F-8007-001, Flon Industry, 122 JAPAN). Initially, the pressure on the outer aqueous phase inlet was increased to 6 kPa so that the 123 outer aqueous phase started flowing steadily through the post channel. Subsequently, increase To evaluate the budding rate, we used the ratio of the generated lipid bilayer area to represent 174 the degree of budding. As shown in the Figure , the area of the lipid bilayer membrane generated 175 by budding is 𝐴 𝑏 , while the area of the paper monolayer membrane between the droplet and the 176 oil phase is 𝐴 𝑚 . The budding rate can be expressed by the following equation: