The　formation　of　liquid　metal　droplets　in　a　microfluidic　cross　junction　with　different　viscosities　of　the　continuous　phase　is　experimentally　and　theoretically　investigated.　The　flow　pattern　is　distinguished　into　squeezing　and　dripping　by　the　presence　of　gaps.　The　differences　in　driving　forces　between　the　two　pat-terns　are　analyzed　theoretically　and　confirmed　experimentally　by　Micro-PIV　results.　Roles　of　the　squeez-ing　force　and　the　shear　force　in　droplet　formation　are　varying　due　to　the　dynamic　evolutions　of　the　gap　width　which　reduces　with　time.　Therefore,　critical　values　of　the　initial　gap　width　are　obtained　which　are　the　outcome　of　the　competition　between　neck　thinning　and　tip　growing.　Compared　to　water-oil　systems,　gaps　are　more　difficult　to　be　formed　due　to　the　extremely　high　interfacial　tension.　Moreover,　universal　flow　pattern　maps　are　constructed　using　dimensionless　parameters　of　Wed,　Cac,　and　Rec,　proving　the　important　roles　of　both　the　squeezing　force　and　the　shear　force.　A　scaling　law　of　the　droplet　volume　con-sidering　the　influence　of　the　viscosity　ratio　is　proposed　and　a　very　good　agreement　between　experimental　data　and　theoretical　predictions　is　obtained　for　different　liquid　systems.　CO　2022　The　Korean　Society　of　Industrial　and　Engineering　Chemistry.　Published　by　Elsevier　B.V.　All　rights　reserved.