Jet ejection device

The invention provides a microfluidic device (1) for jet ejection, wherein the microfluidic device (1) comprises a hosting chamber (100) defined by a chamber wall (110), wherein the hosting chamber (100) is configured to host a liquid (10), wherein along a device axis of elongation (AD) the hosting chamber (100) has a chamber length (Lc) defined by a first chamber end (101) and a second chamber end (102), wherein the first chamber end (101) comprises a first chamber opening (1011) for jet ejection from the hosting chamber (100), wherein the chamber wall (110) comprises a pattern (300) of a first surface material (111) and a second surface material (112), Wherein the first surface material (111) has an equilibrium contact angle 01 > 90° for the liquid (10), and wherein the second surface material (112) has an equilibrium contact angle 02 for the liquid (10), wherein 01-02 Z 20°, wherein the pattern (300) comprises a patch (200), wherein the patch has a patch boundary (205), and wherein (a) the patch (200) comprises one of the first surface material (111) and the second surface material (112), and Wherein (b) at least 50% of the patch boundary (205) contacts the other of the first surface material (111) and the second surface material (112), Wherein the chamber wall (110) has a wall surface area (Sw), Wherein the patch (200) has a patch surface area (Sp), wherein 10' 4 5 Sp/SW : 2*10'1.