Extended Data Fig. 3: Fabrication process of the acoustic device.
From: Acousto-dewetting enables droplet microfluidics on superhydrophilic surfaces
a, step I-II, Spin coat photoresist AZ5214 on the back side of naked \(1{\rm{mm}}\) thick PZT. Step III, Use ultraviolet lithography to photoetch electrode array pattern onto AZ5214 and develop. Step IV-V, Sputter 10 nm titanium and 100 nm Nickle onto PZT in sequence. Immersing the PZT in acetone for 5 mins under ultrasonic treatment to remove redundant metal and photoresist, resulting in the formation of the electrode array. Step VI, Sputter 20 nm titanium, 100 nm Nickle and 20 nm titanium on the top side of PZT in sequence. Step VII, Spin coat SU-8 on the top electrode and ensure the matching layer thickness is 310 μm. Finally, the acoustic device is coated by 5 μm thick Parylene for waterproofing. Not drawn to scale. b-c, Simulation results of the acoustic energy transmission coefficient \({{\rm{T}}}_{1}\) from acoustic device to propagation medium (water) versus SU-8 matching layer thickness and acoustic energy transmission coefficient \({{\rm{T}}}_{2}\) from propagation medium (water) to droplet versus substrate thickness, respectively. The overall acoustic energy transmission ratio from acoustic device to droplet is \({\rm{T}}={{\rm{T}}}_{1}\times {{\rm{T}}}_{2}\).
