  This article describes the design and manufacturing of a microfluidic chip,
allowing for the actuation of a gas-liquid interface and of the neighboring
fluid. A first way to control the interface motion is to apply a pressure
difference across it. In this case, the efficiency of three different
micro-geometries at anchoring the interface is compared. Also, the critical
pressures needed to move the interface are measured and compared to theoretical
result. A second way to control the interface motion is by ultrasonic
excitation. When the excitation is weak, the interface exhibits traveling
waves, which follow a dispersion equation. At stronger ultrasonic levels,
standing waves appear on the interface, with frequencies that are half integer
multiple of the excitation frequency. An associated microstreaming flow field
observed in the vicinity of the interface is characterized. The meniscus and
associated streaming flow have the potential to transport particles and mix
reagents.
