Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Control and ultrasonic actuation of a gas-liquid interface in a
  microfluidic chip   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.

31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph