Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Water-Walled Microfluidics Makes an Ultimate Optical Finesse   Liquids serve microcavity research ever since Ashkins studies on optical
resonances in levitating droplets to recent optofluidic resonators. Droplets
can provide optical quality factor (Q) in proximity to the limit restricted by
water absorption and radiation loss. However, water micro-drops vaporize
quickly due to their large area to volume ratio. Here we fabricate a water-air
interface that almost entirely surrounds our device, allowing for more than
1,000,000 recirculations of light (finesse). We sustain the droplets for longer
than 16 hours using a nano-water-bridge that extends from the droplet to a
practically-unlimited distant-reservoir that compensates for evaporation. Our
device exhibits surface tension 8000-times stronger than gravity that
self-stabilizes its shape to a degree sufficient to maintain critical coupling
as well as to resolve split modes. Our device has 98 percents of their
surrounding walls made strictly of water-air interfaces with concave, convex or
saddle geometries, suggesting an arbitrary-shape microfluidic technology with
water-walls almost all-over.

28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat