Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A photonic crystal cavity-optical fiber tip nanoparticle sensor for
  biomedical applications   We present a sensor capable of detecting solution-based nanoparticles using
an optical fiber tip functionalized with a photonic crystal cavity. When sensor
tips are retracted from a nanoparticle solution after being submerged, we find
that a combination of convective fluid forces and optically-induced trapping
cause an aggregation of nanoparticles to form directly on cavity surfaces. A
simple readout of quantum dot photoluminescence coupled to the optical fiber
shows that nanoparticle presence and concentration can be detected through
modified cavity properties. Our sensor can detect both gold and iron oxide
nanoparticles and can be utilized for molecular sensing applications in
biomedicine.

9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg