Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electrically controlled localized charge trapping at amorphous
  fluoropolymer-electrolyte interfaces   Charge trapping is a long-standing problem in electrowetting-on-dielectric
(EWOD), causing reliability reduction and restricting its practical
applications. Although this phenomenon has been investigated macroscopically,
the microscopic investigations are still lacking. In this work, the trapped
charges are proven to be localized at three-phase contact line region by using
three detecting methods -- local contact angle measurements, electrowetting
(EW) probe, and Kelvin Probe Force Microscopy (KPFM). Moreover, we demonstrate
that this EW-induced charge trapping phenomenon can be utilized as a simple and
low-cost method to deposit charges on fluoropolymer surfaces. Charge density
near the three-phase contact line up to 0.46 mC/m2 and the line width with
deposited charges ranging from 20 to 300 micrometer are achieved by the
proposed method. Particularly, negative charge densities do not degrade even
after harsh testing with a water droplet on top of the sample surfaces for 12
hours, as well as after being treated by water vapor for 3 hours. These
findings provide an approach for applications which desire stable and
controllable surface charges.

18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: eess
15
The categories of this paper are: nucl-ex