Biomedical Engineering Reference
In-Depth Information
(a)
(b)
Figure 12.
Base area,
A
,
vs.
time,
t
, for a bmim.BF
4
droplet immersed in hexadecane on a Teflon-
coated electrode and subjected to a DC voltage (
!
50 V;
" −
50 V;
1
100 V;
2 −
100 V;
P
150 V;
Q −
150 V;
e
200 V;
a −
200 V): (a) spreading droplet; (b) retracting droplet. The solid lines are
the best fits of (a)
A
=
a
+
b
[
1
−
exp
(
−
t/τ)
]+
kt
(exponential saturation with four parameters);
(b)
A
=
a
+
b
exp
(
−
t/τ)
(exponential decay with three parameters). Reprinted with permission from
Paneru
et al.
[50]. Copyright 2010 American Chemical Society.
Figure 13.
Base area,
A
,
vs.
time,
t
, for a Rmim.BF
4
droplet immersed in hexadecane on a Teflon-
coated electrode, subjected to a DC saturation voltage.
D. Discussion
D.1. Electrowetting Performance
The range of static contact angles achievable with the system AF1600-ionic liquid-
alkane is extremely wide: from about 150
◦
down to 48
◦
(when using DC voltage)
or about 15
◦
(when using AC voltage). The large values of the contact angles at
zero voltage,
θ
0
, contribute to that range considerably. Since both alkane and Teflon
are apolar materials [70] (i.e., they interact almost exclusively through dispersion
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