Biomedical Engineering Reference
In-Depth Information
0.2
(b)
0.1
0.0
(a)
3
2
1
0
0
200
400
600
800
1000
Negative bias voltage (V)
FIGURE 19.36
Effects of the bias voltage on (a) intensity ratio of the D-band to G-band and (b) ratio of
polar/dispersive component of the surface energy. (From Yang, P. et al.,
Biomaterials
, 24, 2821, 2003. With
permission.)
Number of platelets
Percentage of unactivated platelets
100
100
80
80
60
60
40
40
20
20
0
0
a-C:H-1
a-C:H-2
a-C:H-4
LTI-carbon
Stainless steel
FIGURE 19.37
Quantity of platelets adhered on the surface of the a-C:H fi lms synthesized at different bias
voltages (15 min incubation in PRP) expressed as a percentage of platelets adhering to stainless steel in the
same test. (From Yang, P. et al.,
Biomaterials
, 24, 2821, 2003. With permission.)
All in all, the study of the surface energy of the fi lms shows that the polar part of the surface
energy decreases with increasing bias voltage, and the tendency is consistent with the change of
the
I
D
/
I
G
ratios. It is believed that this trend is affected mainly by the reduction of the sp
3
content
in the fi lms. Activation and the quantity of adherent platelets on the surface of the a-C:H fi lms are
