Supplementary Information
Highly Flexible, Stretchable, Patternable, Transparent
Copper Fiber Heater on a Complex 3D Surface
Hong Seok Jo1,4, Seongpil An1,4, Jong Gun Lee1, Hyun Goo Park1, Salem S. Al-Deyab2,
Alexander L. Yarin1,3,*, Sam S. Yoon1,*
1
School of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
Petrochemicals Research Chair, Department of Chemistry, King Saud University, Riyadh 11451,
Saudi Arabia
3
Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Illinois
60607-7022, USA
2
4These
authors have contributed equally.
*Corresponding
authors: [email protected], [email protected]
Figure S1. Transmittance spectra of CMFH over the wavelength of 400 - 800 nm
Figure S2. Thermal stability of CFHs with (a) T = 60%, (b) T = 30% evaluated by
switching the applied voltage for 20 cycles.
Figure S3. The temperature and resistance variation at T = 96% and 2.0 V: (a) bending
test, (b) stretching test.
Figure S4. The IR images and SEM images of the repetitive stretching test. (a) N = 1, (b)
N = 3, (c) N = 5.
Table S1. Electroplating time, sheet resistance Rs, transmittance T, fill factor fF, and Tf
of CFH for different electrospinning times.
ts (s)
tp (s)
Rs (Ω·sq-1)
T (%)
fF (%)
Tf (%)
5
2
0.370
96
6
94
90
5
0.266
60
36
64
180
10
0.101
30
65
35
Table S2. PAN nanofibers and copper-plating parameters for each case.
Case
Experimental result
ts (s)
Dp (μm)
Lt (μm)
Ip (A)
Ca (A∙tep∙μm-2)
Dc (μm)
5
0.51
145.76
3.094
0.0270
1.16
90
0.50
367.95
3.193
0.0276
1.18
180
0.51
751.65
3.294
0.0279
1.19
Table S3. The element ratio of the CFH with T = 96% during the 20-cycle test.
Element
(Weight %)
Cu
Before the cycling test
After 10 cycles
After 20 cycles
97.4
96.7
95.3
O
0.4
0.7
0.8
C
2.2
2.6
3.9
Table S4. The properties for the CFHs in Figure 3d.
Case
ts (s)
tp (s)
Df (μm)
Rs (Ω·sq-1)
T (%)
Ts, max (°C)
1
5
3
1.7
0.308
95
216
2
5
6
4.4
0.183
90
243
3
5
12
7
0.076
83
284
4
3
15
9
0.058
90
328
Table S5. The properties of the stretchability of transparent film heater using the
various materials.
Bending test
Stretching test
Nanomaterials
Ref
Strain
∆T/T0
∆R/R0
∆R/R0
Rb
(%)
CuZr
70
0.02
1 mm
0.02
0.5
1
nanotrough
30
Only stretching test
0.69
5
2
AgNW
Cu
30
0.02
2 mm
0.82
2
3
wire/Al2O3/PI
Present
300
0.03
1.3 mm
0.05
1.6
Cu-plated fibers
work
The transmittance of a conductive film with a high content of metal fibers per unit
area is inevitably decreased by the fiber cross-section blocking out light.4, 5 The geometrical
fill factor related with the metal fiber content per unit area is calculated by the following
equation.6
fF 
DL
A
(1)
where D, L and A are the diameter, length and the total area of the Cu fibers in an SEM image,
respectively. As listed in Table S1, fF is increased as the electrospinning time (ts) increases
because the shadowing area increases due to the increase in the content of copper fibers.
In addition, it is possible to calculate the transmittance (Tf) as Tf = 1 – fF. In our case,
fF varies from 0.06 to 0.65 as ts increases, and accordingly, Tf changes from 0.94 to 0.35. As
compared with the data measured by a spectrophotometer, Tf calculated via fF is
approximately the same.
Movie S1 : the measurement of the sheet resistance
Movie S2 : the around view of the 3D heater.
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