Supporting Information
Synthetic Adhesive Attachment Discs Inspired by Spider's Pyriform Silk
Architecture
Dharamdeep Jain#, Vasav Sahni#, Ali Dhinojwala*
#:
both authors contributed equally to the study
*: Corresponding author (ali4@uakron.edu)
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Supporting Figures
FIGURE S1. Electrospinning set-up used in making synthetic attachment discs. Figure shows the main
components of the set-up which includes a capillary tube filled with polymer solution to be electrospun,
a high voltage source for creating potential difference between capillary tip and collector, an air supply
used to control jet stability and a velocity controlled moving stage upon which the aluminum substrate
with the nylon thread are placed to collect the fibers. The electrified jet spins the synthetic attachment
discs on the nylon fiber as the stage moves at a velocity varying from 0.1 cm/s to 5 cm/s. The inset
shows the pattern of the synthetic discs prepared by the electrospinning process.
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FIGURE S2. Synthetic discs prepared at collector velocity of 5cm/s. Figure S2a and S2b depict the optical
and SEM images for the synthetic attachment discs prepared at collector velocity 5 cm/s .The scale bars
for Figures S2a-b is 1000 μm and 100 μm respectively.
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FIGURE S3. Peeling discs at 0.01 mm/s. Figure S3a-c shows the optical images of the deformation zone
observed in the attachment discs prepared at collector velocity 0.1 cm/s, 1 cm/s and 5 cm/s
respectively, peeled at 0.01 mm/s. The scale bar for figure S3a-c is 500 μm.
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FIGURE S4. Stress-strain for single fiber stretching. The experiments were conducted using nano-force
sensor (Nanobionix, Agilent Tech.).The data is recorded at the extension rate of 1 mm/s.
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FIGURE S5. Energy model. Schematic illustrates the pre-peeling and post-peeling scenario of a synthetic
disc, schematically. Figure S5a and S5b show the top-view while figure S5c and S5d show the front view.
The color scheme is described in figure 2e.
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FIGURE S6. Peeling behavior of discs prepared on oxygen plasma treated substrates. Figure S6a shows
the optical image of the peeling behaviour which starts of as a V zone formation but later narrows down
and resembles the behaviour as seen in figure 3i (see main text) while figure S6b depicts optical image
for the peeling behaviour resembling the control substrate. Such variation in peeling behaviour seen but
not often, could be due to loss of effectiveness of oxygen plasma treatment on substrates, leading to
behaviour similar to the untreated substrates. The scale bar for the figures is 1000 µm.
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FIGURE S7. Pendulum rings based on Nylon 6 Electrospinning Nylon 6 was electrospun to create
pendulum ring structures on underlying nylon thread. Figure S7a and S7b are the optical images showing
the variation in the spacing of patterns made at velocity of stage 2.5 cm/s and 0.1 cm/s. Figure S7c
shows the optical image for the deformation zone seen after the disc made at 2.5 cm/s was peeled by
hand. The scale bar for Figures S7a and S7b is 500 µm and for Figure S7c is 1000 µm.
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Supporting Movie
MOVIE S1. Formation of V shaped deformation zone in the synthetic attachment discs. The synthetic
disc made at collector velocity 0.1 cm/s was peeled by hand, depicting the V shaped deformation zone
formation.
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Supporting Tables
TABLE S1. Summary of the parameters related to spacing, peeling forces, fracture width and energy
values for synthetic discs made on aluminum.
Stage speed/
0.1 cm/s
1cm/s
5cm/s
15 ± 8
32 ± 12
74 ± 15
1 mm/s
45 ± 1
4±2
2 ± 0.5
0.1 mm/s
20 ± 3
5 ± 1.3
0.7 ± 0.4
0.01 mm/s
4 ± 0.4
1.8 ± 0.7
0.3 ± 0.1
1 mm/s
3407 ± 274
900 ± 125
420 ± 92
525 ± 110
222 ± 35
330 ± 42
156 ± 49
Peeling rate
Spacing (μm)
Force (mN)
Fracture width (μm)
Max: 6760±545
Min: 54±2
0.1 mm/s
2332 ± 90
Max: 4596±178
Min: 68±2
0.01 mm/s
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437 ± 40
Max: 821±79
Min: 53±1
UT/L0
US/L0
UP/L0
Up/Us
1 mm/s
49.6
7.7
2.4
0.1 mm/s
20.4
7.5
1.8
1 mm/s
2.2
1.2
0.3
0.1 mm/s
1.2
0.7
0.2
1mm/s
47.4
6.5
2.1
0.1mm/s
19.2
6.8
1.6
1mm/s
21.5
5.4
5.4
0.1mm/s
16
9.7
8
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TABLE S2. Summary of the fiber parameters, peeling forces and fracture width related to synthetic discs
prepared on different substrates at a collector velocity of 0.1 cm/s and peeling rate 1 mm/s.
Substrate/
Parameter
Perfluoro plasma
Untreated
Oxygen plasma
treated
aluminum
treated
aluminum
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aluminum
Diameter (μm)
1.5 ± 0.2
1.3 ± 0.2
1.5 ± 0.5
Spacing (μm)
15 ± 8
17 ± 4
15 ± 3
Contact angle (0)
109 ± 2
89 ± 1
0
Force (mN)
54 ± 6
58 ± 3
22 ± 9
Fracture width (μm)
4021 ± 319
3407 ± 274
903 ± 129
Max: 7984±637
Max: 6760±545
Min: 59±2
Min: 54±2
UT/L0
65.9
49.6
29.3
US/L0
3.1
2.2
2.6
UP/L0
62.8
47.4
26.7
Up/Us
20.2
21.5
10.2