2. A New Class of Lightweight
Multifunctional Material to Improve
Size, Weight, and Power
Larry Christy
Product Development Engineer, General Nano, LLC

3. Agenda
I. Introduction
II. Background
- Conventional Shielding Materials
- Carbon Nanotubes
- EMI Shielding Theory
III. Material Development
IV. Results
V. Summary
VI. Future Work

4. Introduction
Problem: Metallic shielding materials are heavy,
shielding effectiveness decreases with frequency.
Need: There is a need in the wire and cable market for
affordable, lightweight continuous shielding tape products.
Customer Inquiry: “Can you manufacture continuous
carbon nanotube tape products?”
- DOD & AEROSPACE PRIMES

5. Background
Common Wire & Cable Shielding Products:
i. Braided Shields – Ag/Cu, Ni/Cu (~8.9 g/cm3)
ii. Foil, Mylar Shields – Al foil, Al/Mylar (mPET)
iii. Serve/Spiral Shields – Cu
Lightweight Wire & Cable Shielding Products:
i. Conductive Textiles – Metallized polymer fibers
- Upwards of 5 g/cm3
- $$$
ii. Carbon Materials – Carbon Nanotubes, Graphene
- 0.3 – 1.5 g/cm3
- $$$

6. Carbon Nanotubes
Graphene
(e)
Nobel Prize in Physics for 2010
to Andre Geim and Konstantin
Novoselov for the 2-D material
graphene.
Nobel Prize in Chemistry for 1996 to Richard Smalley,
Robert Curl, and Harold Kroto for Buckyballs.
Carbon Materials
(Allotropes)

7. General Nano CNT blackbody product is going to space in ’16. Launch to
International Space Station, then re-launch on CubeSat.

8. Carbon Nanotubes
Carbon nanotubes are fullerene-related
structures which consist of graphene cylinders
closed at either end with caps containing
pentagonal rings of carbon.
They were discovered in 1991
by the Japanese electron
microscopist Sumio Iijima.
Individual CNT Properties
i. Electrical Conductivity: 106-108 S/m (Copper ~ 6 x 107 S/m)
ii. Tensile Strength: 10-150 GPa (Copper ~ 220 MPa)

9. Electromagnetic Shielding Theory
𝑆𝐸 = 10 𝑙𝑜𝑔
𝑃𝐼
𝑃 𝑇
𝑑𝐵
𝑆𝐸 = 𝐴 + 𝑅 + 𝐵 [𝑑𝐵
𝐴 = 8.69
𝑑
𝛿
[𝑑𝐵
𝛿 =
2
𝜔𝜇𝜎
=
1
𝜋𝑓𝜇𝜎
[𝑚
𝑅 = 20 log
𝑍0
4𝑍 𝑠
𝑑𝐵
𝑍 𝑠 =
2𝜋𝑓𝜇
𝜎
𝛺 , 𝑍0 =
𝜇0
𝜀0
≈ 377[𝛺
𝐵 = 20 log 1 − 𝑒
−
2𝑑
𝛿 [𝑑𝐵
𝑆𝐸 ≈ 20 log
𝑍0 + 𝑍s
2
4𝑍0 𝑍s
[𝑑𝐵
Impedance MethodPlane Wave Method

10. Material Development
General Nano’s Approach:
i. Build high-caliber relationships through
communication and customer driven innovation
ii. Focused and flexible product development
iii. Rapid design, testing, and iteration
Customer Inquiry: “Can you manufacture
continuous carbon nanotube tape products?”
Shield Tape Specifications:
i. Drop in for Wire & Cable OEM tape layup
ii. Continuous, seamless construction, with no
delamination of CNT material.
iii. < 25 μm thick
iv. Sheet resistance < 0.2 Ω/□
v. Tensile strength > 1.25 N/mm
vi. Density < 2 g/cm3
Test Fast, Fail Fast, Adjust Fast
-Tom Peters
σ > 2,000 S/cm

11. Delivering Results to our Customers is
our Priority

12. CNT Sheet Development
Product Development Challenges:
• Individual carbon nanotube properties don’t translate to
macroscopic sheet products.
– CNT to CNT junctions add electrical resistance within the CNT sheet
network.
– Mechanical properties limited to weakest link → CNT to CNT
adhesion via weak molecular interactions (van der Waals forces).
 Each application will likely require an element of
engineering/design to meet the customer’s needs.
 Recognize the limitations of nanomaterials and leverage
their properties for real world use.

13. CNT Sheet Development
Shield Tape Specifications:
i. Tensile strength > 1.25 N/mm
Proposed Solution:
i. Add carrier material
 PET
i. Manufacture 1 ft2 batch sheets
ii. Characterize sheet properties
iii. Scale recipe using continuous nonwoven process
iv. Slit/convert CNT rollstock to tape
v. Cable Manufacturing → tape layup
vi. Cable Testing
CNT/PET Shield Tape (P4):
 Tensile strength = 1.3 N/mm
 Continuous, seamless tape
 Conductivity = 2,150 S/cm
 Density = 0.44 g/cm3
Customer Feedback:
 Drop-in for Wire & Cable OEM
 Challenge – improve low
frequency shielding.
 Remove carrier to reduce
weight and thickness.

14. Results
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
ShieldingEffectiveness(dB)
Frequency (GHz)
P3
P4
P6
Control: mPET (1 Ω/□,39 dB)
ASTM D4935: 6” x 6” Panel Test

15. Results
Single Braid Ag/Cu (CoTS)
Single Braid Ag/Cu +
2 wraps CNT Shield ‘P4’
Single Braid Ag/Cu +
3 wraps CNT Shield ‘P4’
Double Braid Ag/Cu (CoTS)
 Adding 2 wraps of CNT shield tape ‘P4’: improves shielding effectiveness, adds minimal weight.
 Adding 3 wraps of CNT shield tape ‘P4’: ≥ SE as double braid (above 200 MHz), with 25% weight
savings.
Improves SE by ~25 dB,
adds ~3% weight

16. Results
Shield Tape Specifications:
i. Drop in for Wire & Cable OEM tape layup 
ii. Continuous, seamless construction, with no delamination of CNT material 
iii. < 25 μm thick X
iv. Sheet resistance < 0.2 Ω/□ → σ > 2,000 S/cm 
v. Tensile strength > 1.25 N/mm 
vi. Density < 2 g/cm3 
*CNT Shield Tape ‘P4’ – 4th design iteration
Customer Inquiry: “Can you manufacture continuous carbon nanotube
tape products?”

17. Results
Shield Tape
Product
Conductivity
(S/cm)
Density
(g/cm3)
Basis
Weight
(g/m2)
SR
(Ω/ )
Thickness
(μm)
Linear force
(N/mm)
Tensile
strength
(MPa)
P0 854.70 0.51 23.0 0.26 45 0.07 1.56
P1 1904.76 0.41 29.0 0.08 70 0.53 7.60
P2 826.45 0.44 24.0 0.22 55 0.35 6.44
P3 934.58 0.32 34.0 0.10 107 2.00 18.69
P4 2150.54 0.44 33.0 0.06 75 1.30 17.33
P6 1633.99 0.75 38.3 0.12 51 1.20 23.53
P7 3086.42 1.48 40.0 0.12 27 6.00 222.22

18. Summary
7+ shield tape iterations later…
0
50
100
150
200
250
0
1000
2000
3000
4000
5000
6000
7000
TensileStrength(MPa)
Conductivity(S/cm)
28x Electrical Conductivity Increase, 220x Tensile Strength Increase
Conductivity Tensile Strength
12/27/2014 4/28/2015 8/28/2015 10/28/2015 12/28/2015

19. Summary
• Continuous CNT shield tape was successfully developed
to meet the customer’s specifications.
• CNT tape was a drop-in solution using conventional tape
layup equipment.
• Improved cable performance above 200 MHz, with 25%
weight savings.
– Addressable markets include satellite and UAV cabling.
• CNT shield tape feeback:
– Improve low frequency shielding to open commercial
applications.
– Reduce thickness and weight by removing carrier material.

20. Future Work
Improve Low Frequency Shielding
 Increase electrical conductivity
a) CNT sheet densification
b) Carbon nanotube alignment
c) Doping
d) Protonation
e) Cross-linking
f) Metallization, metal hybridization

21. Larry Christy
Product Development Engineer
larry.christy@veelotech.com
www.veelotech.com
CONTINUOUS
CNT TAPE
CONTINUOUS
CNT FILM
VERTICALLY
ALIGNED CNT
COATINGS
CONTINUOUS
CNT SHEET

22. CNT Sheet Manufacturing
Figure 8. (a) 13” wide continuous nonwoven manufacturing pilot operation, (b) continuous web
in dry rollers, (c) roll stock winder, (d) and SEM image of the highly dispersed CNT network
within the continuous rollstock.
(a)
(b) (c) (d)
Figure 3. Completed 14” x 14” CNT nonwoven sample.

23. CNT Sheet Characterization
Network
Analyzer
Shielding Effectiveness, per ASTM D4935
Figure 4. PC based Delcom conductance monitor [19].
Figure 6. (a) Instron Micro Testing Machine Model 5948 with pneumatic foot-activated grippers,
100 N load cell, and mN resolution. (b) CNT shield tape specimen under test.

24. CNT Shielded Cable
Manufacturing