Technical seminar presentation on the topic "Bio inspired materials for directional fluid transport and manufacturing stealth fabric". Use the references to learn more about the topic....... Best of luck!!!!!!!

1. Technical Seminar
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Presented By
Manikandan R 1RV15CH402
24th February 2018
Department of Chemical Engineering,
R V College of Engineering, Bengaluru – 560059
Bioinspired Materials for
Directional Liquid Transport and
Manufacturing Stealth fabric

2. ®
Department of Chemical Engineering, RVCE24 February 2018 2
Biomimicry is basically taking a design challenge and then finding an ecosystem
that's already solved that challenge, and literally trying to emulate what you
learn. 𝟏
WHAT?
WHY?
Natural organisms have managed to do everything we want to do without guzzling
fossil fuels, polluting the planet or mortgaging the future.1

3. CONTENTS
1. Directional fluid transport
2. Inspiration for bioinspired materials for directional liquid transport
3. Basic theory
4. Application: Condensation
5. Application: Separation
6. Inspiration for manufacturing of stealth fabric
7. Method used
8. Optimization
9. Demonstration of the thermal stealth potential of the fibers
10. References
Department of Chemical Engineering, RVCE24 February 2018
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4. 4
 Phenomenon is based on geometric principles such as, the basic concepts and theories of
surface wettability, droplet motion, and driving force.2
 The key for driving droplet directionally is exerting unbalanced forces at its opposite
side.3
 Ideally, such gradients can also be created in situ by external stimuli, such as light,
temperature, vibration, and magnetic field, which work individually or collaboratively
to transport liquid droplets.3
 Important in many industrial applications and chemical engineering processes, such as
heat transfer, separation, microfluidics, and so on.3
DIRECTIONAL FLUID TRANSPORT
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

5. 5
INSPIRATION
Figure 1. Natural materials for directional liquid transport.3 (a) Spider silk: periodic spindle-
knots and joints. Scale bar represents 50 μm, 2 μm, and 500 nm, respectively. (b) Cactus spine:
conical spines and trichomes on the cactus stem. Scale bar represents 5 cm, 100 μm, 20 μm, 20
μm, 20 μm, and 2 μm, respectively. (c) Shorebird: droplet trapped and transported along its
beaks.
24 February 2018
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

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Figure 2. Natural materials for directional liquid transport.(contd.)3 (d) Butterfly wing:
ratchet-like oriented scales. Scale bar represents 100 μm. (e) Desert beetle: hydrophilic humps
surrounded by wax-covered hydrophobic region. Scale bar represents 10 mm and 10 μm,
respectively.
(f) Nepenthes peristome: second-order microgrooves containing periodic duck-billed micro
cavities with arch-shaped edges.
INSPIRATION (Contd.)
24 February 2018
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

7. BASIC THEORY
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Equilibrium contact angle at the three-phase contact line (TCL) can be described
by the Young’s equation, which is expressed as (Figure 3a)
γ cos θ = γSG − γSL
Figure 3. Basic theories about directional transport of a liquid droplet.3 (a) Force
analysis on the triple-phase contact line (TCL) based on Young’s
equation. (b) Droplet on a gradient surface tends to move toward a more wettable
direction.
24 February 2018
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

8. 8
Figure 4. Droplet easily rolls off along the radial outward (RO) direction on the
wing of butterfly Morpho aega but is pinned tightly against the RO direction.3
24 February 2018
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

9. 9
APPLICATION: CONDENSATION
Figure 5. Dropwise
condensation enhanced
by super hydrophobic
surfaces with different
micro/nano structures:
nanostructures, micro
pillars,
micro pyramids, micro
posts.3
24 February 2018
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

10. 10
APPLICATION: SEPARATION
Figure 6. Superhydrophobic miniature boat keeps high separation
efficiency above 99% even after 50 cycles, showing its durability.3
24 February 2018
Department of Chemical Engineering, RVCE
Bioinspired Materials for
Directional Liquid Transport

11. The hairs of a polar bear have a hollow core, which reflects back IR emissions from
the animal’s body. This structure helps prevent heat loss and keeps the bears warm in
their Arctic environments.4
The hairs have an added advantage: They can conceal the bears from thermal
imaging cameras used in many night-vision devices.4
Textiles that can mimic polar bear hair’s IR-reflecting abilities might be useful in
stealth applications, such as concealing soldiers.4
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Figure 7. Thermal image of a Polar bear5
24 February 2018
Department of Chemical Engineering, RVCE
Manufacturing of Stealth fabric
INSPIRATION FOR MANUFACTURING OF
STEALTH FABRIC

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Mixing of
Raw
materials
Freeze
spinning
using copper
ring
Freeze
drying
 A freeze-spinning method is used to make the fibers that are porous, strong,
and highly thermally insulating.4
 They consist of fibroin, a protein found in silk, along with a small amount of the
polysaccharide chitosan.4
24 February 2018
Department of Chemical Engineering, RVCE
Manufacturing of Stealth fabric
METHOD USED TO MANUFACTURE
STEALTH FABRIC
Figure 8. The porous fiber woven into a
textile with thermal stealth properties.4

13. OPTIMIZATION OF THE FABRIC
Freeze-drying the fibers removed the ice by sublimation to produce strong fibers
about 200 µm wide with up to 87% porosity.4
After varying conditions such as the viscosity of the mixture and the temperature
of the ring, running the process at -100 °C produced pores about 30 µm across,
which offered the best balance between strength and thermal insulation.4
1324 February 2018
Department of Chemical Engineering, RVCE
Manufacturing of Stealth fabric
Figure. 9 Preparing the fur-mimicking fibers at -100 °C produced
pores about 30 µm across.4

14. DEMONSTRATION OF THE THERMAL
STEALTH POTENTIAL OF THE FIBERS
1424 February 2018
Department of Chemical Engineering, RVCE
Manufacturing of Stealth fabric
Figure. 10 A lab
rabbit wearing a
cloak with fibers that
mimic polar bear hair
(top left) is invisible to
a thermal imaging
camera (top right).
Under a polyester
cape (bottom left), the
bunny’s cover is
blown (bottom right).

15. REFERENCES
1. Quotes by Janine Benyus; Source: https://www.brainyquote.com/authors/janine_benyus
2. Directional, passive liquid transport: the Texas horned lizard as a model for a biomimetic
‘liquid diode’; Philipp Comanns, Gerda Buchberger, Andreas Buchsbaum, Richard Baumgartner,
Alexander Kogler, Siegfried Bauer, and Werner Baumgartner. J R Soc Interface. 2015 Aug 6;
12(109): 20150415. doi: 10.1098/rsif.2015.0415 PMCID: PMC4535411; Directional, passive li.
3. Bioinspired Smart Materials for Directional Liquid Transport; Ying Cui, Dewen Li,and Hao
Bai, State Key Laboratory of Chemical Engineering, College of Chemical and Biological
Engineering, Zhejiang University, Hangzhou 310027, China.
4. Polar bear hair inspires stealth fabric; By Mark Peplow; Chemical & Engineering News; ISSN
0009-2347; Copyright © 2018 American Chemical Society.
5. Invisible Polar Bears; Copyright © 2010-2018 Dan Lewis. All rights reserved.
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Department of Chemical Engineering, RVCE 1524 February 2018

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THANK YOU……