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Content uploaded by Clint Zeagler
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All content in this area was uploaded by Clint Zeagler on Dec 19, 2016
Content may be subject to copyright.
Can I Wash It?: The Effect of Washing Conductive Materials Used
in Making Textile Based Wearable Electronic Interfaces
Clint Zeagler
Georgia Institute of
Technology
clintzeagler@gatech.edu
Scott Gilliland
Georgia Institute of
Technology
Scott.Gilliland@gatech.edu
Stephen Audy
Georgia Institute of
Technology
stephenaudy@gmail.com
Thad Starner
Georgia Institute of
Technology
thad@gatech.edu
ABSTRACT
We explore the wash-ability of conductive materials used in
creating traces and touch sensors in wearable electronic
textiles. We perform a wash test measuring change in
resistivity after each of 10 cycles of washing for conductive
traces constructed using two types of conductive thread,
conductive ink, and combinations of thread and ink.
Author Keywords
Electronic Textile Wash Test, Conductive Materials Wash Test.
ACM Classification Keywords
H.5.m. Information interfaces and presentation (e.g., HCI):
Miscellaneous.
INTRODUCTION
Since the beginning of wearable computing and technology
embedded clothing, one question that consistently is asked
of designers and researchers is “Can I wash it?” In
developing wearable computers and functional clothing, the
notion of wash-ability is complex. For example, in Post’s
Jacket with a capacitive fabric keyboard [7] we can ask the
question of wash-ability across a number of different
components. Is the micro-controller washable? Is the circuit
board washable? Are the wires washable? Is the embroidery
washable? Is the denim jacket itself washable? Are the
connections between the components washable? When
these different components are washed what happens to
them; how do they change; and does the device still work at
an acceptable level after the washing? This paper focuses
on the wash-ability of some conductive materials
commonly used in making textile based electrical traces and
capacitive touch sensitive interfaces.
PROCEDURE
There are many ways to wash clothes. For the purpose of
our testing we decided to use a standard upright agitator
washing machine GE Spacemaker Model WSM2700
HAWWW and a standard detergent. one ounce of All 2x
Ultra detergent is used each wash cycle. Lee et al. explain
the variable nature of the mechanical washing actions [6];
however, by using the same water fill level and same cycle
time, we tried to standardize the mechanical aspects of the
washing cycle as much as possible. All washes were made
in warm water, at medium load, and a regular wash cycle.
We chose to wash on the warm cycle because we wanted to
use a harsher condition, hoping that if the conductive
materials withstood a warm wash cycle they would be more
likely to withstand a cold wash cycle. We also chose the
regular agitation and wash cycle because these would be
harsher conditions than a gentle cycle. We chose two types
of conductive thread to test; the first is a coated conductive
thread [2]. The Shieldex size 33 thread is completely
conductive on the outside surface of the thread and is very
useful when embroidering interfaces [4,8] because, as the
thread sews over itself, it increases the conductive surface
and lowers electrical resistance. One downside to the
Shieldex size 33 thread is that the conductive coating on the
thread makes it hard to regulate the tension of sewing and
embroidery machines properly, and it is more difficult to
use within industrial machines when working at industrial
speeds. We also chose to test Shieldex’s size 40 thread [3],
which is a 2 ply mixed yarn consisting of both conductive
and nonconductive polyester. The advantage of the
Shieldex size 40 yarn is that it runs much better through
sewing and embroidery machines, but it can not be sewn
over itself to reduce resistance. As we also wished to
explore how to best combine conductive ink and conductive
embroidery to create the most robust interfaces, we also
tested the effects of washing on combinations of conductive
materials.
We examine the following 12 test conditions:
Less Conductive Thread (Shieldex size 40 22/7 PET sewing thread)
1. Single trace*
2. Double trace**
3. Single trace under conductive ink (sewn first and ink printed on top of
trace and then cured)
4. Single trace on top of conductive ink (ink printed first and thread sewn
on top of cured ink)
5. Double trace under conductive ink
More Conductive Thread (Shieldex size 33 117/17 sewing thread)
6. Single trace
7. Double trace
8. Single trace under conductive ink
9. Single trace on top of conductive ink
10. Double trace under conductive ink
Conductive Ink
11. Ink alone
12. Ink covered with Plastisol***
* Single trace = A single straight sewn line of thread
** Double trace = A single straight sewn line of thread double back over
itself
*** Plastisol Ink is a standard type of screen printing ink. It is a pigment
suspended in a binder which cures into a plastic after being heated.
RESULTS
Each test condition was applied onto a cotton twill swatch.
The swatches were washed for 10 wash cycles. The graph
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ISWC’13, September 9–12, 2013, Zurich, Switzerland.
Copyright © 2013 ACM 978-1-4503-2127-3/13/09…$15.00.
ISWC Posters
ISWC’13, September 9–12, 2013, Zurich, Switzerland
143
(Figure 3) shows the average resistance change from each
test condition over 10 wash cycles. Where the test condition
lines on the graph terminate indicate that at that wash cycle
either the trace was broken or the resistance became so high
as to effectively render the trace useless. As this is an
average graph, some traces might still have been working,
but the majority of the traces failed where the lines
terminate.
A. B.
Figure 1. A comparison of conductive thread sewn under the
conductive ink trace (A) and sewn over the ink trace (B).
Notice how the ink saturates the thread and fills in the fabric
punctures when placed on top of the thread.
Test Condition 12 conductive ink under plastisol ink.
The plastisol ink performed very well at preventing the
conductive ink from being degraded. After three wash
cycles, when it became clear that the increase of resistance
of the exposed conductive inkpads was increasing
significantly faster than that of the ink protected by
plastisol, we began measurements at the edges of the
plastisol as well as from the ends. Clearly, the plastisol
protects the conductive ink and prevents the increase of
resistance we find with uncovered conductive ink. In
addition, a single or double trace of fully conductive thread
coated with conductive ink seems much more robust than
other alternatives.
A. B.
Figure 2A. 12 Swatch B11 conductive ink Figure 2B. Swatch
B12 conductive ink under plastisol ink
CONCLUSION & DESIGN RECOMENDATIONS
We realize that there are currently insulated threads on the
market that might withstand washing conditions better then
the threads we chose to test here. However, currently
insulated threads can be very difficult to connect with
components in a durable way. We chose to test these types
of sewing threads because they are widely available and
widely used, and connect easily to components. When
designing a textile with traces used to carry electricity, we
suggest using the thicker, more conductive thread [6]. If
minimal resistance is desired, add conductive ink on top of
the thread. When screen-printing a trace, we suggest using a
more flexible conductive ink [1] and covering the trace with
insulating plastisol ink in all areas not needed for capacitive
sensing (see Figure 2). For a more comprehensive report
with detailed findings please view a full GVU techreport
[9].
ACKNOWLEDGMENTS
This work was supported in part by a grant from ETRI and a Georgia
Institute of Technology GVU Center Seed Grant.
REFERENCES
1. AG-510 SILVER CONDUCTIVE INK, Conductive Compounds,
http://www.conductivecompounds.com/docs/AG510_SILVER_FILLED_INK.pdf
[accessed: April 7, 2013]
2. Conductive Sewing Thread Size 33,
http://www.shieldextrading.net/pdfs/260151011717oz.pdf , [accessed: April 7,
2013]
3. Conductive Sewing Thread Size 40,
http://www.shieldextrading.net/pdfs/260151022110.pdf , [accessed: April 7, 2013]
4. S. Gilliland. N. Komor. T. Starner. and C. Zeagler. The Textile Interface
Swatchbook: Creating Graphical User Interface-like Widgets with Conductive
Embroidery. In International Symposium on Wearable Computers ISWC, pages
18–25, Seoul, South Korea, 2010. IEEE.
5. N. Komor, S. Gilliland, J. Clawson, M. Bhardwaj, M. Garg, C. Zeagler, and T.
Starner. Is it gropable? - assessing the impact of mobility on textile interfaces. In
International Symposium on Wearable Computers ISWC, pages 71–74,Linz,
Austria, 2009. IEEE.
6. A.Lee, M Seo, S. Yang, J. Koh, and H. Kim. 2008 . The Effects of Mechanical
Actions on Washing Efficiency. Fibers and Polymers (2008) Vol. 9, No. 1, pages
101-106.
7. E. Post, M. Orth, P. Russo, and N. Gershenfeld. E-broidery: Design and
fabrication of textile-based computing. IBM Systems Journal, 39(3):840–850,
2000.
8. C. Zeagler, S. Gilliland, H. Profita, & T. Starner. (2012, June). Textile Interfaces:
Embroidered Jog-Wheel, Beaded Tilt Sensor, Twisted Pair Ribbon, and Sound
Sequins. In International Symposium on Wearable Computers (ISWC), 2012 16th
(pp. 60-63). IEEE
9. C. Zeagler, S. Gilliland, S. Audy, and T. Starner. Can I Wash It? GVU Technical
Report ; GIT-GVU-13-01
Figure 3 – Averaged results of resistance changes on 10 traces of each type over each of ten wash cycles. Red X denotes where the
trace failed or the resistance became so high to render the trace ineffective.
ISWC Posters
ISWC’13, September 9–12, 2013, Zurich, Switzerland
144