Awakened Apparel: Embedded Soft Actuators for Expressive Fashion and Functional Garments

Laura Perovich MIT Media Lab

[email protected]

Philippa Mothersill MIT Media Lab

[email protected]

Jennifer Broutin Farah MIT Media Lab

[email protected]

1ABSTRACT Each morning we select an outfit meant to suit our mood

and our plans. What if our clothes could seamlessly morph

with us as our attitudes and activities change throughout the

day? We created Awakened Apparel; one of the first

shape-changing fashions to employ pneumatically actuated

origami. Our prototype draws from diverse disciplines

including soft robotics and fashion to present a design

vision that advances the growing field of dynamic

interactive garments. We explore technical and fabrication

approaches for shape-changing technology held close to the

body and identify areas for further innovation.

Author Keywords Interactive fashion; origami, pneumatics; soft mechanisms

ACM Classification Keywords H.5.m. Information interfaces and presentation (e.g., HCI):

Miscellaneous

INTRODUCTION Fashion is closely tied to identity and functionality. Our

clothes affect our feelings and express them to the world—

we put on loose pajamas when we need to be comforted and

dress up in tailored suits for job interviews. They also can

constrain or empower us—a bulky winter jacket protects us

from the cold while a tight skirt inhibits our ability to walk.

Yet interaction with our clothing is limited—beyond the

functionality offered by zippers and buttons, few garments

fundamentally change their function and aesthetic.

As part of our design vision for the future of transformable

clothing we created Awakened Apparel—a pneumatic folding, shape-changing skirt that is both aesthetically pleasing and functional. This work draws on diverse

research in soft robotics, folding, and fashion.

BACKGROUND Pneumatically actuated shape-changing objects have been

developed most recently in the field of soft robotics. Key research in this area [7,12] combines the varying material

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properties of stretchy membranes (e.g. silicone) and non-

stretchy membranes (e.g. inextensible fabric or paper) to

create inflatable actuators that bend in a prescribed

direction [14]. The natural flexibility of fabric particularly

befits this developing field of soft-bodied robotic actuators,

such as OtherLab’s Ant-Roach Pneubot [4].

Shape-changing garments have used many forms of

actuation technology to transform: from electronically

activated smart-memory alloy wire to inflatable actuation

[3,11]. Garments such as Diana Eng’s Inflatable Collar

[11] use plastic air bladders encased in a fabric covering to

create clothing that transforms shape while being worn.

Ying Gao’s Walking City dresses [11] use origami folds in

the fabric to give additional structure to the inflated shape.

Awakened apparel builds on advances in soft robotics and transformable fashion by fusing pneumatics and folding with garment design to create aesthetically and tactilely pleasing shape-changing mechanisms for clothes.

MOTIVATION What does a future of interactive shape-changing fashion

offer us? Fashion’s close connection to both identity and

functionality affords many possible triggers for

interaction—from changes in weather [11], to altered

emotional circumstance [11], to safety concerns [6].

In this future of shape-changing clothing, a single garment

can embody several functional states. Awakened Apparel

presents a shape-changing skirt as an inspirational storyline that spans some of the use cases for shape- changing clothing. Motivations for state transitions can be:

informational: acts as an ambient device [13] conveying abstracted information about the self or the world; e.g.

shorter length with positive stock market performance [2]

emotional: reacts to the emotion or situation of the wearer; e.g. more conservative under unwanted attention

functional: allows the user to perform specific tasks, preserve safety, or maintain comfort, e.g. bicycle riding

Figure 1: vision sketch of skirt in its many forms

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SOFT MECHANISMS FOR SHAPE-CHANGING FASHION

Mechanism, materials and actuation With the design storyline and values defined, we

provisionally tested mechanisms, materials, and actuations

that satisfy these constraints in order to determine the

primary path of fabrication. Our work adds to this fruitful

research space by combining pneumatics, folding, and aesthetics with the exploration of suitable materials and actuation in order to create a novel mechanism for shape changing clothing.

Pneumatic folding was selected over scissor linkages, nitinol wire [3], drawstrings, direct material folding [11]

and other more traditional mechanical approaches to size

and shape changing. Origami served as a basis for

geometric construction; though other mechanisms can be

very attractive [1], origami’s thin form factor more closely

satisfies the design values required for fashion garments,

while pneumatics offer an organic and subtle shape change.

Materials must be carefully considered in developing shape-changing garments. Transformable fashion presents

constraints not often found in mechanism design, as

clothing must feel human, move with the body, and look

pleasant. In order to ensure that Awakened Apparel

remains wearable, materials used must be within the range

of typical clothing in their:

Texture: limit unpleasant textures such as extreme stiffness, sliminess, metal; use fabric whenever possible

Aesthetic: colors must be pleasing and piece assembled to be complementary

Robustness: materials must not be excessively fragile or unsuited to daily life

Mechanical actuation was selected over electronic in order to fit with the design goal, since it limits hard fragile parts

and creates an intuitive and immediate interaction. In this

demonstration, a foot operated pump eliminates the need

for bulky batteries or tethered power supply. In the future,

electronic pneumatic actuation will be achievable using

advancements in soft robust electronics that will be

incorporated into our design to provide precise airflow

control and shape-changing detail.

PNEUMATIC FOLDING MECHANISM

Experimentation: origami pattern design Design of the base origami pattern for the shape-changing

skirt was informed by the following parameters:

Naturally curve around the body when folded

Decrease in length and width when folded

Simple enough for repeatable construction

Early designs were based on the Miura fold, a simple non- orthogonal fold that can create up to 90% vertical and

horizontal size change [8]. We also tested the spiral pinecone fold pattern [9], a conical shape that can decrease in length by 80% when compressed. Exact design

dimensions were tested in paper to optimize the shape-

changing effect and aesthetic. The Miura fold satisfied

design parameters 2 & 3 and the spiral pinecone fold

satisfied parameters 1 & 2 but neither performed all desired

functions, leading us to develop a combined design. Select

geometric pattern experiments are shown in Figure 2.

Figure 2: origami pattern experimentation

An A-line skirt was selected as the primary form as it

satisfies the design values and technical constraints: it has a

pleasant aesthetic, is simple in form, and contains enough

surface area to allow for versatility.

Experimentation: pneumatic folding & textiles We tested several approaches to inflation-based folding and

assessed them based on the following parameters:

Maximization of shape-changing effect

Allows mechanical inflation through hand or foot pump

Alignment with material design values (texture,

aesthetic, robustness)

Figure 3: folding inflation mechanism

Using inspiration from soft robotics mechanisms [12],

initial experimentation into creating pneumatically actuated

textiles showed that fusing a long rhombus-shaped inflation channel to one side of a piece of fabric caused it to bend towards the channel when inflated. The limited

deformation in the inextensible fabric, combined with the

greater moment force at the mid-length corners, causes the

textile to fold towards the side of the more extensible

inflation channel. This inflation folding mechanism is

visualized in Figure 3 and applied in further investigations.

Material explorations first built on soft robotics techniques

[7] by casting silicone inflation pockets directly to the garment fabric. This method led to flexible pockets that

were easily inflated and could fold over 40 o

from their flat

deflated state (Figure 4). However, due to the thinness of

the silicone layers the approach was deemed insufficiently

repeatable and durable to meet the design goals.

A more successful technique was heat-sealing plasticized

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sheet materials and fusing them to fabric. Layers of Mylar polyester film and paper fuse the Mylar edges when ironed,

leaving an airtight inflation channel in the shape of the

paper layer. This inflation channel is affixed directly to the

fabric using double-sided fabric fusing material.

Figure 4: select pneumatic experiments: silicon (L); Mylar (R)

FINAL DESIGN

The final design for the Awakened Apparel pneumatic

folding skirt incorporates the following elements:

A body-fitting shape created from a modified Miura fold origami pattern that curves when folded. Heat-fused, laminated Mylar inflation channels embedded into the fabric of the garment.

Shape-change throughout the skirt generated from the

multi-sided mountain and valley inflation channels and activated through use of a single foot-pump.

Unique aesthetic inspired by the underlying origami pattern and a clothing-appropriate texture.

Figure 5: inflation folding pattern—red channels are affixed to the underside of the fabric, blue to the topside

The final origami pattern is based on a Miura fold with curved radial fold lines, and varying angled vertical fold

lines (Figure 5). The ‘mountain’ folds (undersides fold

together) have angles 30-110% greater than the ‘valley’

folds (topsides fold together). This results in a curving

conical shape, which decreases in length by over 90% and

increases in curvature by up to 40% when folded. The

simple repeated pattern enables easier construction.

Figure 6: inflation channel layers heat-sealed in fabrication

Heat-fused laminated Mylar inflation channels (Figure 6) satisfy all of the approach parameters as it provides a

reasonable level of shape-change when inflated by foot-

pump (folding up to 23 o ), is repeatable and robust, and

provides an acceptable softness and pleasing aesthetic.

Figure 7: final Awakened Apparel prototype

Figure 7 shows the modified Miura origami used with heat-fused laminated Mylar channels. Due to the single folding direction when inflated, the alternating mountain

and valley fold inflation sections were distributed on the

underside and topside of the fabric respectively to create the

alternating directions of folding.

For maximum robustness, each air channel had its own inlet

and is connected to the foot pump via a tubing system in the top of the skirt.

DISCUSSION We created Awakened Apparel, a pneumatic folding skirt that values aesthetics and functionality, serves to motivate material explorations, and defines key dimensions for future shape-changing fashion.

Design goals, including material texture, aesthetic, and robustness were largely achieved. The piece was

constructed primarily of clothing fabric paired with small

sections of Mylar film that slightly increased material

stiffness but were not offensively unpleasant. Texture

could be further improved by limiting tubing sections used

to connect skirt to the foot-pump. Careful selection of skirt

form and colors—inspired by architectural examples and

stormy sky palate suggested by pneumatic actuation—led to

a fitting aesthetic. Materials displayed acceptable

robustness, and automation of the assembly process would

minimize leakage caused by human error. Satisfaction of

the design goals lead to a truly wearable garment that serves

as an initial embodiment of our vision.

LIMITATIONS Basic actuation was achieved within the constraints of the design parameters, though further development is required

to reach the full desired effect. Pneumatic folding was

highly successful on small samples (up to 40% curvature

increase), but the weight of the overall garment limited

movement in the larger piece (8% curvature increase; 8%

length contraction). Further work to improve the extent and

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detail of this shape-changing technology will explore

additional techniques from soft robotics such as lighter

materials, improved geometries, and soft electro-pneumatic

control systems [4].

FUTURE WORK A second prototype, which embodies the full storyline of

our vision (Figure 1) and implements transitions between

the various expressive states, remains as future, yet fully

achievable, work. Currently, pneumatic actuation operates

through a foot-pump and depends on manual intervention

by the user. Through future addition of electronics—e.g. bluetooth, basic sensors—we will be able to acquire the

information needed to make our vision of more fluidly

responsive clothing a reality. Information-based transitions

can rely on readily available open-source APIs to access

data such as stock market results or weather conditions to

transform clothing into an ambient device. As the field of

affective computing advances, sensors could be

incorporated into the design to achieve emotion-based

transitions [5, 10]. Functional changes will be situational or

temporal by calling on GPS location or time of day. They

could also remain mechanical, controlled exclusively and

unobtrusively by the user. Our vision for interaction serves

as a launching point for further collaboration with the HCI

community on shape-changing fashion.

CONCLUSION Awakened Apparel is one of the early examples of fully embedded, pneumatically folding, shape-changing fashion. It draws on diverse fields to propose a framework for creating shape-changing garments that fuse the pleasing

aesthetics of fashion with the functional inflation

technologies of soft robotics. Awakened Apparel uses

materials suited to the body and an inflatable structural

design to truly embed shape-changing actuation into the

fabrics we use in our everyday clothing. We hope our

prototypes and design vision can serve as a launching point

for future work in this multidisciplinary area of embedded

textile actuators for expressive and functional shape-

changing garments.

ACKNOWLEDGMENTS This work began as part of the course Mechanical Invention

Through Computation led by Chuck Hoberman, Dr. Erik

Demaine, and Dr. Daniela Rus.

REFERENCES 1. Agrawal, S. K., Kumar, S., Yim, M., & Suh, J. W.

(2001). Polyhedral single degree-of-freedom expanding

structures. Proceedings IEEE International Conference on Robotics and Automation (Vol. 4, pp. 3338-3343).

2. Baardwijk, M. V., & Franses, P. H. (2010). The hemline and the economy: is there any match? (No. EI 2010-40, pp. 1-11). Erasmus School of Economics (ESE).

3. Berzowska, J., & Coelho, M. (2005, October). Kukkia

and vilkas: Kinetic electronic garments. In Wearable Computers, 2005. Proceedings. Ninth IEEE International Symposium on (pp. 82-85). IEEE.

4. Guizzo, E., & Deyle, T. (2012). Robotics Trends for

2012. IEEE Robotics & Automation Magazine, 19(1), 119-123.

5. Hernandez J., McDuff D., Fletcher R., Picard, R. W.,

"Inside-Out: Reflecting on your Inner State", Work-in- progress in Pervasive Computing, San Diego, CA,

March 18-22, 2013

6. Hovding inflatable helmet for cyclists (July 2013)

http://www.hovding.com/en/how_it_works/

7. Martinez, R. V., Fish, C. R., Chen, X., & Whitesides, G.

M. (2012). Elastomeric Origami: Programmable Paper: Elastomer Composites as Pneumatic Actuators.

Advanced Functional Materials, 22(7), 1376-1384.

8. Nishiyama, Y. Miura Folding: Applying Origami to

Space Exploration, International Journal of Pure and Applied Mathematics, Vol.79, No.2, 269-279, 2012

9. Nojima, T. (2007). Origami Modeling of Functional

Structures based on Organic Patterns.

10. Sano, A., Picard, R. W., "Stress recognition using

wearable sensors and mobile phones", to appear Humaine Association Conference on Affective Computing and Intelligent Interaction, September 2013.

11. Seymour, S. (2008). Fashionable technology: the

intersection of design, fashion, science, and technology.

Springer.

12. Shepherd, R. F., Ilievski, F., Choi, W., Morin, S. A.,

Stokes, A. A., Mazzeo, A. D., .Chen, X., Wang, M. &

Whitesides, G. M. (2011). Multigait soft

robot. Proceedings of the National Academy of Sciences, 108(51), 20400-20403.

13. Weiser, M & Brown J.S. The Coming Age of Calm

Technology. Beyond Calculation: 1997.

14. Yao, L., Niiyama, R., Ou, J., Follmer, S., Silva, C.D.,

Ishii, H. (2013) PneUI: Pneumatically Actuated Soft

Composite Materials for Shape Changing Interfaces.

UIST.

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Indian Journal of Fibre & Textile Research Vol.36, December 2011, pp. 327-335

Design and engineering of functional clothing

Deepti Gupta a

Department of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India

The process of design and engineering of functional clothing design is based on the outcomes of an objective assessment of many requirements of the user, and hence tend to be complex and iterative. In this paper, the user requirements (besides the primary requirement of functionality) have been classified under four subtitles, namely physiological, biomechanical, ergonomic and psychological. The correlation between various characteristics of clothing and these requirements has been discussed. Subsequent steps involved in the ergonomic design process such as selection of materials, size and fit determination, pattern making, assembling and finishing have been listed out. Influence of technological advancements in related fields on each of these activities is discussed with a view to emphasise how the process of functional clothing design is different from design of everyday apparel. The fast developing field of functional clothing represents the future of textile and apparel industry, particularly in growing economies like China and India who will be the largest producers as well as consumers of these high tech products. Challenges being faced by this sector and a road map to meet the same have also been proposed.

Keywords: Clothing engineering, Comfort, Clothing design, Ergonomic design process, Functional clothing

1 Introduction Unlike fashion clothing, which is essentially a

product of the designer’s creative instincts, the process of designing functional clothing begins and ends with the user specific requirements. These requirements, whether for performance or for comfort, are determined by the environment in which the user operates, and the activities that he or she performs.

Clothing, by its nature has a restrictive effect on body movement as well as on transport of heat and moisture from the body. Clothing can be abrasive, noisy, smelly or unattractive. Clothing designed specifically for certain functionalities has been shown to cause heat stress, reduce task efficiency as well as range-of-motion

1 of the wearer. The process

of design therefore begins by first establishing the many requirements of the user. Subsequent processes are based on meeting, to the best possible extent, these user requirements. Figure 1 shows the flow chart of steps involved in the design of functional clothing. In this paper, the user requirements (besides the primary requirement of functionality) have been classified under four subtitles and the correlation between various characteristics of clothing and these requirements are discussed. Subsequent steps involved in the

ergonomic design process such as selection of materials, size and fit determination, pattern making, assembling and finishing have also been listed out. 2 Requirements from Functional Clothing

Each class of functional clothing has a well defined functionality which distinguishes it from the other classes. However, in addition to this specific functionality, all functional clothing classes must fulfill certain requirements which are common to all users. These considerations can be classified into the following categories: physiological, biomechanical, ergonomic and psychological considerations. Effective functional wear is based on the integration of all of these considerations into the design of a clothing system. 2.1 Physiological Requirements

These relate to the human physiology and anatomy – shape, size, mass, strength and metabolic activities of the body or the need of the human body to feel comfortable in a clothing system. To what extent these needs are met is determined by the shape, size, feel and design of the garment, materials selected and their response to internal and external stimuli such as extreme cold, heat, rain, sand or snow. Ease of use, wear and removal has to be considered in case of first responders, motor disabled and elderly groups.

—————— a E-mail: [email protected]

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Fig.1—Flow chart showing the steps involved in design of functional clothing

The primary factors affecting the physiological needs are the energy metabolism, clothing thermal properties (as determined by the heat and mass transfer characteristics of clothing assemblies) and the ambient climatic conditions. Given the multitude of responsible variables, it is extremely complex to predict the comfort aspects of a garment accurately. These are affected by clothing penetration by solar and thermal radiation, interactions with moisture in clothing, effective latent heat of evaporation in clothing, heat and vapour resistance and clothing ventilation (through fabrics and specialized openings at optimal body areas).

2.2 Biomechanical Requirements

Biomechanics deals with the mechanical characteristics of human body as well as the kinematic, dynamic, and behavioral analysis of human activity. Its applications address mechanical structure, strength, and mobility of humans for engineering purposes — the unusual postures and movements of the users , such as crawling, crouching, fire fighting, flood relief, climbing, zero gravity and manipulating objects. As clothing forms an intimate covering of the human body, mechanical interactions take place between clothing and muscles, skin and tissue at different parts of

the body, while the body is moving and working. The shape and fit of the garment vis a vis the human body, pressure and friction exerted by the garment on the body are some of the factors which affect this aspect.

Depending on the design and fit, all clothing exerts some pressure on the body. Pressure may also be intentionally applied on specific body parts for therapeutic and rehabilitation applications in the form of compression garments. Distribution of this pressure is determined by the mechanical properties of body parts, e.g. fleshy parts sustain pressure better than bony parts. Biomechanical considerations form the basis of design of specialized clothing classes, e.g. sportswear, where compression may be applied on selected muscles to enhance performance and reduce fatigue. Similarly, clothing for body sculpting is designed to preferentially compress, lift or support body parts based on anatomical and biomechanical considerations.

Application of too little pressure is ineffective while too much pressure can restrict the blood supply and cause edema or severe debilitation

2 .

Designer must know that body parts where major blood and lymph vessels lie, are more sensitive to pressure than the rest. Disregard for these considerations can lead to the wearer experiencing unpleasant and sometime debilitating sensations such as thermal discomfort, rubbing, chafing, localized pressure development and restriction of movement. 2.3 Ergonomic Requirements

Ergonomics is defined as the science of work: of the people who do it and the ways it is done, of the tools and equipment they use, the places they work in, and the psycho-social aspects of the working situation

3 . It has been shown that

compared to a semi-nude body, the movement, speed, accuracy, and range of motion may be reduced in a clothed body, while muscular exertion may be increased, e.g. the integral joint mobility of an astronaut can be reduced to 20% of normal in a typical space suit

4 . The ability to receive visual

and auditory feedback may also be compromised when performance wear is worn

1 .

Ergonomic considerations dictate that the mechanical characteristics of clothing match the motion, degree of freedom, range of motion and force, and moment of human joints. The working

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postures, materials handling, movements, workplace layout, safety and health considerations should be given due consideration while developing the style, cut and features of a functional garment.

Size of a garment vis a vis the size of body or ‘fit’ is another critical consideration in design of functional garments. Clothing which is too loose can get caught during work and may impede movement but that which is too tight will be uncomfortable to work in. Either way, an ill fitting garment can severely compromise the safety and performance of the wearer. In applications where monitoring devices/sensors are built into the clothing, the fit is even more critical as the sensors have to be in intimate contact with the body in order to be effective. The ergonomic efficiency of a clothing system can be evaluated objectively by using specially devised human mechanics and operational performance tests

5 .

2.4 Psychological Requirements

Psychological aspects relate to how human beings feel, think, act, and interact under a given set of circumstances. As clothing is an extension of one’s persona, strong feelings are often associated with its appearance and aesthetics. Considerations in terms of users’ psychological and social behavior in response to events, people and/or environments e.g. acceptance by peer group, pride, identification, etc becomes important. Clothing items which are perfect in comfort and function may be completely rejected by the users if they do not ‘look right’ or are not perceived as smart and conveying the proper image. Psychological expectations and preferences of the user must therefore be given due consideration so as to create functional clothing which is in tune with their social and cultural background, geographical location, age, sex, activity and work profile.

These considerations are of vital importance when clothing is designed for special groups such as disabled or elderly. Clothing items have been known to be often not accepted by the target groups as it makes them stand out from the rest. These groups prefer clothing which has enabling features for their needs but does not look different and helps them to appear “normal”. In other words, people prefer the functionality to be unobstrusive.

For other user groups, aesthetic requirements are secondary in importance to functional requirements in design of functional clothing, but are nevertheless

important. It has been reported that medical clothing which looks good can actually facilitate effective social acceptance and lead to an improved quality of life for the disabled. Aesthetics of the clothing are as important as performance aspects in some sports such as tennis, skiing, motorbiker’s clothing and swimming. Assessment of psychological aspects of clothing can be done through subjective methods based on user surveys, feedback and preferences as well as study of cultural and demographic features. 3 Process of Clothing Design

Once the user requirements have been established, the next step is to identify and select appropriate materials, followed by the design of clothing assembly, pattern engineering and the final assembling of these heterogeneous materials to create multilayer or composite assemblies in a manner that allows them to adequately fulfill the requirements of comfort, protection and functionality

6 .

3.1 Material Selection

The material properties of fabrics can be extremely complex and difficult to predict. Textile fabrics are made up of a series of yarns produced from fibres, which interact with each other in many ways. The constituent fibre or yarn properties, weave or knit patterns and geometry of yarn and fabric structures, affect the overall material properties. Anisotropy, non- linearity and hysteresis are some characteristic features of textile structures. The stresses and strains to which textiles would be subjected by the working body need to be considered while choosing materials. Some requirements common to all functional clothes are that they should be light in weight, thermoregulatory, elastic, antimicrobial, aesthetic and durable. Specialised applications require materials that are anti UV, anti ballistic, anti impact, fire retardant, abrasion resistant, cut resistant, water repellent, high visibility and NCB (nuclear, chemical and biological) barrier.

Innovative fibres with special properties, special fabric and web forming technologies and developments in chemical and mechanical finishes make high performance textiles an important element of functional clothing design. A variety of materials with widely varying properties are now available due to rapid progress made in the field of technical textiles. Specific functional needs may require the use of judicious combination of

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materials ranging from polymers and metals to ceramics, composites, laminates and membranes

7 .

Some innovative developments in material science, which are expected to play an increasingly important role in the design of functional clothing, are discussed below. 3.1.1 Stretch Fabrics

Stretch fabrics are integral to design of functional clothing. From additional comfort to enhanced mobility, muscle support, muscle alignment and body part compression—all are now possible by strategic use of stretch fabrics. The efficiency and performance of textile sensors and electrodes, in particular, depends on the nature of contact with the body which can be controlled by the stretch characteristics of the fabric. Fabrics with 1 way, 2 way and 4 way stretch are being developed to offer controlled stretch and functioning. Pattern pieces have to be suitably engineered to provide the required stretch and fit in a product. 3.1.2 Smart Textiles

Smart textiles are materials that sense and react to environmental conditions or stimuli, such as those from mechanical, thermal, chemical, electrical, magnetic or other sources. Examples include chromatic materials which change colour with change in environment, phase change materials for thermoregulation and shape memory polymers which change shape with change in temperature.

3.1.3 Biomimetic Textiles

Biomimetics is a field which deals with development of materials which are inspired by natural phenomenon. From mimicking skin’s function to enhancing skin performance, more and more materials are being developed which imitate living systems. Breathable wet suits - based on the pores of leaves, self cleaning effects based on the lotus leaf and sharkskin effect (Fig. 2) for better hydrodynamics in water are some concepts which have already been commercialized. 3.1.4 E-textiles

Incorporation of ICT components into textiles has added a whole new functionality to this field. These sophisticated materials can exhibit complex multidirectional behaviour by sensing, reacting and activating a specific function. Conductive yarns, flexible and elastic sensors, wireless tools and alternate power sources form an area of intensive research for the development of electronic textiles. Textile based wearable products for health and fitness monitoring in patients and athletes are available. Research continues to expand the applications of use and develop products which are lighter and more comfortable to use. 3.1.5 Nanotechnology in Textiles

Developments in nano fibres (electrospinning), nano finishes, nano membranes and nano composites can be used to impart functionalities which were

Fig. 2—Biomimetic fabric for low hydrodynamic surface drag for swimsuit inspired by shark skin 8

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hitherto not possible to achieve in textiles. Antimicrobial, anti UV, stain repellent, fire resistant, antistat, moisture control and thermoregulation properties can be imparted at the molecular level without affecting the inherent flexibility and comfort of fabrics. Progress in this field is expected to yield multifunctional fabrics which are flexible, lightweight and comfortable, making them the ideal choice for complex functional clothing applications.

3.1.6 Use of Air in Textiles

Another innovative development, specifically relevant to the design of functional clothing is the increasing use of air in protective and medical clothing to keep the systems light in weight. Hollow core fibres, woven spacer fabrics, raised knits and 3D fleece fabric are all means of introducing air in the system for cushioning, insulation or moisture transport. Double layer fabrics with a 3D spacing structure between the inner and the outer fabric face offer superb moisture management and great thermal insulation or ventilation, depending on the construction

9 . These fabrics are used in medical

field for applying compression, providing support or transport of fluids

10,11 . They can also be used instead

of foams in protective gear for shock absorption.

3.2 Membranes and Coatings

Breathability is an overriding factor in material selection today. Coatings while imparting special properties often make a fabric non breathable. Developments in membrane technology over the last few decades allow the fabric to remain breathable on the inside while being impenetrable on the outside. Membranes have micro pores which provide a barrier against wind, water, chemicals, microbes and harmful vapours present in the environment while allowing vapour (perspiration) to escape. Other properties that can be imparted by membranes include transparency, flexibility, elasticity, oil resistance and high tensile and abrasion resistance. They are being increasingly used to provide breathability to otherwise water or wind proof clothing used in high-performance sports apparel, foul weather clothing, military and industrial uniforms and medical clothing.

3.3 Accessories and Trimmings

While fabrics form the major component of functional clothing, an equally important component is the accessories that go into making up of the complete assembly. Today, it is possible for a garment to be made up of up to 25 different materials

that include buttons, zippers, pullers, snaps, fasteners, tapes, cords and braids, high visibility strips, labels, wadding, padding, belts and buckles. Suitable selection and placement of accessories can go a long way in providing multiple looks, ease of donning, opening, maintenance, handling, improved comfort and safety to the user. Special fasteners for motor disabled, water proof and fire retardant zips for specific applications are some such examples. 4 Clothing Design

As discussed above, technical textile materials are the primary building blocks of functional clothing. However, to capitalize on the special functionalities provided by high tech materials, it is important to club them with equally innovative methods and techniques of clothing design and manufacturing. New materials require newer methods of cutting, sewing and joining to handle and convert them into performance clothing systems. Design of clothing must move away from the conventional domain of designing in 2D (material centric) to designing in 3D (garment shells). Availability of advanced CAD/CAM technologies in the last few years has made this possible to a large extent. For example, 3D body scanning technology allows the creation of anatomically accurate models of the human body which can be used as a base for virtual or real designing as well as fit testing of garments in actions and postures which closely simulate real life usage of clothing. Once finalized, CAD systems are further able to translate the final design into patterns, pattern grades and markers while CAM systems including computerized sewing machines take care of the sewing process

12 .

4.1 Steps in Clothing Design

Development of a piece of clothing takes place in several interdependent yet disparate processes with its final appearance, fit and functionality being influenced by each one of these steps

13 . The following

paragraphs discuss the steps employed in design of functional clothing and the way in which modern technologies and advances are transforming the same. 4.1.1 Body Measurement and Sizing

Generating body measurements of the target group tend to serve as the first step in clothing design. Conventional standardized size charts used for traditional apparel design cannot be used for design of functional clothing as those are based on traditional

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anthropometry, where the body measurements are taken in fixed, static poses and the data available is one dimensional in nature. Such data contains measurements which indicate the size but do not yield any information about the complex human body shape in curvature or postures.

Ergonomic block development requires 3D anthropometric data captured in multiple realistic postures. 3D body scanners can be used to measure the population in static as well as dynamic mode to capture the shape, size and posture data. Ergonomic measures such as the range of motion also need to be collected and considered in designing. For more accurate understanding of the change in body shape or the restrictions posed by clothing while performing specific activities like swimming, jumping, crouching, human motion analysis systems can be used.

The issue of sizing is further made complex by the fact that since the type and nature of measurements required varies from one type of application (swimming, skating, cycling, skiing) to another, independent size charts will be needed for each type of clothing. The size roll in each case will also have to be developed depending on the type of clothing being designed. 4.1.2 Pattern Engineering

Making of patterns is the next step in the development of a garment. It is the process of converting a 3D garment design into flat 2D constituent pieces. These flat irregular shapes represent various sections of a garment which when joined together using a process such as sewing will yield the 3 D garment shape

14,15 . Making of

patterns currently is a multi-step process which is largely iterative, empirical and based on trial and error approach

16,17 . A lot of tweaking, adjustment or

fitting is required in this 3D-2D-3D process to achieve the desired fit and performance.

Functional clothing design needs to be based on a system that accurately represents the geometry of the human body not only in a static mode but also in the kinetic mode during work and motion. It is because of this, that the traditional pattern making approach of working on flat front/back/sleeve panels is found to be limiting. Pattern shapes of ergonomic garments need to follow the 3D contour and physiology of the human body and correspond exactly to the size and posture of the user. Functional clothing patterns are therefore best designed in 3D, i.e. on the body itself.

Further, functional garments would require “zoning” of patterns, i.e. several different fabrics to make up a pattern piece such as front or side panel, mesh fabric for ventilation in the underarm area, compressive fabric for applying pressure on specific muscles, stretch fabric for providing additional joint mobility, spacer fabric for insulation or impact resistance in the chest area and so on (Fig. 3). Thus, pattern blocks may need to be developed in totally new ways to allow for use of multiple pieces in a block. Based on the study of a moving body, patterns need to be engineered for ergonomic design in such a way that they allow enhanced mobility and reach in areas that show strain during vigorous activity (crotch, under arm, knee and elbow). Articulated knee and elbow designs need to be worked out. There are number of current research efforts in the field of 3D body modeling and computerized pattern making systems using 3D data

18-21 .

Availability of 3D body scans and corresponding advances in pattern engineering has made it possible to design in 3D keeping the above considerations in mind. Pattern shapes are drawn directly on the 3 D scan of the body in action, conforming to the surface contours as shown in Fig. 4. These selected 3D regions are flattened to produce 2D patterns. Mechanical properties of fabrics can be factored in the 3D pattern and a coloured simulation of the deformation stresses and strains when the garment is worn can also be seen. Such research will hopefully lead to reduction in development times and improvement in fit, besides reducing the uncertainties inherent in the current design process

22-24 .

4.2 Assembling of Garment Components

Pattern engineering involves the process of determining the shape and size of each 2D pattern that

Fig. 3—Garments showing zoning of patterns (a) first gear Kilimanjaro motorcycle jacket, and (b) 2XU men compression shorts

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Fig. 4—Designing in 3D (a) drawing patterns on a cyclist in motion, and (b) flattening of the 3D patterns

24

will be put together to create a 3D shell. Once these patterns have been created, they have to be cut, assembled and joined. They also have to be connected to the means of opening and closing the garment (buttons, zippers, fasteners) and such other accessories that go into the making up of a complete garment assembly. The shape of patterns as well as the selection of joining and assembling technologies (sewing, bonding, fusing) is again dictated by the activity, posture and environment in which the user will be operating as well as the properties of materials used.

Assembling of multiple fabric panels having varying properties requires sophisticated handling techniques. Traditionally sewn seams can sometimes compromise the integrity and functionality of engineered clothing. New techniques of joining materials such as taped seams, welding (high frequency, ultrasonic and laser) and adhesive bonding are often used to assemble these systems. 3D moulding is another technique used in contoured garments used for body shaping and support. Because of these trends, the new age garments are looking cleaner, fitting better, they are also lighter in weight and less bulky (Fig. 5).

5 Testing of Clothing for Functionality Once an assembly has been created, it has to be

tested extensively for performance. Test methods such as EN469, 1995 are available for testing of performance clothing, particularly protective clothing for certification purposes and quality control. However, these methods continue to test the properties of constituent materials such as material heat and vapour resistance, flammability, tensile behaviour, etc. No matter how good the properties of fabric are, poor garment design or construction can compromise its functionality

Fig. 5—Women's mountain hardwear effusion power jacket having clean lines, non bulky appearance and better fit

severely. Hence, methods that test the whole garment assembly rather than just the fabric are required

25 . The compatibility of materials with each

other, their durability and robustness of construction are also important considerations. Other aspects of concern relate to the interaction of garment with the human body, effect of garment design, size, fit and manufacturing processes on material properties, etc. Hence, holistic test procedures which test for physiological load, heat protection, loss of performance, rain/moisture protection and conspicuity/visibility of the clothing under actual conditions of use are the need of the hour.

Development of such test methods can be quite complex as different classes of functional clothing are designed for performing under different conditions of activity and the climatic conditions. Therefore, what may work under one set of conditions (extreme cold) will be completely unsuitable in another set of conditions (hot and humid weather). The efficiency of a functional clothing system can thus be best determined by field testing on real humans and then supported by more precise objectives measures of fabric properties that correlate to the field results

26 .

Therefore, testing of each type of clothing has to be carried out under environmental conditions that simulate the actual conditions of its use. Then again, use of human subjects for testing and evaluation raises several issues. Different people will react and respond differently under identical conditions making inter and intra subject variability a major problem. Statistical considerations pertaining to comparison of different data sets as well as the ethical issues of conducting tests on humans also have to be tackled. According to Havenith et al.

27 , standardisation on

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all these matters needs to be put into place, while developing what may be called as ‘ergonomic test procedures’. 6 Challenges Faced by the Functional Clothing

Industry 6

The field of functional clothing is one of the fastest growing segments of technical textiles market and has seen tremendous growth in the last one decade. Yet there are following issues which need to be addressed before it can attain its real potential:

• This field requires intense R&D inputs to grow but as of now, suffers from a lack of adequate research data base, scientific guidelines and procedures which are needed to aid the design process. Interdisciplinary nature of the field further makes research difficult and expensive.

• Though the industry has seen significant growth in developed countries, there is a total lack of information and awareness about the nature of hazards and current practices in developing countries. The problem is compounded by the fact that functional clothing design is based on geographical, psychological and socio- cultural considerations. This makes it difficult to develop generic designs which are standardized and globally relevant. First hand data for each geographical and climatic zone need to be generated.

• Many of the technological developments in the field of clothing production and assembling discussed above are still in incipient stages of adoption by the manufacturing industry. Till the time that these become mainstream, affordable and adequate numbers of workers become proficient in their use and operation, growth is going to be sluggish.

• Market forces provide another challenge, in that there is monopolization of high-tech materials (fibre /yarn /fabric/membranes/ coatings) by a few large international players. High material costs and high technological inputs make entry difficult into this sector.

• The largest buyers of functional clothing are either government bodies or large corporates who are often not the users and therefore not aware of the actual conditions and problems faced by the users. Unrealistic technical requirements are

therefore put forth in such cases. Good and reliable user feedback is crucial to the design of performance wear. Direct channels of communication between the user and producer should be opened to facilitate two way flow of information to facilitate optimal design.

7 Roadmap for Future

Functional clothing industry is a Greenfield industry with tremendous prospects of growth. But in order for its true potential to be realized several steps should be taken. The first relates to an accurate estimation of the size of the various sectors particularly in the developing countries with large population and workforce. Guidelines for research need to be proposed with global and regional focus. Multidisciplinary, collaborative, multinational research groups need to be developed for working together. Technological developments across relevant sectors need to be tracked and relevant technologies integrated into the field on a continuous basis. Active support and participation by industries in research can provide a major impetus to the sector.

8 Conclusion

Design and engineering of functional clothing is a complex and challenging process. What adds to the complexity is the fact that the existing systems governing the design of fashion clothing cannot be used to design performance wear clothing and no guidelines are available for designing these high tech systems. User requirements and conditions of use play a critical role in the entire process of design, manufacture and testing. Availability of innovative materials and associated technologies for production and assembling of clothing ensembles for specialized functional applications has paved the path for development of new and innovative garments capable of providing enhanced comfort and productivity and reduced physiological strain for the users. Joint involvement of engineers, designers, physiologists and ergonomists and the user is needed to fine tune the material choice, composition, sizing and assembling issues related to designing of clothing for a specific end use.

References 1 Adams P S, Slocum A S & Keyserling M K, Int J Computer

Sci Technol, 6 (1994) 6. 2 Langan L M & Watkins S M, J Hum Fac Ergo Soc,

29 (1987) 67.

GUPTA : DESIGN AND ENGINEERING OF FUNCTIONAL CLOTHING

335

3 Stephen P & Haslegrave C M, Bodyspace: Anthropometry, Ergonomics, and the Design of Work (Taylor and Francis, CRC Press, UK), 2006.

4 Hu H, Ding L, Yang C & Yuan X, in Digital Human Modeling, HCII 2007, edited by V G Duffy (Springer, Heidelberg), LNCS, 4561 (2007) 855.

5 Rahmatalla S, Kim H, Shanahan M & Swan CC, Transactions Journal of Passenger Cars-Electronic and Electrical Systems (paper no. 2005-01-2688, SAE 2005), (2006).

6 Hendricks D, The European lead market for protective textiles and clothing, paper presented at the PPE Lead Market Workshop, Brussels, 14 December 2009. www.ec.europa.eu/enterprise/policies/.../lead-market.../files/ ptw_hendriks_en.pdf.

7 Shishoo R, Int J Computer Sci Technol, 14 (2002) 201. 8 Singh A V, Rahman A, Kumar N S, Aditi A S, Galluzzi M,

Bovio S, Barozzi S, Montani E & Parazzoli D, Materials Design, (2011), in press.

9 Bruer S M, J Text Apparel Technol Management, 4 (2005) 1. http://www.tx.ncsu.edu/jtatm/volume4issue4/Articles/Bruer/ Bruer_full_149_05.pdf.

10 Anand S, Knit Int, 110 (2003) 38. 11 Elsner P, Karger Gazette, 67 (2004) 2. 12 Ondogan Z & Erdogan C, Fibre Text Eur, 14 (2006)62. 13 Anderson K, Pattern Making: Past to Present,

http://www.techexchange.com/library/Patternmaking%20-%20 Past%20to%20Present.pdf.

14 Young Sook Cho, Keiichi Tsuchiya, Masayuki Takatera, Shigeru Inui, Hyejun Park & Yoshio Shimizu, Int J Computer Sci Technol, 22 (2010) 16.

15 Koh T H, Lee E W & Lee Y T, Int J Computer Sci Technol, 9 (1997) 367.

16 James T, Andy H, Roy J, Tim L & Dan P, Proced Eng, 2 (2010) 3349.

17 Rodel H, Schenk A, Herzberg C & Krzywinski S, Int J Computer Sci Technol, 13 (2001) 217.

18 Cho Y S, Okada N, Park H J, Takatera M, Inui S & Shimizu Y, Int J Computer Sci Technol, 17 (2005) 91.

19 Bigliani R & Eischen J W, in Cloth Modeling and Simulation, edited by A K Peters (Ltd. Natick, MA USA), 2000, 199.

20 Heisey F, Brown P & Johnson R F, Text Res J, 60 (1990) 690.

21 Kim S & Park C K, Int J Computer Sci Technol, 19 (2007) 7. 22 Krzywinski S, Rodel H & Schenk A, J Text Apprael Technol

Management, 1 (2001) 1. 23 Siegmund J, Krzywinski S, Paul L & Kleban V, Text

Network, Nov/Dec (2010). http://www.textile-network.com/ 11-12-2010-november-december/artikel_3d-design-for- protective-workwear-and-men%E2%80%99s-outerwear- _13772_9_924_en.html.

24 Krzywinski S, Siegmund J & Meixner C H, Proceedings, Avantex Symposium, , Frankfurt, 2009.

25 Xiaolin M & Colby C S, J Engg Fibres Fabrics, 2 (2007) 10. 26 Barker R L, J Fiber Bioengg Informatics, 1 (2008) 173. 27 Havenith G & Heus R, Appl Ergonomics, 35 (2004) 3.