mems in textiles

8/13/2019 MEMS in Textiles

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M MS IN T XTIL S

SUBMITTED BY,

M.KUMAR&

S.SANTHANA RAJAM kumartexstyle@ma!l."#m

sa$t%a$araam@re'!((ma!l."#m

DE)ARTMENT *+ TETI-E TEHN*-*/Y,

JAYA EN/INEERIN/ *--E/E,

HENNAI.

SUBMITTED T*,

+UTURA012

DE)ARTMENT *+ TETI-E TEHN*-*/Y,

BANNARI AMMAN INSTITUTE *+ TEHN*-*/Y ,

SATHYAMAN/A-AM.

mailto:[email protected]






ABSTRACT

MicroElectroMechanical Systems, or MEMS, is an emerging high technology that

has proven to be very successful in several industries such as medical, automotive and

ink jet industries. The technology philosophy is to integrate sensors, actuators and

electronics onto a silicon substrate (polysilicon batch) to form as small as a suare

millimeter micromachine at lo! manufacturing cost. Such advantages prompted

investigating the potential applications of MEMS in te"tiles.

#nitially, it identified possible applications of MEMS technology in spinning,

!eaving, knitting, fiber formation, non!ovens, testing and evaluation, and dyeing and

finishing. $ased on a perceived real need and large potential market for a successful

device, it !as decided to concentrate efforts into the development of a MEMS based

detection device to monitor !arp tension and end breaks in !eaving. Thus replacing the

abrasive and passive traditional drop !ire !ith gentle and active device that has the

potential to e"pand the markets for !eavers. This paper deals !ith the technologies of

MEMS and its various applications in te"tile.



GOAL AND OBJECTIVES:

The potential uses of micromachines in te"tiles have been assessed. Monitoring

!arp yarns tension in !eaving !as selected as the MEMS application to develop. The

traditional heavy drop !ires that detect !arp yarn breaks have been replaced !ith MEMS

based strain and force sensors. %onseuently, yarn breaks are instantaneously detected

and the !eaving machine is stopped. #n addition, !arp tension is measured continuously

during fabric formation and sensors can accommodate high&density !arps. Eliminating

the heavy and vibrating drop !ires should significantly reduce yarn abrasion and filament

breakage. This should improve !oven fabric manufacturing efficiency, uality. ' custom

designed micromachine is under development and is to replace the off shelves sensors

currently used to measure !arp tension. 'n economic analysis and modeling of

!orthiness of using micromachines in te"tiles is also under!ay.

INTRODUCTION

or the last fifteen years, the uiet revolution of microtechnology has taken place

and is promising a bright future for most industries including te"tiles.

Microelectromechanical systems, or MEMS, also popularly referred to as micromachines,

nanomachines, or transducers are characteried by being less than a suare millimeter in

sie. #n the most general form, MEMS consist of mechanical microstructures,

microsensors, microactuators, and electronics, all integrated onto the same chip. MEMS

industry is still at a very early stage of development and the on&going efforts are to!ards

fundamental research rather than commercial applications.

MICROMACHINES: A SUMMARY

DEFINITIONS:

Microelectromech!icl S"#tem#, or MEMS, are integrated micro devices or

systems combining electrical and mechanical components. They are usually fabricated

using integrated circuit (#%) batch processing techniue and can range in sie from



micrometers to millimeters. These systems can sense, control and actuate on the micro

scale, and function individually or in arrays to generate effects on the macro scale.

Micromachines are divided into t!o functional groups* the sensors and the actuators.

A #e!#or is defined as a device that provides a usable electrical output signal in

response to a

signal. The signal is also called in the literature measurand or stimulus. +hen a sensor is

integrated !ith signal processing circuits in a single package (usually a polysilicon chip),

it is referred to as an integrated sensor or smart sensor.

A! ct$tor, is a device that converts an electrical signal, !hich may be taken

from a sensor,

to an action. 'ctuators are further divided into three categories*

Simple actuators that move valves or beams using one simple physical la!

Micromotors, more comple" in the design and the possibilities, and

Microrobots !hich are the latest release in micro&technology and by far the most

fascinating.

A tr!#%$cer is considered as a device that transforms one form of signal or energy

into another form. Therefore, the term transducer can be used to include both sensors and

actuators and is the most generic and !idely used term for micromachines.

SENSORS AND SMART SENSORS:

Smrt Se!#or#:

Sensors are kno!n and been used for several decades. e! advances in electronic

industry have permitted the development of smart sensors. The main difference bet!een

a traditional sensor and a smart sensor is the !ay that they are manufactured. Smart

sensors have all the electronic integrated in a MEMS structure. This is the revolution. The

electronic is usually the e"pensive part !hen using sensors and being polysilicon batch

!hile the sensor is fabricated makes them ine"pensive. igure depicts a photo of a smart

accelerometer used in airbag systems, !ith all the electronics integrated. #ts total sie is



less than -cm. igure sho!s a photo of a silicon !afer !ith one hundred

microstructures, one could be the smart accelerometer of igure.

Air&' AD(L)*

Silico! +,er

-ri!ci.le# U#e% i! Se!#or#

Sensor principles are based on physical or chemical effects. More than /01 effects

are kno!n, most of !hich can be e"ploited for sensor technology. Table sho!s these

physical principles or effects grouped according to the si" forms of physical energy.

T&le: E/m.le# o, #e!#or #i'!l# i! the #i/ e!er'" %omi!# ,or MEMS ..lictio!#



Tem.ert$re Se!#or# E/m.le

Several phenomena or effects are used to assess temperature change, for

temperature sensors. The simplest and most !idely utilied phenomenon is thermal

e"pansion. The most famous e"ample is the liuid&in&glass thermometer. 2o!ever,

sensing temperature can be measured !ith resistive temperature detectors (3T4s),

thermistors, thermocouple, thermoelectric contact sensors, semiconductor, optical and

pieoelectric temperature detectors. 'll these effects can be used for sensors.

5ther 6thermal&based7 effect e"amples are thermistors and 3T4s. They are based

on the change of mobility inside the conductor !ith temperature 8/9. The thermocouple

has a Seebeck effect property. T!o different materials (usually metals) are joined at one point to form a thermocouple. ' temperature difference at the contacts of different

conductors induces an electromotive force in the circuit. 's the temperature changes, the

voltage reading changes too.

Stri! !% Force Se!#or E/m.le

'mong all physical effects given above in Table, strain and force sensors, SS,

are one e"ample of mechanical type of sensor. SS are different from pressure sensors

because they measure a force on a solid, !hile pressure sensors deal !ith a force on a

fluid (i.e., liuids or gases).

There are t!o types of SS* uantitative and ualitative. 0$!titti1e Strain and

orce Sensors, such as strain gauges and load cells, assess the force and proportionally

represent its value into an electric signal. 0$litti1e Strain and orce Sensors are a

$oolean type of output signal and do not represent the force value accurately. They detect

if there is a sufficient force applied and the output signal indicates !hen the

predetermined threshold is reached. %omputer keyboards are using this type of sensor.

This distinction !ill be relevant for the te"tile application described belo!, !here a

uantitative strain and force sensor !as selected to measure yarn tension in !eaving.

irst igure is a picture of t!o load cells and second igure is a picture of t!o strain



gauges used for the application described in belo!, the left one being a half bridge and

the right one a full +heatstone bridge.

Lo% cell ,rom Ome' Stri! '$'e# ,rom Ome'

ACTUATORS

A Re1ie2 o, A1il&le Tech!olo'ie#:

There are several technologies available to linearly actuate simple beams,

microvalves 8-:9, or diaphragms. +hen combined together, these microstructures can

form micromotors. Microrobots are just the most complicated combination of severalmicromachines and they are still at an early stage of development. Table is a tentative

summary of the technologies available in the actuator field.

T&le: Com.ri#o! o, microct$tor# .ro.ertie#



T!o technologies to actuate micromachines have been revie!ed in the follo!ing

section* Shape Memory 'lloy (SM'), using thermal effect and magnetostrictive

principle, using electromagnetic properties. These are just t!o e"amples among others, of

ho! a simple physical phenomenon is used to actuate a micromachine.

A--LICATION OF MEMS IN TE(TILE

A..lictio! Selectio!

$ased on the e"tensive literature survey on micromachines, it !as decided to focus on

an application that !ould have the follo!ing characteristics*

$e feasible !ithin t!o years (time resource limited), in our facilities.

;imited to sensors and smart sensors, not actuators (off shelf sensors e"isting and

being cheaper, please read previous report on the subject)

ulfilling a real need from customers

ot e"isting on the market yet

<enuine !ork (no publication or patent at the time of decision)

;arge market sie to enhance the lo! cost of batch production, and

inally, that !ould meet our second objective for this project* #mprove traditional

manufacturing te"tile



The application chosen !as the combination of t!o ideas that !ere identified

during Spring -::: as potential applications of MEMS in te"tile* monitoring !arp

tension during the formation of !oven fabric and eliminating drop !ires on a !eaving

machine, using sensors and then using smart sensors. %ombining the t!o ideas !as

logical because a broken yarn has a kno!n tension value of ero c. Therefore, if

monitoring !arp tension dynamically is feasible, then, removing the drop !ires is an

additional bonus.

The follo!ing discussion is divided in four different sections. Section - is a

summary of the revie! of e"isting products that monitor yarn tension, regardless of the

area of application. Section !ill demonstrate the usefulness of having a device

measuring online !arp tension and give some potential end use applications. Section /

!ill concentrate on the drop !ires constraints and usefulness.

3. Ex!st!$ 4r#'u"ts measur!$ yar$ te$s!#$

There are many !ays to assess yarn tension, ho!ever, none !as found adeuate for

measuring !arp tension on&line. 4evices measuring yarn tension manually, !ith 2and&

tension meters (Tensitron, 0), or electronically (Shirley, =) are available and been used

for many years in the knitting industry. Some systems measure an average of multi&ends

tension (Shirley, =), or individual multi&!eft tension (Elte", >). Se!ing thread tension

meters and various single threads tension meters used for !arping, un!inding, or yarn

packaging !ere found. 's yarn tension is also of interest in te"turing, t!isting, and

tufting, more devices !ere available.

$y conclusion it !as found that*

+arp tension is often assessed on a single thread basis and the assumption is that

the rest of the !arp is of similar tension.

o device is capable of measuring several single threads tension simultaneously.

Electronic tension meters are for single threads only.

Most devices are not suitable for high&density !arp.

+henever a tension adjustment is performed, it is for the !hole beam, not

individual ends.



Therefore, it is concluded that there is a need for an individual !arp end tension

measurement, !ith a sie accommodating high !arp density, !ith data recording

capabilities and the possibility of capturing several ends tension simultaneously. ' patent

survey sho!ed that this type of device is not patented yet. Some patents !ere related to

!arp tension measurement but nothing close to !hat is envisioned. The vision is a device

made of several sensors, lying under the !arp, capable of recording real time !arp

tension.

5. Im4#rta$"e #( 6ar4 Te$s!#$ Measureme$t

Measuring !arp tension continuously, on single ends, is greatly improving

traditional te"tile manufacturing. +arp tension is the most important cause for end breaks

during the formation of !oven fabrics. 4r. +einsdorfer proved that the number of end

breaks !as directly related to !arp tension. ;o! yarn tension creates a clinging effect,

resulting in yarn breaks. 2igh yarn tension increases yarn stress resulting also in yarn

breaks. igure - sho!s the influence of !arp tension on machine stops.

+r. te!#io! 1#3 e!% &re4# c$r1e

The gray areas represent the three different type of shedding motion. 3egardless

of the type of shedding, there is an optimum !arp tension !here end breaks are



minimied. 4efining the 5ptimum +arp Tension is an important parameter since it

ma"imies the !eaving efficiency of a machine. This number can be used for initial

machine settings for similar fabric patterns and !arps. This number can be estimated

empirically.

4ynamic feedback machine setting can be done. 3eal time information on each

individual yarn tension should decrease the number of yarn breaks as the 5ptimum

'verage ?arn tension is calculated. #f the average of all measured ends is changing

significantly, then the let&off motion could be adjusted, and the overall !arp tension

controlled. #f each end is controlled individually then, each end could be dynamically

optimied. This should reduce the number of breaks dramatically. ' direct conseuence

of this reduction of end breaks is the reduction of stop mark. Every time the !eaving

machine is stopping, there is a stop mark on the fabric. The fabric is then of lesser value.

Measuring !arp tension !ill improve dyeing and finishing uality. Tight and

slack yarns sho! !hen the fabric is dyed. %ertain shades are more sensitive than others.

@sing a fabric !ith a lo!er standard deviation !ill give better results for these shades.

The ratio of yarn crimp to !eft crimp is also dependent on the !arp tension. 's a

conseuence, dimensional fabric stability !ill change according to this ratio. #f the ma"

sett is not reached, a fabric !ill tend to shrink if the !arp tension increases, at constant

pick density, because most of the !arp crimp had been removed. Therefore, under the

conditions specified above, a fabric of higher average !arp tension !ill behave

differently !hen !ashed then a fabric of lo!er average !arp tension.

inally, a fabric !ith a 6!arp tension road map7 gives tremendous information on

its uality. +hen testing a fabric, it is recommended to leave out -1A on each side

(selvage) as they are not representatives of the !hole !idth of the fabric. This number

may increase or decrease thanks to accurate !arp tension data. This road map may also

be used for choosing fabrics !ith critical porosity properties. ' lo! standard deviation

across !idth and across time !ill optimie a controlled porosity.

The end uses applications are numerous. 2o!ever, this device is targeted for high

tech fabric applications* fabrics !ith critical porosity, fabrics that must be close to

perfection (for bio&medical applications), or fabrics that are fragile by nature (like



microfibers) that can not hardly be !oven !ith drop !ires. The tension road map finds

application in the testing of e"pensive fabrics.

7. El!m!$at!$ Dr#4 6!res

's mentioned earlier, eliminating drop !ires is really a conseuence of measuring !arp

tension. Some attempts have been made to eliminate drop !ires, for e"ample Brotecna in

-::0. They presented a laser based device (;aserstop CD1) at #TM' :0. The laser is

placed under !arp sheet and generates a laser beam from one side to another. ' laser

sensor is placed at the other end. The system assumes that if a yarn break it !ould cause

the yarn to fall under its o!n !eight and cut the laser beam. Thus, a yarn break !ould be

detected. The major dra!back of such system is that a yarn does not fall do!n under its

o!n !eight due to yarn friction. %ling bet!een the broken yarn and its neighbor is high

enough to hold it and not necessarily cut through the laser beam that triggers the

detection.

The actual research is focused on lighter drop !ires, !ith improved materials, made of

composites. Therefore, if the !arp tension measuring device is successful, it !ill be

possible to remove these drop !ires. The result !ill be less stress on the yarns and a

reduced abrasion.

Yr! Te!#io! Me#$reme!t !% Co!trol:

?arn tension measurement and control is of interest in many te"tile processes

such as Spinning, !inding, knitting and !eaving. Tension is a critical factor and currently

there are fe! e"pensive !ays to achieve this task. Today, hand held tension&meters, such

as sho!n on igure, are used to test individual yarn one after the other and it takes about

ten minutes for a !ell trained te"tile operator to check a circular knitting machine !ith :=

feeds.

Te"tile manufacturers are interested in identifying tension variations bet!een

spindles. There is a need to kno! !hich spindles are out of the control limits so

correction may be done. 5nline yarn tension and control using MEMS could offer an

integrated solution to the tension variation problem in spinning.



H!% te!#io! meter DTMB

Tension can be assessed using pressure sensors or load cells but a problem of sie

occurs bet!een the yarn and the MEMS. MEMS sensors seem to be too small andMEMS actuators not strong enough to handle the speed, the friction, the lint and the sie

of the yarn. ' possible type of sensor and technical solution could be freuency

resonance based sensor. Many technical issues arise such as machine vibration, lint or

yarn speed. @sing high&speed resolution video camera could also be a non&MEMS

solution. 2o!ever, the environment !ould have to be lint free and this euipment is still

uite e"pensive if used for each individual end in spinning, knitting or !eaving

machines. Strain and force sensors might be the solution.

Mo!itori!' E!% Bre4#

#n !eaving, each !arp yarn is dra!n through a holeFslot of a drop !ire. The drop

!ire is supported by the yarn as long as the yarn is under tension. ' yarn break causes the

drop !ire to fall on a bar !hich is a part of the electrical circuits that triggers the machine

to stop. +hile this traditional !ay of monitoring !arp breaks has been successful for

many years, there are problems associated !ith it. 4rop !ires add abrasion stress and

vibration to !arp yarns, !hich cause yarn breaks or filaments breaks. The problem is

severe !hen !eaving yarns of microfilament. ' filament in such yarn could be easily

broken a matter, !hich causes potential efficiency and uality problems. +eavers have

been searching for a ne! gentle method to replace drop !ires !ithout success. ;oad cell

or Strain and force sensors could offer a solution for this long&standing problem. More



details on replacing drop !ires and yarn tension measurement !ill be given in the ne"t

chapter.

Electro!ic Te!#io! Meter#

This electronic version is using the same principle as the hand tension meter

described previously, ho!ever, it can be interfaced to a computer to record data for the

purpose of acuiring tension over selected period of times. Shirley 4evelopments

#nternational offers an electronic device, based on a three&pulley system, for individual

thread tension measurement 8==9. igure sho!s the device. This apparatus can interface

!ith a computer to record and do!nload some data to be analyed separately. This device

uotes for G,1-=. The main problem is the sie of the device* 0cm " >.0cm " / cm. This

sie issue makes the device not suitable for high density !arp monitoring. Hivy&El&-1from ;a!son&2emphill is a very similar product.

Shirle" electro!ic "r! te!#io! meter

M$lti5Thre%# Te!#io! Meter#

Shirley 4evelopments #nternational also offers a manual tension meter !hich

measures the tension of several ends, igure C.C. This apparatus does not allo! the

measurement of single !arp yarn and there is a high degree of subjectivity as the device

may be lifted up or pushed do!n !hich causes significant variation from an operator to

another. 2o!ever, this is a good ine"pensive (G01) measuring device, compared to

previous devices, for a uick check on !arp tension.



Shirle" m$lti5thre%# te!#io! meter



Smrt Clothi!' S"#tem ,or Fireme!:

'pparel applications are the most feasible because 6traditional7 sensors are

already commercialied and they could easily be replaced by MEMS sensors. #f the

sensor is polysilicon batch and integrates some of the electronics, then it ualifies as a

micromachine and in this respect, 6MEMS sensors7 find the same type of applications as

6Traditional sensors7 do.

There are niche markets !here there is a need for monitoring the environment.

Sensors are so small that they could be easily integrated in the garment itself. or

e"ample, there is a vital need for firefighters to measure temperature, moisture and

motionFconsciousness. 'nother e"ample is protective apparel for the ne"t millenium

soldier !here there is a gro!ing need for protection against chemical and biological

threats. More and more gases are used as lethal !eapon and their lack of odor and color

make them difficult to detect !ithout the use of such smart sensors.

The concept is to insert temperature sensors, moisture sensors, and

chemicalFbiological sensors throughout the vest and connect them to a central unit !hich

is able to remotely convey data, thus rescue efforts could be deployed before it is too late.

The current problems are -) !hich sensor should be used, ) ho! to interface the sensors

and the !iring cables and /) ho! to analye the information given by the sensors.

Some products on the market e"ist and meet some of the reuirements. Smart

%oat has commercialied a very nice jacket for firefighters, !hich is currently in the

process of being tested. igure sho!s the jacket and the device. 2o!ever, the device is

combining all the sensing elements only in one location.



Smrt cot .ri!ci.le !% ..lictio!

<eorgia Tech developed a Smart T&shirt, sho!n in igure /.D, that is able to

detect if a soldier has been shot and monitor his vital sign 8=1, >-9. They used optical

!ires and conductive fibers to fully integrate the sensing properties into the garment and

they have attached sensors in their last version of the vest, no! commercialied !ith

Sensate" #nc. #n this case, they are a step beyond !hat is suggested here, using

conductive fibers in the !eave of the garment. The sensors are then mounted at any

location on the garment and allo!s the transmission of information from the sensors.



Smrt Tee5#hirt ,rom Se!#te/

' current research done here at %S@ deals !ith using beta&cyclode"trine that

creates a comple" !ith the lethal gas. The comple" is big enough to be stopped through

the thickness of the protective apparel. The idea is to use this volume and !eight to bend

a micro beam that !ould chemically react or attract the compound. This micro&device

!ould be attached in many different locations on the garment, and the threat could be

transferred to a central unit by telemetry.

A&r#io! Detectio! S"#tem:

Te"tiles fabrics durability is assessed by standard abrasion tests that are

performed to evaluate the resistance of a fabric to continuous rubbing 8C:9. 'STM

specifies a standard test 809 in !hich a fabric sample is sand!iched bet!een t!o sand&

papers and is abraded to a preset number of cycles. 5nce the number of cycles are

reached an operator checks the fabric and compares it to four standard control samples

80D9. ' variation of this standard test is to abrade the fabric until the operator can see

through it. The test is uite subjective because 6see through7 is a subjective

measurement. The idea is to replace this human subjective measurement !ith a sensor

that !ould stop !hen the fabric is abraded. ollo!ing igure is a picture of a Martindale

machine commonly used to evaluate te"tile fabrics abrasion resistance.



Mrti!%le &r#io! te#ti!' mchi!e

There are several !ays to accomplish such evaluation, among these are* pressuresensors, electrical contact or magnetic field intensity. ' better solution !ould be to use

telecommunication s!itches, using a light beam reflection on a micro mirror, as igure

/./ sho!s, to send a signal to a machine s!itch. +ith this techniue, hundred micro

mirrors could even spot the e"act location of abrasion. #n addition, MEMS !ould live

much longer in the ultra clean testing lab rooms than on the harsh environment of te"tile

manufacturing facilities. To the author kno!ledge, abrasion testers manufacturers are

not currently conducting research to develop ne! abrasion machines !ith such proposed

approaches. 4espite these advantages of having a more precise and less subjective test,

customers may not be ready for this device. %urrent abrasion testers have been accepted

for a long time and generated huge fabric databases that fabric producers or buyers are

yet not ready to give up.

Secondly, from a market side, abrasion testing machines are less numerous than

spindles, needles or looms in the !orld. Since MEMS are manufactured using batch

process, such application is not economically attractive at this stage.



CONCLUSION

Someho!, micromachine and te"tile do not seem to belong to the same !orld,

6micromachine7 being the latest high&tech bu!ord, !hile 6te"tiles7 !ith centuries of

e"perience refers traditionally to heavier steel machinery. 2o!ever, using emerging

technologies is a challenge that the te"tile industry has long been embracing as the only

!ay to survive at the turn of this millennium. Matching t!o industries as diverse, even

opposite as the micro&!orld and te"tile manufacturing is no! possible. ot only ideas of

potential projects !ere identified, but also one !as pursued to its full realiation as a

proof that yes, micromachines and te"tile do belong to the same !orld.

#t is no! feasible that !arp tension can be monitored and !arp breaks can be

detected simultaneously on individual !arp ends, using micromachines sensors thus the

abrasive drop !ires (!hich limited !eavers to handle delicate yarns) can be replaced.

+hile the project prototype used a commercial strain gauge to proof the concept, MEMS

chip replacing such strain gauges is being produced and results are e"pected to correlate

!ith those of the commercial strain gauge sensors. #t is e"pected that MEMS !ould find

significant applications in other te"tile processes such as spinning, !inding, !arping,

knitting, non!ovens, and testing and evaluation euipment. 'dditionally, MEMS may be

incorporated into fabrics and garments to produce smart products.

REFRENCES:

www.ntcresearch.org

www.lib.ncsu.e

www.p2pays.org

http://www.ntcresearch.org/

http://www.lib.ncsu.e/

http://www.p2pays.org/

http://www.ntcresearch.org/

http://www.lib.ncsu.e/

http://www.p2pays.org/

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