NZ630024B2 - Composite sensor fibres and applications therefor - Google Patents

Abstract

composite sensor fibre comprises a filamentary core and an outer layer encapsulating an intermediate sensor layer of a detectably thermochromic liquid crystalline material. The outer layer is transparent and the filamentary core is configured to provides a contrast for facilitating the observation of temperature or temperature gradient changes in the thermochromic material. A fibrous material formed from the above described thermochromic composite sensor fibres is disclosed such as a fabric or clothing item. A dressing that includes a fabric having a matrix of the above described thermochromic composite sensor fibres which fibres indicate localised body temperature changes adjacent the dressing by visibly exhibiting a change in colour or colour gradient is also disclosed. A method of making a above described thermochromic composite sensor fibre comprises continuously delivering the filamentary core as a solid from a supply thereof and co-extruding the thermochromic liquid crystalline material about the core and the outer layer about the thermochromic liquid crystalline material at a temperature that facilitates the coextrusion but at which the core remains substantially solid and the outer layer does not substantially inhibit delivery of the thermochromic liquid crystalline material. n of temperature or temperature gradient changes in the thermochromic material. A fibrous material formed from the above described thermochromic composite sensor fibres is disclosed such as a fabric or clothing item. A dressing that includes a fabric having a matrix of the above described thermochromic composite sensor fibres which fibres indicate localised body temperature changes adjacent the dressing by visibly exhibiting a change in colour or colour gradient is also disclosed. A method of making a above described thermochromic composite sensor fibre comprises continuously delivering the filamentary core as a solid from a supply thereof and co-extruding the thermochromic liquid crystalline material about the core and the outer layer about the thermochromic liquid crystalline material at a temperature that facilitates the coextrusion but at which the core remains substantially solid and the outer layer does not substantially inhibit delivery of the thermochromic liquid crystalline material.

Description

therefor sensor fibres and applications Composite Field of the invention containing thermoresponsive generally to composite sensor fibres invention relatés This particularly advantageous application, such fibres. In a material, and to methods of making incorporating fabrics or non-\ilovens composite thermoch¡omic fibres and to invention relates to or other garment that is with a dressing In one aspect, the inveñtion concerned such fibres. wound in which such provides method monitoring a fabric and a of includes the thermoch¡omic can also be used fibres of the invention a ís applied to the wound. The cornposite sensor dressing (e.g' elements such as building of temperatures over engineering surfaces l0 for the monitoring pþs. wires, cables and . walls, floors and ceilings), invèntion Bacþround of the for applications including bedding, products have been described A number of textile pigments are incorporated thermochromic apparel; hygiene and toys in which microencapsulated patent application phase (e.g. patent 6,444,313 and US fibres as a dispersed US into synthetic (e'g. US using a binding medium a coating on the surfaces of the fibres 2003/0087566), or as Japanese garments a¡e also disclosed in yams, fabrics and patent,4,68l,7gI). Therrnochromic patent publication 48044522 discloses patent publications arrd 4756267. Japanese 59144613 containing cholesteric liquid crystals' composite fibres body garments to track 200810279253 discloses thermoch¡omic patent application US pârents and caregivers' child¡en for use by clinicians, temperature regulation of patients a¡rd to a each being sensitive dyes or colourants, ga¡ment contains at least two thermochromic whether a body is overheating provides a facitity to identify different range. This temperature Described device is working sufficiently' is too or to ascertain whether a heating or cooling cool, polymer fibrous webs leuco dyes into include the addition of mincroencapsulated embodiments .blowing pigments or gaÍnent thermocluomic incorporating by melt techniques. Another 2009/00467760' is described in US patent application thermochromic strip thermometers prevention of cold exposure detection and proposed as a means of providing early garment is or venous insufftciencies. skin surfaces, clinical applications a range of disclosures of medical or There have been proposed patent such materi4ls are crystalline materials. In US 5,806,528, thermoch¡omic liquid are not patients, to ensure that they for fluids intravenously delivered to as temperature indicators patient. US patent application is either uncomfortabte or hamlful to a at a tempfiatu¡e that behaviour when applied product that exhibits thermochromic 2Ot1/0028804 discloses a topical onset of conditions such to be used for diagnosing the to the skin. The product is intended increased temperatures due in the skin of a patient, by identifying necrosis and decubitus ulcers product is described as prèsent early stages of ulcer formation. The topical to inflammation in the the use of either possibly applied as a spray. The patent application suggests being a liquid and is dispersed into a body mixtures or leuco dyes as a thermochromic component, l0 liquid crystalline lotion or soap. indicator a wound dressiríg containing a thermochromic US patent 5,181,905 discloses wom. The while the dressing is being for monitoring the condition of an underlying wound has a liquid crystal tape that is in the forrr of a temperature sensitive thermoch¡omic component tuned to appear colou¡ed containing liquid crystalline mixtures pturality of labelled boxes appear which box or boxes Ternperature determination is dependent on different temperatures. while being worn. coloured the dressing is crystals, sheet coated with liquid patent 4,433,637 describes a thin flexible means for measuring temperatures.of microencapsulated or otherwise, over a btack backing as a the skin. the surface of provide a novel and least aspects, to It an object of the invention, at in one or more useful composite senso¡ fibre. as, an and should not be taken prior art in the specification is not, Reference to any general forms part of the common that this prior art acknowledgment or any form of suggestion jurisdiction prior art could reasonably or that this knowledge in Australia or any other person skilled in the art. rçgarded as relevant by a ascertained, understood and expected to be Summary of the invention provides sensor fibre that In a hrst aspect, the invention a novel structure o1'composite hbre. In this aspect, the invention also rnay be usefully adapted as a composite thermochromic plovides a method of f-olming the cornposite sensor fìbre, fbrmed invention entails a realisation that a fabric or non- woven A second aspect of the in by which from composite thermochromic f,rbres may be effectively incorporated a dressing wound may be monitored witl-rout the use of extemal the condition of an underlying provides of probes. In this aspect, the invention also a method electronics or temperature monitoring a wound.

In its first aspect, the ir"rvention provides a cornposite sensor fìbre comprising ochromics liouid crvstalline material- wherein intermediate sensor laver of a detectablv or temnerature sradient chanses in the facilitatins the observation of temoerature material. thermochromics provides a method of making a composite sensor In this aspect, the invention fui'ther one of claims 1 to 8 core as a d crvstalline material at thermochromics liqui material about the core and outer laver about the solid facilitates the coextrusion at which the core remains substantiallv a temnerature that thermochromics liouid and the outer laver not substantiallv inhibit deliverv of the crystalline material materials. may typically be In an embodiment. thernochromic liquid crystalline predetermined in ordel to achieve a temperature mixtures of liquid crystalline compounds accuracy over predetermined temperature range. indication a generally and the outer layer is transparent For thermochlomic applications, the the observation fìlarnentary core is prelèrably configured to provide a contrast fol facilitating material, for example of or tempelature gradient changes in the thermochromic ten-rperatule <flename> gradients. embodiments of the filamentary core specifrc colour appearances or Advantageous generally genelally section. exhibit a circular or trilobal cross <fìlename> non- not limited to fabrics, extends to materials, e.B. but fi.rst aspect of the invention composite sensor fibres of incorporating the fibrous materials, formed from or wovens and other the invention. that includes a fabric there is provided a dressing the aspect of the invention, In second to the first aspect of sensor fibres according of therrnoch¡omic cornposite having a matrix adjacent the dressing localised body temperature changes which fibres indicate invention, gradient- colour or colour exhibiting a change in visibly wound of monitoring a provides a method the aspect, the invention further In second a matrix of includes a fabric having to the wound a dressing that comprising applying the invention, which to the first aspect of composite sensor fibres according l0 thermochromic visibly exhibiting adjacent the dressing by temperature changes fib¡es indicate localised body or gradient. change in colou¡ colour are preferably'composite aspect of the invention thermochrornic fibres of the second layer contains intermediate sensor the first aspect in which the fibres according to sensor preferably but not material is this application, the thermoch¡omic thermoch¡omic material. For colou¡ or so that the observed materials selected a mixture of liquid crystalline exclusively of the adjacent environr.nent provide indication of the temperature gradient changes an colo¡r range suitable temperature defined temperature range. A a predetermined accuracy over a within Suitable liquid limited to this range. to 45oC but is not for wound monitoring may be 25" in nature. also be non-sterol based compounds but may materials are cholesterol crystalline "comprise" otherwise, the term except where the context requires As used herein, are not intended and "comprised", as "comprises" variations of the term, such "comprising", components, integers steps. exclude fi¡rther additives, the aspects described and further embodiments of of the present invention Fwther aspects given way description, by the following paragraphs will become apparent from in the preceding the accompanying drawings. and with reference to 'of example description of the drawings Brief with reference to of example orily, will be further described, by way The invention now in which: the accompanyrng drawings, embodiments of composite idealised cross-sections of I is a diagram of altemative Figure first aspect àf ,n" invention; sensor fibre according to the composite for forming of a suitable melt extrusion arrangement Figure 2 is a schematic in Figure l; sensor fibres such as those depicted in Figure the of the arrangement illustrated a cross-section of die Figure 3 is simplified visible range as a ñ¡nction plot of the reflectance spectra in the Figure 4 is a based particula¡ mixture of choleste¡ol fibres incorporating a temperature for composite sensor crystalline materials; and liquid response to the application greyscale the thermochromic Figure 5 depicts (by shading) to that fibres similar knitted from composite thermochromic a warming human hand to a fabric illustrated in Figure 4. response cha¡acteristic having the the Invention of embodiments of Detailed description for composite altemative cross sections two prefened but non-limiting Figure I shows core 12 cornprises a so-lid filamentary the invention. Each fibre sensor fibres l0 according to of a detectably thermoresponsive an intermediate sensor layer an outer layer 30 encapsulating core is of solid In one case, the of generally tubular configuration. material. Outer layer 30 is íllustrations trilobal. Both other the core is symmetrically cylindricat form while in the these forms. idealized: real fibres approxirnate in which the intermediate composite sensor fibre is one particularly useful form of the provides a contrast core 12 thermochromic material, the layer 20 comprises sensor and the the intermediate layer, gradient changes in visibility of colour and/or colou¡ facilitating or colour gradient changes- colour transparent for viewing those outer layer 30 is substa¡rtially pigment dark containing black or core 12 is a polymer particula¡'interest, the embodiments of a fibre mixtu¡e' Such liquid crystalline layer 20 is a thermoch¡omic and the intermediate ssnsor temperature is to blue as the the full visible spectrum from red changes colour through reversibly of the liquid by the composition range determined through a working temperattue increased ther¡nochromic unehcapsulated general behaviour of Consistent with the crystalline mixnue. behaviour. thermoch¡omic the exhibits clear and reversible mixftres, fibre liquid crystalline fibre, preferably made or multifiiament may be a monofilament The filamentary core 12 process of formation metal in view of the polymer or high temperature stability from a (PEEK) ketone polymer is polyether ether particularly suitable such below. A described provides essentially preferably though not pigment. The core black or dark containing layers of the fibre' support for the further mechanical trilobal rnaterial, the layer 20 is a thermoch¡omic the where the intermediate l0 In case viewed contrast backgrormd when this maximises the I is prefened because shape of Figure later described material in the the flowability of the given angle without compromising from any layer 20 is case, the inlermediate fibre.Inthis process for formation of the compòsite coextrusion tip of the outer layer 30 at the the core L2 contacts segments and into th¡ee longitudinal divided layer. anchored to the outer lobe, and is thereby each generally ci¡cular in cross-section' core 12 may be the case, hoúever, the In simplest elliptical, or, in with flat sides, or linear or elongated it may be, for example, other embodiments, etc- quadralobal, hexalobal, more complex shapes, melting point wax, or general a low may in be a tiquid, The intennediate sensor layer oily at room mixtwes are waxy or preferred liquid crystalline temperature. The solid at room temperature,20"C. particular invention, in fibre of the the composite sensor A preferred process for forming of the process. A schematic a melt coextrusion fibre, is preferred composite thermoch¡omic into fed simultaneously provided Figure 2. The three components process is in setup for this profile simplified cross-sectional coating" coextrusion. A for "wire strand a die 40 configured in Figure 3. configuration is shown a successful die black containing polymer fibre/filament high melting temperature A prè-prepared through the vertically pigrnent) is threaded containing carbon black (for example PEEK pigment spool at a steady rate as controlled point 42 and through from a supply 5l die 40 via feed drawn liquid pre-prePared thermochromic godet 50. At'the same time a a downst¡eam system point a liquid purnp 52, a¡rd rate into feed 44 from crystalline mixture 20' is fed at a steady point 46 by a melt extruder 54. a steady rate as a melt intô feed appropriate polymer 30' is fed at polypropylene, which layer is polymer for the or¡ter transparent An example of a suitable for below than the iruner core material, example, temperature substantially lower has a melting PEEK has a melting perform very well in the illusuated setuP- and was found to 200oC, temperature of 343"C. mixture to enable the liquid crystal pump 52 is maintained at a temperature to The iiquid for in the range 40-80"C. l0 flow sufficiently, example fibre 12' as it passes polyner are coated onto the core The crystalline and layers liquid about the crystalline material 20' of the thermochromic liquid ttuough the die by co-extrusion the die at '. On exiting layer 30' about the liquid crystalline material core 12' and of the outer intermediate layer between and traps the thermoch¡omic 48 the outer polymer layer solidifies godet system 50 then passed through the resultant composite fibre t0 is core fibre and itself. The at the winder onto a bobbin further elongation) and is collected (which may or may not involve godet The liquid by the system. 12' ís draurn/pulled through The PEEK fibre/filament dependent on into the die at rates polymer melt are simultaneously fed crystalline material and of the liquid loadings. The rate of release fibre and the desiréd the throughput speed of the PEEK frbre formed pump 52. The composite sensor controlled by the liquid crysølline material is to 300 micrometres, in the range 5 to 300 micrometers, typícally has a diameter þreferably on the relative to these ranges,.depending but not limited preferably 60 to 300 micrometres, most profile' of each component in cross-sectional amounts even coating a substantially prccess conditions are maintained to enstue the above During cool for example, PEEK fibre. If the die is too onto the outside of the of bpth components the die between material out of the progress of liquid crystalline polypropylene melt blocks the co- a r¿mge that facilitates temperature of the die is set in polymer layers. Thus the little (and typically suffers therefore the core remains substantìally solid but at which extrusion material. A not inhibit delivery of the liquid crystalline and the outer layer does or no distortion), feed components is meets these requi¡ements for the described temperatwe range that suiøble below the melting of the outer material but be above the melting temperature found to to 200oC. in the range 170'C of the inngr core material, for example temperature the invention include fibres according to the first aspect of Applications of composite surfaces, for example for thermal mapping of both engineering indicator devices ternperatr:re pipes, human body surfaces. (walls, ceilings), wires, cables and and surfaces floors and building with the second of the illustrated composite fibre, in accordance A particularly useful application the composite fibre l0 may wound dressing. ln one ernbodiment, aspect of the invention, is a e.g. between 2mrn wound dressing of .varying diameter, l0 \ryoven or knitted into a tubular layer 20 is the intermediate sensor the thermochromic material of lQcm. For this application range 25.- temperature working anywhere within the "pathological" tuned to have a temperature working temperature would €.g. frostbite patients,'the 45'C. In more specialist applications, patients themselves to the fibre enables clinicians and adapted. As a wound dressing, suiøbly wound beds, especially across and around or map the temperature distribution monitor, observe the dressing is food ulcers, while such as leg ulcers, pressure ulcers and diabetic chronic wounds use of any in that it does not rely on the worn. This type of system is advantageous being and otherwise impractical. or probes, which can be invasive, expensive electonic equipment within the colour observed be achieved by comparing the localised Temperature indication can can be cha¡t. Absolute temperatures fibres with a calibrated colou¡ temperature therrnochromic wound bed gradients different a¡eas of a as well as temperature differences or between recorded give colour gradient should ideally tissue. The observed colour or and undamaged surrounding within 0.1 and 0.5"C temperature of the sunounding environment an accruate indication of the mo¡e "C to 45"C, or a range, e.g. the aforementioned over a defined pathological temperature focused range e.9.27-37"C or 33-37oC. problems such as the early detection of monitoring of wounds can aid in Temperature (typically a local increase in temperature), and infection accompanied by harmful inflammation (typically by a local blood supply to tissue accompzinied necrosis and intemrptions of o¡ tissue lead to more relevant developing problems can in temperature). Early detection of decrease faster wound closure. of wounds and therefore treatment garments such as thermochromic fibrous material include applications for Other be at risk of monitoring of undamaged skin deemed to ot socks for the temperature stockings the wound formation a venous leg ulcer, with the hope that a chronic wound such as developing cases. prevented altogether in some may be appears red at the lower a liquid crystalline mixture, the material By careful selection of through the full visíble spectrum r¿mge and the colour shifu range of its working temperature is completely green as the temperature increases. The behaviour (red to yellow to to blue) reversible. to be satisfactory a¡e mixtures crystalline mixtures that have been found Liquid (COC), ca¡bonate cholesteryl cholesterol based compounds including cholesteryl oleyl (CD), mixtures include: nonanoate (CN) and cholesteryl 2, 4dichlorobenzoate Acceptable % CD I 50Y'COC,40%CN, 40Yo COC,40% CN, CD cN, 30% cD iii 300Á coc,40% include but are not limited to cholesteryl cholesterol based derivatives Other relevant chloride. The mixture propionate, cholesteryl oleate, and cholestèryI benzoate, cholesteryl into a glass vessel and more cholesterol based derivatives be prepared by weighing two or to form a homogenous until all components melt and cornbine heating to 90-110"C with mixing when cooled to room develops a thick and oily consistency clear liquid. The resulta¡rt mixture determine the working and their relative amounts temperatue. The compounds chosen mixtures include both mixture. Other suitable temperanue range of the the¡moch¡omic compounds. cholesterol based and non sterol based changed, crystalline are not dramatically that these liquid mixtures It has been established passage through the die and resultant responses, by their in respect to their thermochromic polypropylene polymer layers' the PEEK and trapping between from the red end of specûa in the visible range shifts 4 shows how the reflectance Figure (ii) mixture for the liquid crystalline as thê temperature is increased the spectnrm to the blue mixture and found to compare well to that of the unincorporated above. The behaviour has been is reversible. (ii) a PEEK core, liquid crystalline mixture Composite thermoch¡omic fibre comprising of varying diameters was knitted into a tubular fabric dressing and a polypropylene outer layer (by greyscate shading) the the fabric 100, and depicts f¡om 2mm to l0cm. Figure 5 shows fabric. of a warming human hand to the thermoch¡omic response'to the application THE INVENTION ARE AS FOLLOWS: THE

Claims (1)

1. CLAIMS DEFINING core and an outer layer 1. A composite sensor fibre comprising a filamentary detectably thermochromic liquid crystalline encapsulating an intermediate sensor layer of a core is configured to wherein the outer layer is transpalent ancl the f,rlarnentary 5 material, gradient oÍ temperature provide contrast for fàcilitating tl-re observation of temperature material. changes in the thermochromic liquid to claim 1 wherein the thermochromic 2. A composite sensor fibre according selected to achieve a material is a mixture of liquid crystalline compounds 10 crystalline a predetennined temperature range. predetermined tempelature indication accuracy over I or 2 wherein the ternperature or A sensor fibre accorcling to claim 3. composite in coloul or colour gradient. tempelature gradient changes comprise changes hlamentary core is sensor fìbre accolding to claim 7,2 or 3 wherein the 4. A composite generally generally trilobal sections. cross-section selected fiom circular and I to 4 wherein the outer layer A composite sensol fibre according to any one of claims below that of the ltlamentary core. 20 has a melting temperature substantially of clairns 1 to 5 wherein the hlamentaly 6. A composite sensor fibre according to any one fibre. core is a monofilament or multifilament 1 to 6 wherein the hlamentary 25 7 . A composite sensor hbre according to any one of claims pigment. polyester (PEEK) containing black or otherwise dark core is ether ketone in the any one of claims I to 7 of a diameter 8. A composite sensol' fibre according to preferably 30 to 300 micrometers. range 5 to 300 micrometers, sensor fibres according material fonned from ol incorporating composite 9. A fìbrous one of claims I to 8. fabric' material according to claim 9 comprising a 10, A fibrous <frlenâme> according to clairns 9 or 10. 1 1, A clothing item that includes fìbrous material fabric fibrous material according to claim 9 comprising a non-woven 12. A claims 1 to 8 sensor f,rbre according to any one of 13. A method of making a composite core as a solid from a supply thereof and comprising continuously delivering the hlamentary layer material about the core and outer co-extruding the theln-rochrornic liquid crystalline that fäcilitates the thermochromic liquid crystalline matelial at a temperature about the solid and the outer layer does 10 coextrusion but at which the core remains substantially liquid crystalline material. substantially inhibit delivery of the thermochromic rnaterial wherein the thermochromic liquid crystalline 14. A rnethod accolding to claim 13 a predetermined ternperature liquid crystalline compounds selected to achieve is a mixture of or oily at predetermined range, which mixture is waxy 15 indication accuracy over a temperature about 200C, liquid crystalline compounds A rnethod according to claim 14 wherein the mixture of to enable the mixture to flow sufficiently. is fed by a pump at an elevated temperature selected sensor of thermochromic composite A dressing that includes a fabric having a matrix body temperature I 8, which fibres indicate localised fìbres according to any one of claims to in colour ol colour gradient. the dressing by visibly exhibiting a change changes adjacent fibres are selected claim 16 wherein the composite sensor 25 17. A dressing according to 25"C to the dressing within the range localised body ternperature changes adjacent to whereby or colour gradient. 45'C are visibly exhibited by a change in colour liquid crystalline to claim 17 wherein the thennochromic 18. A dressing according selected to is mixture of liquid crystalline compounds material of the composite sensor fibres a range 25"C to accllracy within the temperature a predetermined temperature indication achieve 4s"c. <fìleneme> mixture of liquid crystalline compounds 19. A dressing accolding to clairn 1 8 wherein said is a mixture of cholesterol based compounds. <filenâme>