Naslov
Thermochromic Medical Textiles

Autori
Đurašević, Vedran ; Long, Lin ; Parac-Osterman, Đurđica

Vrsta, podvrsta i kategorija rada
Poglavlja u knjigama, znanstveni

Knjiga
Young Scientists in the Protective Textiles Research

Urednik/ci
Bischof Vukušić, Sandra ; Katović Drago

Izdavač
Tekstilno-tehnološki fakultet Sveučilišta u Zagrebu

Grad
Zagreb

Godina
2011

Raspon stranica
285-308

ISBN
978-953-7105-41-9

Ključne riječi
smart textile, healthcare, sensor, temperature-sensing, thermochromism, tehrmochromic colorants

Sažetak
THERMOCHROMIC MEDICAL SENSING TEXTILES Vedran ĐURAŠEVIĆ ; Long LIN & Đurđica PARAC-OSTERMAN Smart textiles have attracted increasing research interests in recent years due to the potential roles that they can play in advanced technologies for healthcare, largely driven by the increasing healthcare demand as a result of the continuing trend of aging population. In the last few decades, breakthrough findings in the fields of material science, medicine and electronics have allowed creation of a new generation of textiles namely, smart and intelligent textiles. By definition, these are active materials capable of sensing and actuation properties, of which the potential is enormous. In terms of sensing, smart or active textiles can be perceived as structures and materials capable of reacting to changes in environmental conditions, deriving from e.g. heat, light, chemical, electrical, magnetic or other sources [1]. According to the extent of intelligence smart textiles can be divided into three subgroups: a) passive smart textiles – i.e. sensors, capable of sensing the environment, b) active smart textiles – sense the stimuli from the environment and react to the changes, they also have an actuator function and c) very smart textiles – adapt their behaviour according to the circumstances in the environment. Potential applications of “smart dyes and pigments” in the development of smart textile materials include various indicators and sensors for elevated UV irradiation, presence of acids, alkali and water, mechanical, magnetic or electric loading or thermal changes. Temperature sensitive textiles employ the phenomenon of thermochromism, meaning that they undergo a reversible colour change caused by changes in heat. In most cases, thermochromic pigments in form of microcapsules are applied to textile, usually by screen printing. The system is composed of three components, encapsulated into a polymeric sphere to form a solid particle. The first component is a pH sensitive dye (spiropyran or fulgide), known as colour former. The second component is the colour developer or proton donor, usually a weak acid (phenol derivative). The third component is a co-solvent, non-volatile, hydrophobic medium in which the colour former and colour developer are distributed. Usually, the co-solvents are hydrocarbons, fat acids, amides and alcohols. Interactions between the colour former and the colour developer are only possible at lower temperatures, in which case they appear in solid state. The result of this interaction is the emergence of a colour. At higher temperatures, the system starts to melt and the interactions are no longer possible. This results in the disappearance of the colour. Although many systems exhibiting similar properties have been synthesised and registered so far, the precise mechanism has not yet been explained completely. There is also a possibility of calibrating the system to respond to a specific temperature and to have a well defined transition temperature range, by incorporating a specific compound. Application spectra of microencapsulated systems very broad and they have found their use in technologies such as carbonless copying paper, liquid crystal [1], adhesives [2], cosmetics [3, 4], insecticides [5, 6], pharmaceutics [7-13], medicine [3, 12] and food [14-16]. Potential impact of “intelligence” that can be attributed to textile materials is significant, whilst too the economic should not be neglected, considering high added value. In terms of medical and protective textiles, diagnosis will be faster and more accurate, treatment and care brought about to a higher level. As smart textiles have already found their way into medical textiles, one can now speak of smart medical textiles. This concept encompasses the use of either electronics or small organic counterparts, such as dyes and pigments combined with a suitable form of textile material. Typical examples of smart textile-based healthcare devices include smart T-shirts and bed sheets for the monitoring of chronically ill patients via embedded sensors for electrocardiograph (ECG), respiration movement, pulse rate, skin temperature, blood oxygen saturation and body position/movement. One remaining challenge in this field of research is the development of a low-cost means to display the changes detected. Therefore, this paper investigates a possibility of using thermochromic microencapsulated pigments in sensing elevated body temperature. Two different application methods of depositing microcapsules onto textile fabrics were investigated. It was found that textile fabrics printed with thermochromic pigments reacted to targeted temperatures by decreasing colouration depth in sufficient percentages for the change to be clearly noticeable. Fastness properties of the printed textile fabric were investigated and results commented, respectively. Due to fastness property issues, the printed thermochromic textiles as presented in this paper are limited to indoor use and low number of washing cycles (Figures 1a and 1b). a. b. Figure 1 SEM images of textile samples printed with thermochromic microcapsules at 5000x magnification: a) After light fastness test ; b) After one washing cycle ; c) These issues are the result of the inclusion of inappropriate binder and may be resolved through altering ink formulation. Guidelines into formulation of thermochromic inks suitable for use on various textile fabrics are given. 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Izvorni jezik
Engleski

Znanstvena područja
Tekstilna tehnologija

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