Laboratory Color and Appearance Measurement,
Faculty of Textile Science, Technical University of Liberec

 

ABSTRACT

Sunburn, skin cancer, premature aging, and suppression of the immune system are some of the harmful effects of acute and cumulative exposure to ultraviolet radiation (UVR). A decrease of 1% in ozone would lead to increases in the solar UVR at the earths surface and may eventually lead to a 2,3% increase in skin cancer. Wearing clothing, hats, and other protective apparel during sun exposure may reduce risks associated with overexposure. However, fabrics used in summer time apparel often provide poor protection against solar UVR, because they are usually made from light to medium weight fabrics.

Our contribution is not to develop of new UV protective materials, but with advantage use well-known photo chromic dyes or pigments for constructions of new textile based sensors as integrated parts of summer clothes. In our study we would like detect not only UV radiation with sensors as indicators, but also detector of quantity UV radiation dose. We have prepared for this study concentration scale of different UV absorbers and different photo chromic dyes. We will show comparison of sensitivity modulation of our UV textile based sensors with measuring units (spectroradiometers) and reproducibility.

Key words: UV radiation, textile-based sensor, photochromism

INTRODUCTION:

In present time become worse living conditions and increase harmful pollutants in environment, which can non-reversible damage our health and jeopardize full quality our life. Big attention is given in research area respectively in development and perfection of protective clothes specially their barrier features. Protective barriers we understand how the clothes or textiles protects wearer against above mentioned dangerous conditions and if the protection is only partial or the protection is time limited by ambient conditions. Most of protective clothes are not developed for long time wearing. During development of these barrier structures we have to keep in our mind full comfort of acting persons without limitation. Some of protective clothes are equipped by electronics, respectively other sensors or devices, which monitoring and quantify dangerous substances in environment. In present time is big attention given to miniaturization of electronics and also flexibility their connection with computing units [1].

Above mentioned describe concept of protective clothes we call as intelligent structure. Disadvantage of this intelligent structure is no adequate response on the external stimulus, there is only monitoring of external dangerous conditions. This structure we call as passive intelligent textile structure.

Sensors and textile structures, which react adequate response and they are able modulate protective degree in accordance on the external stimulus (change of intensity UV, temperature, press, electrical field etc.) is called as SMART textile. As example of passive intelligent textiles are optical fibres, which leading the not only signal, but they are also sensitive on the deformation, concentration of substances, press, electric power etc. As example of active intelligent textiles could be textiles which react by change own colour in dependence on external stimulus (light, temperature) and called as a chameleonic textiles or heat containing textiles, which are able to store or slack energy according external temperature.

Moreover textile based sensors and active protective textiles has advantages that textile structure is easy customizable by sewing, thermal bonding or gluing. Also there are advantages of easy maintaining (washing, chemical drying) and low specific weight with good strength, tensibility and elasticity. Good features are also workability without change of technology of production and extremely large specific surface. Big advantages are possible integration these types of sensors into system of protective clothes and also their price availability. From these reason is this article directed to research of textile-based sensors with photo chromic behaviour, respectively to study of dynamic behaviour and modulation of sensitivity photo chromic sensors.

In this work is described new definition of colour reversible hysteresis, which is described by hysteresis of colour change curve. This colour hysteresis curve is described by kinetic model, which defines the speed of colour change initiated by external stimulus UV light. Kinetic model verification is done for textile sensors with photo chromic pigment applied by textile printing, fibre mass dyeing.