Components for Smart Textiles

Hochschule Niederrhein. Your way.

Luminaires in multicolor

Optical fibres

 

Optical fibres guide light along their fibre axis, which is fed into the core of the fibre by a laser light source. If the cladding is damaged, the light can also escape laterally and unique light effects can be created, which can be used for fashion and medical purposes.

Using a special stitch device in the field of technical embroidery, the Tailored Fiber Placement (TFP), optical fibers are automatically attached to the textile as a laying medium. In this way, particularly individual designs can be realized.

 

Our electroluminescent textiles consist of several layers that build upon each other. On basis of a capacitor principle, a transparent electrode layer, a light-emitting layer and a top electrode layer are first applied to the backside of a transparent textile structure. Turning the front side of the fabric up, the light is emitted through the textile substrate. The pattern on the front side of the textile has been digitally printed so that the light penetrates more prominent in non-printed areas.

Electroluminescent textiles

A textile pixel

 

Electrochromic coatings can be used to relize passive displays that change color when (low) voltage is applied. For this purpose, poly-3,4-ethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS) was sprayed onto a polyethylene polyethylene terephthalate (PEPES) membrane. Together with an electrolyte layer, an ion storage layer and a textile counter electrode made of coated polyester fabric, it is possible to generate individually addressable pixels. These change color within just 2 seconds when a voltage of only 2 volts is applied. The textile pixel is born.

The full publication on the subject can be found at DOI: 10.3390/s20195691

 

 

 

Functional sequins are conventional jewelry sequins that are provided with a conductive circuit layout using a specially modified process of printed circuit board technology and equipped with electronic components using automated assembly. Surface mounted devices such as light emitting diodes, pressure, temperature, acoustic, humidity and motion sensors, resistors and solar cells are mainly used due to their very small design. The functional sequins are placed on a textile using embroidery technology in an automated process, attached and contacted with conventional embroidery thread or directly with a conductive embroidery thread. Not only the contact is made with the conductive embroidery thread, complex embroidered circuits can be designed as well.

Functional LED sequins

Sensor technology on and from textile

Moss embroidered electrodes for electromyostimulation

 

 

Moss-embroidered textile electrodes are washable, adapt to the geometry of the muscle groups to be stimulated, offer high and even skin contact with low pressure and have a pleasant surface feel. In addition, the electrodes can be individually positioned and offer a wide variety of electrodes. Moss-embroidered electrodes are made with the moss and chain stitch. These are special embroidery processes with a one thread system based on the principle of loop formation using a hook needle.

 

 

Electrodes can pick up and deliver electrical impulses in a targeted manner. Polyacrylonitrile (PAN) and an electrically conductive yarn were processed into a textile electrode structure using a special knitting technique. The resulting bandage is intended to stimulate human muscles. An electrically conductive and stretchable hydrogel was developed for the electrode structure for good impulse transmission and protection of the skin. The electrodes only come into contact with the environment on one side and are closed on the back by PAN.

Hybrid textile electrode structure for biomedical applications

Textile pressure sensors

At Niederrhein University of Applied Sciences we have developed textile pressure sensors based on both the resistive and capacitive measuring principles. We often use technical embroidery and screen printing for realizing these textile sensors. We have also already completed initial studies on knitted and woven sensors.

Textile Humidity Sensors

Monitoring of humidity is a widespread application for process control, lifetime assessment of components and assemblies, environmental control systems, medical textiles, working clothes and personal safety systems. To allow spatially resolved mapping of this parameter over a larger textile surface, discrete sensor elements are presently placed separately onto the textile material. Hence, the actual integration level of sensors in textile materials and therefore the value creation is rather low. To achieve a higher integration level, textile sensors are needed. To serve this need the development and characterization of different textile-based humidity sensors using spinning, printing and coating technologies have been realized at our labs. We could show that the developed sensors were sensitive towards relative humidity in the range of 25 to 80 % rel. humidity.

We need "juice" - Textile energy sources

Textile solar cells and photodiodes for textiles

 

 

A self-sufficient power supply is indispensable, especially for portable Smart Textiles solutions. Basically, at our research facilities we pursue two approaches in this area:

the integration of miniaturized photodiodes, which can be applied to textiles using sequin embroidery we develop textile-based dye solar cells (Grätzel cells) on textile materials with solvent-free electrode and semiconductor layers.

 

The increasing interest in smart textiles leads to the necessity of local textile-based power supplies which are flexible and compact regarding size and weight. There are two designs to realize textile batteries: fabric- and yarn-based batteries. Both types could be successfully realized at Hochschule Niederrhein using gel-electrolytes on basis of gelatin.

 

DOI: 10.1088/1757-899X/175/1/012058

DOI: 10.1088/1757-899X/254/7/072016

 

Textile Batteries

 

Especially using textile batteries in immediate proximity to the human body, it is desirable that the used materials are non-toxic and eco-friendly. We developed a prototype of a textile-based battery using a biodegradable gel-electrolyte. Thanks to a textile separator, the battery can be bended without getting short circuits.

 

The research project "Development of a puncture sensor for stab-protection clothing" was carried out by the project partners Bache Modeland GmbH, Freyer & Siegel Elektronik GmbH & Co. KG and the Niederrhein University of Applied Sciences. The aim of the project was to develop an alarm system for stab-resistant outerwear. By means of conductive yarns and the application of conductive dispersions, a grid-like sensor was integrated into a stab-resistant cardigan, which controls the integrity of the jacket. A microprocessor monitors the conductive tracks by testing them at regular intervals with a test current of a few microamperes. If the processor detects that the test current is outside a previously specified range, an alarm will be triggered. The alarm can be sent to a central control centre, such as a taxi station or public transport control centre, together with a GPS signal to locate the attacked person. From there, contact can be made with the victim and, if necessary, an ambulance service can be alerted.

Stab Detection Sensor