Realization of smart textile applications with high customer acceptance by use of 3D printing technologies (Smart3D)

3D printing is an innovative technology that enables the development of customised products with high added value. For the European industry, this is therefore an interesting technology to remain competitive in comparison to mass production.

In the Smart3D, 3D printing techniques are used to develop smart textile applications. 

Smart textile products are able to perceive changes in the environment and provide the wearer with additional functionality. The main application areas are safety and protection (e.g. personal protection equipment), medical support (e.g. monitoring and assisting the elderly) and performance enhancement (e.g. fitness and sports). 

A smart textile product usually consists of an energy source (e.g. battery), sensors, a data processor and communication paths. All these components need to be integrated into the textile, which poses challenges. Where current methods fail, e.g. in encapsulation and connections, 3D printing can offer an alternative solution.

The research is conducted by Centexbel (Belgium) and the Hochschule Niederrhein FTB (Germany), supported by FKT (association of the German textile and fashion industry).

To realise smart textile applications through 3D printing, the Smart3D project uses extrusion-based printing techniques that work with thermoplastic polymers: on the one hand Fused Filament Fabrication (FFF), on the other hand pellet 3D printing (e.g. Pollen AM and Arburg Plastic Freeforming).

These printing techniques were used in three different routes: 

In route 1, conductive polymers (more specifically thermoplastic polyurethane, TPU) were developed by adding conductive additives (e.g. graphene, carbon black, carbon nanotubes). These polymers were either printed directly with pellet printers or first converted into filaments for FFF printers. The results show that combining several additives is the most interesting way to obtain good processability, low financial cost and low environmental impact while maintaining an equally good conductivity.

In routes 2 and 3, the focus was on custom encapsulation of electronic components, e.g. sensors or batteries.

In route 2, there are two possibilities that can be combined: direct 3D printing on textile or 3D printing of stand-alone units. For example: an encapsulation unit printed on a T-shirt to hold electronic components (sensor, processor, ...), covered with a 3D printed removable lid, which can have a logo on it. 3D-printed conductive paths can also be placed in the encapsulation unit as a removable element.

In route 3, a custom-made mould was first printed, which was then used to fix an electronic component on textile via low-pressure injection moulding.

Among other things, moulds were designed to encapsulate cable ends on textile, so that external control is possible. Text and figures (e.g. logos) can also be applied to the encapsulation via the mould. Low-pressure injection moulding is possible with both thermoplastic polymers (polyamide, TPU) and 2K PUs (polyurethanes). Based on the results, it appears that 2K PU's offer more possibilities for fine-tuning properties.

Relevant properties of the materials and polymer-textile combinations were extensively tested (e.g. washability, changes in conductivity, ...). Finally, the various possibilities for ecodesign and end-of-life were also examined.