Comparison of suitable digital technologies to build robust and washable electronic textiles
Customized textiles can be rapidly produced by digital printing in an efficient way.
The digital printing technology permits not only to style textiles. Printed electronic circuits and even solar cells are today able by digital printing processes on films and foils.
The digital print technology has the potential to structure textile surface and to functionalise it as well.
Comparable textile structures are described in publications as well as are demonstrated on fairs. However, they do not permit the performance characteristics needed by the costumers.
When we focus on electronic textiles highly conductive lines with surface resistances of 0.1 - 0.2 Ohm/□ are required.
Surface resistances of the conductor tracks of less than 0.2 Ohm/□ can already be achieved on the basis of classical metal particles with silver particles of approx. 30 μm by screen print pastes.
The flexographic print of a combination of silver nanoparticles and carbon nanotubes combined with a with flash light sintering step yields 1 Ohm/□.
Such formulations have a viscosity of about 500 mPas which is also typical for inks used with the ChromoJet technology.
However, trails have not been successful. Suitable with the ChromoJet technology are dispersions of conducting polymers yielding a surface resistance of >200 Ohm/□, novel gold nanoparticle s chemical modified by conducting polymers as well as silver nanowires.
First simulations of the surface resistant and results of silver nanowire prints by the Chromojet technology are shown in present contribution. However, the highly conductive inks tend to sediment.
That is why a bypass system was developed in the frame of the research project MF150063 with the project partner Zimmer Austria to print such inks reliable by changing the supply lines to the print heads. In addition, the latest results of two novel powder digital application technologies DigiFixPrint and DigiFixLASER will be presented.
These two technologies enable to apply microparticles digital to a textile substrate in a much higher concentrations (70%) compare to the ChromoJet application of a 5% dispersion of silver nanowires. The results the powder technologies as well as the silver nanowire ChromoJet print technology will be compared in the present contribution. Both technologies represent promising solutions for the realization of washable electronic textiles.
The results are bendable, robust and especially the digital applied powder coating stays after heat setting permanent on the textile surface. Furthermore, the digital powder technologies DigiFixPrint and DigiFixLASER permit do apply afterglow, electroluminescent, magnetic as well as other functional pigments digitally to a textile substrate by keeping the textile properties.
 B. Oppermann, „Schaltkreise aus leitfähiger Tinte auf sensiblem Untergrund“, medizin&technik 10 (2018) 1. Vgl. auch https://medizin-und-technik.industrie.de/technik/forschung/schaltkreise-aus-leitfaehiger-tinte-auf-s...