Electrohydrodynamic Printing of Conductive Microstrips on Hyperelastic Substrates for Fabrication of Flexible and Stretchable Sensors

Recently, sensors are subjected to a vast transformation process from planar and rigid devices towards flexible or rather stretchable versions. This can be traced back to a continuous development of novel functional materials and the enhancement of various fabrication techniques. Thus, entirely new sensor designs and applications can be realized. In the present paper, electrohydrodynamic (EHD) printing as advanced non-contact printing technology is utilized for patterning of conductive microstrips serving as stretchable sensor elements. As printing medium particle-based silver inks with particle diameters in the range of 50nm and 1μm are used. In contrast to the most commonly applied substrate materials for flexible printed sensors, e.g. polydimethylsiloxane (PDMS), hyperelastic and shape-adjustable thermoplastic polyurethane (TPU) with a thickness of 100μm is applied within this work. In addition to straight conductive silver lines more complex geometries such as meanders with improved stress-strain characteristics are realized. With respect to the antagonistic material behavior of TPU and the silver inks as well as their processability, EHD printing represents a promising fabrication technique for future stretchable sensors.