Tünde Kirstein

Design and Characterization of Purely Textile Patch Antennas

In this paper, we present four purely textile patch antennas for Bluetooth applications in wearable computing using the frequency range around 2.4 GHz. The textile materials and the planar antenna shape provide a smooth integration into clothing while preserving the typical properties of textiles. The four antennas differ in the deployed materials and in the antenna polarization, but all of them feature a microstrip line as antenna feed. We have developed a manufacturing process that guarantees unaffected electrical behavior of the individual materials when composed to an antenna. Thus, the conductive textiles possess a sheet resistance of less than 1Omega/squarein order to keep losses at a minimum. The process also satisfies our requirements in terms of accuracy meeting the Bluetooth specifications. Our investigations not only characterize the performance of the antennas in planar shape, but also under defined bending conditions that resemble those of a worn garment. We show that the antennas can withstand clothing bends down to a radius of 37.5 mm without violating specifications

Electrical characterization of textile transmission lines

In this paper, electrical characterization and modeling of conductive textiles are presented. A dedicated measurement setup has been developed to allow reliable connection of the textile samples with the equipment cables. Geometrical fabric structures and fabrication tolerances as well as high frequency properties up to 6 GHz for four types of textiles have been determined. Transmission lines with controlled characteristic impedance have been realized enabling the characterization of typical line attenuation factors. This work shows that textile transmission lines can be used for frequencies up to 1.2 GHz and 120 MHz with the maximal lengths of 10 and 100 cm, respectively.

Organic field effect transistors for textile applications

In this paper, several issues concerning the development of textiles endowed with electronic functions will be discussed. In particular, issues concerning materials, structures, electronic models, and the mechanical constraints due to textile technologies will be detailed. The idea starts from an already developed organic field-effect transistor that is realized on a flexible film that can be applied, after the assembly, on whatever kind of substrate, in particular, on textiles. This could pave the way to a variety of applications aimed to conjugate the favorable mechanical properties of textiles with the electronic functions of transistors. Furthermore, a possible perspective for the developments of organic sensors based on this structure are described.

Wireless, low-cost interface for body area networks

Embedding of electronics in clothing raises the demand for wireless interconnections for short distances. A low-power transmitter-receiver concept of low-complexity is a crucial factor for maintaining low costs and battery life in a distributed on-body sensor network. This paper presents such a transmission system based on inductive coupling giving a locomotion sensor mounted on the boot as example.