III. RESULTS AND DISCUSSION

A. Electrocardiogram detected by fabric electrodes

The wearable system realized by flat-knitting technology, showed in Fig. 1, is able to acquire simultaneously five ECG leads. An example of signals detected is reported in Fig. 4.

Fig. 4: Detail of ECG signal in basal condition detected by using fabric electrodes realized by flat-knitting technology

Similar results have been obtained by detecting ECG signals with the seamless garment, see Fig. 5.

A more accurate analysis of system performances has been reported on previous publication [8], [4].

Fig. 5: Detail of ECG signal in basal condition detected by using fabric electrodes realized by a seamless-knitting technology

B. Characterization of piezoresistive fabric sensors

The electrical resistance variation of strain fabric sensors due to mechanical deformation has been studied.

The change in resistance is correlated with the change in strain amplitude. The piezoresistive behaviour of knitted of piezoresistive fabric sensors is mainly due to the change of conductive contacts during the local deformation of textile structure. This mechanical deformation modifies the charges path, not only for the different interaction among the single filaments inside the yarn, but also for the deformation of the knitted fabric loops during the stretching and relaxing phase

[3]. A yarn is a very complex structure where several filaments or fibers are twisted together, the resulting fabric is a network where the contacts among the single filaments are random.