Printed Sensors on Textiles for Biomedical Applications

The respiratory rate is an important biomedical parameter to monitor human physical condition and investigate potential respiratory dysfunctions. The pulmonary plethysmography (PP) is a technique for measuring changes in tidal volume during the respiratory activity. The PP often requires intrusive and invasive devices that are not comfortable, as masks or mouthpieces. In the literature, there are less invasive techniques available for respiration measurement based on woven conductive yarns and metal electrodes (Paradiso et al. Proc. 25th Ann. Int. Conf. IEEE EMBS 4:3720–3723, 2003; Yang et al. 2012 IEEE-EMBS International Conference on Biomedical and Health Informatics (BHI):875–877, 2012; Maarsingh et al. J Appl Physiol 88:1955–1961, 2000; Di Rienzo et al. Proc. 27th Ann. Int. Conf. IEEE EMBS:7167–7169, 2005). In this paper, a sensor measuring the respiratory rate was implemented by screen printing (serigraphy) of the piezoresistive material on T-shirt directly. The printed pastes have produced a flexible thick film in order to measure horizontal stretching movement of the T-shirt. A circuit the amplitude impedance modulus variation close to a resonance condition was implemented. The experimental results show a maximal amplitude sensitivity of about −5.18 Ω/cm.