Woven Temperature and Humidity Sensors on Flexible Plastic Substrates for E-Textile Applications

In this paper, a woven textile containing temperature and humidity sensors realized on flexible, plastic stripes is presented. The authors introduce two different sensors fabrication techniques: the first one consists of a conventional photolithography patterning technique; the second one, namely inkjet-printing, is here presented as an effective, low-cost alternative. In both cases, we obtain temperature and humidity sensors that can be easily integrated within a fabric by using a conventional weaving machine. All the sensors are fully characterized and the performances obtained with the two different fabrication techniques are compared and discussed, pointing out advantages and drawbacks resulting from each fabrication technique. The bending tests performed on these sensors show that they can be successfully woven without being damaged. A demonstrator, consisting of a mechanical support for the e-textile, a read-out electronic circuit, and a graphical PC interface to monitor the acquisition of humidity and temperature values, is also presented and described. This paper opens an avenue for real integration between printed electronics and traditional textile technology and materials. Printing techniques may be successfully used for the fabrication of e-textile devices, paving the way for the production of large area polymeric stripes and thus enabling new applications that, at the moment, cannot be developed with the standard lithography methods.