Washability of Flexible Printed Circuitry for Wearable Electronics Applications

Abstract

Wearable electronics are predicted to be 60 billion dollars market by 2024, according to the recent 2020 International Data Corporation (IDC) news. Textile substrates are typically porous and hence the fabrication of electronic circuitry is by heat-transferred which initially was printed on a non-porous substrate such as heat transfer polymer (HTP). Such a fabrication process paved the way for developing new smart clothes. However, most of the developed smart wear clothes are still not practical as they cannot be washed. Therefore, in this study, the effect of the washing, such as water immersion and mechanical stress/bending, towards printed circuitries will be investigated. The test vehicles are silver and carbon circuitries on HTP-polyester and polyethylene terephthalate (PET)-based substrates. The test vehicle on PET serves as a reference. The test vehicles include printed heater patches. The heater patch consists of printed carbon in a rectangle shape and printed silver lines on the two sides. The resistance values of the circuitries were monitored before and after twisted and immersed in water. The results indicate that the effect of water immersion is significant. The resistive value in water could increase up to 12% and 2% for HTP and PET-based test vehicles, respectively. However, the increase in resistance is temporary.