Quality assurance of encapsulation architecture, including subsequent washing process for permanently mounted wearable sensors

The overall objective of the project wearITmed, Wearable sensors in smart textiles, is to develop a novel wearable sensor system demonstrator. This sensor system aims to monitor symptoms of neurological disorders such as epilepsy, Parkinson's disease and stroke. The wearable sensor system demonstrator, including both integrated gyros/accelerometers and textile sensors, is useful for the evaluation of clinically relevant movement patterns and other physiological parameters, and further to establish disease discriminating and treatment responsive objective variables. The work presented in this paper is focused on ensuring that the wearable sensor system can be cleaned and washed without first removing the electronics. The work includes three main areas; the adhesion and architecture, the molding and finally the washing test performance. Standard wettability and peel tests (Volvo Standard STD 185-0001) were performed on standard test board IPC-B-5 and IPC-9202 test vehicle for selecting the best adhesive and encapsulation materials in form of an epoxy (Epotek 302-3M) and a medical approved silicone (Nusil MED-6019). The molded components were washtested (Standard SS-EN ISO 6330:2012) followed by testing of the electrical resistance (Standard IPC-9202). As a result a total of 22 garments were produced with four individually mounted boards in each garment. The tests showed that the wearable sensors passed the washing tests and were still functional after 10 repeated washing cycles without any change or degradation in resistance or sign of electrical failure. The wearable electronics therefore meets the requirements of being simultaneously resistant to; water, temperature (40 °C), chemical detergents and dynamic forces.