In this paper, the washability of wearable textronic (textile-electronic) devices has been studied. Two different approaches aiming at designing, producing, and testing robust washable and reliable smart textile systems are presented. The common point of the two approaches is the use of flexible conductive PCB in order to interface the miniaturized rigid (traditional) electronic devices to conductive threads and tracks within the textile flexible fabric and to connect them to antenna, textile electrodes, sensors, actuators, etc. The first approach consists in the use of TPU films (thermoplastic polyurethane) that are deposited by the press under controlled temperature and pressure parameters in order to protect the conductive thread and electrical contacts. The washability of conductive threads and contact resistances between flexible PCB and conductive threads are tested. The second approach is focused on the protection of the whole system—composed of a rigid electronic device, flexible PCB, and textile substrate—by a barrier made of latex. Three types of prototypes were realized and washed. Their reliabilities are studied.

In this work, three designs of textile antennas, namely, a rectangular microstrip patch antenna, annular slot antenna, and planar inverted-F antenna (PIFA), operating in the 2.45 GHz WLAN band were developed for smart clothing applications. Conductive textile, a copper-plated polyester fabric, was used for fabricating antenna radiators and grounds. An insulating neoprene fabric with a thickness of 4 mm and a permittivity of 1.5 was used for preparing the substrates. The textile patch antenna achieved a maximum gain of 5.96 dBi and a bandwidth of 4.6%. The annual slot antenna showed a moderate gain and bandwidth of 2.9 dBi and 13.1%, respectively. The PIFA achieved the widest bandwidth of 31% but the smallest gain of 1.2 dBi. Furthermore, the performance deterioration of the proposed antennas under various bending conditions was analyzed to evaluate their suitability for wearable applications. Moreover, two 2 × 2 patch and slot antenna arrays were assembled to increase gain and bandwidth. The measured results proved that the developed antenna designs provide superior performance.

Recently, smart textiles, especially for wearable garments that capable of recording vital signals, have attracted a lot of attention. There are many reports about wearable garment-based platforms focusing on the monitoring of ECG, but most of them are for static situation. In this paper, we report a fabric-based garment sensing system to monitor the exercise electrocardiogram (ECG); a wireless communication configuration based on Bluetooth to transfer the signals into a PDA; and an algorithm to retrieve the desired ECG signals from the raw data. In addition, PDA can communicate with a remote server by WiFi to insure that all data could be stored exactly. The experimental results in resting, walking, or jogging, show this wearable garment system can steadily, continuously and precisely get the ECG, RRI and HRV.

In the last few years, smart textiles with fabric-based sensors to monitor gesture, posture or respiration have become popular. Although the fabrics seem to have nice performance to some extent, the 2-D form of fabric-based sensors limits the resolution. In this paper, a yarn-based sensor is developed. The performance of the sensors relies on the structure of the yarns and the response while extended depends on the twists per meter (TPM) of the yarns. For verifying the feasibility, a simulation system based on respiration monitor using yarn-based sensors is reported. We find the sensors output can closely track the periodic input signals.