Textile based colorimetric pH sensing: a platform for future wearable pH monitoring

Wearable electronics is a natural application field of miniaturized sensors, low-power analog and digital devices, microcontrollers and efficient power conversion components, that are able to manage battery power in an optimal way. In the wearable electronics field for biomedical applications, smart textiles are very attractive as sensing devices. They can be fixed with dedicated indicators in order to detect physical quantities which could otherwise be difficult to measure with standard methods. This paper presents the development of a novel platform that using smart textiles, retrieves the information about the pH value by measuring color, which is easily manageable by a readout electronic system. The pH meter consists of a cotton fabric, with a color indicator sol gel fixed on it, in association with an extremely low-power and high-sensitivity electronic system. The device main blocks were fabricated and characterized, with the aim to obtain a wearable sweat pH-meter. The paper discusses the electronic readout innovative features, from the standpoints of performance and sensing properties.