Textile sensors to measure sweat pH and sweat-rate during exercise

Sweat analysis can provide a valuable insight into a person’s well-being. Here we present wearable textile-based sensors that can provide real-time information regarding sweat activity. A pH sensitive dye incorporated into a fabric fluidic system is used to determine sweat pH. To detect the onset of sweat activity a sweat rate sensor is incorporated into a textile substrate. The sensors are integrated into a waistband and controlled by a central unit with wireless connectivity. The use of such sensors for sweat analysis may provide valuable physiological information for applications in sports performance and also in healthcare

BIOTEX-biosensing textiles for personalised healthcare management.

Textile-based sensors offer an unobtrusive method of continually monitoring physiological parameters during daily activities. Chemical analysis of body fluids, noninvasively, is a novel and exciting area of personalized wearable healthcare systems. BIOTEX was an EU-funded project that aimed to develop textile sensors to measure physiological parameters and the chemical composition of body fluids, with a particular interest in sweat. A wearable sensing system has been developed that integrates a textile-based fluid handling system for sample collection and transport with a number of sensors including sodium, conductivity, and pH sensors. Sensors for sweat rate, ECG, respiration, and blood oxygenation were also developed. For the first time, it has been possible to monitor a number of physiological parameters together with sweat composition in real time. This has been carried out via a network of wearable sensors distributed around the body of a subject user. This has huge implications for the field of sports and human performance and opens a whole new field of research in the clinical setting

Development of a capacitive bioimpedance measurement system

Bioelectrical impedance spectroscopy (BIS) is a well-established and non-invasive method to determine and monitor body composition. Commercially available bioelectrical impedance systems use coated hydrogel-aluminium electrodes, where the hydrogel acts as an adhesive and as an electrolytic medium. The gel/adhesive is physiologically inert over short periods. However, when used over longer periods, hydrogel-aluminium electrodes present limitations, which capacitive electrodes may overcome. First measurements using capacitive electrodes have shown that commercial devices are not designed to work with these kind of electrodes. The presented high impedance, specially at low frequencies (e.g. 5kHz), presents a challenge for the current injection and therefore for the design of the current source. Within this project, a bioimpedance spectroscopy (BIS) system to perform measurements using capacitive electrodes has been developed. The system has been tested in the critical frequency range, namely in the lower frequency range (5 kHz - 43 kHz). Measurements have been performed using dummy electrical models, which simulate di erent values of skin and electrode impedance. The results obtained show the better performance of the device in comparison to a commercial device (Xitron Hydra 4200, Xitron Technologies) for that frequency range. An important item in this thesis has been the design of a multi-frequency current source able to perform measurements using capacitive electrodes

Development of a capacitive bioimpedance measurement system

Bioelectrical impedance spectroscopy (BIS) is a well-established and non-invasive method to determine and monitor body composition. Commercially available bioelectrical impedance systems use coated hydrogel-aluminium electrodes, where the hydrogel acts as an adhesive and as an electrolytic medium. The gel/adhesive is physiologically inert over short periods. However, when used over longer periods, hydrogel-aluminium electrodes present limitations, which capacitive electrodes may overcome. First measurements using capacitive electrodes have shown that commercial devices are not designed to work with these kind of electrodes. The presented high impedance, specially at low frequencies (e.g. 5kHz), presents a challenge for the current injection and therefore for the design of the current source. Within this project, a bioimpedance spectroscopy (BIS) system to perform measurements using capacitive electrodes has been developed. The system has been tested in the critical frequency range, namely in the lower frequency range (5 kHz - 43 kHz). Measurements have been performed using dummy electrical models, which simulate di erent values of skin and electrode impedance. The results obtained show the better performance of the device in comparison to a commercial device (Xitron Hydra 4200, Xitron Technologies) for that frequency range. An important item in this thesis has been the design of a multi-frequency current source able to perform measurements using capacitive electrodes