Wearable technology for bio-chemical analysis of body fluids during exercise

Abstract

Abstract-This paper details the development of a textile based fluid handling system with integrated wireless biochemical sensors. Such research represents a new advancement in the area of wearable technologies. The system contains pH, sodium and conductivity sensors. It has been demonstrated during on-body trials that the pH sensor has close agreement with measurements obtained using a reference pH probe. Initial investigations into the sodium and conductivity sensors have shown their suitability for integration into the wearable system. It is thought that applications exist in personal health and sports performance and training. I. INTRODUCTIONO date the majority of research in the area of wearable sensors has focused on the development of devices which measure physical parameters such as motion, respiration and heart rate [1]- [3]. However, textiles are often employed in sports applications to capture body fluids and wick them away from the skin surface. Such fabrics can be used as a platform for the development of biochemical sensors used to monitor the changing composition of fluids such as sweat under stress or exercise.Sweat is a clear hypotonic odorless fluid often described as an ultrafiltrate of plasma. Its major constituents are sodium, potassium, calcium, magnesium and chloride [4]. It is easily accessible with the sweat rate in human males during exercise measured in the region of 0.85 mg cm -2 min -1 for the lower back. Changes in the composition of sweat can be used to provide information on a person's physiological condition [5]. In addition, prolonged exercise can lead to dehydration and a change in the electrolyte concentrations in sweat. For elite athletes, a visible reduction in performance will occur for a 2 % drop in body weight due to dehydration. Further fluid loss can lead to symptoms such as irritability, headache, dizziness, cramps, vomiting, increased body temperature and heart rate, increased perceived work rate, reduced mental function, slower gastric emptying [6].

A review of wearable sensors and systems with application in rehabilitation

“…Specifically, the BIOTEX project deals with the integration of bio-chemical sensors into textiles for monitoring body fluids. Within this project, researchers have developed a textile based fluid collecting system and sensors for in-vitro and in-vivo testing of pH, sodium and conductivity from body sweat [ 31 , 32 ]. By in-vitro and in-vivo testing of the wearable system, researchers have shown that the system can be used for real-time analysis of sweat during physical activity.…”

Skin-interfaced systems for sweat collection and analytics

“…Sensors include amperometric devices for the detection of various metabolites, including glucose ( 46 , 61 – 66 ), lactate ( 46 , 60 , 67 – 69 ), and alcohol ( 70 , 71 ), through enzymatic reactions that generate an electric potential. Ion-selective electrodes (ISEs) serve as the basis of potentiometric means for detecting various electrolytes such as Na + ( 44 – 46 , 50 , 69 , 72 ), K + ( 46 ), NH 4+ ( 47 ), and Ca 2+ ( 73 ) and for determining pH ( 61 , 69 , 73 – 75 ) levels. Alternative strategies based on electrochemical voltammetry provide routes for sensing heavy metal species, such as Zn, Cd, Pb, Cu, and Hg ions ( 76 , 77 ).…”

E-Skin: The Dawn of a New Era of On-Body Monitoring Systems

“…The platform, tested during cycle ergometry and treadmill running [275], wirelessly transmitted real-time data generated by the continuous flow of sweat that stimulated the sensors within: (1) the potentiometric Na + sensors of polyvinyl chloride (PVC) functional membrane on Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer, (2) the pH sensing layer on an iridium oxide (IrOx) membrane with high sensitivity, and (3) the amperometric-based lactate sensor of doped enzymes on a semipermeable copolymer membrane and surface polyurethane layers. Developing wearable technology could be applied to sports to identify the related chemical changes within biofluids [276,277]. Analytes in sweat and selected detection methods were summarized by Bariya et al [261] in a review that addressed the state-of-the-art wearable sweat sensors within common athletic accessories designed as wristbands or headbands or medically dedicated patch-like devices.…”