Wearable sensors present a new frontier in the development of monitoring techniques. They are of great importance in sectors such as sport and healthcare as they permit the continuous monitoring of physiological and biological elements such as ECG and human sweat. Until recently this could only be carried out in specialized laboratories in the presence of cumbersome and often expensive devices. Sweat monitoring sensors integrated onto textile substrates are not only part of a new field of work but they also represent the first attempt to implement such an innovative idea on a system which will be worn directly on the body. The purpose of this dissertation is to present the design and creation of low cost, wearable, sweat rate and conductivity sensors integrated onto a textile.
Table of Contents
Introduction
Chapter 1 – Wearable sensors
1.1 BIOTEX project
1.2 Sweat
1.3 Applications and sensors requirements
1.4 Market innovation analysis and level of innovation
Chapter 2 – Sweat conductivity and temperature sensors
2.1 Definition and preliminary tests
2.2 Geometry and substrate of electrodes
2.3 Temperature sensor
2.4 Conductivity and temperature sensors
Chapter 3 - Sweat rate sensor
3.1 Measurement of flow
3.2 Humidity sensors
3.2.1 Resistive humidity sensors
3.2.2 Thermal conductivity humidity sensors
3.2.3 Capacitive humidity sensors
3.3 Wearable humidity sensors
3.3.1 Test system
3.4 Sensors based on conductive yarns coated with hydrophilic polymers
3.5 Sensors based on conductive polymer fibres
3.6 Sensors based on a layer of hydrophilic polymer between conductive fabrics
3.7 Test of the sweat rate sensor
Chapter 4 - Calibration of the sensors and results
4.1 Choice of body area for sweat sampling
4.2 Calibration of the sensors
4.3 Results
4.4 Conclusions
Research Objectives and Core Topics
The primary objective of this work is to demonstrate the feasibility of developing non-invasive, wearable sensors capable of performing real-time chemical analysis of human sweat directly on the body. The research addresses the need for low-cost, continuous monitoring solutions in sports and healthcare, aiming to correlate physiological data with biochemical information without the limitations of traditional, invasive laboratory methods.
- Development of wearable textile-integrated sensors for sweat rate and conductivity monitoring.
- Analysis of sweat composition and its potential as a non-invasive diagnostic fluid.
- Design and calibration of multi-parametric sensor patches using conductive polymers and fabrics.
- Investigation into the integration of humidity and temperature sensors into textile substrates.
- Evaluation of system reliability through on-body exercise trials and controlled laboratory testing.
Excerpt from the Book
3.3.1 Test system
A test system was prepared that allowed the flow of air at different degrees of humidity obtained by mixing dry air and saturated water vapor in different proportions. Air of chromatographic quality was supplied at a pressure of 3 bar by a zero air generator (Domnick Hunter, mod. UHP-35ZA) to a distributor from which several gas lines came out. For each line, a valve and a mass flow controller provided a flow of perfectly dry air in the range 0 e 500 ml/min. In the saturated water vapor line (Fig. 21) the dry air was bubbled into a glass vessel containing milliQ water at 50 °C and then cooled in a pipe coil at 25 °C. By mixing dry air and saturated water vapor in various proportions, all the possible relative humidity values (R.H. 0-100%) were obtained. To avoid artifacts due to the inertia of the system (the time needed to reach a stable set-up humidity value), a four-way valve was used either to convey the same flow of dry air or test vapor into the flow-through chamber housing the sensor. The relative humidity of the outcoming air was checked by a thermo-hygrometer, Delta Ohm Digital DO9406), while the sensor impedance was monitored by a precision LCR meter, Agilent E4980A, working at 1 kHz. These instruments were connected to a PC by a RS-232 and USB interface respectively.
An application written in Labview was developed to control the test system and to acquire data in a reproducible way.
Summary of Chapters
Introduction: Outlines the growing demand for wearable sensors in sport and healthcare and establishes the goal of non-invasive sweat analysis.
Chapter 1 – Wearable sensors: Introduces the BIOTEX project, details the physiological properties of sweat, and discusses sensor requirements and market innovation.
Chapter 2 – Sweat conductivity and temperature sensors: Covers the physical and chemical principles of sweat conductivity, electrode geometry design, and the integration of temperature sensors.
Chapter 3 - Sweat rate sensor: Explores humidity sensing technologies, experimental test setups, and the development of sensors using conductive yarns and hydrophilic polymers.
Chapter 4 - Calibration of the sensors and results: Presents the methodology for sensor calibration, analyzes data from on-body exercise trials, and discusses overall findings and future work.
Keywords
Wearable sensors, sweat analysis, sweat rate, conductivity, BIOTEX project, non-invasive monitoring, textile sensors, humidity sensors, conductive polymers, physiological parameters, healthcare, sports medicine, bioengineering, sensor calibration, textile integration.
Frequently Asked Questions
What is the core focus of this research?
This research focuses on the development of wearable, textile-integrated sensors designed to measure physiological parameters from human sweat, specifically sweat conductivity and sweat rate, in a non-invasive manner.
Which fields could benefit most from this technology?
The technology is primarily aimed at sports science for performance monitoring and healthcare for patient monitoring, particularly for those suffering from conditions like cystic fibrosis, obesity, or diabetes.
What is the primary goal of the proposed sensor system?
The primary goal is to enable real-time, on-body monitoring of human sweat without requiring the collection of samples for laboratory analysis, thus providing a more convenient and cost-effective method for users.
What scientific methods were employed?
The study utilized electrochemical sensor design, laboratory testing of material properties (such as hydrophilic polymers and conductive yarns), and controlled on-body human trials to validate the sensor performance.
What does the main body of the work cover?
The main body covers the theoretical framework of sweat monitoring, the design and testing of specific conductivity and temperature sensors, the development of sweat rate sensors using various humidity sensing techniques, and the calibration of these systems.
Which keywords characterize this work?
The research is best described by keywords such as wearable sensors, sweat analysis, conductive textiles, bioengineering, and real-time physiological monitoring.
Why is the "priming time" mentioned as an issue?
The research identified a "priming time" of 10 to 30 minutes as a necessary phase for the sensors to begin functioning effectively, which represents a potential area for future improvement to increase user convenience.
How were the sensors protected against environmental factors?
The sensors utilized materials like kapton for insulation and specific configurations, such as placing sensors on the underside of substrates, to protect delicate electronic components from sweat contamination while maintaining measurement accuracy.
- Quote paper
- Dr. Ir. Pietro Salvo (Author), 2009, Development of wearable sensors to measure sweat rate and conductivity, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/199721
