Textile-based sensors

Principles of textile-based sensors for sleep-monitoring... 

Textile-based sensors have been integrated into mattresses, pyjamas/underwear, and caps/patches to monitor various parameters. This section gives an overview of the state-of-the-art textile-based sensor systems for sleep monitoring. 

In conclusion, and bearing market reports and trend analyses in mind, textile-based sensor systems are and wUl remain promising, providing a lot of area and freedom for integrating new features into our garments and the textiles surrounding us. 

Guo, L., Berglin, L., Li, Y.J., Mattila, H., Mehijerdi, A.K., Skrifvars, M., 2011. Disappearing Sensor -Textile Based Sensor for Monitoring Breathing, Control. In 2011 Intemational Conference on Automation and Systems Engineering (CASE). Singapore, http // dx.doi.org/10.1109/ICC ASE.2011.5997723. 

Meirit, C.F. (2008) Electronic Textile-based Sensors and Systems for Long-term Health Monitoring, PhD thesis. Available from http //repository.lib.ncsu.edu/ir/bitstream/1840. 16/4448/1/etd.pdf (assessed 31.08.14.). 

Table 10.1 Physiological signals that may be measured using textile-based sensors...

There are two main approaches in smart garments for monitoring biomechanics. One area is the use of inertial sensors together with advanced algorithms, the other area is the development of textile-based sensors (De Rossi and Veltink, 2010). 

To improve the comfort and wearability of sensors much research effort is put in the development of textile-based sensors by carefully selecting appropriate materials and designing suitable textile structures. The textile sensors are modelled, washed and tested over a long-term period to guarantee their suitability. 

Results showed that the textile-based sensor behavior is close to the expected one and already at this stage the stmcture might be used to indicate the presence of a pressure. The deviation was mainly due to the lateral movement of the conductive layers. As the distance decreases the rigidity of the spacer stmcture produces a shear force, which makes the conductive layers move laterally so that the overlapping area is no longer constant. Future work should aim to resolve the unwanted lateral motion of the conductive layers as well as to make a precise model of the partially filled capacitor in order to predict the effective permittivity of the dielectric. If fliese issues are taken care of the stmcture will also be suitable for making absolute measurements of either distance or pressure. 

Technical textiles are used primarily for their technical functionality in many different industries. To monitor the functionality of textiles, it is possible to integrate sensors into the textiles. Because textiles are made of yams or two- or three-dimensional strac-tures, the sensor systems should be designed as a part of them accordingly. Smart textiles are concerned with textile-based sensors integrated mechanically and stractu-rally into a textile. The definition is given in Section 4.2. 

The state of the art in developing textile-based sensors extends from sensor fibres to over-coated yams and textiles, but without using a methodical approach. Therefore, a standardized tool that allows the development of textile-based sensors for different application fields has been created for textile manufacturers. It is called the smart 7-step tool, and it is described in Section 4.3. 

The development of a textile sensor and its interpretation of a specific application have been associated with many investigations into different conductive materials, which are lengthy and costly developing processes. Knowledge has already been generated on textile sensors, which now require an appropriate classification and stmc-ture. A classified catalogue, which allows a direct selection of textile-based sensor modules on the basis of measured values, will be presented in the second part of Section 4.3. 

The classified catalogue for textile-based sensors is a tool to give textile manufacturers an overview about all existing sensors and their working principles. 

The textile-based sensor is part of the textile, as seen in Figure 4.2. The textile is also considered part of the sensor. 

Figure 4.5 Smart 7-step tool methodical approach for developing textile-based sensors (using the classified catalogue for textile-based sensors Bosowski et al., 2013).

The smart 7-step tool consists of seven steps to develop a textile-based sensor for a special application area and product with a certain functionality. It concludes a classified catalogue for textile-based sensors, which allows the textile manufacturers to use already existing textile-based sensors (see Figure 4.5). 

Benefits and conveniences are helping produce smart products. The catalogue on hand was designed according to VDl-guideline 2222, sheet 2, Compilation and application of construction catalogues of February 1982. Its purpose is to provide suggestions for the methodical use of textile-based sensors. 

Types of textile-based sensors (measurement parameters)... 

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