Biosignals often have to be detected in sports or for medical reasons. Typical biosignals are pulse and ECG (electrocardiogram), breathing, blood pressure, skin temperature, oxygen saturation, bioimpedance, etc. Typically, scientists attempt to measure these biosignals noninvasively, i.e., with electrodes or other sensors, detecting electric signals, measuring optical or chemical information. While short-time measurements or monitoring of patients in a hospital can be performed by systems based on common rigid electrodes, usually containing a large amount of wiring, long-term measurements on mobile patients or athletes necessitate other equipment. Here, textile-based sensors and textile-integrated data connections are preferred to avoid skin irritations and other unnecessary limitations of the monitored person. In this review, we give an overview of recent progress in textile-based electrodes for electrical measurements and new developments in textile-based chemical and other sensors for detection and monitoring of biosignals.

Textile-Based Sensors for Biosignal Detection and Monitoring.

The digitization of textiles (textronics) has created new opportunities for integration with conformable sensors to enable unobtrusive, noninvasive, and continuous decoding of vital body signals. This article provides an in‐depth review of the materials and fabrication methodologies used for textronic sensors per their form‐factor in the textile manufacturing process chain—fiber, yarn, fabric, and apparel. Next, it analyzes the performance characterization techniques currently used for these sensors and highlights the needs for standardized test methods in the following aspects: biocompatibility, thermal and tactile comfort, aging, and operation of the biomedical sensing modality at standard human stretch. It also identifies the significance of pretreatment and conditioning reporting of the textile form‐factors based on their impact on mechanical and electric performance of the textronic sensor. The study concludes by recommending a universal testing roadmap for textronic sensors which is expected to veritably complement the work of different standardization committees, including CEN TC‐248/WG‐31, IEC TC‐124, ASTM D13.50, and AATCC RA111.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/aisy.202100223

Electronic Textile Sensors for Decoding Vital Body Signals: State‐of‐the‐Art Review on Characterizations and Recommendations

Protocol to assess the quality of transmission lines within smart textile structures

Electrically conductive fibers are required for various applications in modern textile technology, e.g., the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. According to the state of the art, fine copper wires, carbon rovings, or metallized filament yarns, which offer very good electrical conductivity but low mechanical elongation capabilities, are primarily used for this purpose. However, for applications requiring highly flexible textile structures, as, for example, in the case of wearable smart textiles and fiber elastomer composites, the development of electrically conductive, elastic yarns is of great importance. Therefore, highly stretchable thermoplastic polyurethane (TPU) was compounded with electrically conductive carbon nanotubes (CNTs) and subsequently melt spun. The melt spinning technology had to be modified for the processing of highly viscous TPU–CNT compounds with fill levels of up to 6 wt.% CNT. The optimal configuration was achieved at a CNT content of 5 wt.%, providing an electrical resistance of 110 Ωcm and an elongation at break of 400%.

https://www.mdpi.com/2073-4360/13/4/590/pdf

Melt Spinning of Highly Stretchable, Electrically Conductive Filament Yarns.

Small portable medical heating device utilizes conductive polymer or a ceramic or the like, an electric heater is formed from a self-regulating conductive material. Materials, heat production from a current through the material, so to vary the resistance has an electrical resistance which varies gradually with temperature. Insulation jacket comprises a self-regulating heater element may be connected to a power source. In one embodiment, a probe that is thermally coupled to the heater extends outwardly from the envelope. In another embodiment, a self-limiting conductive material, adapted electrode pair to deliver radio frequency energy to tissue (or, three electrodes) which is one electrode and the series of the.

Medical heating device and method with self-limiting electrical heating element

Novel textile temperature sensors based on strain-relieved braiding constructions offer attractive monitoring possibilities for numerous application fields involving e-textiles in general, and medi...

Novel temperature sensors based on strain-relieved braiding constructions:

Novel textile moisture sensors based on multi-layered braiding constructions offer attractive monitoring possibilities for many application fields of e-textiles (electronic textiles), especially fo...

Novel textile moisture sensors based on multi-layered braiding constructions:

/pdf/c7-2-textile-based-sensor-systems-for-condition-monitoring-5a1bvwb4e0.pdf

C7.2 - Textile-based sensor systems for condition monitoring in composite and medical applications

A number of special machines are available for the integration of additional threads in circular-knitted fabrics, for instance from Maschinenfabrik Harry Lucas GmbH & Co (MHL). Other approaches are documented in patents.1−7 These include primarily technicalconstructive solutions for Single-Jersey machines Figure 1a with only a single needle bed, which allows an incorporation of additional thread material in stitch wale direction by overhead feeding to the vertically arranged cylinder needles, or extensive and sophisticated modifications of standard circular knitting machines with a standing needle cylinder and revolving creel Figure 1B.

/pdf/integration-of-additive-threads-in-stitch-wale-direction-of-3wavxbf1im.pdf

Integration of additive threads in stitch wale direction of circular knitted fabrics for smart textile applications-add-on device with rotating yarn feeder for double-jersey and interlock machines

Johannes Wendler

Papers

Novel temperature sensors based on strain-relieved braiding constructions:

Novel textile moisture sensors based on multi-layered braiding constructions:

C7.2 - Textile-based sensor systems for condition monitoring in composite and medical applications

Integration of additive threads in stitch wale direction of circular knitted fabrics for smart textile applications-add-on device with rotating yarn feeder for double-jersey and interlock machines