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Page 28 of 38 Wei et al. Soft Sci 2023;3:17 https://dx.doi.org/10.20517/ss.2023.09

gesture interaction, VR and AR control, and smart home.

Although great progress has been made in theoretical research and application demonstration of electronic
textiles in recent years, there are still great challenges in their practical industrial application. The problems
that need to be solved in the practical application of electronic textiles are listed in the following six aspects:
materials, manufacture, sensing, circuit, wearability, and intelligence, as shown in Figure 14.

(1) Material: Flexible materials are the basis and core of flexible electronic devices, so the progress of
electronic fabrics should first focus on the innovation of materials. In order to achieve a balance between
softness, high sensitivity, and stability, the design and synthesis of new composite-sensitive materials are
urgently expected to realize multimodal sensing of electronic textiles by modulating the amount of material
doping and the interface binding state. The composite doping of flexible substrate materials and functional
[218]
materials is currently the main way to achieve multimodal sensing . Representative flexible substrate
materials include silicone rubber, PDMS, polyurethane elastomer, hydrogel, and more [219,220] . Commonly
used functional materials include 1D/2D/3D nanomaterials, conductive polymers, ionic liquids, and
more [221,222] . However, the applicability, adhesion stability, and durability of these flexible substrates and
functional materials with textile substrates need to be improved.

(2) Manufacture: At present, most functional yarns cannot be mechanically manufactured, which limits the
large-scale mechanized production and practical application of electronic textiles. In addition, functional
yarn encapsulation technology has been the focus of the manufacturing process, which is an important
guarantee for the stability, woven and mechanical properties of electronic textiles. How to realize the
integration and weaving of multimodal functional yarns and reduce the wear in machine weaving
manufacturing is also a problem to be considered. The structural design and integration of functional yarns
in commercial knitting machines is one way to achieve large-scale manufacturing of smart textiles [30,213,223] .
Functional yarns, such as silver-plated conductive yarns, cotton yarns, PA yarns, PP yarns, and more, are
typically available for commercial purchase, machine-knittable, and durable. However, when using this
approach, the resulting strain sensing function is limited, which makes it challenging to integrate
multimodal sensing. Additionally, the applicable sensing mechanism is single.

(3) Sensing: There is a lack of a fully integrated textile design solution that implements multi-signal sensing
on a piece of clothing for monitoring more comprehensive information about human movement,
physiology, health, environment, etc. When electronic textiles are used for human monitoring,
multi-channel information is often measured at the same time, which poses a great challenge in terms of
crosstalk-free, accurate decoupling of information and freedom from external interference. As we conclude
in this review, most multimodal sensing textiles only implement a few stimulus-response functions. Further
research is needed for the detection of information in the whole human body domain. In addition to
functional integration, accuracy is a key issue to consider, particularly in human-machine control. This is
especially important in industrial applications, where there are high risks involved.

(4) Circuit: In terms of circuits, mainstream electronic textiles still have not got rid of the traditional
electronic circuit boards. Fiber shape sensors still need to be connected with rigid or semi-rigid circuit
boards to achieve various detection functions. The development of intelligent clothing in the future requires
the weaving of the circuit system. The connecting wires between devices and circuits have developed from
traditional wires to high-performance conductive yarns or fibers. The whole clothing is used as a circuit
board, and various electronic components are arranged on the clothing surface. Further, all kinds of basic
components, such as resistors, capacitors, diodes, etc., will be fiberized, and then the complete circuit system