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Huang et al. Soft Sci 2024;4:40 https://dx.doi.org/10.20517/ss.2024.37 Page 11 of 35

shoelaces, and net-shape composite preforms [153,165] . Furthermore, non-woven structures stand apart from
traditional weaving or knitting. They are formed by fixing fibers together using adhesives, heat pressing, or
electrospinning, resulting in anisotropic, inhomogeneous fabrics with porosity and permeability [41,166,167] .

Regardless of the structures, functional fabrics can be formed by individual functional fibers/yarns, or by
weaving functional fibers/yarns with insulating fibers/yarns, which are then made into garments. Moreover,
the previously discussed techniques for the functionalization of insulating fibers, such as carbonization and
deposition, are equally applicable to insulating fabrics. Taking the woven structure as an example, as shown
in Figure 5C, the fabrication of functional fabrics can be achieved through weaving with individual
functional fibers, weaving with different fibers, and carbonization [168-170] .

DESIGN STRATEGIES OF TEXTILE HEALTH MONITORING SYSTEM
The design and fabrication of textile electronics constitute a complex endeavor, as they involve integrating
electronic systems with a textile platform. A simple health monitoring system includes a power module,
sensing module, interconnections, data processing module, communication module, and display module. In
such integrated systems, the design of textile electronics necessitates well-considered manufacturing
decisions, which involve selecting appropriate materials and processes to ensure adherence to design
specifications under specific constraints.

Power module
The power module serves as the energy core of the system, providing the necessary power to other modules.
The power management circuitry is responsible for voltage regulation, current control, and power
distribution. Recently, beyond conventional commercial energy devices, a variety of textile-based energy
harvesting and storage devices, such as solar cells, supercapacitors and batteries, has emerged.

The energy harvesting devices effectively capture ambient energy sources, including solar radiation, thermal
gradients, mechanical vibrations, and kinetic energy from human motion, to power wearable health
monitoring systems. They typically leverage specialized materials optimized for energy conversion, such as
photovoltaic, triboelectric, piezoelectric, and thermoelectric materials, to achieve efficient energy
management in wearable applications. The use of photovoltaic materials to create solar cells is the primary
technology for solar power generation . When two triboelectric materials come into contact and then
[171]
[172]
separate, they generate electrical energy due to the triboelectric effect . Additionally, piezoelectric
materials generate an electric charge when subjected to mechanical stress, also leading to the production of
electrical energy [173,174] . Furthermore, thermoelectric materials are capable of converting thermal energy into
electrical energy, making them particularly useful for waste heat recovery or in environments with
[175]
significant temperature differences .
When ambient energy is insufficient, energy storage devices become essential to maintain reliable operation
of health monitoring systems. Critical factors in designing these devices include volume, weight, flexibility,
safety, charge-discharge rate, and cycle life. For example, Li et al. demonstrated that zinc-ion batteries are
highly suitable for textile applications due to their high theoretical capacity and low redox potential, making
them effective for powering display modules . In an intelligent health monitoring system, energy storage
[176]
devices should be capable of working in tandem with energy harvesting systems to enable seamless
transitions during periods of low energy supply.