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Wei et al. Soft Sci 2023;3:17 https://dx.doi.org/10.20517/ss.2023.09 Page 19 of 38

provide a more natural interface for human-machine interaction, which is the key to connecting the human
physical world and the digital space of machines to better support human life. The electronic textile with
multimodal sensing function shows its potential application in intelligent human-machine interface and
plays an important role in the coming intelligent era. In this section, we summarize the exciting applications
of multimodal electronic textiles in health monitoring, motion recognition, gesture interaction, VR and AR
control, and smart home.

Healthcare monitoring
A mainstream application of intelligent human-machine interfaces is the healthcare monitoring system.
With the growing demand of consumers for improving the quality of life, more flexible and comfortable
healthcare monitoring devices are attracting extensive attention in the consumer electronic market. The
healthcare monitoring system can be divided into three categories based on its shape: patch [51,177,178] , wearable
device [155,179,180] , and clothing [26,181] . Through monitoring various physiological indicators, including ECG,
pulse, body temperature, and sweat components, and by algorithms on smartphones or cloud computing
platforms, the health status of users can be comprehensively analyzed.

The patch is a widely used shape by various flexible sensors because it is easy to manufacture and has a
flexible structure. In the field of healthcare monitoring, patch sensors are often used in physical signal
sensing (such as stress, temperature, etc.). Film sensors and textile-based patch sensors are two types of
patch sensors. Traditional film patch sensors are designed on flexible substrates such as PDMS. Zhou et al.
[177]
designed a stress sensor patch based on the magnetoelastic effect to generate electricity through the
magnetic changes of the material. They attached the patch on the wrist to better fit the artery, and then it
can measure weak signals such as wrist pulse. This design has better performance and a more flexible design
but poor air permeability, so it is not suitable for large-area sensing. The textile-based patch sensor has
better air permeability and wearing comfort. Fang et al. have designed a multi-layer textile-based stress
[178]
sensor patch , in which the CNTs-coated cotton fabric substrate and the non-woven fluorescent ethylene
propylene textile are used as the triboelectric layers, and the outermost layer is encapsulated by PDMS and
fabric. The textile-based patch can be used to measure wrist pulse signals and send them to mobile phones
to calculate blood pressure and other physiological information. At the same time, the device has good
waterproof performance due to the outer PDMS layer, so it can be used by sportsmen such as swimmers
and divers. Lin et al. designed a liquid metal-based conductive fiber by injecting liquid metal into a hollow
flexible pipe, and a clothing surface embroidery antenna was designed by using a computer-aided design
[51]
and embroidery machine . This customizable embroidery pattern can transmit data from the temperature
sensor on the clothing to the smartphones through the NFC function of smartphones or other devices, as
shown in Figure 9A.

Wearable devices are a relatively mature technology at present, such as wristbands, smart bracelets, and
smart glasses. With the developed system of wearable devices, sensors can work and transmit signals with
smartphones or other personal terminals more stably. Wristband healthcare monitoring devices are mostly
used for pulse monitoring. Convenience and small size are the main advantages of this monitoring device.
In addition, the wristband can also be compatible with traditional wearable devices such as watches to
achieve functional integration. Meng et al. developed a fabric-based stress sensor using silver-plated fabric
[155]
as the substrate and conductive yarns wrapped with insulating fibers as triboelectric layers . They
designed a wrist strap and a headband that can detect and collect people’s pulse signals by wearing these
devices and connecting them to a smartphone, as shown in Figure 9B. Zhao et al. designed a flexible
magnetoelastic material by dispersing solid nanomagnets in silica gel and obtained the magnetoelastic fiber
through an adjustable nozzle . By textile layout designing, the crossed conductive fibers form an induction
[180]
coil and wrap the magnetoelastic fibers in it to make a stress sensor fabric. At the same time, a pulse-sensing