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Zou et al. Soft Sci 2024;4:19 https://dx.doi.org/10.20517/ss.2024.13 Page 7 of 10

[68]
in intrinsically stretchable conductors/substrates (for instance, replacing the meandering interconnects
using intrinsically stretchable conductors/substrates) and more accurate micro-assembly processes should
be considered to simultaneously achieve excellent stretchability and resolution. Vertical stacking of multi-
color Micro-LED chips may be another useful strategy toward further enhanced resolution of the flexible
device . Second, the long-term operation stability and biocompatibility of such deformable Micro-LEDs in
[38]
bio-environments needs to be clearly established, especially for healthcare purposes. These devices
encapsulated by bio-polymer generally can tolerate harsh environment attacks. However, whether they have
any long-term side effects on the skin or human organs needs to be confirmed. It has been known, for
example, that wearable devices with poor air permeability can affect the long-term wearing comfort .
[69]
Bonding failure at the Micro-LED/soft substrate interface is another issue worth future investigation. It may
be worthwhile to develop intrinsically stretchable solders that can enhance the interfacial bonding strength.
It is also urgently needed to develop flexible Micro-LEDs with full-color emitting capability. Monochromic
[70]
Micro-LEDs combined with flexible quantum dot patterns , for example, may be a practical approach
toward full-color wearable displays in the future. Finally, a system-scale, universal fabrication process for
wearable Micro-LEDs is required. Currently, most fabrication techniques are only demonstrated at the
laboratory, lacking consistent reproducibility. There is still a long way to extend the lab concept to large-
scale fabrication.

DECLARATIONS
Authors’ contributions
Wrote the original draft: Zou S, Li Y, Gong Z
Supervised, reviewed and revised the manuscript: Gong Z

Availability of data and materials
Not applicable.

Financial support and sponsorship
This work was supported by the National Key Research and Development Program of China (Grant No.
2021YFB3600100); the National Natural Science Foundation of China (Grant Nos. 62104049 and 62304055);
the Key-Area Research and Development Program of Guangdong Province (Grant Nos. 2019B010925001,
2020B010183001, and 2020B0101320002); the Guangdong Academy of Sciences’ Project of Science and
Technology Development (Grant Nos. 2022GDASZH-2022010111, 2019GDASYL-0103070, 2019GDASYL-
0103071, 2020GDASYL-20200103118, and 2021GDASYL-20210103067); the Guangzhou Basic and Applied
Basic Research Foundation (Grant No. 202201010572); the Guangdong Basic and Applied Basic Research
Foundation (Grant Nos. 2022A1515110397, 2020B1515120020, 2020A1515110509 and 2019A1515110682).

Conflicts of interest
All authors declared that there are no conflicts of interest.

Ethical approval and consent to participate
Not applicable.

Consent for publication
Not applicable.

Copyright
© The Author(s) 2024.