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towards commercial applications. Researchers are now delving into probing techniques and methods to
enhance the overall properties of those sensors. For example, Wang et al. introduce an innovative intronic
pressure sensor that achieves both high sensitivity and a wide sensing range, partly addressing a critical
[112]
bottleneck in the development of sensors for E-skins and wearable electronics .

Moreover, integrating TE sensors into wearable and implantable biosensors requires innovative design
approaches that prioritize both functionality and comfort. However, though existing sensors could
somewhat integrate materials such as semiconductors and hydrogels, they still faced some challenges that
impede border and commercial applications. When ensuring the biocompatibility, adaptability, and
comfortability of biosensors through encapsulation, their thermal efficiency is sacrificed to some extent.
Wu et al. present an innovative approach to enhance the output of flexible TEGs (FTEGs) by leveraging the
infrared reflection effect, which addresses the challenges of heat loss limitations, ensuring sufficient power
for sensing . For TE hydrogel, there is unavoidable dehydration in dry conditions and hydration in humid
[113]
environments, which would negatively affect their original sensing performance. Hence, the encapsulation
also matters for the TE hydrogel, and some researchers have delved into those areas. For instance,
enlightened by mammals’ skin, Huang et al. have reported a novel surface-encapsulating method to
enhance the stability of hydrogel sensors by preventing dehydration and swelling. The researchers
developed a chemical approach to create an elastic coating on the hydrogel surface, resulting in less than 6%
weight loss when exposed to air at 28 °C for 20 days and no significant weight increase when immersed in
[114]
water for 60 days . Meanwhile, the integration of anode/hydrogel interfaces presents a significant
challenge due to side reactions of anodes. Recent scientific research has provided valuable insights into this
issue. The development of an in-situ physical/chemical cross-linked hydrogel electrolyte has been reported
to stabilize the zinc anode-electrolyte interface, thereby preventing side reactions and dendrite growth in
zinc-ion batteries . To ensure long-term wearability and reliability, The developing self-healing materials
[115]
and self-assembly strategies could also contribute to the creation of more robust and adaptable TE devices.
IoT also offers vast opportunities for enhancing the capabilities of TE sensors. By integrating these sensors
with IoT platforms, real-time data can be collected and analyzed more effectively, leading to more accurate
health monitoring and environmental sensing.

When it comes to manufacturing, scaling up production methods while maintaining or improving material
quality would be a significant task. This includes the exploration of low-cost fabrication techniques and the
use of abundant, non-toxic materials. Additionally, the optimization of device architectures to require fewer
materials or simpler manufacturing processes can significantly reduce costs. Meanwhile, as the demand for
miniaturized and flexible TE sensors grows, particularly for wearable applications, there is a need for
scalable manufacturing processes that can produce high-quality devices in large quantities. Advances in
printing and flexible electronics technologies could play a crucial role in meeting this demand.

In conclusion, the future of TE-based sensors for health and environmental monitoring is promising but
requires a concerted effort to address the challenges in materials optimization, device design, cost reduction,
and integration with emerging technologies. By tackling these issues, we can pave the way for the next
generation of TE sensors that are not only more efficient and reliable but also more accessible and
sustainable.

DECLARATIONS
Acknowledgments
The authors acknowledge the support from Mr. Huangshui Ma and Miss. Shiyu Jia.