Emerging electronic materials for next generation soft bioelectronic applications: From material designs to devices performances

Liquid-based materials have emerged as promising soft materials for bioelectronics due to their defect-free nature, conformability, robust mechanical properties, self-healing, conductivity, and stable interfaces. A liquid is infiltrated into a structuring material endowing the material with a liquid-like behavior. Liquid-based electronics with favorable features are being designed and engineered to meet requirements for practical applications and even replacing conventional rigid electronics.

In this review, various types of liquid-based electronic materials and the recent progress on bioelectronics in multiple applications are summarized. Liquid-based electronic materials include ionic liquid hydrogel, nanomaterial-incorporated hydrogel, liquid metal, liquid-infused encapsulation, and liquid-based adhesive. These materials are demonstrated via electronic applications, including strain sensor, touch sensor, implantable stimulator, encapsulation, and adhesive as necessary components comprising electronics. A team of scientists summarized the considerable progress of liquid-based electronic materials for bioelectronics including current trends and challenges. Their work is published in Industrial Chemistry & Materials on 05 Mar. 2024.

“A paradigm shift in soft electronics is underway as researchers unveil the significant potential of liquid-based materials in overcoming longstanding limitations of conventional solid-state electronics.” said Jungmok Seo, an associate professor at Yonsei University, “In this review, we comprehensively discuss the current challenges in conventional bioelectronics owing to mechanical disparities and biological compatibility, alongside recent breakthroughs leveraging liquid-based materials.”

Liquid-based materials offer inherent flexibility and conformability, mitigating mechanical mismatches between human tissues and electronic devices and vastly improving usability. By adopting liquid-based materials that are intrinsically soft and conformal, the gap between soft tissues and electronics is significantly narrowed.

As components of soft electronics, liquid-based conductors utilizing ionic liquids, liquid metals, and nanomaterial-incorporated hydrogels have been introduced, providing versatile functionalities and enhanced mechanical durability compared to their solid-state counterparts.

Recent innovations in defect-free encapsulation technology, such as liquid-infused encapsulation, promise to minimize device performance degradation by reducing defects within polymer structures and preventing water permeation. Additionally, the anti-biofouling properties of encapsulation ensure long-term stability, particularly in implantable soft electronics.

Nature-inspired adhesive materials enable stable and conformal adhesion of solid electronic materials to moist, irregular, and dynamic tissue surfaces, further enhancing the usability of soft electronic devices.

From strain sensors to touch sensors, implantable stimulators to encapsulation solutions, and adhesives, liquid-based electronics are proving to be indispensable components in modern electronics. Their ability to seamlessly integrate with biological systems and adapt to dynamic environments makes them invaluable tools in fields such as healthcare, wearable technology, and beyond.

"We are at the moment of a revolution in bioelectronics, and liquid-based materials are at the forefront of this transformation," Jungmok said. "Their unique properties offer unprecedented flexibility and functionality, paving the way for a new generation of innovative bioelectronic devices."

In conclusion, liquid-based materials in soft electronics represent a significant step towards practical applications, offering superior conformality, biocompatibility, flexibility, mechanical durability, and adaptability to diverse applications without compromising electrical conductivity. However, further research is required to fully exploit their potential.

The research team includes Jungmok Seo from Yonsei University

This research was supported by the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (project numbers: 2022M3E5E9082213; NRF-2022R1A2C4001652). This work was supported by the Korea Medical Device Development Fund grant funded by the Korea government (Ministry of Science and ICT, Ministry of Trade, Industry and Energy, Ministry of Health & Welfare, Ministry of Food and Drug Safety) (project number: RS-2023-00243310).

Industrial Chemistry & Materials is a peer-reviewed interdisciplinary academic journal published by Royal Society of Chemistry (RSC) with APCs currently waived. Icm publishes significant innovative research and major technological breakthroughs in all aspects of industrial chemistry and materials, especially the important innovation of the low-carbon chemical industry, energy, and functional materials.