In a recent development published in Engineering, researchers have introduced a novel hybrid keratin (KE) hydrogel integrated with liquid metal (LM), offering new possibilities for monitoring the health of marine inhabitants. This innovation addresses the limitations of traditional wearable electronics in terms of biocompatibility, mechanical strength, and conductivity.
Monitoring the health and migration of marine organisms is crucial for maintaining the balance of marine ecosystems, advancing climate change studies, and safeguarding human health. However, developing sensors for marine organisms is challenging due to the complex marine environment and the unique characteristics of marine life. Existing hydrogel sensors often suffer from low conductivity, poor mechanical strength, and insufficient self-recovery capabilities.
To overcome these challenges, the research team combined KE, a protein abundant in feathers and wool, with eutectic gallium-indium (EGaIn) liquid metal. The KE provides biocompatibility, while the EGaIn enhances conductivity and mechanical properties. The resulting keratin liquid metal (KELM) hydrogel was prepared by dispersing LM in a 5% KE solution, followed by ultrasonication and polymerization.
The KELM hydrogel exhibits excellent mechanical properties, with a tensile strength of 166 kPa and a stretchability of 2600%. It also has a high conductivity of 6.84 S/m and a gauge factor (GF) of 7.03, making it highly sensitive to strain. The hydrogel's adhesion strength on various substrates, including human skin and biological tissues, is remarkable, ensuring stable attachment for monitoring.
Biocompatibility tests on human epidermal keratinocyte (HACAT) cell lines demonstrated that the KELM hydrogel has minimal cytotoxicity and excellent cell compatibility. The hydrogel adhered well to human skin and aquatic animal skin without causing adverse reactions.
The KELM hydrogel-based wearable electronics were successfully used to monitor the heartbeats of invertebrate and vertebrate aquatic animals, such as scallops, sturgeons, and giant salamanders. The sensors can detect subtle changes in heartbeat patterns and transmit data wirelessly, providing valuable information for assessing the health of aquatic organisms.
While the current study shows great promise, the researchers acknowledge that for vertebrate aquatic animals, the invasive methods used for heartbeat monitoring may disrupt their physiological status. Future research will focus on developing minimally invasive installation techniques and improving the postoperative recovery environment. Additionally, multiple sensor arrays will be employed to achieve more precise behavioral monitoring.
This research on the KELM hydrogel not only provides a new approach for monitoring marine inhabitants' health but also has potential applications in flexible electronics, medical monitoring, and wearable devices. It represents an important step forward in the development of biocompatible wearable sensors for diverse applications.
The paper "Biocompatible Protein/Liquid Metal Hydrogel-Enabled Wearable Electronics for Monitoring Marine Inhabitants' Health," authored by Lidong Wu, Jinxue Zhao, Yuanxin Li, Haiyang Qin, Xuejing Zhai, Peiyi Li, Yang Li, Yingnan Liu, Ningyue Chen, Yuan Li. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.12.030
