Synthetic hydrogels exhibit great hope in drug delivery, tissue repair, medical implants, and other applications. Hydrogels functionalized with electrically conductive components could be employed in bioelectronic devices for neural or cardiac interfaces, for applications like cardiac patches, neural prosthetics, and electronic skin.
Electroconductive hydrogels for wearable electronics. Image Credit: The University of Hong Kong
A study group headed by Dr. Lizhi Xu of the Department of Mechanical Engineering in the Faculty of Engineering at the University of Hong Kong (HKU) has produced a new kind of electroconductive hydrogels with excellent manufacturability and mechanical strength, developing opportunities for the engineering of different bioelectronic devices.
Nature Communications published this breakthrough.
Synthetic hydrogels are water-rich polymeric materials that appear like biological soft tissues. They are porous, soft, and biocompatible, allowing a physical interface between advanced biomedical tools and natural biological tissues. Specifically, electroconductive hydrogels have gained a broad research focus, as they can be employed in bioelectronic devices for neural or cardiac interfaces.
Existing hydrogels are mechanically weak and difficult to manufacture, which limits their practical utility. We used a unique microscale scaffold for the synthesis of conductive hydrogels. The architecture of the composites provided a combination of properties inaccessible by other hydrogels, which is crucial for realistic applications in bioelectronic devices.
Dr. Lizhi Xu, Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong
In the new hydrogels produced by the team of Dr. Xu, a 3D nanofiber network was used as a template to direct the arrangement of conducting polymers (for example, polypyrrole). The nanofibers’ high connectivity offered structural strength and an operational pathway for electron conduction.
For potential biomedical applications, the device needs to withstand repeated mechanical loading associated with body motion. In this regard, mechanical robustness of the materials would be very important.
Dr. Lizhi Xu, Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong
The consequent material produced by the team includes 80% water by weight, while at the same time exhibiting a high electrical conductivity of ~80 S/cm and a mechanical strength of ~9.4 MPa.
These conductive hydrogels are easy to fabricate. One can pattern them into arrays of electrodes, interconnects, and biosensors, enabling functional systems such as wearable health monitors or cardiac tissue engineering platforms. It opens opportunities for many advanced medical tools down the road, such as neural prosthetics, cardiac patches, electronic skin, and so on.
Dr. Lizhi Xu, Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong
Dr. Xu and his study group had already produced another new kind of hydrogel that imitates tendons, featuring notable mechanical properties that closely look like those of natural tendons, as well as several functionalities that are ideal for biomedical applications.
Journal Reference:
He, H., et al. (2023). Hybrid assembly of polymeric nanofiber network for robust and electronically conductive hydrogels. Nature Communications. doi.org/10.1038/s41467-023-36438-8.