Summary:
Researchers in the UCLA Department of Materials Science and Engineering have developed a facile, rapid method to print soft, wearable electronics.
Background:
Soft electrical circuits have garnered significant interest in a broad range of emerging technologies, including wearable electronics, brain-machine interfaces, and soft robotics. A common method of producing them is screen printing, which requires physical masks to be fabricated first. Other popular methods rely on prepatterned structures (mask, mold or pattern solid metal) for liquid metal printing, which can require considerable time and cost. Direct writing and inkjet printing can achieve fast and direct patterning of liquid metal, but clogging of nozzles, difficulties in precise control of extrusion pressure, limited resolution and serial printing processes still limit their applications. There is large market opportunity for techniques that improve the efficacy of room temperature liquid metals (LMs) in soft electronics manufacturing.
Innovation:
A research team led by Professor Ximin He has developed a facile and scalable fabrication strategy to make soft electronics using LM particles. By using a photo-reactive ink containing LM particles and a polymer precursor, the team can precisely layer conductive surfaces onto stretchable materials. The researchers demonstrate a resolution of 20 µm and a maximum electrical conductivity of 3×106 S m-1. The fabrication process is performed at room temperature with a simple light exposure, drastically reducing manufacturing costs. This system has been demonstrated for multiple wearable sensors, including gesture monitoring, thermal therapy delivery, and humidity monitoring. Widespread adoption of this technology could greatly advance adoption of soft electronic systems. This liquid metal printing technique is a fast, scalable, nozzle-free, photo-induced, parallel direct printing process, which avoids the drawbacks of other liquid metal printing techniques. It offers the capability of fabricating flexible and stretchable LM-polymer patterns with high resolution, high electrical conductivity, high stretchability and excellent electromechanical stability, in mild manufacturing conditions, using simple commercially available optical maskless lithography with low energy input and short processing time.
Potential Applications:
• Rapid prototyping and manufacturing
• Wearable electronics
• Flexible electronics
• Soft robotics
• Brain-machine interface
Advantages:
• Ambient temperature operation
• Low-cost optical instrumentation
• High electrical conductivity
• High stretchability and electromechanical stability
Development-To-Date:
Researchers have fabricated soft electronics for multiple wearable applications.
Related Papers:
Fast and Facile Liquid Metal Printing via Projection Lithography for Highly Stretchable Electronic Circuits, Advanced Materials, D. Wu, et al. 2023. https://doi.org/10.1002/adma.202307632
Reference:
UCLA Case No. 2024-031
Lead Inventor:
Ximin He, PhD, UCLA Associate Professor of Materials Science and Engineering