Ultra-thin silk layers carefully aligned on graphene mark a significant milestone for achieving the control necessary in microelectronics and the development of advanced neural networks.
Silk, valued for thousands of years, continues to amaze us. It now holds the potential to lead microelectronics and computing into a new era.
Although silk protein has been utilized in specialty electronics, its application remains limited due to the chaotic structure of silk fibers, which resemble tangled spaghetti.
A research team from the Department of Energy’s Pacific Northwest National Laboratory has managed to organize this chaos. They report in the journal Science Advances that they have created a uniform two-dimensional (2D) layer of silk protein fragments, known as “fibroins,” on graphene, a carbon material celebrated for its superb electrical conductivity.
“These findings offer a consistent method for the self-assembly of silk protein, which is vital for the design and production of silk-based electronic components,” said Chenyang Shi, the primary author of the study. “It’s also crucial that this system is nontoxic and water-based, ensuring its biocompatibility.”
The combination of silk and graphene may lead to the creation of sensitive, adjustable transistors that are highly sought after in the microelectronics sector for wearable and implantable health monitoring devices. The PNNL researchers also envision their use in memory transistors, or “memristors,” which are integral for computer simulations of human brain functions within neural networks.
The Silk Road
For many centuries, the production of silk from silkworms was a closely shielded secret in China, gaining fame through the historical Silk Road trade routes to India, the Middle East, and eventually Europe. By the Middle Ages, silk had become a symbol of prestige and was highly sought after in European markets. Today, silk remains synonymous with luxury and status.
The same qualities that make silk fabric cherished globally—such as elasticity, durability, and strength—have prompted its application in advanced material technologies.
“Extensive research has explored using silk for modifying electronic signals; however, due to the inherent disorder of silk proteins, effective control has been limited,” explained James De Yoreo, a Battelle Fellow at PNNL who also serves as a Professor of Materials Science and Engineering as well as Chemistry at the University of Washington. “Given our background in controlling material growth on surfaces, we considered the possibility of creating a better interface.”
To accomplish this, the team meticulously managed the reaction settings, introducing silk fibers into a water-based medium in a deliberate manner. They successfully generated a highly organized 2D array of proteins configured in parallel β-sheets, a common protein formation in nature. Additional imaging and theoretical analyses confirmed that this thin silk layer possesses a stable structure similar to natural silk. This electronic structure—less than half the thickness of a single DNA strand—enhances miniaturization, a trend evident across the bio-electronics field.
“This type of material is ideal for what we call field effects,” noted De Yoreo. “It means that it acts as a transistor switch, changing between on and off states with an incoming signal. For instance, if you attach an antibody, the binding of a target protein will trigger the transistor to switch states.”
Furthermore, the researchers aim to utilize this foundational material and methodology to develop artificial silk infused with functional proteins that will improve its specificity and utility.
This research marks an initial step toward controlled silk layering on functional electronic components. Future research areas will focus on enhancing the stability and conductivity of silk-integrated circuits and investigating silk’s possibilities in biodegradable electronics to promote the adoption of eco-friendly chemistry in electronic production.
Along with De Yoreo, co-lead authors of the study include PNNL materials scientist Shuai Zhang and Xiang Yang Liu from Xiamen University in China. Other collaborators comprise Marlo Zorman from the University of Washington, Seattle; Xiao Zhao and Miquel B. Salmeron from Lawrence Berkeley National Laboratory; and Jim Pfaendtner from North Carolina State University.
This research received funding from the DOE Office of Science’s Basic Energy Sciences program. Support for the molecular dynamics simulations and scanning Kelvin probe microscopy measurements came from the DOE BES Energy Frontiers Research Centers program, through the Center for the Sciences of Synthesis Across Scales at the University of Washington.
