Imagine being able to create incredibly tiny structures with the same ease and sustainability as printing on paper.
This is the frontier of microfabrication—the process of making microscopic structures that are crucial for the operation of everything from computer chips to medical devices.
Traditionally, microfabrication has been an intensive process that involves environmentally toxic chemicals that are difficult to safely dispose of. However, scientists at the University of Chicago are hoping to change that.
In their latest publication in Nature Sustainability, the laboratory of Prof. Bozhi Tian has developed an environmentally sustainable method of microfabrication that uses water and natural materials—including paper—to create and transfer patterns.
The process draws inspiration from nature—mimicking, for example, how geckos naturally stick and unstick from walls, according to Tian.
A new use for water
Traditional microfabrication, which creates tiny patterns on a microscopic scale using a process called photolithography, has long relied on harmful chemicals for manufacturing integrated circuits found in most home and consumer electronics.
However, UChicago investigators discovered a more eco-friendly approach to microfabrication by using water as a green activation agent instead of traditional toxic agents.
Their innovative technique is a new spin on an old process known as salt-assisted photochemical synthesis. The new version utilizes lasers to create patterns on paper, which can then be easily transferred using water.
"We discovered that water could gently and effectively separate the tiny patterns from their base materials," said Tian.
Using this technique, the team was able to improve the process of turning cellulose in paper into conductive carbon. They could then turn that carbon into advanced sensors by carefully adjusting the carbon’s surfaces and using stimulators to efficiently boost reactions in nanoscale materials.
This valuable carbon, created through water and laser writing, has been shown to have diverse applications, ranging from advanced sensors to intricate medical devices.
Chuanwang Yang, a postdoctoral researcher with the Tian lab and first author of the paper, added, "Using water instead of toxic solvents is a major step forward.”
Making the machine
To further enhance their method, Yang developed an innovative tool called a "Roll-to-roll Laser Writer." This device automates laser-based writing and pattern transfer, making the process faster and more dependable.
—Prof. Jacqueline Stewart
