Imagine being able to create incredibly small structures with the same ease and sustainability as printing on paper. This is the frontier of microfabrication – the process of creating microscopic structures that are critical to the functioning of everything from computer chips to medical devices.

Traditionally, microfabrication has been a laborious process that involves environmentally harmful chemicals that are difficult to dispose of safely, but scientists at the University of Chicago hope to change that.

In her latest publication in Nature SustainabilityProf. Bozhi Tian’s laboratory has developed an environmentally friendly method of microfabrication that uses water and natural materials – including paper – to create and transfer patterns.

The process is inspired by nature and, according to Tian, ​​mimics, for example, the natural way geckos stick to and detach from walls.

A new use for water

Traditional microfabrication, which uses a process called photolithography to create tiny patterns at the microscopic level, has long used harmful chemicals to produce the integrated circuits found in most home and consumer electronics devices.

However, researchers at the University of Chicago discovered a more environmentally friendly approach to microfabrication by using water as a “green activator” instead of traditional toxic agents.

Their innovative technique is a new twist on an old process known as salt-assisted photochemical synthesis. The new version uses lasers to create patterns on paper, which can then be easily transferred using water.

“We discovered that water can 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 converting cellulose in paper into conductive carbon. They were then able to use this carbon to create sophisticated sensors by carefully tailoring the carbon surfaces and using stimulators to efficiently accelerate the reactions in nanoscale materials.

This valuable carbon, produced by water and laser writing, has proven to have a wide range of uses, from sophisticated sensors to complex medical devices.

Chuanwang Yang, a postdoctoral fellow in the Tian lab and lead author of the study, added: “Using water instead of toxic solvents is a big step forward.”

Manufacturing the machine

To further improve her method, Yang developed an innovative tool called the Roll-to-roll Laser Writer. This device automates laser-based writing and pattern transfer, making the process faster and more reliable.

“It took about six months to develop and build this machine, but it has significantly improved our manufacturing speed for large-scale applications,” Yang said.

While the researchers are aware that their method cannot replace the high-precision techniques used to manufacture complex computer chips, they are optimistic that it will also have potential for other applications, such as low-cost disposable sensors for medical tests or wearable devices.

“We think this is particularly useful for devices that do not require the extreme precision of silicon chips but still require high functionality,” Tian said.

Pengju Li, a graduate student in the Tian lab who also worked on the project, added: “Our design improves the manufacturing efficiency of ultra-thin medical devices, including those used for cardiac and nerve stimulation and sensing.”

By harnessing the power of nature and using simple, eco-friendly materials, the team’s innovative method is able to redesign the microfabrication process, contributing to the growing wave of green technologies shaping the future of the science and technology industry.