Wearable health care devices – such as glucose monitors, ultrasound patches and blood-pressure monitors – can be invaluable for keeping patients safe.

A new study from Cornell University and the University of Chicago found that demand for such health care electronics could approach 2 billion units per year by 2050. But unless measures are taken to reduce the environmental impact, these devices could cumulatively generate more than a million tons of electronic waste and 100 million tons of carbon dioxide by 2050.

Published Dec. 31 in Nature, the study’s co-first authors are Bingzheng Wang, doctoral student at Cornell, and Chuanwang Yang, postdoctoral researcher at UChicago.

Surprisingly, the plastics weren’t the biggest problem. Instead, the study found, a device’s printed circuit board is by far the largest contributor to its carbon footprint, accounting for 70% of the total, partially due to the intensive mining and manufacturing required for its integrated circuits.

The research offers two potential avenues for reducing the environmental impacts of these wearables.

Chipping away at a problem

As electronics have gotten smaller and more flexible, they’ve been incorporated into more uses in the field of health care. The ability to continuously track a patient’s blood pressure, glucose or heartbeats can help doctors and caregivers keep them stable and avert crises.

But most of these devices are designed to be disposable – even more so than consumer electronics, in many cases, since longer-term use can pose the risk of performance degradation or infection.

The laboratory of Bozhi Tian, professor of chemistry at UChicago, found little research had been done on this ballooning market and its potential environmental impact. To tackle this challenge, they joined forces with the research group of Fengqi You, the Roxanne E. and Michael J. Zak Professor in Energy Systems Engineering in Cornell Engineering, whose team focuses on systems-level sustainability and life-cycle decision-making.

First, the team modeled global use of these devices. Extrapolating from current trends, by 2050, the demand for healthcare electronics worldwide could be 42 times higher than today, accounting for about 2 billion units annually.

Next, the team developed a framework for measuring the environmental footprint of these devices.

A comprehensive analysis is important but difficult, because it must pull together many threads. The researchers incorporated every part of a device’s “life cycle”: from the impacts of the mining required for ingredients, to the energy used in manufacturing the devices, all the way to the waste created after disposal. They judged carbon footprint, toxicity of the materials and electronic waste.

The analysis found that the printed circuit board – the “brain” controlling the device’s electronics – dominated the device’s environmental impact by a wide margin.

“When these devices are deployed at global scale, small design choices add up quickly,” said You, who co-authored the study. “Our analysis shows that the electronics architecture, not the plastics, is what really drives the environmental footprint.”

A systems solution

The team identified two major potential solutions to lower the devices’ carbon footprint.

The first is for chemists and engineers to develop new chips that can use more easily obtainable minerals, such as copper or aluminum, instead of rarer minerals like gold. Copper and aluminum are less stable than gold, which is why they haven’t been used in chips. But there may be ways to design around this problem.

“A lot of people assumed you would have to sacrifice performance if you use more reactive metals, but our analysis suggests it should be okay if you provide extra protection for the circuitry,” said Tian.

The second major solution is to design the devices to be modular.

Most health care devices need to be changed periodically; but if the covering can be discarded and the integrated circuit kept intact, that would avoid the largest carbon culprit.

There are other pieces, too. For example, if all the devices were manufactured using solely renewable energy, the carbon footprint drops by 15%.

“Sustainability at this scale can’t be solved with one material swap,” You said. “It requires a systems-level approach that considers the entire life cycle as these technologies continue to grow.”

With global tech and health care companies investing heavily in wearable devices, the team hopes their framework can make this type of analysis more widespread, which is increasingly important as digital health technologies become part of global infrastructure.

The research was funded by the U.S. Army Research Office, UChicago, Suzuki Postdoctoral Fellowship, National Science Foundation, Karin Bain & John Kukral Foundation, Eric and Wendy Schmidt AI in Science Fellowship.

This article was adapted from a version written by Louise Lerner with permission from the University of Chicago.