In 2022, according to the Global E-waste Monitor 2024, humanity produced 62 million tons of e-waste—discarded phones, printers, and other devices. By 2030, that number is projected to rise another 32%, reaching 82 million.
To address this significant environmental problem, Tingyu Cheng, assistant professor of computer science and engineering at the University of Notre Dame, and his lab have developed a new, more sustainable electronic prototyping technique. Cheng’s lab fabricates hardware components from biodegradable materials that can be dissolved, easily recycled, or even safely eaten.
Two of these enviro-friendly components were introduced by his team at the Association for Computing Machinery (ACM) User Interface Software and Technology (ACM UIST) conference: a dissolvable 3D-printed circuit board (DissolvPCB) and a biodegradable soft robot actuator (BIOGEM).
Conventional circuit boards are made from unrecyclable fiberglass and resin, but DissolvPCB uses polyvinyl alcohol—the same dissolvable polymer used in laundry and dishwashing pods. To conduct electricity in the board, they use an easily recoverable liquid metal (EGaIn).
“Our method allows the fabrication of advanced, eco-friendly circuit prototypes with everyday materials and a standard home 3D printer rather than specialized equipment,” said Cheng.
Their open-source plugin automatically converts printed circuit board design files into 3D-printable models so that anyone can quickly fabricate a more sustainable circuit board.
Their work was recognized with a best paper award at the 2025 ACM UIST conference.
BIOGEM, a biodegradable gelatin-based actuator, is another eco-friendly innovation from Cheng’s lab. Made from the same material as gummies, its properties can be tuned—from stiff to flexible to conductive—by adding sugar, glycerol, and salt.
Actuators generate motion by expanding and contracting like muscles, making them important components in soft robots. In BIOGEM, the pneumatic actuator’s motion also activates a strain sensor—made from gelatin—that allows it to modify its motion based on how its “muscles” are responding.
To test BIOGEM, the team created a soil bot. The bot successfully tunneled beneath the soil, planted radish seeds and decomposed naturally, thereby eliminating the need for retrieval and reducing both labor and waste.
To showcase the lighter side of their biodegradable actuator technology, the team created an edible interactive cake, with chocolate stars that rise and fall in a rhythmic motion driven by edible BIOGEMs.
“I’m interested in creating electronics that can sense, communicate, respond, and gracefully repair, regenerate and fade away,” said Cheng. “BIOGEM and DissolvPCB are part of that effort.”
Cheng collaborated with colleagues at the University of Maryland and Georgia Tech on the DissolvPCB project; colleagues at the University of Washington partnered with Cheng on the BIOGEM project.
—Karla Cruise, Notre Dame Engineering