Dresden: Research Team Develops Sustainable Magnetic Field Sensors Using 3D Printing
Magnetic field sensors are found in cars, smartphones, and security systems. However, many of these components are made from materials that pose health and environmental risks and are produced using resource-intensive methods. An international research team led by the HZDR is now presenting a sustainable alternative.
The solution: printed sensors made of iron, iron oxide, and bio-based materials such as cellulose or starch. They reliably measure magnetic fields, can be manufactured in a resource-efficient manner, and are designed to be safely degraded or recycled after use.
Iron, cellulose, and beeswax: An international research team at the Helmholtz Center Dresden-Rossendorf (HZDR) demonstrates that these environmentally friendly ingredients are entirely sufficient to create novel magnetic field sensors. Instead of relying on traditional manufacturing processes, the team uses bio-based inks and industrial printing technologies.
Magnetic field sensors are now among the invisible mass-produced items in the electronics industry. They measure movements, positions, or distances and are found in window contacts, steering wheels, hard drives, packaging, or smartphones. Billions of these components are produced every year. “Many of these sensors contain materials such as nickel or cobalt,” says Dr. Denys Makarov, head of the Intelligent Materials and Functional Elements Department at the Institute of Ion Beam Physics and Materials Research at HZDR. “These are substances that can pose environmental and health risks if not disposed of properly.” At the same time, their production often requires energy-intensive processes and complex manufacturing steps.
Developing sustainable sensors is technically challenging. Although iron is considered readily available and biocompatible, it alone does not achieve the sensitivity of many of today’s magnetic field sensors. The research team therefore combined iron with iron oxide and developed special core-shell particles in which an iron core is surrounded by a thin oxide layer.
“Humankind has known about iron and cellulose for centuries,” says Lin Guo, who is carrying out the project as part of his dissertation: “The challenge lies in developing a sensor with usable performance from these sustainable materials.” The exact composition and processing of the particles were crucial in this regard. According to the team, the printed sensors achieve sensitivities that are comparable to today’s commercial solutions in certain applications.
The sensors are produced using screen printing, a process more commonly associated with the textile industry. Instead of removing material from unnecessary areas, the sensor layer is applied precisely where needed. “We print sensors only where we need them,” explains Makarov. This saves not only material but also energy.
When sensors can disappear
The end of the sensors’ life cycle also played an important role in the development. Conventional electronics are usually used until they break and must be disposed of. The goal of the current study, however, is to create materials that can be controlled to degrade or be recycled. The iron-iron oxide sensor layer was therefore embedded in a matrix of biocompatible materials such as cellulose or starch. A layer of biocompatible polymers or natural materials such as beeswax protects the sensors from moisture and simultaneously determines their lifespan. “Through encapsulation, we can control how long a sensor remains stable,” says Guo. The service life can be specifically tailored for various applications. When the biological matrix later dissolves in water, mainly oxidized iron particles remain. “That’s basically rust,” says Denys Makarov. Potentially toxic substances such as certain nickel or cobalt compounds are deliberately not used in the concept.
The technology for manufacturing printed magnetic field sensors has already been licensed. Now the team is working on specific applications. Areas where electronic components are needed only for a limited time—such as in smart packaging, single-use medical products, or specialized sensor systems for agriculture—are of particular interest to the researchers. In these areas, sustainable magnetic field sensors could help manufacture electronics in a more resource-efficient manner in the future.
At the same time, the team is already working on further concepts. Future projects will focus, among other things, on more durable encapsulations, new biocompatible materials, and the integration of the sensors into flexible electronic systems.