# Eco-sustainable magnetoresistive sensors towards disposable magnetoelectronics

## TL;DR

This paper introduces eco-friendly magnetoresistive sensors made with sustainable materials and high sensitivity, enabling disposable electronics that are biodegradable and safe for the environment.

## Contribution

The novel contribution is the development of biodegradable, high-performance magnetoresistive sensors using eco-friendly materials and printing techniques.

## Key findings

- The sensors are fabricated using screen-printing with eco-friendly inks containing Fe/Fe3O4 core-shell particles and biodegradable binders.
- The sensors exhibit an order-of-magnitude improvement in low-field sensitivity compared to traditional printed magnetoresistive sensors.
- The approach enables disposable magnetoelectronics with biocompatibility and environmental sustainability.

## Abstract

This work presents a holistic integration of environmental sustainability and enhanced sensing performance throughout the full lifecycle of magnetoresistive sensors. Utilizing industry-scale screen-printing techniques combined with eco-friendly inks (formulated from engineered Fe/Fe3O4 core-shell magnetic microparticles, bioderived polymeric binders, and water solvent), the fabrication process avoids harsh treatments and hazardous chemicals. The resulting sensors, constructed entirely from naturally sourced materials, inherently exhibit biocompatibility, biodegradability, and environmentally benign recyclability. These properties collectively demonstrate key attributes for a sustainable life cycle. Through rational engineering of the Fe/Fe3O4 core-shell structure particles, two synergistic mechanisms are activated within the composite: spin-dependent hopping across Fe3O4 shell grain boundaries and in situ magnetic flux concentration induced by Fe cores, thereby yielding an order-of-magnitude enhancement in low-field sensitivity relative to sputtered Fe film and printed Fe3O4 particle-based counterparts, resulting in a higher magnetoresistance ratio at 10 mT relative to all printed magnetoresistive sensors reported previously. The convergence of eco-sustainability and high performance enables previously unattainable disposable magnetoelectronics, unlocking new opportunities for environmentally responsible and user-safe transient electronics and Internet of Things (IoT) applications.

A fully green printing strategy enables biodegradable and recyclable magnetoresistive sensors made from iron-based materials. By combining sustainability with high low-field sensitivity, the work opens a pathway toward environmentally responsible disposable magnetoelectronics.