2D mineral substrate leads to more sensitive flexible magnetosensors

Flexible sensors are crucial components of several high-tech devices, including folding displays and wearable electronics. Flexibility usually comes at the expense of sensitivity, power consumption, or economic cost. Wang et al. developed a magnetosensor that is both flexible and highly sensitive by using a layered mineral substrate, which could make these electronics more accessible.

A magnetosensor typically requires piezomagnetic and piezoelectric materials. While there exist flexible materials with strong piezomagnetic properties, most strong piezoelectric materials are brittle and rigid. Conversely, most materials that exhibit significant flexibility also have extremely weak piezoelectric properties.

The authors found the key to making a flexible material with high piezoelectricity was to deposit a piezoelectric film onto a 2D substrate, which could then be thinned. Their ideal candidate turned out to be a layered mineral called mica.

“Layered mica is flexible, chemically stable, and resilient at high temperatures, so it is a very wonderful substrate for our piezomaterials,” said author Yaojin Wang. “And since mica is a 2D material, we can easily reduce its number of layers after depositing the piezomaterials, creating even more flexibility.”

The piezoelectric material, lead zirconate titanate (PZT), was deposited onto the layered mica and annealed. After adding interdigital electrodes on top of the PZT, the heterostructure was thinned by taking layers of mica off the bottom, making the entire device more flexible.

These magnetosensors can endure 5,000 bending motions without showing degradation and can sense magnetic fields as weak as 1 microTesla. Wang said the next step is to make larger and more sensitive sensors.

“For flexible materials, the main application is the skin, where we can sense temperature and pressure, but can’t sense magnetic fields.” Wang said.

Source: “Ultrasensitive flexible magnetoelectric sensor” by Nana Yang, Hanzhou Wu, Shidong Wang, Guoliang Yuan, Ji Zhang, Oleg V. Sokolov, M. I. Bichurin, Ke Wang, and Yaojin Wang, APL Materials (2021). The article can be accessed at https://doi.org/10.1063/5.0039089 .