Engineering 101

Flexible Magnetic Sensor Systems Improve Sensitivity Tenfold

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Because conventional magnetic sensor circuits are made of silicon-based hard electronic elements, integrated on a substrate, they can only be placed on flat surfaces. As hard as glass, they’re obviously not suitable for all potential sensor applications, especially not biomedical ones.

While flexible soft magnetic sensors have also been developed, the lack devices that integrate a driving circuit, sensor scanning mechanism, signal processing circuit, and wireless measurement unit, all of which are required to form a system.  Fabricating flexible magnetic sensor elements is difficult, and it’s hard to integrate the fabrication process with circuit technology,” according to lead author Masaya Kondo of a recent study reporting on work done by a team of researchers from Osaka University and Leibniz Institute for Solid State and Materials Research.

They’ve been able to develop the world’s thinnest and lightest magnetic sensor matrix sheet system that visualizes the two-dimensional distribution of magnetism on various surfaces. The joint research team has developed a thin and soft (“skin-like”) magnetic sensor matrix sheet system by integrating flexible electronic elements called organic transistors and giant magnetoresistive elements on a 1.5-μm-thick plastic film. This imperceptible circuit fabricated on a thin plastic film can be attached onto the skin of a person without causing discomfort and can function properly even when folded (Fig. 1).

The magnetic sensor matrix sheet system, with a sensitivity 10 times higher than that of conventional systems, not only detects and amplifies weak magnetic signals, but also visualizes the two-dimensional distribution of magnetism in real time by automatically scanning magnetic sensor elements arranged in a matrix pattern (Fig. 2).

Figure 2: Magnetic field mapping by using a magnetic sensor matrix system. Image Credit: Osaka University

Among physical information, magnetic information obtained via a two-dimensional sheet-type magnetic sensor system is much more precise than electrical information because magnetic sensors have high spatial resolution due to the high permeability of magnetism in substances. A sheet-type sensor provides high-precision physical information as it can be adhered to a variety of objects regardless of shape.

By attaching a sheet-type sensor to a reinforced structure the precise locations of damage can be identified by mapping the distortion of magnetism caused by deteriorated reinforcing steel bars. And when the sensor’s sensitivity is further improved, it will be possible to make cardiac diagnoses with higher precision than electrocardiography by magnetic mapping.

Source: Osaka University

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