## Nanotechnology and Materials

## Measurement and analysis technology, Sensors

## Technology Transfer of the Extremely Small Magnetic Field Measurement Technology

Keyword: Fluxgate magnetometer, Frequency division, Visualization, Nonlinearity

Organizations Involved

○ Hisashi Kado, Kanazawa Institute of Technology

○ Junji Hirama, Kanazawa Institute of Technology

○ Akira Iwayama, PFU Limited

## 【Abstract】

Kanazawa Institute of Technology(KIT), having a long history of sensing technology development of extremely small magnetic field, has succeeded in embodying the technology as a multi-sensor system which integrates and visualizes the acquired data. This accomplishment allows the visualization of the magnetic field which otherwise is undetectable to human eye. Application of this technology is expected in the areas such as security checks, IC failure analysis, and estimation of target-object movement or inner structure through non-contact measurement.

## 【Summary of the technology transfer】Technological Impact

The magnetic field of a nonlinear magnetic material can be readout linearly as follows: generate second harmonic by winding a magnetically excited coil around the magnetic material; detect the generated amplitude with a detection coil wound separately; apply negative feedback. We applied negative feedback by frequency division, fulfilling both wide dynamic range and high-speed response. The technology enabled measurement of extremely small magnetic field even under large DC magnetic field exposure such as earth magnetism. Measurement can be conducted under influence of slow and large magnetic noise source due to range-wise measurement of frequencies.

## Market Impact

Other than application in the areas such as security checks, IC failure analysis, and estimation of target-object movement or inner structure through non-contact measurement, the technology is expected to contribute to geophysical instrumentation and earth resource sensing because the environmental magnetic field measurement using this technology allows the measurement of geomagnetic variation induced by tectonic activity, or geomagnetic anomaly attributed to underground mineral resources. Previously, SQUID magnetometers which are highly sensitive but expensive have been used for such measurement although they lacked handling facilities due to liquid helium/ liquid nitrogen requirement. The new sensors open ways to easy-to-use measurement in an extensive field of application.

Prof. Hirama

Prof. Kado

## Project Background

Upon learning through press release about the new magnetic field sensor developed by KIT, Ishikawa-based PFU Limited has perceived the sensor’s technological and market potential and decided on in-house development utilizing technology transfer.

## Funding History

1. Knowledge Cluster Initiative 2004-2008

“Ishikawa Hi-tech Sensing Cluster”

2. University research fund

## I ntellectual property protection

Domestic patent application : 1

“Magnetic field measurement equipment”

No. 2003-315678

Mr. Iwayama

## Fluxgate Array

Fluxgate-type magnetic sensors are positioned by 8x8 matrix in vertical and horizontal directions, number of channels totaling to 128.

## V isualized Magnetic Field

Visualization of magnetic field generated by electric current running through a cable.

## Turning point in the Project

○ A good judge must be organized as a system to connect the new accomplishment and the social demands.

○ A performance tradeoff between spatial and magnetic resolution must be set.

For more information, contact : Gen Uehara, Applied Electronics Laboratory, Kanazawa Institute of Technology, 81-3-5545-8181, uehara@ael.kanazawa-it.ac.jp