Development and Fabrication of the Micro Eddy Current Sensor by Using UV-LIGA Process
An analytical model of an eddy current sensor designed for noncontact distance measurement is presented. The device consists of two planar coil (driver coil and pickup coil) stacked on the magnetic core. The planar coil fabricated by UV-LIGA technology with SU-8 photoresist is illustrated, and the permalloy magnetic core electroforming process is presented also. Tested with 10-50 KHz sine signal, the output voltage of the sensing coil reached 30mv with a Ni target placed at a distance of 20μm. And the experimental showed a linear relation between the distance and output voltage within 60μm distance. The amplitude trend increases with the increasing of the frequency and amplitude of excited signal, which is according with the theory analytics. The whole size of the device is: Φ5mm×1.5mm. The results demonstrated that the device could nondestructive evaluate the distance and be easily integrated on chip, and the UV-LIGA Process could be used as a new method to fabricate the micro eddy current sensor massly.
Liangchi Zhang, Chunliang Zhang and Tielin Shi
X. H. Zheng and F. Gu, "Development and Fabrication of the Micro Eddy Current Sensor by Using UV-LIGA Process", Advanced Materials Research, Vols. 139-141, pp. 2283-2286, 2010