研究目的
To present a novel concept that uses the mutual inductance of a spiral dual-coil to identify fingerprint patterns, enabling the measurement of a fingerprint by the effect of ridges and valleys on electrical impedance.
研究成果
The study successfully used silicon-based microfabrication technology to produce a sensing chip with a coplanar dual-coil array; it was successfully used to reconstruct a fingerprint image by measuring phase variation. Operating at the resonant frequency of 8 MHz, a maximum induced current of 1 mA and the phase shift of 41.3 degrees were obtained. A 10×15 pixel-sensing image exhibits a good match with the user’s finger pattern.
研究不足
The study mentions that using high dielectric constant materials such as thin films of SiO2, Si3N4 and SiC to replace PR passivation layer can provide a better mechanical protection and electrical isolation, indicating potential areas for optimization.
1：Experimental Design and Method Selection:
The study proposes a novel mutual inductance spiral dual-coil fingerprint sensor. The electrical impedance of the spiral dual-coil and its operating performance were evaluated by experimental measurement.
2：Sample Selection and Data Sources:
A typical sensing chip with a 3×128 dual-coil array was fabricated by microfabrication process.
3：List of Experimental Equipment and Materials:
A multimeter and an LCR Meter were used for measuring the RLC electrical properties of the dual-coil. A function generator and oscilloscope were used for signal input and observation.
4：Experimental Procedures and Operational Workflow:
The sensing chip was fabricated using a simple silicon-based microfabrication process. The RLC electrical properties were measured, and the sensing signal was observed on the connected oscilloscope when an excitation signal was input from a function generator.
5：Data Analysis Methods:
The variations of coupling capacitance and mutual inductance were used to verify the properties of different mediums. The phase shift between the excitation and sensing electrical signals was analyzed.
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