STEM与日常科技·英语30篇（3）
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Ultrasonic Fingerprint Sensors and Spoof Resistance
超声波指纹传感器与防伪能力
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Ultrasonic sensors send high-frequency sound waves through your fingertip to map its 3D structure.
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Unlike optical scanners, they capture ridges, valleys, and even sub-surface features like sweat pores.
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This 3D depth data makes it extremely hard to fool them with photos or silicone molds.
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They work reliably even with wet, dry, or slightly dirty fingers because sound travels well in such conditions.
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Manufacturers embed these sensors under smartphone glass, eliminating visible cutouts and improving durability.
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The system converts acoustic echoes into digital maps using time-of-flight calculations.
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Spoof attempts fail because fake materials reflect sound differently than living tissue.
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Battery usage is higher than capacitive sensors, but modern chips optimize power per scan.
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Medical-grade validation shows ultrasonic sensors reject over 99.7% of common spoof materials.
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Their precision supports secure mobile banking and biometric ID without external hardware.