STEM与日常科技·英语30篇（3）

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超声波指纹传感器与防伪能力

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