Samsung S1 has an off-screen fingerprint design. Samsung has equipped S1 with an ultrasonic off-screen fingerprint, which makes S1 the first mobile phone equipped with off-screen fingerprint. Because of the use of ultrasound, fingerprint sensing occurs in the blink of an eye, which helps it to work in different weather conditions.
ultrasound instead of optics means that it can work in wet conditions, and it can read 3D fingerprints, which is safer in theory, but it also means that you can't simply use the general toughened glass screen protective film. In addition, fingerprint identification has passed the FIDO alliance certification.