In-display fingerprint sensors have a major limitation – they work with an OLED panel, but not an LCD display. In a major breakthrough, Xiaomi’s Redmi sub-brand has managed to get an in-display fingerprint sensor working on a phone with an LCD panel.
Redmi has managed to do that by using a special film material to improve the transmittance of infrared light that could not pass through an LCD panel. The infrared transmitter below the panel emits infrared light, and once a fingerprint is reflected, it penetrates the screen and shines on the fingerprint sensor to complete verification.
Since LCD panels are cheaper than OLED panels, we expect the price of phones with an in-display fingerprint sensor to further come down. As for Xiaomi itself, affordable LCD screen Redmi phones with an in-display fingerprint might hit the shelves soon.