An Apple iPhone 7 can be seen in this picture taken in Bordeaux, France, Feb. 1, 2017. Reuters/Regis Duvignau

Display-embedded fingerprint sensors were expected to be features on leading smartphones such as the Samsung Galaxy S8, Apple iPhone 8 and the Google Pixel 2. But, half the year has already passed and we are yet to see one on a smartphones and most probably we won’t see a smartphone with such as sensor this year.

Fingerprint sensors on smartphone became commonplace in 2014 and have been there on smartphones till now. Different companies have taken different approaches to the placement of the sensor though. While companies like Samsung have chosen to place the sensor at the back, others like Apple have featured it on the front, inside the home button.

Read: Samsung Decides To Place Galaxy S8’s Fingerprint Sensor On Its Back ’At The Last Minute’

From just locking and unlocking the phone, the sensors have become multi-usage sensors, which can be used to access the camera or open the contacts, as done on the Google Pixel 2. But, the placement of this sensor on the display itself would have much better accessibility for users and that is what many companies seemed to be working towards at the start of the year.

But the advent of edge-to-edge displays starting with the Samsung Galaxy S8 turned the whole concept of a display embedded fingerprint sensor on its head. These displays don’t have any bezels, so the manufacturing process differs from traditional smartphones. To include a display embedded fingerprint sensor with high sensitivity on an edge-to-edge display might be difficult, given the tight production schedules of these devices.

Moreover, edge-to-edge displays are designed to provide the user a feel of an undisrupted display that covers the front of the device. Placing a fingerprint sensor anywhere on the screen would make that area of the smartphone hands-off for any other functions. Another reason behind the unfeasibility of display-embedded fingerprint sensors is the obliteration of the home button concept. Both Samsung and Apple had proprietary home buttons on their devices for around a decade. So much so, that these home buttons became a signature of these companies' smartphone designs — all phones from both companies had a home button.

Read: iPhone 8 Rumors: Analyst Says Qualcomm In-Screen Fingerprint Sensor Not Ready Yet

This year seems different. While Samsung has already gotten rid of the home button, Apple is expected to move on the same lines and ditch its proprietary home button on the iPhone 8. The lack of a home button simply does not leave for placing the fingerprint sensor on the front of the device, which is why devices like the S8 have it at the back.

Another important reason, that a display-embedded fingerprint sensor on a major smartphone might never see the light of day is that the technology itself is getting outdated. Phones such as the iPhone 8 are expected to go with face recognition instead of fingerprint recognition as a security feature. It seems to be the correct move, since fingerprint sensors aren’t fool proof and might be easily fooled using fingerprints taken on surfaces such as plastic.