Samsung unveiled the concepts at the Display Week 2021 virtual event. Other technology previews included a display with a camera underneath.
The S-foldable model comes with three panels and folds out like the letter Z. It acts as a smartphone when folded and a 7.2-inch tablet when opened. The other smartphone design was the slidable model, a smartphone that can slide apart to form a larger screen.
The under-display camera eliminates the need for a bezel around the screen, which lets an image take up the entire panel.
Samsung emphasized the portability and versatility of the smartphones and the tablet that unfolds into a laptop. None of the designs have visible creases when expanded.
Foldable and other expandable smartphones have not had much market success, analysts said. Nevertheless, Samsung remains committed to the devices while acknowledging that the latest concepts might not make it into actual products.
In a promotional video, Samsung showed how a person could prop up the foldable and slidable smartphones to watch videos or take photos. When unfolded, the displays can show either one image across the entire space or run separate apps on each panel.
According to the video, the displays also feature Samsung's Eye Care technology, which limits the amount of blue light the screen emits.
Both the S-foldable and the slidable models resemble concepts put forward by other vendors. LG was working on a slide-out smartphone before it closed its smartphone operations this year. TCL released a prototype for a triple-panel foldable called DragonHinge.
Samsung was one of the first vendors to introduce a foldable smartphone when it released the Galaxy Fold in 2019. The Galaxy Fold opened horizontally from a 4.6-inch display into a 7.3-inch screen. Samsung later released the Galaxy Z Flip, which opened vertically like a flip phone into a 6.7-inch screen.
At the time, T.M. Roh, Samsung's head of mobile, said the devices were "just a hint of what's to come as we continue to explore, evolve and expand this category-changing space."
Since then, Motorola released its Razr flip phone foldout and Huawei released the Mate foldout. Others, like OPPO, are expected to come out with foldable models this year.
Maxim Tamarov is a news writer covering mobile and end-user computing. He previously wrote for The Daily News in Jacksonville, N.C., and the Sun Transcript in Winthrop, Mass. He graduated from Northeastern University with a degree in journalism. He can be found on Twitter at @MaximTamarov.