Technological innovation continues to push the boundaries of what we once thought was possible. Looking back at technology's evolution, we can see how devices have gradually transformed from relatively large, rigid forms into the more compact, ergonomic designs we use today. Speaking of ergonomic design, one technological innovation that has captured considerable public attention is the emergence of foldable phones, or foldable smartphones.

Today, foldable smartphones have shifted attention toward innovations offered by several high-end flagship devices, including Samsung's Fold Series, the Xiaomi 18 Fold, and the iPhone Duo, which has attracted significant attention among Generation Z.

When we think about the surface of a conventional smartphone display, the idea of a screen that can be folded may initially seem almost impossible. This is understandable, considering that most conventional devices are still manufactured using glass materials that tend to be rigid. However, the same principle does not apply to foldable displays.

The ability to open and close like a passport book is certainly fascinating not only from an ergonomic design perspective, but also from the standpoint of mechanical engineering and material science. According to Taufik Nur Isman, S.T., M.T., a lecturer in Mechanical Engineering at Universitas Dian Nusantara (UNDIRA), the key to foldable smartphones lies in the use of Ultra Thin Glass (UTG), a thin and flexible type of glass combined with a polymer layer that provides additional protection.

“From a manufacturing perspective, we are talking about how to produce a display that is strong while still maintaining image quality. The smaller the bending radius at the center of the display, the greater the stress concentration and the higher the possibility of cracking. That is why the hinge area, or the center section of a foldable device, is designed with a space that allows the device to fold much like a book. In Mechanical Engineering, this is related to the concept of Young’s Modulus,” explained Taufik Nur Isman, S.T., M.T.

He further explained that, mechanically speaking, a foldable display is not simply made of a single layer of glass. Instead, it consists of a series of thin layers that are integrated.

“The display in a foldable device is not just a single screen. It consists of several integrated layers, with an average thickness of only around 60–100 µm. The first is the flexible substrate, which is made from polyimide and provides the basic structural support for the foldable display. Then there is the emissive OLED layer, Thin Film Encapsulation (TFE), and TFT, which protect and control the OLED’s performance in producing images. Next, there are the touch sensor layer, polarizer, and Optically Clear Adhesive (OCA), which detect finger touches while also helping reduce reflections from external light. Finally, there is the Ultra Thin Glass (UTG), along with a protective polymer layer or anti-reflective coating. Although foldable displays are designed to withstand repeated folding, that does not mean they are resistant to everything. Dust and water can interfere with the performance of the hinge and the foldable structure as a whole,” continued Taufik Nur Isman, S.T., M.T.

From the explanation above, it becomes clear that a display capable of being folded hundreds of times is not simply some kind of “magical glass.” Rather, it is the result of continuous advances in material engineering, mechanical engineering, and manufacturing processes.

When discussing the manufacturing of foldable displays, we inevitably enter a field closely related to Mechanical Engineering. The discipline is not limited to studying vehicle components or machinery. It also explores the various devices, technologies, and manufacturing systems that surround us, including the smartphones we use every day.

The Mechanical Engineering Study Program at Universitas Dian Nusantara (UNDIRA), under the Faculty of Engineering and Informatics, equips students with the very same fundamental knowledge needed to explore the case discussed above, from mechanics and strength of materials to manufacturing engineering and engineering materials.

So, instead of simply being a consumer of technology, why not become someone who studies it, designs it, or perhaps even contributes to improving it someday?

Sources of References:

Mengenal Teknologi Foldable Display pada Smartphone - RRI Indonesia

How Folding Phone Screens Are Changing Tech

Wawancara singkat dengan Dosen Teknik Mesin UNDIRA - Bapak Taufik Nur Isman, S.T., M.T.