Cracked smartphone displays could soon become a thing of the past thanks to an innovative mobile case made by a German engineering student that acts as an airbag to protect dropped phones from smashing.

The case, created by Philip Frenzel of Aalen University in Germany, senses when a phone is in a free fall and deploys small legs to protect it from damage.

The shock-absorbers in the four corners of the case do not make the case look odd as they lie flat inside the case in normal situations. They get released only when the case senses a free fall.

The student-built the sensors that detect the free fall of the cell phone and developed a metal spring that unfolds during the fall and the power and energy cushions the fall, according to a report in the German publication Preview Online. The dampers can be folded in manually after a fall and are reusable.

For his invention, called "AD Case" where AD stands for "active damping", Frenzel won an award from the German Mechatronics Society.

He expects to launch the device on Kickstarter this month along with another student at the university.

Frenzel founded a start-up together with Peter Mayer, a graduate in economics from Aalen University, in order to launch his "AD Case" as a product.

Frenzel's invention has already been registered for a patent.