Since Harry Potter inspired the idea, invisibility cloaks have been an obsession with scientists. Several prototypes have already been created. Most of these invisibility cloaks use metamaterials that bend radiation around whoever is wearing the cloak. The problem is that these cloaks only work with a small range of frequencies. Because of this limitation, other frequencies actually make the cloak (and whoever is under it) more visible. For example, a cloak created to be invisible in red light would stick out like a sore thumb when exposed to blue light. Needless to say, these cloaks are ineffective, not really being invisible at all. These current cloaks are also bulky, making them uncomfortable to wear for any amount of time.

However, physicist Andrea Alu from the University of Texas at Austin thinks there’s a way to fix this by making cloaks out of materials that are electrically active. Alu proposed a design that starts with the standard metamaterials but adds CMOS negative impedance converters (NICs) at the corners of the cloak. Although we’re not entirely sure how NICs really work yet (they’re not widely in use), Alu believes that using them in this way would allow cloaking of multiple frequencies. This would make the invisibility cloak more invisible, as well as thinner and lighter.