Turning WiFi and Body Heat into Usable Energy

A portable device being developed by physicists at the Massachusetts Institute of Technology (MIT), currently known as a “terahertz rectifier,” converts ambient waves into a direct current capable of charging our personal electronic devices, from a cell phone or tablet to a wireless medical implant. 

The energy is produced from high frequency terahertz waves, or “T-waves,” which are produced almost non-stop in our everyday lives. Until now, no technology has been able to capture and convert these waves in a practical way, let alone in the form of a portable device. Hiroki Isobe, the researcher and lead author of the article, explains that we are constantly surrounded by electromagnetic waves in the terahertz range. "If we can convert that energy into an energy source we can use for daily life, that would help to address the energy challenges we are facing right now." 

Three things to know about this groundbreaking technology:

• These electromagnetic waves, which are practically everywhere, have long been considered a wasted form of potential energy. They are produced by nearly anything that registers a temperature, from the human body to objects or signals, like the ones that radiate from phones and WiFi.
• Researchers say they were able to create the design for the direct current by modeling it on the behavior of the carbon material graphene. The electrons in graphene are capable of skewing the direction of other electron’s motions, so when incoming T-waves meet with graphene’s electrons, the materials are pulled to move in a single direction.    
• This is the first time that researchers have been able to harness ambient energy into usable electrical energy using a frequency in the terahertz range. Earlier experiments were only able to convert terahertz waves into “direct” currents in “ultracold” temperatures.