A team of researchers from the Massachusetts Institute of Technology developed a rectenna or a rectifying antenna. These 2D materials obtain AC electromagnetic waves from the air and convert them into DC power.  Existing rectennas are made of silicon or gallium arsenide that strengthens the material in order to supply power to small electronics. The researchers developed one that is only a few atoms thick that allows the rectenna to be fabricated to larger sizes. Their research was published in Nature

The new rectenna is made of a three-atom-thick semiconducting material called molybdenum disulfide (MoS2). It only has a 30 percent efficiency which is less than 60 percent efficiency of rigid rectifiers, despite its flexibility compared to other designs. Its capacity is that it can convert a maximum of 10 GHz wireless signals. 

How it works

A novel device comprised of a two-dimensional semiconductor connects to the antenna. The AC signal is converted into a DC voltage through the semiconductor and is utilized to recharge batteries or power electronic circuits. 

This method allows the device to capture and transform wifi signals into DC power. This flexible device allows it to be fabricated and cover larger areas. 

"What if we could develop electronic systems that we wrap around a bridge or cover an entire highway, or the walls of our office and bring electronic intelligence to everything around us? How do you provide energy for those electronics?" says paper co-author Tomás Palacios, a professor in the Department of Electrical Engineering and Computer Science and director of the MIT/MTL Center for Graphene Devices and 2D Systems in the Microsystems Technology Laboratories. "We have come up with a new way to power the electronics systems of the future - by harvesting Wi-Fi energy in a way that's easily integrated in large areas - to bring intelligence to every object around us."

Possible uses of this device

The proposed rectenna can be applied in providing power to medical devices, wearable electronics, and sensors for the "internet of things." Major tech firms will catch on to this tech fever as smartphones are the trend. A 150 microwatt wifi signal power level can produce around 40 microwatts using the device of the researchers. This could drive silicon chips and light up an LED. 

Co-author and researcher at the Technical University of Madrid Jesus Grajal says that the device can power the data communications of implantable medical devices. Scientists can obtain real-time health data from pills that can be swallowed by patients.

"Ideally you don't want to use batteries to power these systems, because if they leak lithium, the patient could die," Grajal says. "It is much better to harvest energy from the environment to power up these small labs inside the body and communicate data to external computers."