The market is burgeoning in the area of flexible and wearable electronics. They are not only incorporated into a wide array of electronic devices such as displays, solar cells, automotive systems, and cell phones, they are being exploited in the fashion world. Flexible electronics also have enormous potential in wearable health monitoring devices and medical implants.
But if you wanted to communicate information efficiently from these electronic devices while retaining their flexible and sometimes transparent qualities, you were stuck – until now. Prof. Zhaohui Zhong and his team of graduate students, Seunghyun Lee, Kyunghoon Lee, Chang-Hua Liu, and Girish S. Kulkarni, have built the first flexible, transparent digital modulator for high speed communications, made solely out of graphene.
Existing digital modulators are typically made from silicon, which is rigid and non-transparent, and therefore not suitable for applications where you want the electronics to be flexible. Graphene has previously been investigated for use in high speed communications because it’s fast (it can operate up to 300 GHz) and it’s reliable.
Compounding the importance of Zhong’s work is the fact that this is the first time anyone has shown quaternary modulation with a graphene circuit. Why is this important? It results in 2x the speed of binary modulation, which was the former state of the art. Zhong’s group demonstrated a quaternary modulation scheme called Quadrature Phase-Shift Keying (QPSK) modulation on their all-graphene circuits. QPSK modulation is the building block for more complicated modulation schemes found in current telecommunication standards.
Their device is also relatively simple, thanks to graphene’s unique quality of being nonlinear and ambipolar (normal transistors are unipolar). Their QPSK modulation uses only two transistors to accomplish the same amount of work accomplished with a multitude of circuits in other methods.
Prof. Zhong has applied for patent protection on this technology.