Biocomputing: DNA computes a square root.

465 news & views of amplifiers and logic devices based on graphene, actually enables a new class of nonlinear radiofrequency electronic devices. Frequency multipliers 5,6, , high-frequency mixers 7 and digital modulators 8,9 have all been recently demonstrated using this principle, with operating frequencies as high as 16 GHz and radiofrequency efficiencies in excess of 90% (ref. 10). Infrared photodetectors are another class of graphene device that shows higher performance than its silicon counterpart today, despite its relative immaturity 11,12. Again, these devices benefit from the zero bandgap of graphene, which allows them to absorb light from the infrared to the ultraviolet with almost equal strength. Graphene photodetectors have already been fabricated at very high frequencies and at wavelengths that cannot be accessed with silicon-based devices. These devices will have an important role in the next generation of infrared night-vision systems, optical communications and chemical analysis. Finally, a key property of graphene, which is often forgotten, is its ability to integrate with almost any substrate. This means that it does not need to replace silicon to be useful: rather, graphene can complement silicon. In the near future, it will be possible to transfer a variety of graphene-based devices onto a prefabricated silicon chip and connect the devices to the chip through the top-level metallization (Fig. 1). In an early demonstration of this concept 13 , a silicon chip was covered with a graphene layer that was patterned to form interconnections and delay lines that were controlled by the chip. A huge amount of research has been devoted to the development of methods for integrating new materials (such as III–V semiconductors) with silicon: with graphene, the integration is remarkably simple. Graphene is an amazing material looking for an application. Meanwhile, the electronics industry is a trillion-dollar giant looking for the next switch. Although graphene may very well provide that switch, it is important to keep our eyes open to other opportunities, particularly those that result naturally from the properties of graphene. Ambipolar nonlinear electronics, broadband photodetectors and advanced sensors are some of them, and they can be easily integrated onto silicon platforms. It is tempting to try to fit any new material into existing technologies and needs. However, we should never forget the words of the semiconductor pioneer and Nobel Prize winner, Herb Kroemer, which he calls his lemma on new technology: " The principal applications of any sufficiently new and …