Nnews
Science | DOI: 10.1145/1409360.1409365
Kirk L. Kroeker
Living machines
Researchers of molecular computing and communication
are focusing on the type of breakthroughs needed to make
the vision of ultrasmall, biocompatible computers a reality.

focused on the type of breakthroughs needed to make the fantastic vision of ultrasmall computers a reality.

Researchers working in molecular computing and communication—the inspiration for which can be traced, in part, to John von Neumann’s theory of cellular automata and Alan Turing’s work in autonomous self-structuring— seek to provide fundamentally new methods of solving challenging computational problems at microscale sizes. Currently, nanomachines created from biological materials are capable only of simple functions, such as detecting molecules, performing chemical reactions under certain conditions, and generating motion. While simple, these functions translate into sensing, logic, and actuation, respectively, each of which is a key element in any computing or communication system. But as with any advanced science, several major challenges in molecular computing must be overcome for the technology to make its way from lab to industry.

One of the challenges facing researchers working in this area, which requires advanced expertise in multiple disciplines, is to develop new languages

Physicis Ts have loNg postulated the idea that machines would become so sophisticated one day that scientists would be able to build increasingly smaller and more sophisticated devices until, at an advanced stage, entire computational systems would be able to operate inside the boundaries of a device no larger than a single cell. One early example of this type of speculation was a landmark 1959 lecture titled “Plenty of Room at the Bottom.” In the lecture, delivered at the California Institute of Technology (Caltech), Nobel laureate Richard Feynman talked about engineering circuits at the molecular level, with the idea being to build a tiny set of tools that would be able to build an even smaller set of tools, and so on, until scientists reach the point at which they can create circuits consisting of a mere seven atoms.

Feynman’s lecture has been credited many times for inspiring researchers working in nanotech and quantum computing. “The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom,” said Feynman. “It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big.” Science hasn’t yet realized Feynman’s vision of an atomic- or even a molecular-scale computer, but it has been steadily moving in that direction for the last 50 years. Much research has focused on moving beyond the speed limitations of traditional semiconductors with quantum computing, using bulky machines that rely on atoms themselves as bits and bytes, but another branch of research, molecular computing and communication, has

 

in an experiment on cell-to-cell communication conducted by tadashi nakano and colleagues at caltech, a mechanically induced calcium wave propagates through several cells. the networked cells, behaving much like nodes on a Lan, propagate signals in all directions.