Think Things Are Small Now?

Aug. 5, 2008
What the One-Molecule Sensor Might Mean for Process Control

By Jeffrey R. Harrow, Principal Technologist, The Harrow Group

When you were a kid, did you build a “crystal radio”? I was beyond the days of the “cat’s whisker” (really a thin copper-bronze wire) radio, but I still remember my amazement that a little1N34 diode and a few other things could receive radio signals like their much larger “tube radio” cousins.

Things progressed, of course, through the original vacuum tube portable radios that used several odd batteries (one was 67.5 volts, if I recall), through the 1950s archetypical “six transistor radio” (more transistors were considered better, even though some manufacturers upped the transistor count by using some as diodes where needed!) to the tiny radios of today. But “tiny” is a relative term. Now we have the “one molecule radio.”

I’ll Have A Radio Please; Hold the Coils, Hold the Capacitors, Hold the…

University of California, Berkeley professor Alex Zettl decided that even today’s radios were far too large and complex. So in about two weeks, he and his students created a single carbon nanotube molecule to tune and snatch radio signals out of the air and convert them to audio. This single molecule incorporates the radio’s antenna, tuner, amplifier and demodulator! (You can see and hear the nanotube radio work here.)

Of course the point of this isn’t to listen to the Beach Boys or Nine Inch Nails, but to form the basis for future radios that will “change the rules” in ways more fundamental than those first pocket transistor radios—especially since Zettl expects his molecule to transmit as well!

What might it mean to automation if virtually every sub-component in a machine or system could participate in a mesh network, within every device, to report its condition and allow it to tune its function based on the other sub-components around it? Could we be building truly “smart” machines that could self-regulate and, perhaps, self-heal (by switching to redundant elements as needed, as the overall device’s functionality degrades)?

What about completely new classes of devices that use wireless molecular nanotube sensors to sample various chemical, biological or environmental states virtually everywhere within a system, and have the entire “organism” alter its operation as needed? Truly “rule-changing” potential.

Oh―and the most significant issue, I believe, is that we’re sitting here and discussing single-molecule electronic machines―not in a “some day” time frame, but “today.”

“Yes,” “No,” “Maybe.”

Speaking of “machines,” why stop at molecular components―why not bend atoms themselves to our purposes? An interesting case in point is that odd thing called quantum computing.

Quantum bits, or “Qbits” have an unusual property compared to the traditional binary (1 or 0) states that we know and love. Qbits are multi-state, in that they can represent several values all at the same time, and can even share their state instantly (the speed of light being no limitation here) with other “entangled” Qbits far away! (I know―it defies common sense, but…)

Labs have been playing around with Qbits for some time now, but just recently Gerhard Klimeck, professor of electrical and computer engineering at Purdue University, has created an “exotic flat atom” that, as part of a specially “engineered molecule,” allows a quantum state to be controlled by the physical location of an artificial atom on the molecule’s surface. “We can control the location of the electron in this artificial atom and, therefore, control the quantum state with an externally applied electrical field.” Just as with our now-cumbersome transistors, being able to control a device’s state allows for limitless results.

This is still very much in the lab, so don’t hold off purchasing your next microcontroller. But it is one more example of how our beginning use of atomic and molecular building blocks, rather than our old transistor logic gates of yore, will be changing all the rules again and again.

Reaching Out And Touching…

We may be getting better at working with things at the atomic and molecular levels, but we’re still babes in the woods when it comes to interpreting and making use of the signals generated by our brains. More than a few people have (jokingly?) wished to “plug in” directly to our computers and the Internet to bypass their slow fingers and senses, or especially for the disabled, to control the things around us.

We can’t yet read minds or interpret the nuances of our brains’ electrical signals, but we are getting better at using the insights that we do have to make important strides.

Using electrodes implanted directly into the brain (to get around much of the “noise” of non-invasive connections to the skull), scientists have previously demonstrated that a person can control a cursor on a computer screen and type using an on-screen keyboard. Now, Andrew Schwartz of the University of Pittsburgh has taken this to a new level by giving a monkey sophisticated, seemingly natural, three-dimensional control of a robotic arm.

“Technology Review” magazine offers a fascinating movie of the monkey using his robotic “arm” to reach out and pick up a marshmallow and then put it into his mouth. He then moves the arm and hand quite naturally so that he can lick off the sticky residue.

The potentials for this technology to empower people who have lost a limb or are suffering from paralysis are obvious, but there are many other applications for this improving technology that will change a lot of rules. For example, people could work with hazardous or dangerous objects at a distance without resorting to the cumbersome and slow “waldos” of today. Pilots could control remotely piloted vehicles without the delay of using joysticks. Indeed, fighter pilots within planes might one day gain the competitive advantage of “speed of thought” control of their aircraft, which could save their lives. And don’t forget video games...

Overall, the more we know, the more we know we need to know. Don’t blink!