Nov 15, 2011Science and Technology
The world's smallest electric car: Nanotechnology gone mad?

I have noticed a growing trend over the past decade for researchers to garner publicity for their efforts by embedding their (often brilliant) work into some impractical but notable form that will gain attention from the public. 


An example is the recent tendency for NASA to announce new developments and discoveries as having special relevance to the existence/discovery of extraterrestrial life.  Other participants include the push toward ‘cute’ (but barely functional) robots, nano-scale ‘trotting horses’, a functional nano-scale hula-hoop, the ‘lab on a chip’ described as enabling Star Trek tricorders, micron-scale steam engines, describing nano-scale van der Waals adhesive effects as enabling a Spiderman suit, and, of course, metamaterials as offering us a copy of Harry Potter’s invisibility cloak. 


Along these lines, a vast array of functioning but totally impractical micro-size objects has been developed over the years.  These include such micron-scale musical instruments as guitars, violins, harps, and complete orchestral synthesizers.  Famous works of art have been fabricated, such as a 10 micron copy of Robert Fludd’s alchemical drawing of the Sun. Printed characters smaller than single atoms have been written at Stanford University in the electron clouds of a metal surface.


A long-standing niche for record-setting functional yet whimsical machines has been the electric car.  In 1995, Nippondenso was awarded a Guinness World Record for the fabrication of the world’s smallest motorized car.  This record setter was a 1/1000th scale copy of Toyota’s first production automobile, a 1936 model AA sedan. 4.7 mm in length, the Nippondenso Micro-Car weighed about 15 milligrams, and was powered by a 0.67 mm permanent magnet electric motor, supplied with 3 VDC at 20 milliamps for a total of about 60 microhorsepower, one millionth of the power of the original model AA.


Built using ultra-precision machining and semi-conductor processing technologies, it had a top speed of 1 cm/sec.  This would scale to a speed of about 23 mph – considerably slower than its full sized counterpart at 70 mph.  Presumably there was a good deal of power loss in the tiny bearings.


MEMS, LIGA, and nanoscale cars have owned this niche since about 2002.  The most recent claimant is the result of collaboration between the University of Groningen and the Swiss Federal Laboratories for Materials Science and Technology.  Published in Nature on Nov. 9, 2011, their car is formed from a single molecule about 2 nm x 4 nm in size, a million times smaller than the Micro-Car, having a molecular weight of ~2000. 


Such single-molecule cars have been made before, but with wheels based on rotaxanes (a chemical compound in which a ring of atoms is held on a carbon chain by capping groups), or rotation of buckyballs or carborane groups around the end of a carbon chain.  None of these previous devices had a handedness associated with wheel rotation – they could move forward or backward, but the direction could not be chosen. 


A ‘nano dragster’ fabricated at Rice University set the standard for speed by travelling at 9 nanomiles per hour (about 4 nm/sec.)  The new nanocar has flat wheels consisting of fused aromatic rings attached to motor groups that flip the wheels around a carbon chain, resulting in a bumpy but sure-footed ride. The motor groups are driven by the electric field associated with an STM tip (on the order of 109 V/m), and can only move in one direction. 


As a result, this is the first truly controllable molecular car.  Unfortunately, it has not yet been tested for top speed. Such demonstration devices are all well and good, but do they really add to our technological progress? Concerning the Nippondenso Micro-Car, an anonymous commenter said ‘Didn’t they (Nippondenso) have any real work to do?’  Such comments have been also made about the superconducting supercollider, Apollo missions 18-20, and the James Webb Space Telescope – usually by people who wanted to divert funding to their favorite projects. 


The question, however, is a good one.  Assume that you have made a promising technological advance, but it will take one or two more decades of work before that technology yields practical results. How do you convince people to continue funding your work?


Itinerant cabinetmakers in the 18th Century faced a similar problem.  No one knew them or their work, so how did they convince people to hire them for a job? Their answer was the cabinetmaker’s tradition of showing their best work in making their own toolboxes, which then acted as a form of resume. To see a small scale project completed with the highest construction and aesthetic standards encouraged their potential clients.  In many ways, whimsical demonstrations of new technology serve the same purpose. 


If at the early stages of technology advances, an expert in the field can produce a small precision stand-in for the future fully developed technology, it encourages funding sources to support further work.  There is also the political effect, of course.  A technological advance that can be presented to senators and representatives with a ‘Wow’ factor will usually receive more funding than a more important advance that is difficult to illustrate or explain. 


We must also keep in mind that a huge driver for space telescope development and implementation is fascination of people in the street with the near-constant stream of incredible astrophotos taken by Hubble.  As the Irish writer Brendan Behan noted ‘There’s no such thing as bad publicity except your own obituary.’  This wise quip explains the trajectory of many technological advances.  Isn’t it a wonderful world?  

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