Manufacturing In a Small Space

Try one-billionth of a meter. That would be a nanometer—about the length of ten hydrogen atoms or one-hundred-thousandth the width of a human hair.

The Institute of Nanotechnology (www.nano.org.uk/) is not bashful in extolling its benefits. “Nanotechnology is an exciting area of scientific development which promises ‘more for less.’ It offers ways to create smaller, cheaper, lighter and faster devices that can do more and cleverer things, use less raw materials and consume less energy. There are many examples of the application of nanotechnology from the simple to the complex. For example, there are nano coatings which can repel dirt and reduce the need for harmful cleaning agents, or prevent the spread of hospital-borne infections.”

Even the U.S. National Aeronautics and Space Administration (NASA, www.ipt.arc.nasa.gov/nanotechnology.html) is interested in it. Its Web site lists anticipated benefits including ultrasmall sensors, power sources, communication, navigation and propulsion systems for new science and exploration missions. Further on its list are networks of ultrasmall probes on planetary surfaces, micro-rovers that drive, hop, fly and burrow, and collections of microspacecraft making a variety of measurements.

More down to earth, some researchers at Harvard University have used products from National Instruments Inc. (www.ni.com), the Austin, Texas, instrumentation and automation supplier, to create a virtual, high-channel-count, lock-in amplifier for nanotechnology research. Charles Lieber and Quan Qing used NI LabView software and a CompactPCI computer to develop the tool. "Using NI software and hardware, we’re able to build a virtual system with improved cost, smaller dimensions, and more flexibility than its traditional counterpart," states Lieber.

Locking in

A lock-in amplifier is an instrument used to detect very small AC signals in a noisy environment. For example, a 50 millivolt (mV) signal of interest may be surrounded by 5 volts of white noise. Scientists use these amplifiers in many areas of research, including medical, biological, geological and materials research. There are several manufacturers of lock-in amplifiers, and various frequencies, amplitude and phase measurement ranges are available.

“At the Lieber Research Group, which is in the Department of Chemistry at Harvard University, we had an application to detect specific bio-molecules/viruses using nanowire field effect transistor (FET) arrays,” says Lieber. “The diameter of a nanowire is a scant 10 billionths of a meter (10 nanometers) in diameter, or about five times smaller than a virus. Nanowire FETs are superior to conventional bulk silicon (Si) FETs in terms of surface charge sensitivity because of their one-dimensional structure and direct vs. buried device geometry. Nanowires have potential applications in detecting disease markers in body fluids that are indicative of malignancies, such as breast and ovarian cancers, and other types of diseases, as well as pathogens used in biological warfare. The sensor is so small it may be possible to implant detectors in the body to continuously monitor levels of insulin and other critical molecules. By correlating signals from an array of multiple sensors instead of from a single element, statistical methods can be used to reduce and/or eliminate noise and false positive signals, thereby enabling much more robust disease diagnoses.

“Using the National Instruments Lock-In Amplifier Start-Up Kit, we found an example of a virtual instrument (VI) that could be modified and expanded to meet our needs. The example provided in the start-up kit included an algorithm written in NI LabView that handles the phase-locked loop, filtering, and demodulation steps necessary to perform a lock-in measurement. The equipment is in use today in nanotechnology research.”

Even though nanotechnology may seem like an exotic and futuristic manufacturing discipline, today’s automation solutions hold promise to help boost this new manufacturing sector.

Gary Mintchell, [email protected], is Editor in Chief of Automation World.

The Institute of Nanotechnology
www.nano.org.uk/

U.S. National Aeronautics and Space Administration
NASA, www.ipt.arc.nasa.gov/nanotechnology.html

National Instruments Inc.
www.ni.com