ELECTROSTATICS NEWSLETTER

September/October 1999 No.146

I would like to share with you excerpts from a proposal that the ESA recently submitted to the National Science Foundation to fund a joint ESA/IEJ workshop on electrostatics in the year 2001. It nicely highlights the evolution of electrostatics from the early part of this century to the present time and provides a view of future directions in the field. In my President's Message for the next issue of the Newsletter, I would like address the role that electrostatics education must play if the technical community is going to be able to meet the challenges of the future. (Portions of this excerpt were written by various people, including Al Seaver, and Ed Law. My apologies for not giving credit to any other contributors).

"During the first two thirds of the 20th century, innovations such as the electrostatic precipitator, electrostatic paint spraying, the Van deGraaff generator, and electrophotography led to important advances in environmental pollution control, manufacturing, particle and x-ray physics, and inexpensive document reproduction. The electrostatic precipitator, for example, is a high efficiency device used throughout the world today to remove air pollution particles, smoke, and fly ash from the waste stacks of industrial and power plants. The technological advances that made electrostatic precipitation possible are attributable to the pioneering work of Frederick Cottrell, a university researcher. Later improvements by Prof. Gaylord Penney of Carnegie-Mellon University, and others, contributed to the establishment of electrostatic precipitation as a mature and reliable technology that forms a billion-dollar industry today. A similar example of the important role of electrostatic technology can be found in the invention of electrophotography, or "xerography", by Chester Carlson in 1938. Dr. Carlson's invention, which eventually led to the now ubiquitous and indispensable copy machine, transformed the way the world did business and has been responsible, in part, for the success of the computer revolution by making inexpensive, high-speed desktop printing a reality. In fact, all modern printing techniques rely on electrostatics, including laser printers, copiers, ink-jet printers, plain-paper fax machines, and high-speed color image reproduction. Ink jet printing, and subsequently cell sorting for biomedical research, grew out of an adaptation of electrostatic paint spraying, a coating method invented by the American industrialist Ransburg in the 1940's. This widely used method for applying decorative and protective coating on manufactured objects utilizes electrostatic forces to attract paint droplets directly to the workpiece. Throughout the world, electrostatic paint spraying has greatly reduced environmental pollution both from volatile paint solvents and wasted coating materials. Its transformation to a mature technology required the joint efforts of numerous academic and industrial researchers, and it remains a topic of considerable research to this day. Over the past decade, conventional, liquid-based electrostatic paint spraying has been largely supplanted by a new coating method based on solvent-free, dry powder electrostatic coating. Powder particles, charged by various methods, are attracted to the workpiece electrostatically, then baked to form a durable coating that is superior to many solvent-based paints. This dry power method eliminates entirely the need for volatile organic compound-based solvents (VOCs), leading to a safer and less polluted environment. Electrostatic coating techniques have also been developed for agricultural crop spraying, where commercially available machines apply pesticides directly to the undersides of plant leaves using electrostatic forces, thereby drastically reducing the amounts of pesticide introduced into the environment.

"The same powder handing techniques used in the coating industry also have found their way into other industries, including chemical processing and agriculture. The widespread use of powders in industry has created a new set of problems: Charged airborne particles of the correct powder-air mixture can become explosive. Indeed, numerous industrial accidents have been traced to the electrostatic ignition of airborne powders. An entire branch of electrostatics research has emerged to address the problems associated with powder handling, but they are far from being solved, and much additional research is needed before the hazards of powder handling are fully understood.

"Electrostatics has also played an important role in the microelectronics industry. Initial attempts to develop CMOS integrated circuits met with early disaster because of the damaging effects of electrostatic discharge, or ESD. Following a period of intense fundamental, academic-based research aimed at understanding the problem, a worldwide industry in electrostatic control was spawned that has become a key part of every semiconductor fabrication and electronics assembly plant today.

"While these examples emphasize the accomplishments of the electrostatics community over the past several decades, other examples demonstrate that electrostatics will continue to play a vital role in emerging technologies of the next century. The fields of environmental control, airborne pollution reduction, environmentally-safe manufacturing, biotechnology, DNA manipulation, micro-scale and nano-scale devices, ultra-large-scale integrated electronics, and photonics all will require a deeper understanding of electrostatics fundamentals as well as the development of new electrostatic technologies. In the area of biotechnology, numerous U.S. researchers work with electrostatics to sort DNA molecules via electrophoresis. This sorting technique involves electrostatic migration of charged DNA molecules placed in an electrified gel. Cell level biomechanics is the wave of the future, and electrostatics will be one of the enabling technologies in this area. Electrostatics also plays an important role in a new understanding of how airborne pollutants and allergens enter and interact with the human body. Novel electrostatic-based methods for administering medicinal aerosols for respiratory therapy are rapidly developing.

"In the areas of microelectronics and photonics, electrostatics continues to play a vital role. As the state of the art brings us beyond sub-micron devices to the realm of nanotechnology, the importance of understanding and controlling electrical overstress and electrostatic discharge (ESD) becomes increasingly important. Present 1-mm line width devices, considered the mainstay of semiconductor manufacturing in late 1990's, require that voltage buildup due to charge accumulation and triboelectrification be kept below levels in the tens of volts. As the size of devices decreases, this voltage limit will fall as well. One estimate predicts that by 2010, voltage levels in excess of one volt will be considered detrimental to some classes of electronic devices."

These examples, and others, provide continuing evidence of the vital role that electrostatics, in its many forms, plays in the technological health and well being of society. The ESA has a long history of advocacy for all things electrostatic -- a trend that I hope will continue long into the future.

For the Friendly Society

Mark Horenstein

ESA President

In the life of a bird, there are many hazards: four-legged predators and some on two legs, pests and pesticides, and natural weather variations. But one might not name communication towers. These tall structures provide startling mortality for birds by simple collisions.

ESA members will ponder the whys. Why do birds collide at all? They can see and they have marvelous navigational aids. Is there an interaction between the tower signals and the birds? Are the birds attracted by the lights used to warn aircraft?

Many years ago, at an annual meeting we discussed this and heard a paper or two. Was there an electromagnetic interaction? Recently, the Knight Ridder News Service reported again on the birds. And the numbers are quite striking. Occasionally one tower will kill a thousand birds in one night.

There are two challenges here. First, for the inventors and creators. What can we do? Is there a simple change that can be made in the signals that will warn off birds? A simple change in construction? Can we save the birds (at reasonable expense)?

Then the second challenge. What about calculations for our numerate members. Do they make sense? One amateur birder has collected around a single tower for about 45 years, and kept count. Total 120,000 carcasses. (If you work this out, that’s seven per day average). But the same birder reports 12,000 on one night! Is this credible? Look at it another way. If 12,000 birds were spread out in a hundred foot diameter circle, there would be one or two per square foot! Is this what the birder saw?

And another calculation. The news service reported about 4 million deaths per year from approximately 80,000 towers. Break this down for another surprise. Each tower only kills one bird per week!

I hope I have left you confused. Why is there so much variation between towers and between nights? Are these towers equipped with lightning rods? Are they passive rods (Franklin)? Are there some active rods (special points or radioactive materials)? As the 21st century draws nearer, questions multiply and much good science lies ahead. By the 22nd century our questions will seem as naive as dragons in the forest.

Glenn Schmieg

Some years back Emery Miller and I discussed a problem. ESA was strong. ESA was filled with good science. ESA was filled with interesting people. But we were not spreading the word "electrostatics" enough.

Soon we formed a plan. Emery had connections to several science fairs and several companies. I volunteered to take some toys and show ‘em static electricity. With the help of the officers and a little travel money, we started. In the spring of 1987, we introduced static electricity to 300 science fair attendees and some parents), two high school classes, and a roomful of arson investigators who had some pretty strange ideas about static!

Now it’s 1999. Shouldn’t we do this again? Would you volunteer? Would you speak to a few groups? Tell them why you like electrostatics and what you do with it. My bet is that if you volunteer, and ask the ESA for a bit of supply money or travel, it could work again. The world is waiting to learn about static. Please do it.

Glenn Schmieg