Update: A video capture of Ed Generazio's presentation "Electric Potential and Electric Field Imaging With Dynamic Applications and Extensions" is now available.
The United States Patent and Trademark Office granted NASA’s Office of Safety and Mission Assurance Nondestructive Evaluation (NDE) program a patent for its Electric Field Quantitative Measurement System and Method. The patent covers both the Electric Field Imaging (EFI) sensor and the methods developed by Edward Generazio, NDE program manager.
When Generazio started working in NDE, he learned no one was working on the low end of the electromagnetic spectrum or electrostatics, and decided to focus his efforts there. Electric fields are everywhere and on everyone at all times. As people walk, they pick up charges that they then carry with them. However, it’s never been possible to image this field.
“Once you put a measurement system in the place of the electrostatic field, the field moves and changes, so you can never measure it,” explained Generazio.
He compares the experience to placing a thermometer in cold water — the temperature of the water prior to measurement can’t be measured because once inserted into the water, the thermometer is warming the water while the water is cooling the thermometer. The thermometer is changing the temperature of what’s being measured.
Generazio’s sensor made imaging these fields possible for the first time.
His interest was spurred by two events: the shuttle exceptions where anomalies in electrical systems were detected and the Trans World Airlines Flight 800 crash that involved a wire with poor insulation.
“My goal was to measure the electric field outside a wire insulation,” said Generazio, which is the same method outlined in his patent.
In 2002, he set out to learn how to identify when these electric fields start to change and the point before the electric fields become so large that they result in a critical arcing event that could lead to flight system failure. As he started making measurements, he found that surface charges on objects may be made visible and those images stayed for a long time — over days. Essentially, these charges left a forensic record of what happened.
Generazio’s efforts led to the development of three systems or EFI sensors, which can give quantitative measurements without changing the field they are measuring. The first is a tall, linear array that shows the electric field of objects as they pass through. This sensor can pick up and image charges on anything from plastic to humans, and even sense electronic signals from muscles. The sensor also can use a big quasi-static generator that illuminate objects and then images them.
This development could improve detection systems for weapons; for example, although guns are required by law to have some metal in them, however with new technology, people can build guns that are all plastic and undetectable by current metal detectors. This sensor is able to image the plastic gun in a container, simply because someone or something had to have touched it to place it there.
“There is no other system that could do that easily,” said Generazio.
A second system is the same sensor, but it rotates. This creation came about while trying to determine the range the sensor was capable of picking up. As it turns out, the rotating sensor is 10 times more sensitive. This technology could allow scientists to predict real lightening by generating electric field images of the sky, and also guide aircraft away from electrically charged clouds.
The third array addresses a problem with the linear system. A person’s potential is changing constantly with every breath and heartbeat, which makes it impossible to get a unique image of a person with the first system. This third array allows snapshots of specific areas and removes all those uncertainties.
“It will be a real-time movie of the electric field over the area it’s covering,” said Generazio.
Other Benefits and Applications
All three arrays amount to a whole new inspection area that hasn’t been done before: It’s now possible to measure the electrostatic properties of materials. Traditionally, when an object has internal damage scientists are limited to X-rays or other methods for characterizing that physical damage. With these EFI sensors, electrostatic fields may be used to highlight flaw locations, as well as changes in electronic properties, like failing wire insulation.
One of the first things to come out of Generazio’s efforts is the testing of a composite system. By putting the composite system into the sensor, engineers and scientists can see the flaws on both sides of the specimen. Charges move towards and polarize where cracks are, so they can see determine where cracks exist.
In addition, Electrostatic Discharge is a major issue in manufacturing and other areas, and Generazio’s system’s ability to readily image surface and subsurface charges can help ensure that proper mitigation methods are used and verified.
There are other spinoff applications of this new technology as well. One area that could benefit is the medical field. For NASA, Generazio is confident these systems could be used to measure cardiac activity in astronauts in the future, but he feels there could be other uses as well. Currently, when doctors do electromyography to evaluate the electronic signals from specific subsurface nerves, needles are inserted into the patient. If these sensors were used to conduct these tests, there would be no need for needles or any other touch points. There are no health risks associated with use or repeated use of the technology on humans.
As a result of the detection capabilities, there also are security applications. These systems could be used as a part of airport security or home burglar alarms. In addition, U.S. national security, defense and intelligence services have requested information on the technology. The technology is still very new, and the possible applications are growing.
For additional information, read Generazio’s paper, “Electric Potential and Electric Field Imaging with Applications.”