has made huge strides since the 19th century ads for painless
dentists, but fear of pain still keeps many people from getting dental work
done. Electronic technology is helping dentists reduce pain by tricking the
brain so patients barely notice the injections of anesthetics.
Dentists long ago noticed that if they vibrated the check area around the spot
of the injection needle's entrance, nerve signals were interrupted so patients
felt less pain. Florida dentist, Dr. Steven G. Goldberg, decided to capitalize
on this idea. He first used a vibrating flosser but decided to commercialize a
more rugged product, so he linked up with an engineering team to create DentalVibe, a device now being marketed to
"We provide a vibrating lip retractor that stimulates the region and has a
light to illuminate the area," says Dave Schiff, director of engineering
at Bresslergroup, the Philadelphia contract design house that designed
DentalVibe. The fork on the handheld tool vibrates while the dentist injects
anesthetic into the patient gums, pointing the needle between the prongs of the
The engineers use an eccentric cam to vibrate the fork, which is covered with
rubber so it's soft enough to be comfortable for patients. Finding the right
durometer rubber to permit vibration was a challenge, as was figuring out how
to trick the brain so it doesn't adjust for the vibrations and let pain signals
go to the brain.
"We run at about 120 Hz with 0.5 mm of amplitude. We found that if it is
on for about a second then turns off briefly, it keeps refreshing signals to
the brain and continuously masks the pain," Schiff says.
Fitting a powerful motor into the handle was a key design challenge, one that
required getting the most vibration from the smallest motor. "One concern
was to get the maximum force so we use a dc motor that delivers the most torque
on the 1.2V the battery supplies," Schiff says.
Making the unit compact and light were also critical elements in the design.
The unit can't take up much space and it can't be bulky. The motor, light
source and battery fit in the handle. A light pipe permits illumination at the
point of injection while letting designers keep the fork thin so it's not intrusive
It uses a rechargeable battery that easily lasts the 30 seconds or less that
it's activated for injections. Simplicity in design was important to keep costs
down and ensure that electronics aren't damaged during the many washdowns endured
by dental equipment. "It's a three-part, overmolded assembly that uses a
light pipe to shine the light where the dentist will be making the
injection," Schiff says.
Engineers at Fuel Cell Energy have found a way to take advantage of a side reaction, unique to their carbonate fuel cell that has nothing to do with energy production, as a potential, cost-effective solution to capturing carbon from fossil fuel power plants.
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This is part one of an article discussing the University of Washington’s nationally ranked FSAE electric car (eCar) and combustible car (cCar). Stay tuned for part two, tomorrow, which will discuss the four unique PCBs used in both the eCar and cCars.
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