''A New Way to Kill Mosquitos''
“United States patent 6,708,443,
a wide-ranging patent covering several approaches that he
contends might help control mosquito populations across
wide areas such as wetlands or regions in Africa where
mosquito-borne illnesses like malaria are rampant. Most of
Mr. Hall’s approaches rely on the same principal: killing
the mosquito eggs rather than the mosquitoes themselves. “A New Way to Kill Mosquitoes
July 5, 2004
By TERESA RIORDAN
WITH the threat of West Nile virus and the invasion of
fierce Asian tiger mosquitoes in his neighborhood in
Arlington, Va., Donald R. Hall was beginning to worry about
his young granddaughter playing outside.
So Mr. Hall, 60, who retired as an electromechanical
engineer in the military and intelligence sectors to spend
his days dreaming up inventions in his backyard skunk
works, went on the offensive several years ago in the war
against the mosquito.
Mr. Hall recently received United States patent 6,708,443,
a wide-ranging patent covering several approaches that he
contends might help control mosquito populations across
wide areas such as wetlands or regions in Africa where
mosquito-borne illnesses like malaria are rampant. Most of
Mr. Hall’s approaches rely on the same principal: killing
the mosquito eggs rather than the mosquitoes themselves.
“They will breed in a bottle cap,” Mr. Hall said. “The idea
is to interrupt the life cycle.”
His first weapon: a birdbath. According to Mr. Hall, the
birdbath, which can run on batteries, solar power or
electricity, provides an attractive place for mosquito
mothers to lay their eggs. (Under a microscope, the eggs
resemble little clusters of beach balls floating on a
raft.)
Every few days a tiny computer chip embedded in the
birdbath instructs a pump to flush the water out, pushing
it through a fine-mesh filter. As the mosquito eggs go
through the filter, they are crushed. Of course, some early
bloomers may already have developed into larvae or nymphs.
But since they are too young to fly and they don’t really
know how to swim, Mr. Hall said, they drown as they take
the mosquito’s equivalent of a whitewater rafting trip
without a life vest.
Another device Mr. Hall has invented is a shallow tray
powered by what is known as a bimetal coil. As rainwater
stagnates in the tray, which has a fine mesh at the bottom,
it becomes an attractive spot for mosquitoes to deposit
their eggs.
The coil – made of two different metals strapped together,
each with different expansion and contraction rates –
expands as it warms during the day, pushing the mesh above
the water line. The mesh captures the eggs, which bake in
the sun during the day. In the evening, the coil cools and
contracts, pulling the mesh back under the water, waiting
for more unsuspecting mosquitoes to lay their eggs.
Mr. Hall said such devices would require little or no
maintenance and would be cheap to build, making them
appealing for the developing world or for places where they
would need to be distributed widely, such as wetlands.
“You could give them away,” he said.
Mr. Hall is not the
only inventor preoccupied with mosquitoes. In April, for
example, Mary Robison, who lives in Missouri, patented a
sticky mosquito trap whose main attraction is lactic acid,
which humans secrete when they sweat.
One invention already on the market is the Mosquito Magnet,
a propane-powered device that mimics mammals by exhaling
carbon dioxide. Then it sucks in mosquitoes which think
they have just found a warm meal. But that product is
relatively expensive, Mr. Hall points out, with models
ranging from $195 to more than $1,200. And the propane tank
must be changed every three weeks, at a cost of about $20.
The Mosquito Magnet has garnered mixed reviews from
customers on Internet sites that sell the device, like
Amazon.com and Target.com.
So far, Mr. Hall has not licensed any of his mosquito
ideas. But he is busy at work on other projects, including
a utopian-sounding plan for linking neighborhoods to
communal hard drives on telephone poles, for which he
received patent 6,402,031 two years ago. Which is not to
say that the rest of the insect world is safe from his
inventive zeal: percolating in his mind at the moment, he
said, is a scheme involving cat food and bug zappers as a
way to do in that other flying pest, the common housefly.
Patents may be viewed on the Web at www.uspto.gov or may be
ordered through the mail, by patent number, for $3 from the
Patent and Trademark Office, Washington, D.C. 20231.
http://www.nytimes.com/2004/07/05/technology/05patent.html?ex=1090038844&ei=1&en=f7842d31f546ab45
Tags: Health, Malaria