|OK, so you are interested in the whole sorted story of how we
got dust mites to ride on our MEMS device. I will reveal for the first time ever
the whole story of WHY we did it and HOW we did it. It was in the
mid-1990's and many people at the time were saying that MEMS would never be able
to do any useful functions. People working on MEMS were accused of
"playing in the sandbox" and of being "dreamers". In
particular, work on complex motors and so forth was scorned. At one
conference a respected professor stood up and said in disgust that MEMS really
stood for "Micro Engines Move Squat". Indicating his opinion
that MEMS work focused on complex mechanical elements would never amount to
anything. At the time, we were struggling to get even the most simple
mechanical functions working. Well, we took the "Micro Engines Move
Squat" comment as a direct challenge, and we purposed ourselves to show
that MEMS devices could indeed move real mechanical loads, and therefore, would
in fact some day find significant and relevant applications. But at the
moment, the goal was to show that MEMS could move real loads. Now the question
at hand was, what would be a relevant demonstration. We considered several
things like salt (too boring), blood (too messy), or hair (wrong shape).
In the end, we decided the most impressive demonstration would be to get a live
spider mite to crawl up on the device, and then give him a ride
around. This demonstration also gave us the opportunity to respond to
the respected professor the following year, that in fact, MEMS stood for
"Micro Engines Move Spider mites".
So, we set about to do the demonstration. Immediately, it turned
out to be a lot harder than we had imagined. The first problem was
finding mites in New Mexico. Apparently, mites love damp, moist
environments, something hard to find in New Mexico. The next problem we
found was that mites come in many different sizes . . . some too small and
some too large for our MEMS device. The other problem we found was
than some mites are transparent under the the bright light of the optical
microscope. So, we needed a special mite . . . one not too large,
and not too small, and one with a thick skin so he would show up nicely
under the microscope. It was clear that we were quickly getting out
of our area of expertise, so we decided to find an entomologist to help
us. We called around at a nearby university and found that there was
actually one of the world's premier mite experts right down the street
from us. We contacted him and he agreed to help us in our endeavor
to find the perfect mite. He said that he had the perfect place to
"catch them" and if we would send someone to meet him at 10:00
PM, he would help to track down the illusive critter.
Well, we immediately put Glenn, one of our top technicians, on the job,
and gave him the contact information for our newly found entomologist
friend. Glenn met the good bug doctor at his office at the specified
time. He told Glenn that he had a special place for catching the
mites. So, he piled Glenn in his car and started driving.
After some time they pulled into a deserted area. Glen became a
little uncomfortable when he realized that the guy had driven him to a
remote grave yard. Sensing Glenn's discomfort, he quickly explained that
the graveyard was the perfect place to catch the particular species of
mite we were looking for because they water the grass there a lot,
creating the moist environment the mites crave. At the same time,
the grave yard had much less foot traffic than, say, a golf course,
so the mite colonies can grow relatively undisturbed.
They wander around the grave yard, and at about the stroke of midnight,
the bug man finally finds the perfect spot, and sets his traps. Yes
folks, there are such things as special purpose dust mite traps.
They find a comfortable spot nearby to sit, and the bug man then
proceeds to tell Glenn more than he ever wished to know about mites . . .
not just any mites, but the particular type of mites that were the perfect
size and opaqueness for our project. The man explained that dust
mites live for only a short period of time, so to be successful, we would
have to host our own colony, ensuring we would have live specimens to take
the wild ride on the MEMS device. Glenn learned that a miniature
rose bush would be the perfect venue for hosting the colony. The man
explained it was critical to mist the small bush several times a day in
order to maintain the humidity necessary for the colony to thrive.
After several hours on the proper care and feeding of the new colony, they
determined that there would be a good starter set of mites in the trap, so
they retrieved the trap, just as the sun was beginning to rise over the
Glenn showed up in the lab the next morning at about 7:00 AM. In
his hand was a miniature rose bush in a small pot, teaming with our colony
of perfectly sized and tinted mites. The mite colony . . . I mean
rose bush was placed in the test lab, and we now had the specimens we
needed to make the above video. However, at the time we did not have
any MEMS of the proper size and power for the desired demonstration.
Within about a month, some new devices came out of the fab. Devices
with the perfect size and power to give the mites a ride. It was
during this period of time that several technicians working in this lab
developed a peculiar and unexplained scalp irritation.
Then came the moment . . . we had the bugs, we had the MEMS, but how to
get the bugs to crawl up on the MEMS and take a ride. Our first try
was to simply shake the rose bush over the wafer, and have an army of mite
paratroopers invade the surface of the wafer. This worked, but after
several hours of staring at the microscope, we found that the mites were
running all over the place, but none of them happened to crawl up on the
particular MEMS device we had up and ready to run and under the
Those of you who have done any testing of wafer level microelectronics
know what probes and micromanipulators are. They are the precise
alignment devices that allow you to bring electrical signals onto the
surface of a wafer to test microelectronics in wafer form. To the
microelectronics engineer, they are the valuable tools that allow this
important testing to be done . . . . to us they became micro-cattle-prods
for the purpose of "herding" the mites where we wanted them to
go. We found that we did not have to energize the probes with high
voltages like you do with traditional cattle prods, but rest assured we
were prepared to should it become necessary in order to get the shot.
Simply nudging the mites with the probes provided the mechanical
stimulation needed to get the mites to go where we wanted them to.
After perfecting the art of mite wrangling, the big day came to make the
video. It was a Saturday, since we would never dream of doing this
work on company time. We had a guy to run the video camera, we had
Glenn, the mite wrangler, and we had someone to run the MEMS.
Everything was ready, so Glenn shook the miniature rose bush over the
wafer, and sure enough got a really nice herd smack in the middle of the
wafer. As they made their way across the wafer, Glenn spotted one
particularly lively mite on the outskirts of the herd. At about the
time the herd was approaching the MEMS mirrors, Glenn skillfully
brought the probe tip around and cut the lively mite from the herd.
Immediately, the mite made a b-line towards the optical shutters, but
Glenn headed him off at the pass, and nudged him back in the direction of
the gear we were shooting for. With success within site, the camera
was turned on, and within seconds, the mite crawled up on the MEMS
gear. Immediately, the MEMS was turned on. The mite was startled,
and stopped walking. He stood on the gear, as the MEMS spun up to
several thousand RPM. After five or six seconds, the MEMS was
turned off, and the mite was temporarily disoriented. After a minute
or two, the mite regained his sense of direction, and scurried off to join
the rest of the herd, which by this time was over by the MEMS accelerometers
on the upper quadrant of the wafer.
The wafer was then shaken over the top of the rose bush to return the
mite colony to their home.
The colony survived on the rose bush for several years in the
lab. We periodically would borrow a few for various pictures as new
devices came out. In about 1997 the mite colony became so populous
that they actually killed the rose bush. Losing their source of sustenance
and protection, the colony died. It was about that time that the
mysterious scalp ailments of the people working in the lab cleared up.
Since that time, the video of the mite has been featured on television
shows around the world, including the ABC evening news with Peter
Jennings, CNN, Discovery Channel, and the NBC nightly news. And now you
know the whole story of how it was done.