Someone asked me what the absolute coolest project was that we have worked on at Nordex. There have been many, but one of the seminal projects that firmly established us in the world of mechanical miniaturization was a device to control a miniature probe that was inserted into the brain of an awake, freely moving animal.
I can’t give many details because I’ve signed – and honored – nondisclosure agreements for everything I’ve ever done. But I can say this: it was long before the Internet was available to ordinary folks, and it was at a time when brain probes and laser-guided surgery were the stuff of science fiction.
We made this tiny little linear actuator, which is a device that will extend or retract in a straight line. An example would be when you stretch your hand out from your head – your arm is the linear actuator. (Compare this to a rotary actuator like your wrist, which allows you to turn your hand rather than extend it.)
For our linear actuator, we attached a screw to a little gear on the end of a tiny little Swiss-made motor that was 1/8 inch in diameter by 3/16 inch long. Little motors are extremely fast, and this one went 10,000 rpm, so we put a little gear ratio in it to slow it down to 5,000 rpm. Then we attached a screw with tiny little bearings and a nut with a very special shape. So the motor and the two gears and the screw and nut all fit into a housing, which was like a little “hat” that the animal wore.
When the motor was turned on, the screw through the gearing would rotate, and the nut would move up and down along this track in the housing. To this was affixed a probe with an electrode that could move in and out of the animal’s brain while it was alive, without its even being aware of it.
In doing all this, we had a very strict mass limit to the device, because if it weighed too much, the animal would notice it was there. If it was under the limit, the animal would go about its business as if it didn’t even have a hat on – you know sometimes you have a hat on so long you don’t even realize you’re still wearing it? They used the probe to map the animal’s activities, and later found they could deliver electrical impulses to certain areas of the brain and make it want to eat or sleep or do other specific activities.
That project was fun, and it was something that grew out of our catalog. The guy said “You make gears, right? Can you make them really small?”
And we said, “Oh yeah! Miniaturization is among our fortes.”