World's Tiniest Radiometer To Power Medical Scanner

BuzzSkyline writes "University of Texas physicists have built the world's smallest radiometer. The minuscule radiometer is only 2 millimeters across and operates on the same principles as the common light-driven toy, which consists of spinning black and white vanes in a partially evacuated bulb. The researchers attached a mirror to their tiny radiometer and used it to rapidly scan a laser beam. Their hope is that they will be able to incorporate the radiometer into catheters to drive scanners that produce medical images of the interiors of blood vessels and organs. The devices would replace micromotors in conventional catheter-based scanners, eliminating the need to run potentially risky electrical currents into the body."

Comments

But they're NOT radiometers!

[Ancient_Hacker]

The "common toy" is not a radiometer. It's a heat engine. The bulb is only partially evacuated and the hotter, black side of the vanes heats up the gas molecules, which then bounce off it with increased vigor, compared to the white side. So the vanes spin with the white side going forward.

A true radiometer would be bouncing photons off the white side, and spinning with the black side leading.

The heat-engine version has many times the efficiency of the photon one.

 

Re:But they're NOT radiometers!

[chgros]

This led me to look at the wikipedia article for "radiometer".
A radiometer measures the strength of the radiation; whether the measurable effect is caused by heat or anything else is not relevant as long as it's proportional to the quantity being measured; in that sense the common toy *is* a radiometer.
As for the reason it moves, it turns out it's more complicated than that.

Re:a spinning, laser powered catheter?

[BuzzSkyline]

It does, literally, spin. Look at the video.