Build a Very Small Robot: Make The World's Smallest Wheeled Robot With A Gripper.

Step 8 Other Magnetically Powered Robots

Robots controlled by magnetic fields of various types are nothing new. Some of them are microscopic and some are larger so they can be deployed medically in a human body. Some use computer controlled electromagnets and some use movable permanent magnets. Here are some links to some of the best and smallest experimental magnetic robots researchers are working on.

Flying magnet robot on a penny.
While it doesn't actually fly, it hovers in a computer controlled magnetic field, much like those toys that suspend a small globe of the earth. It also has a gripper that expands when heated with a laser and then grips as it cools. Unfortunately, the robots magnetic north and south ends are vertical, so there is no way to control the rotational spin to precisely orient the gripper. It is slightly larger than the smallest robot I made which is shown in step 9.

http://www.sciencedaily.com/releases/2009/04/090413205339.htm
http://news.cnet.com/8301-11386_3-10216870-76.html

Swimming magnet robot
A truly microscopic robot that is a spiral with a magnet at one end. With an external pivoting and rotating magnetic field, it can be aimed in any direction and swim underwater.
http://www.sciencedaily.com/releases/2009/04/090418085333.htm

Steerable camera pill by magnets.
http://www.spectrum.ieee.org/aug08/6469

Medical robots.
http://www.medindia.net/news/view_news_main.asp?x=5464

Magnetically controlled camera.
http://www.upi.com/Science_News/2008/06/05/Controlled_pill_camera_is_created/UPI-60051212691495/

Here are some microscopic magnetically controlled grippers that can be chemically or heat activated.
http://www.sciencedaily.com/releases/2009/01/090114210651.htm
Unfortunately, these micro grippers cannot release once they grab. So they are more like a microscopic bear trap than a fully functional gripper.
http://www.sciencedaily.com/releases/2009/01/090112201137.htm
http://www.rsc.org/chemistryworld/News/2009/January/13010901.asp

pic 10 shows the Magbots R-19, R-20 and R-21, the three robots I made for these experiments. The smallest one was made smaller by eliminating one pivot and the wheels. A wire tail keeps it from tipping over backwards.