Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.


'MicroTug' Robot Pulls Objects 2,000 Times Its Weight

D-briefBy Carl EngelkingApril 27, 2015 10:24 PM


Sign up for our email newsletter for the latest science news


Every tug-of-war champion knows one thing: The power to pull lies not in your arms, but in planting your two feet firmly in the dirt for leverage. Engineers at Stanford University put this basic tug-of-war principle into practice when they designed tiny robots, which they've called MicroTugs, that can drag objects hundreds of times their weight. A 9-gram MicroTug, for example, can pull a 2.2-pound load vertically up glass. That’s equivalent to a human climbing a skyscraper while carrying an elephant. The MicroTugs owe their pulling power to their sticky feet, which borrow a page from geckos’ evolutionary playbook.

Making it Stick

Geckos are some of nature’s most adept climbers, and they can stick to slippery surfaces with ease. Their clinging power resides in microscopic, hair-like structures on their toes that employ what are called van der Waals forces – a weak force that draws molecules together. The gecko’s thousands of points of contact on each toe create a weak electromagnetic connection to the surface, allowing the animal to stick and unstick its feet with ease. Engineers covered their robots’ feet with tiny rubber spikes that emulated geckos’ feet. When MicroTugs plant their feet, the rubber spikes bend and strongly adhere to a surface. When the foot is lifted, the spikes straighten and the foot easily detaches. The military is using the same technique to give soldiers Spider-Man-like abilities.


MicroTugs’ super-strong base allows them to pack some serious power. The strongest model can pull 2,000 times its own weight — the equivalent of a human dragging a blue whale around the beach. A miniature bot that weighs just 20 milligrams and was assembled under a microscope can pull objects 25 times its weight.

The Power to Interact

There’s been one nagging problem with miniaturized robots: They’re too small to actually move objects in their world. Engineers, who will unveil MicroTugs next month at the International Conference on Robotics and Automation, believe their robots can overcome this fundamental roadblock. They believe larger and more powerful MicroTugs could find jobs lifting heavy loads in factories or construction sites. Other more specialized models could be used in rescue operations to, for example, deliver a ladder to a person trapped in a burning building.

3 Free Articles Left

Want it all? Get unlimited access when you subscribe.


Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 50%


Already a subscriber? Register or Log In