Some are cute, blue and able to talk, others are made of metal and look like primitive, brute machines. With wheels, round like a ball, small or big: robots come in many flavours. But there is a particular need in situations in which space is limited for tiny flexible robots that can jump, crawl and move. For example, monitoring the environment or, after an earthquake, such mini-robots could participate in search missions. Another, yet totally different, space-restricted terrain is the human body.
Just this month, researchers from the University of California undertook the first step towards the usage of micro-machines within a body. They fed mice with the 20 micrometer long devices, so called artificial micromotors, which traveled straight to the stomach – where the acid environment reacts with their zinc coating. This chemical reaction releases hydrogen bubbles that propel the devices into the stomach wall.
The attached machines then release their cargo, for example drugs. Beside the tempting possibility of efficient drug delivery, this project marks the first report of an artificial device travelling inside a living organism. However, one has to confess that the locomotion of these devices is still quite simple and would not be suitable to precisely maneuver a robot through the blood stream to a desired destination within the body. For such endeavours, more sophisticated forms of motion are needed.
Smartly moving robots do exist. Thus, the obvious conclusion is to just shrink those, right? Well, it is not that straight forward. Electromagnetic motors, used for movements, do not work on a sub-millimeter scale. Scientists at Harvard elegantly handled the problem by using “piezoelectric actuators”. A fancy term for ceramic stripes that contract or expand when in contact with an electric field, allowing them to built a flying mini-robotic insect: Robobee.
Watch how Robobee takes off:
As flapping wings are not so helpful to crawl or jump, microroboticist Sarah Bergbreiter (check out her TED talk here) is keeping an eye on insects, particularly ants and cockroaches. Drawing the inspiration from their movement and body shape, she developed teeny-tiny robots that can crawl and overcome obstacles of 80 times their height. She and her team were able to create this rice grain-sized robots by combining solid and soft materials and a light sensitive sensor that functions like a rocket to accelerate.
All for one and one for all – collective “artificial” intelligence
Whoever thinks that the light-weighted miniature robots have not enough power to perform useful tasks is misled by their tiny, simple appearance. As with ants, the solution is an army of individuals. In nature, large and complex systems can be generated by self-assembly of individual units that cooperate. The collective power arises from the numerous individuals, each of them error prone and unreliable, but they come together to build a stable structure. What sounds so easy has been a long-lasting challenge for engineerers: to recapitulate this ability in artificial systems. Not surprising, in 2014 most lists of scientific breakthroughs contained the experiment of a group of scientists, who built an autonomous swarm consisting of 1024 low-cost robots, called Kilobots, capable of performing a complex task.
Watch how these thousands of kilobots interact via infrared to form 2D shapes without human intervention:
Romo, a robot for yourself
Microrobotics is still in its infancy, but undoubtedly will impact all areas of our lives sometime in the future. Until then, we have to take potluck with slightly bigger, but still small-scale commercially available robot versions. One of which was presented in a TED Rinaudo Keller‘s talk. May I introduce ROMO!
Header image credits royalty free