Once in a while I find some curious approach to technology innovation, whose merit is not as much in the result achieved, rather in the ingenuity of the idea. This is the case here.
One of the difficult challenge in robotics is to create a grabbing mechanism that can pick up objects with a variety of shapes in a secure and effective way: What comes natural to us (well, in the range of “things” we can pick up, not too heavy, not too small…) is actually a very complex activity involving several sensors, neural activity and actuators. You need to know the difference between a raspberry and a marble, their weight is different even if their size may be similar and the pressure you have to (and can) exert is different. Use too little pressure and you cannot pick up the marble, use too much pressure and you’ll squeeze the raspberry…
If we are looking into picking up very tiny “things” both we and a robot may face an impossible challenge. On the other hand, a student at the Preston Innovation Lab, Rice University, noticed that spiders, specifically wolf spiders, can easily use their legs to pick up very small things with a variety of sizes.
Spiders have 8 legs forming a circle, that can flex in a great number of ways making it possible to grab any (small) objects. These legs have tiny muscle used to contract them but they do not have any muscle for extending them. The spider uses a sort of hydraulic system to extend its legs. The liquid is stored in a reservoir inside their body and is pushed in the legs in a coordinated way to achieve the desired extension.
The researchers noted that when a spider dies it becomes a sort of ball, with its legs curled up around its body. That is because the muscles contract and the legs curl. They took the dead spider and found out that by injecting some air in the body (watch the clip) the legs can be extended, removing the air they will contract again. If you place the dead spider on the tiny thing you need to grab you can inject air to expand its legs and then remove it to have the legs grabbing the object. This makes for a very good gripper, actually a better one that what can be created artificially at such tiny scale.
They have found out that such a gripper can work for 2 days and up to 1,000 grips, then it is no longer useful. However, if the spider is covered with bee-wax its useful lifetime (as a gripper) can be extended.
As I said I like the ingenuity of this research. I am not so confident that it will have a real industrial application. Not so for the researchers that feel their necrobots might have a future …