This Robot Will Self-Destruct in 5, 4…

Researchers spend a lot of time refining soft robot designs and developing new materials to make them sturdy and functional. Much progress has been made in these areas in recent years, however, if you need that solidly-built robot to self-destruct on command, there are not a lot of good options. The materials most commonly used in soft robotics are highly resistant to factors like heat, acids, and chemicals that might otherwise be used to melt them into pools of nothingness. Some materials have been developed that are heat sensitive, but they do not so much disappear as they do turn into a big pile of melted thermoplastic elastomer, or whatever the case may be.

You might be wondering why anyone would want a robot that could self-destruct in the first place. Is this even a useful feature? Judging by some of the players involved in developing such capabilities, the answer is clearly yes. In the past, Amazon has explored the possibility of creating self-destructing delivery drones, such that if they malfunction or are disabled, they can break apart to minimize the risk of harm or property damage. The United States Department of Defense has also tested gliders that are able to fly long distances, then dissolve in a matter of hours — you will have to use your imagination as to how those gliders might be put to work. And self-destruction of robots is also desirable from an environmental standpoint if they are to travel to remote or hazardous locations where retrieval is not possible.

A novel material has been developed by a team of researchers at the Seoul National University in Korea that is durable and strong, yet is also capable of turning into nothing more than an oily puddle on command. Using this material, they developed a walking robot, and demonstrated how, under the right conditions, it can be dissolved in under two hours.

The desirable mechanical properties, like stretchability and strength, were able to coexist with the self-destruction capability through the use of fluoride-generating diphenyliodonium hexafluorophosphate mixed with a silicone resin. When this material is exposed to ultraviolet light, fluoride ions are generated. This weakens the molecular structure of the material, leaving it susceptible to heat. High temperatures will then reduce the entire structure to an oily liquid that completely obscures the original form.

To test their invention, the researchers built a pneumatic gaiting soft robot. The flexibility of the material made it ideal for this application. As pressurized air is pumped in and out of an internal channel in the robot, it walks along on its four feet at a rate of 2.5 centimeters per second. And when it was exposed to ultraviolet light and heat, it disappeared, almost without a trace, in about two hours.

Since ultraviolet rays are naturally present under normal conditions, it is not clear exactly how a robot made from this material would perform outside of the laboratory. But if secrecy or minimal environmental impact are required of a robot, this technology may prove to be useful in the future.