Ring of Protection

Since physicists made progress toward an invisibility cloak, I’m pleased that chemists are taking initial steps towards a different “magical” object – in this case, a ring of protection. It’s actually a ring of detection that alerts you if invisible yet dangerous fumes or liquids are close by. You still have to run away to protect yourself!

Hot off the press from the journal ACS Sensors is “Wearable Ring-Based Sensing Platform for Detecting Threats” by a group in the department of NanoEngineering at UCSD. The citation is ACS Sens. 2017, 2, 1531-1538, for those who want to read the article in full. Here’s a snapshot of the abstract complete with a picture of the ring. The ring itself is not the most fashionable wearable out there; attaching the device to a hat or coat would be less obtrusive. But the ring does illustrate the engineering feat of miniaturization that went into this multi-detector system.

The ring was tested with two types of potentially explosive material, 2,4-dinitrotoluene (DNT) and hydrogen peroxide, and one nerve agent, methyl paraoxon. It can detect these compounds in both the liquid and vapor phases. These hazardous substances were distinguished from other common vapors – there were no false positives or negatives – but the size of these interference-samples was small. Clearly more work needs to be done to expand the scope of its detecting capabilities. The detector sends output via a Bluetooth signal that can be read by a mobile device alerting you of the threat (along with appropriate data).

No, this isn’t the ring of power that the world would covet. But if you could combine invisibility with a wearable ring, it might start to resemble a famous ring of power. If octopi were reading The Hobbit, Bilbo’s disappearing trick would be less dramatic. It’s just a wearable device that signals a chemical cascade triggering a response in chromatophores on the skin. How exactly the device signals the cascade is not so obvious. If it sent out some sort of electromagnetic signal that cells near the surface of the skin can react to, this might be workable. Coincidentally, the same research group has a recent paper titled “Edible Electrochemistry: Food Materials based Electrochemical Sensors” in Adv. Healthcare Mater. 2017, 1700770. Perhaps there is a way to combine edible sensors that initiate a biochemical reaction. Or one could design a camouflage potion, as two groups did in my non-majors chemistry class last semester. The groups took different approaches, but both involved extracting chromatophores from octopi. (Nautilus, in its October “Monsters” issue, has a cool article on octopi including pictures of chromatophores.)

The ring of protection is a staple of fantasy role-playing games such as Dungeons & Dragons. (Coincidentally, there was a fun article this week about how D&D is like academia in the Chronicle of Higher Education.) Wearables are associated with protection – perhaps that is not surprising since medieval knights used heavy armor against sword and spear. But to protect yourself against magic, that’s where you need a ring! Designing a compact quick-deploying protective device, though, is not easy. And you don’t want to be walking around in a spacesuit. Perhaps the closest familiar analog is the airbag in vehicles, although it can only be deployed once before replacement is needed. A ring is likely too small to house an airbag, but a ring that called a drone that carried the necessary protective equipment could work well. The drone would have to not be too far away, but not intrusively close either. A day might come when we are all walking around with personal drones overhead and wearing rings of summoning instead.