For a thing to be considered "smart", it must have an interface to receive commands and respond to them. And this means the availability of electronic components and batteries for them, but there is also an alternative. Engineers at the University of California, San Diego have developed LiveTag technology that can help make any subject a little smarter at no extra cost.
LiveTag are strips in the form of some patterns made of metal foil, fixed on a cellulose-dielectric base. They do nothing themselves, they only reflect, relay the radio signal, for example, from a Wi-Fi router to a smartphone. The highlight is that the reflected signal has a certain handwriting, which can be changed by touching the LiveTag with your finger.
It works like this: we install a utility on the home theater that constantly scans the signal reflected from the LiveTags from the router. It does not carry information, it is just a communication channel. We attach the tags to your favorite sofa and now, if you press the Stop tag with your finger, the signal will be distorted and the utility will send the appropriate command to the gadget. Another label duplicates the "Pause" button, the third "Decrease the volume", etc. If we imagine a “smart home” system, where all radiation and radio signals are processed, we get an ideal budget solution instead of old switches and remote controls.
You can simply attach LiveTag to a bottle of water so that by the amount and duration of signal distortions, you can calculate how many times you drank from it during the day. Or stick it on the office toilet door to keep track of how often it is used. By changing the material and structure of the tags, you can adapt them to the signal of Bluetooth, LTE, etc. So far, the range of the reflected signal is only 1 m, but this is a matter of technology. You can also print LiveTag on plain paper or stick it by hand.