What are standalone sensors for remotely turning on devices?

Question

Electronics

I want to turn on a simple device (a simple microcontroller + a minimum of peripherals) remotely. The device will start up every few days for a few seconds, so I don’t want to interrogate the sensor so as not to drain the battery, but I want the sensor to close the contacts when it receives a signal and thus turn on the device.
What are the sensors for such purposes?
Z.Y. The transmitter will be at a distance of up to 10 meters. Line of sight is not guaranteed.

Answer 1

so that the sensor itself closes the contacts when a signal arrives at it and thus turns on the device.

That is, the sensor will constantly listen to the air and eat the battery?
An old cell phone, a car alarm, a child's toy with a remote control, ..., and a bunch of other options.

Answer 2

As an option - something like passive RFID (without its own power source). But this is still a "direction for study." On it here I to you more or less ready decision I can not advise.
The only thing I saw on the Internet, the guys made a passive RFID tag for opening the lock on the gate for the competition of devices based on 155 series chips (there is a tag like an electronic pass on the checkpoints), you can google this topic - take the power supply scheme from there (I honestly speaking, I didn’t understand at all how they managed to power such microcircuits from such a weak source) and power some switch you need with it.
upd.
Found habrahabr.ru/post/155973