Transmitters are microscopic crawlers that are applied in the ears of all the orphans in the Grace Field House. Their true form is unknown because they are not externally visible.
Transmitters are applied to infants before being sent to a farm. They are applied from some kind of stapler, leaving a small scar on the back of their ear, which disappears in time.
The transmitters work as some kind of safety measure for the Mamas and Demons because they can monitor the location of the orphans with the Radar. The Transmitters are undetectable by the children unless it is newly implanted, and it is possible to see the needle mark. Once the transmitter is removed in some way, it will automatically send a message to the radar and headquarters, but this is not the case if the ear itself is removed. This was implied when Emma removed her ear and no alarm went off.
Although they are of utmost confidence of the "Demons", the transmitters have some disadvantages. First, the transmitters have a unique identification, not allowing the radar user to find out which child is being detected. For some reason, the transmitters completely lose the signal when the child is near the gate or the wall.
After 6 years of study and experiments, Ray discovered a way to turn off the transmitters. Gathering gifts she earned from Mama Isabella for being "good to her," like handheld video games and other things he asked for, Ray was able to create a device that could cripple the transmitters by bringing them closer to the ear and pushing the button.
- Possibly, the transmitters were created after 2015, considering that Ray affirms that at that time there was no technology that could create them.