I'm looking for small microchips to implant in mouse pups in order to track them individually and obtain information on their distance travelled and their interaction with the mother using RFID technology.
Radio Frequency Identification (RFID) is a form of wireless technology that is encoded in smart tags and captured by a reader through radio waves. Also RFID tags are used in many different industries including healthcare, manufacturing, inventory mangement, shipping and retail...
For more details about this subject, i suggest you to see links on topic.
RFID is a technology that employs electromagnetic fields to automatically identify and track tags attached to things. When activated by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag communicates digital data back to the reader, often an identifying inventory number.
https://www.researchgate.net/publication/225373548_A_system_utilizing_radio_frequency_identification_RFID_technology_to_monitor_individual_rodent_behavior_in_complex_social_settings,kindly check this link.
I used RFIDs with the live mouse Tracker (LMT, really good system to study mice, but not designed for pups). I implanted at P21 the RFIDs but never tried before weaning.
An obvious issue with younger mice will be that 2 RFIDs in the same magnetic field from the coil will not produce any signal (an antenna can read only one at a time and would not be able to distinghuish two chips). So before pups move I guess it might be useless. But after P10-12 when activity increases, why not, it could work.
For a RFID size, I think the 'mouse RFIDs' could work pretty early as they are implanted for LMT.