System Specifications


Sensor glucose assay method
Amperometric electrochemical sensor
Sensor glucose reading range
40 to 400 mg/dL
Sensor size
2.9 mm height and 21 mm diameter
Sensor weight
1 gram
Sensor power source
One silver oxide battery
Sensor data
Up to 14 days
Sensor memory
Up to 14 days (glucose readings stored every 5 minutes)
Sensor transmission range
33 ft (10 meters) unobstructed
Operating temperature
50 °F to 113 °F
Sensor Applicator storage temperature
36 °F to 82 °F
Operating and storage relative humidity
10-90%, non-condensing
Sensor water resistance and ingress protection
IP27: Can withstand immersion into 3 ft (one meter) of water for up to 30 minutes. Protected against insertion of objects > 12 mm diameter
Operating and storage altitude
-1,250 ft (-381 meters) to 10,000 ft (3,048 meters)
Radio Frequency
2.402-2.480 GHz BLE; GFSK; 4.6 dBm EIRP

Please refer to the User's Manual for updates to the information.

Security Measures and Quality of Service:

Security Measures:

  • The communication between the App and Sensor during an activation scan is a short range Near Field Communication (NFC) method which makes it difficult to interfere with or intercept during transmission. The communication between the App and Sensor for glucose data is a standard Bluetooth Low Energy (BLE) connection. Mutual authentication is performed between the App and Sensor during the pairing process using application certificates, preventing unauthorized devices from connecting to the Sensor. The transmitted data is protected by encryption. This prevents unauthorized devices from accessing the data if they are within range and intercept the transmission. Under normal operation, the industry standard BLE protocols allow for many users to be in the same vicinity. In the case where the connection is lost due to out-of-range or interference, only the authenticated App that is paired with the Sensor will be able to reconnect and receive glucose data. Only apps logged into the same LibreView account that activated the Sensor are able to complete pairing with the Sensor.

Quality of Service (QoS):

  • QoS for the FreeStyle Libre 3 App and Sensor wireless communications using BLE is assured at regular 1-minute intervals. If connection is lost between the App and Sensor for 5-minutes, the App will display an indication of “Signal Loss” on the Home screen. If connection is lost for 20 minutes, the App alarms the user if the alarm is turned on. If connection is lost between the Sensor and the App, all lost glucose data will be automatically retrieved when the connection is restored. The App is designed to only accept BLE data from recognized and paired Sensors.