Does the sensor probe has to be immersed in glycol or just at ambient temperatures

This device requires an external probe which must be purchased separately.  If you are using it to monitor vaccines we would recommend purchasing it as a vaccine monitoring kit which can be found here - https://microdaq.com/logtag-vaccine-transportation-temperature-monitoring-kit.php

This kit includes the logger, probe, glycol buffer, and calibration certificate.  Please note that this device is designed to be used for vaccine transport.  It’s not intended to be used for fixed site monitoring.  For fixed site monitoring we would recommend the VAC-TRED30-KIT-2 which can be found here: https://microdaq.com/logtag-vaccination-storage-kit.php

This kit also includes the logger, probe, glycol buffer, and calibration certificate. 

If you are just monitoring ambient air temperature you can use a logger with an internal probe.  Here is an example of one of those: https://microdaq.com/logtag-direct-usb-temperature-data-recorder-pdf-reports-display.php