Sensor for very low temperature (liquid nitrogen)
You probably want a K-type thermocouple (the most common type).

They have a range of around -200°C to +1350°C (depending on probe).

Alternatively a Resistive Temperature Device (RTD) can be used, since these have a typical range of around -240°C to 650°C with higher accuracy.

This might be of help to you: http://digital.ni.com/public.nsf/allkb/C50FA55B3B2F85D9862572D00083350E