What do you mean by hot spot?
The victim heater is usually a 4x4cm Thermoelectric Cooler Peltier (One side gets cool and the other gets hot)
For the temperature sensors, MLX90614, TPA81 and TPA64 are the most used ones.
I only tried MLX90614 and TPA81. TPA81 is a lot better, but also more expensive. I guess TPA64 should me similar.