What are the Analog to TTL serial ICs called?
Such ICs Are Called As

Analog To Digital Converters

Once your sensor measures the analog signal you need to convert analog signal to digital format and then transmit via Bluetooth since it operates with TTL(Digital) signals whose levels are typically 5V range.

Transistor–transistor logic (TTL) is a class of digital circuits built from bipolar junction transistors (BJT) and resistors.(Source WIKI: https://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_logic)