The Universal Asynchronous Receiver and Transmitter (UART) is probably one of the oldest ways to talk to a chip. The transmitter of the controller will be connected to the receiver of the sensor and the receiver of the controller will be connected to the transmitter of the sensor.
This mode supports huge amounts of data being transmitted.
An example of the UART-based sensor is the fingerprint scanner. The data from the fingerprint scanner is sent to the controller over UART for further processing, after a user scans a finger. You can read more about the fingerprint scanner here: https://cdn-learn.adafruit.com/downloads/pdf/adafruit-optical-fingerprint-sensor.pdf.
