Sensors are key components of Mechatronic systems, and are typically used for feedback in control systems. The defining characteristic of a sensor is that it produces some sort of electrical change (resistance, capacitance, voltage, current...) in response to some external stimulus (temperature, pressure, light, humidity...). This electrical change can then be exploited by circuitry designed to measure and interpret the electrical change. Sensors are a rapidly developing area of engineering. Some resources are listed below.
BASIC MATERIAL is required reading for all students
Reading Encoders with Arduino
IN DEPTH material is additional reference and can be pursued by students depending on the design approach being pursued.
Handbook of modern sensors — Handbook of modern sensors: physics, designs, and applications by Jacob Fraden . You must be at UCSD to access this online library resource.
Potentiometer — See pages 9-11 of Electronic Devices for MEs