Touch sensor

Converts physical contact to an electrical signal. Common types of touch sensors include, tactile switches, capacitive, and force sensitive resistors. Tactile switches work by having two conductors (typically metal) which contact each or separate when touched. This will cause the switch to send an open or closed signal. Capacitive touch sensors work by sensing the capacitance of a conductive surface. When another conductive surface (such as skin) contacts that surface, its capacitance changes. Force sensitive resistors vary in resistance by the force applied to them.

References:

https://www.digikey.com/en/articles/the-basics-of-tactile-switches

https://components.omron.com/us-en/products/switches/tactile-switches/tactile-switch_features

https://fieldscale.com/learn-capacitive-sensing/intro-to-capacitive-touch-sensors/

https://www.allaboutcircuits.com/technical-articles/introduction-to-capacitive-touch-sensing/

https://learn.adafruit.com/force-sensitive-resistor-fsr/overview