A sensor is a device that produces an output signal for the purpose of detecting a physical phenomenon.
An infrared sensor
A LIDAR sensor (bottom, center), as part of the camera system on an iPad Pro.
A tactile sensor is a device that measures information arising from physical interaction with its environment. Tactile sensors are generally modeled after the biological sense of cutaneous touch which is capable of detecting stimuli resulting from mechanical stimulation, temperature, and pain. Tactile sensors are used in robotics, computer hardware and security systems. A common application of tactile sensors is in touchscreen devices on mobile phones and computing.
The SynTouch BioTac, a multimodal tactile sensor modeled after the human fingertip