DIY Flex Sensor

A cheap way to flex sensor. It will be very useful for your projects

flexible tube
LED(any colour)
LDR(light dependant resistor)

Fix one of the tube with LDR and another end by LED.
Supply power to LED.
when you bend the tube the resistance changes at LDR with respect to luminance of LED.

It gives voltage as output thus it is connected to analog pin.