Flex Sensor - 2.2 inch

Bend it and its resistance goes up. That is the whole idea, and it makes this one of the easiest ways to get physical movement into a circuit without any moving parts, gears or linkages to wear out.

Flat, the strip sits at its lowest resistance. Curve it and the conductive ink on the surface stretches, the path narrows, and resistance climbs. Wire it as one half of a voltage divider and a microcontroller's analogue input reads the bend directly.

What you would use it for

• Sensing finger position in a glove or wearable
• Detecting whether a door, lid or hinge has opened
• Measuring deflection in a beam or arm as it takes load
• Any control input where something flexes rather than slides or turns

Wiring it up

The sensor is a variable resistor, not a powered module, so it needs a fixed resistor to work against. Put the flex sensor and a resistor of roughly 10kΩ in series across your supply, and read the junction between them with an analogue pin. Swap the fixed value if you want more sensitivity over a particular part of the bend range.

The connector is on 0.1 inch spacing, so it drops straight into a breadboard.

Specifications

• Length: 2.2 inch (approximately 56mm)
• Type: resistive bend sensor, resistance increases with flex
• Connector: 0.1 inch pitch, breadboard friendly
• Direction: bend one way only, with the printed side on the inside of the curve

Look after it

Do not flex or strain it at the base where the pins are. That is where they fail. Clamp or mount the base solidly and let only the sensing length do the bending, and it will last. Creasing it sharply will damage the conductive layer permanently.

A note for teachers

This is a genuinely good component for teaching diagnostic testing, because it gives students something to measure rather than something to look up. Bend it around cylinders of a few known diameters, record the resistance at each, plot the results and compare the curve against the expected behaviour. It is a real characterisation exercise with a real answer, and it takes about twenty minutes.

Worth knowing before you order a class set: this is an economical version of the part rather than the original Spectra Symbol sensor. It behaves the same way and is well suited to classroom characterisation work, but unit-to-unit consistency is looser, so groups should expect to calibrate their own sensor rather than share one set of figures. For most teaching purposes that is a feature, not a problem.