Contributors: jimblom, bboyho

Introduction

This flex sensor is a variable resistor like no other. The resistance of the flex sensor increases as the body of the component bends. Sensors like these were used in the Nintendo Power Glove. They can also be used as door sensors, robot whisker sensors, or a primary component in creating sentient stuffed animals.

Flex Sensor 2.2"

SEN-10264

A simple flex sensor 2.2" in length. As the sensor is flexed, the resistance across the sensor increases. Patented technology…

$12.50

Flex Sensor 4.5"

SEN-08606

A simple flex sensor 4.5" in length. As the sensor is flexed, the resistance across the sensor increases. Patented technology…

$18.95

Flex sensors are available in two sizes: one 2.2" (5.588cm) long and another coming in at 4.5" (11.43cm) long.

Left flat, these sensors will look like a 30kΩ resistor. As it bends, the resistance between the two terminals will increase to as much as 70kΩ at a 90° angle.

By combining the flex sensor with a static resistor to create a voltage divider, you can produce a variable voltage that can be read by a microcontroller's analog-to-digital converter.

Suggested Materials

This tutorial serves as a quick primer on flex sensor's, and demonstrates how to hook them up and use them. Aside from the sensor, the following materials are recommended:

Arduino Uno -- We'll be using the Arduino's analog-to-digital converter to read in the variable resistance of the sensor. Any Arduino-compatible development platform -- be it a RedBoard, Pro or Pro Mini -- can substitute.

Resistor Kit -- To turn the flex sensor's variable resistance into a readable voltage, we'll combine it with a static resistor to create a voltage divider. This resistor kit is handy for some trial-and-error testing to hone in on the most sensitive circuit possible.

Breadboard and Jumper Wires -- The flex sensor's terminals are breadboard-compatible. We'll stick that and the resistor, then use the jumper wires to connect from breadboard to Arduino.

Resistor Kit - 1/4W (500 total)

COM-10969

Nothing stops a project dead in its tracks faster than not having the right resistor. These components are arguably the most …

$9.95

SparkFun RedBoard - Programmed with Arduino

DEV-13975

The SparkFun RedBoard combines the simplicity of the UNO's Optiboot bootloader, the stability of the FTDI, and the shield com…

$22.50

Breadboard - Self-Adhesive (White)

PRT-12002

This is your tried and true white solderless breadboard. It has 2 power buses, 10 columns, and 30 rows - a total of 400 tie i…

$6.25

Jumper Wires Standard 7" M/M - 30 AWG (30 Pack)

PRT-11026

If you need to knock up a quick prototype there's nothing like having a pile of jumper wires to speed things up, and let's fa…

$3.50

Force Sensitive Resistor Adapter -- While the FSR terminals are breadboard-compatible, we've found that it may be loose in the breadboard. For those looking for a way to make a more secure connection without soldering, try looking at the associated Amphenol pin adapters. You will need a pair of needle nose pliers to clamp the the adapter down.

Amphenol FCI Clincher Connector (2 Position, Female)

COM-14194

These Clincher connectors from Amphenol FCI can be used to terminate Flat Flexible Cables (FFCs) to an easy-to-use standard h…

$2.95

Amphenol FCI Clincher Connector (2 Position, Male)

COM-14195

These Clincher connectors from Amphenol FCI can be used to terminate Flat Flexible Cables (FFCs) to an easy-to-use standard h…

$2.95

Amphenol FCI Clincher Connector (3 Position, Female)

COM-14196

These Clincher connectors from Amphenol FCI can be used to terminate Flat Flexible Cables (FFCs) to an easy-to-use standard h…

$1.75

Amphenol FCI Clincher Connector (3 Position, Male)

COM-14197

These Clincher connectors from Amphenol FCI can be used to terminate Flat Flexible Cables (FFCs) to an easy-to-use standard h…

$1.50

Suggested Reading

Analog components, like these flex sensor's, are a great sensor-reading entry-point for beginners, but there are a few electronics concepts you should be familiar with. If any of these tutorial titles sound foreign to you, consider skimming through that content first.