Force Sensitive Resistor Hookup Guide

Contributors:

jimblom,

Introduction

Force-sensitive resistor's (FSR) are easy-to-use sensors designed for measuring the presence and relative magnitude of localized physical pressure.

Force Sensitive Resistor 0.5"

SEN-09375

$7.50

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Force Sensitive Resistor - Long

SEN-09674

$22.50

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Force Sensitive Resistor - Small

SEN-09673

$7.50

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Force Sensitive Resistor - Square

SEN-09376

$12.50

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FlexiForce Pressure Sensor - 100lbs.

SEN-08685

$21.50

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FlexiForce Pressure Sensor - 25lbs (1" area)

SEN-11207

$26.95

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FlexiForce Pressure Sensor - 25lbs.

SEN-08712

$23.50

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FlexiForce Pressure Sensor - 1lb.

SEN-08713

$21.50

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The resistance of an FSR varies as the force on the sensor increases or decreases. When no pressure is being applied to the FSR, its resistance will be larger than 1MΩ. The harder you press on the sensor’s head, the lower the resistance between the two terminals drops. By combining the FSR 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 FSR's and demonstrates how to hook them up and use them. Beyond a FSR of your choice, 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 FSR. Any Arduino-compatible development platform -- be it a RedBoard, Pro or Pro Mini -- can substitute.

Resistor Kit -- To turn the FSR'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 FSR's terminals are breadboard-compatible. We'll stick in that and the resistor, then use the jumper wires to connect from breadboard to Arduino.

Resistor Kit - 1/4W (500 total)

COM-10969

$8.95

189

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Breadboard - Self-Adhesive (White)

PRT-12002

$5.50

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SparkFun RedBoard - Programmed with Arduino

DEV-13975

$21.50

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

PRT-11026

$2.45

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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.