Hardware-Sensors
From Physical Programming
The following list of sensors are suitable for interfacing with the Arduino micro-controller. This list is not definitive, there are thousands of different types of sensors (for a more comprehensive range see the SparkFun, Modern Device, Adafruit, and Little Bird websites). These sensors range in price from a few dollars to a few hundred - pick the sensor that suits your project and your budget.
Temperature Sensor. One of the cheapest and easiest sensors to work with, this sensor will generally output a voltage level that varies with temperature. Connect it to an analogue pin on the Arduino.
The LM335 temperature sensor above can be purchased from Jaycar for $4.00.
Modern Device sell a similar sensor (above), mounted on a board, with a serial interface for US$8.00 (the SparkFun equivalent is here).
Hall Effect Sensor. Another cheap sensor, this device senses changes in a magnetic field - run a magnet past the sensor and it's output voltage will peak. Often used in bicycle computers where a magnet is attached to the bike wheel.
The sensor above can be purchased from Jaycar for $6.00. A similar component is also available from SparkFun.
Magnetic Switch. These low cost switches are also triggered by magnetic fields however unlike the hall effect sensor above they have just two states - open or closed. The are often used in burglar alarms to sense the opening of doors or windows. Complex interfaces may be achieved through imbedding magnets and reed switches into objects.
They may be purchased 'naked', as above (Jaycar has them for $2.00),
or packed in plastic with a matching magnet (available in most local hardware stores).
Air Pressure Sensor. These devices will measure differences in pressure. They are generally designed to report on a specific pressure range. Make sure you check the range is appropriate for your application.
The sensor above is from Jaycar and costs $45.00.
Alternatively, the Modern Device pressure sensor above sells for US$25.00. Both sensors are in the 10kPa range - good for breath controlled devices.
Another pressure sensor from Modern Device. This one is suited for barometric measurements (changes in air pressure due to weather or altitude). It is sensitive enough to register a change in altitude of just a few metres. Similar devices are available from SparkFun. Prices range from US$20 - US$40.00.
Humidity Sensor. Often combined with a temperature sensor on the one device, these sensors will measure the moisture content in the air.
The sensor above from Modern Device combines humidity with temperature for US$40.00. SparkFun has a similar product here.
Light Sensor. For sensing ambient light levels or for use in constructing a light triggered switch.
Basic Light Dependent Resistors (LDRs), as shown above, are available from Jaycar and SparkFun for as little as $2.00.
More advanced light sensors, like the one above from Modern Devices for US$5.00 and this one from SparkFun for US$6.00 are also available.
Colour Sensor. This sensor combines a white LED with a CMOS IC and integrated RGB filters to give accurate colour readings (hold the object up to the sensor to get a reading).
Available from SparkFun.
Wind Sensor. Anemometers for measuring wind speed may be constructed from a reed switch, magnet, bearings, and table tennis balls...
or purchased commercially. The one above is from SparkFun.
Alternatively, the wind sensor above from Modern Device is based on the 'hot wire' technique and has no moving parts.
Touch/Capacitive Sensor. Due to the bodies conductive properties it is possible to construct a touch sensor using the Arduino and two piece of wire. The sensor can be configured for contact or non-contact (near contact) operation. The Arduino website has an informative page and associate software library here. It is also possible to construct more complex 1 or 2 dimensional touch surfaces or buy these pre-assembled with or without control circuitry.
The above ribbon sensor is from Adafruit. It costs US$15.00 and can be used for slider controls.
SparkFun sell a rotary version of this device for US$19.00.
Pressure/Force/Flex Sensor. These devices are similar to touch sensors however they register the amount of force applied to the sensor. SparkFun have a great range of these sensors.
The force-sensitive resistor above from Adafruit is at the low-end of the spectrum at US$7.00.
The flex sensor above from SparkFun costs US$13.00 and is similar to those used in the Nike commercial.
Tilt Sensor. The tilt sensor is a simple mechanical switch that registers when the device is tilted or turned upside down. Tilt switches generally have just two states - either on or off.
The above tilt switch from Adafruit uses a metal ball housed inside a small cylinder. Available for US$2.00.
The same effect is achieved in this $3.00 mercury tilt switch from Jaycar.
Digital Compass. These sensors will give a reading to magnetic North. Useful for digital compasses and robot navigation. Expensive units have tilt compensation. Prices range from US$30 - US$250.
The above compass module from Modern Device is a basic unit selling for US$30.00. Arduino software libraries are available for this component.
SparkFun have a large range of compass modules. The one above uses similar components to the Modern Device unit and sells for US$35.00.
Accelerometer. These sensors measure changes in speed and gravitation pull. They can come as a one, two, or three axis devices (this is the sensor that lets the iPhone know whether it is in landscape or portrait mode).
The 3-axis accelerometer above is from Modern Device and sells for US$19.00. Arduino code is available for this component. SparkFun have a large range of single, dual, and triple axis accelerometers.
Gyroscopic Sensor. These sensors measure rotational movement. Available as one, two, or three axis devices. Use this with an accelerometer to get full positional sensing (as with the Wii controller).
The dual axis gyro module above is from Modern Device and costs US$33.00. SparkFun have an extended range of gyro devices here.
Inertial Measurement Units (IMUs). These devices combine accelerometers and gyroscopes in a single package (and sometimes a digital compass too). IMUs generally have between two and six degrees of freedom (DOF), IMUs with six DOF will measure both acceleration and rotational movement on all three axis.
The above IMU from SparkFun is specifically designed for the Arduino and gives 4DOF for US$45.00 (expandable to 6DOF with additional boards). For a detailed explanation of Accelerometers, Gyroscopes, and IMUs see the SparkFun Buyers Guide.
