S3237520 Temprature Sensors - Project 4
From Physical Programming
Temperature Sensors
A temperature sensor is a device that records and measures temperature change.
There are two main types of temperate sensors available on the market, being Contact and Non-Contact devices.
Contact sensors are sensors which are in direct contact with the heat source. Non-contact sensors measure the thermal radiant power of the infra-red or optical radiation received from a monitored and calculated surface.
The seven basic types of temperature sensors are thermocouples, resistive temperature devices (RTDs, thermistors), infra-red radiators, bimetallic devices, liquid expansion devices, molecular change-of-state and silicon diodes.
A simple Contact temperature sensor would be a Thermometer. Thermometers are well-known liquid expansion devices and have been around for many years. The classic thermometer is made using mercury. When heat is applied to the liquid it reacts and expands, and measuring the expansion gives the temperature. Mercury devices, however, have certain limitations when it comes to how they can be safely transported or used due to the toxic chemical.
Infra-red sensors are a perfect example of a non-contacting sensor. If you place a typical infra-red sensor in an average room without contact towards an object will will likely measure 68°F, normal room temperature. If it is placed near a heater it will convert the thermal radiant power to a higher temperature.
Temperature sensors are one of the easiest sensor to purchase, and basic units are not expensive. The temperature sensor above this the LM335Z, and each unit costs $1.50. They have a sensing temperature of -40°C~100°C, and are the cheapest sensors for this temperature range.
They are also easily placed into an Arduino Board, and programmed to do various commands in relation to the heat change. The circuit will send serial information from the Arduino about the temperature so you can use on your computer to manipulate the results. To assemble the sensor connect the 5V output from arduino to the 1st pin of the sensor, ground the 3rd pin and the 2nd one, you connect to the 0 Analog Input.
These interactive projects using this temperate sensor technology were found on ebay:
The left image is a 'Water Glow LED Temperature Sensor Sink Tap' valued at $3.69, and a 'Digital LCD Thermometer Food Temperature Sensor Probe' valued at $11.41.
This image of a 'Smart Coaster' gave me some inspiration for a bowl or cup that when it had hot food or liquid inside it would inform the user, using light, when the item can be safely consumed. I would have to create a cavity that would be large enough to encase the Arduino Board and wiring, and have to ensure it was fully waterproof.
Sources: - http://www.lycos.com/info/temperature-sensor--applications.html - http://cgi.ebay.com.au/LM335-LM335Z-Precision-Temperature-Sensors-40C-100C-/350267670819?pt=LH_DefaultDomain_0 - http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1273500807 - http://en.wikipedia.org/wiki/Sensor - http://en.wikipedia.org/wiki/Thermometer
