Differential Thermal Analysis Using Arduino and PhyPhox
Introduction: Differential Thermal Analysis Using Arduino and PhyPhox
When a solid substance is heated the increase in energy manifests itself in the form of an increase in temperature.
If the heating rate is constant the temperature increase is also constant as long as there is no change in the structure of the substance.
At the time when some kind of transition is initiated in the substance, for example fusion, change of crystal structure or other, the temperature will not increase at the same rate because part of the heating energy will be used in that change of state.
If we compare the temperature of the substance that is experiencing the change of state (Sample) with that experienced by another substance that remains stable (Reference) during heating under identical conditions and subtract a temperature value from another (Sample - Reference) we will be performing what is known as Differential Thermal Analysis (DTA).
The objective of this Instructable is to show the basics of the DTA using Arduino microprocessor, a home heater and a free access program (PhyPhox) that will allow us to obtain on our cell phones curves of Sample Temperature vs Difference (Sample Temperature - Reference temperature) known as thermograms.
Supplies
* Cell Phone (Android or iOS).
* PhyPhox app (Google Play or AppStore).
* 1 Plastic container with multiple compartments.
* 2 Waterproof DS18B20 temperature sensor.
* 2 Breadbord mini modular.
* 1 Arduino Nano V3.0 CH340 with mini usb cable.
* 1 Bluetooth Low Energy BLE CC2541 Bluetooth 4.0 UART.
* 1 1k ohm resistance.
* 1 2k ohm resistance.
* 1 4,7k ohm resistance.
* Male/Male jumpers wire.
* Male/Female jumpers wire.
* 1 Portable battery charger (6000 mAh 3.7V, Out 5V, Output Max. 2.4A).
* 4 Glass test tubes (approximately 1 cm in diameter and 7.5 cm long)
* Wooden base (circular or square of approximately 20 cm in diameter or side).
* 1 Ceiling lampholder (E27).
* 1 Incandescent light bulb of 25 Watts (E27).
* 1 Rotary dimmer switch.
* Approximately 1 m of electrical cable (two cores 0.4 mm thick).
* 1 Two pin electric socket.
* 1 Clothes dryer aluminum duct reducer (10.16 cm to 7.62 cm).
* 2 Disposable circular aluminum plates of approximately 20 cm in diameter.
* 2 Wire insulate screw cap.
* Electrical tape.
* Silicone or Epoxi glue.
* Plastic fasteners.
Step 1: Heating Device
A DTA equipment basically consists of a furnace containing two containers, one for the Sample and one for the Reference and two sensors that measure the temperature of Sample and Reference simultaneously.
The temperature inside the furnace and its heating or cooling rate must be very well regulated so the construction of the furnace in professional equipment is an important factor in the design of a DTA apparatus, however for the illustrative purposes of this Instructable it was chosen to make a rather modest design using homemade materials (see supplies list) as indicated below :
* Fix on a wooden base a ceiling lampholder (E27) provided with two core electrical cable with two pin electric socket.
* Section one of the cores of the electrical cable and connect a rotatory dimmer switch, using wire insulate screw cap or electrical tape to reestablish the cable connection.
* Screw an incandescent light bulb (25 Watts, E27) into the ceiling lampholder.
* With the help of glue, fix on the surface of the ceiling lampholder a clothes dryer aluminum duct reducer (10.16 cm to 7.62 cm) so that the end of smaller diameter is like a chimney around the incandescent light bulb (Caution: Once the bulb is turned on this surface will be hot so there will be a danger of burn).
* Fold the surface of a disposable circular aluminum plates in such a way as to form a concavity that fits on the chimney formed by the clothes dryer aluminum duct reducer (see video in Step 3).
* Using another plate repeat the previous operation forming a concavity that fits on the first and in which two holes near the top of the concavity but separated from each other will be drilled, with a diameter that allows to receive the test tubes (approximately 1 cm in diameter and 7.5 cm long) of Sample and Reference.
* Insert the Sample and Reference test tubes into the drilled holes by pushing until only about 1 cm is left outside. Deform the surface of the aluminum sheet in such a way that they fit on the surface of the test tubes and fix them. 152