The Ice Nucleation Cold Stage (INCS) is a project using an Arduino and Raspberry Pi to control a Peltier module to cool and film droplets to the point where they freeze.
The Ice Nucleation Cold Stage on a desk.
The electronics fits in a project box, with a touchscreen, enabling ease of transport in the field.
Peltier circuit inside the project box.
In addition most of the other parts are 3-d printed.
A substantial part of this project is the buck converter circult, which is controlled by an Arduino using pulse width modulation. A buck converter is required to control the Peltier module because Peltier modules require a smooth input voltage. Pulse width modulation alone is not sufficient.
The circuit is based on a so-called low-side switch design, meaning the MosFET switch is on the "low-side" of the load see here.
The circuit for the buck converter is shown below.
Buck converter circuit. It consists of an Arduino Nano; a gate driver; MosFET, Inductor, Capactor, and Schottky diode. In addition there is a 3 A buck converter and linear regulator to power the arduino from a DC input.
I needed to install a library for the Arduino for PID control. The library is: PID controller by Brett Beaugard. I also had to use "Wire.h" (installed by default) .for I2C communication between the Raspberry Pi and Arduino.
For the Raspberry PI the following python libraries were used: smbus; struct; time; numpy.
The repository structure is now discussed
.
├── arduino # code for the Arduino
├── images # image files for the project
├── links # some links that I used
├── matlab # matlab files (e.g. to process video to get freezing events)
├── openSCAD # Design files in openSCAD
├── python # Raspberry Pi files to do temperature ramps, etc
├── README.md # This readme
└── stl # stl design files
REQUIRED PARTS
In order to make your own Ice Nucleation Cold Stage, you may use the part list below to acquire all the components on your own. Note, although Amazon is suggested, I often used a company supplier, which was cheaper.
Raspberry Pi 3 7 inch touchscreen  |
Amazon | £63 |
Raspberry Pi 3 b+  |
Amazon | £35 |
Raspberry Pi Camera Board 8 Megapixel Version 2 1080p  |
Rapid Online | £23.70 |
Arduino Nano A000005 Board V3 |
Rapid Electronics | £15.60 |
2.54mm Pitch Vertical 8 Way, Through Hole Turned pin Open Frame IC Dip Socket, 5A |
RS Components | £0.38 |
Rapid Stripboard 95 x 127mm (x2) |
Rapid Online | £3.84 |
2200 uF capactor, 35V. |
Farnell | £1.27 |
470 µH, 7A, 0.064 ohm, ± 20%, Inductor |
Farnell | £9.89 |
IRF520NPBF - MOSFET Transistor, N Channel  |
Farnell | £0.65 |
VS-15TQ060PBF - Schottky Rectifier  |
Farnell | £2.05 |
Cooler Master Hyper TX (RR-PCH-s9U1-GP)  |
This was given to me. It is discontinued, but any similar heat sink could be used (e.g. the Cooler Master Hyper TX3i) | approx. £30 |
mc34152 Gate Driver  |
RS Components | £1.15 |
Enclosure  |
Ebay | £10 |
Micro SD card |
Amazon | £8 |
2 Pin 5 mm Pinch PCB Mount Screw Terminal Block Connector |
Amazon | £6 |
Buck converter  |
Amazon | £8 |
Linear regulator 10V, 1A |
Farnell | £3 |
Slide switch  |
Amazon | £0.15 |
PCB Header Connectors  |
Amazon | £5 |
Dupoint wires  |
Amazon | £6 |
20AWG Wire  |
RS Online | £13.03 |
Affix Pozi Pan Head Stainless Steel Screws M2.5 12mm  |
Rapid online | £3.40 |
Affix Stainless Steel Plain Washers M2.5  |
Rapid online | £1 |
M2.5 nuts  |
Rapid online | £1.20 |
Potentiometer  |
Amazon | £1.27 for 5 |
Terminal Blocks  |
Amazon | £6.32 for 10 |
Fuses for DC Power supply  |
Amazon | £5.29 for many! |
Raspberry Pi camera cable, 50cm  |
Ebay | £1.20 |
AD8495 thermocouple  |
Amazon | £4.99 |
Heat sinks for mosFET and 5V linear regulator.  |
Amazon | £2.00 |
24V, 15A Universal Regulated Switching Power Supply.  |
Ebay | £13.59 |
3 Pin IEC320 C14 Inlet Module.  |
Ebay | £1.01 |
3.5mm Pitch 2Pin PCB Mount Screw Terminal Block Connector.  |
Amazon | £2.94 |
10 Metres 4mm Brown Sleeving On A Roll.  |
Amazon | £2.99 |
40 mm fan guard  |
Rapid electronics Or Part No: 50-5136. SUNON FG-04 Fan Grill |
£3.50 |
40 mm fan  |
Reichelt electronics Or SUNON EE40100S1-00U-999 DRR / 50-5096 | £2.50 |
550 x 250 x 8 mm perspex sheet (clear)  |
Plastic sheets | £12.38 |
LED  |
Amazon | £0.65 |
IEC Cable  |
RS Components | £6.50 |
Peltier Element, 16V, 7.8A  |
Farnell | £99.89 |
25x25mm microscope slides  |
Fisher | £30.76 exc VAT for 1000 |
0.1 uF capacitor  |
RS Components | £1.00 |
1 uF tantalum capacitor  |
Rapid Online | £0.27 |
Affix Black Pozi Pan Head Machine Screws M3 12mm - Pack Of 100  |
Rapid Online | £1.55 |
Affix Slotted Countersunk Machine Screws BZP M4 16mm - Pack Of 100  |
Rapid Online | £1.58 |
Affix Pozi Countersunk Machine Screws BZP M4 12mm - Pack Of 100  |
Rapid Online | £2.47 |
Toolcraft 193152 Slotted Countersunk Screws DIN 963 4.8 Steel M4x20mm Pk 100  |
Rapid Online | £4.78 |
Affix Stainless Steel Nuts M4 - Pack Of 100  |
Rapid Online | £3.00 |
LIGHTWEIGHT ZINC EFFECT METAL BUTT HINGE, PACK OF 2  |
B&Q | £1.47 |
|
Linear regulator |
Amazon | £3 |
5pcs 90 x 90mm Cooling Fan Grill Metal Iron Wire Finger Guards System Pack (only need one)  |
Ebay | £1.96 |
Plus:
- Resistors: 680 Ω ;2x220 Ω ;50 k Ω
- USB keyboard and mouse;
- M4 washers (already had some)
- M4 rod for screwing down cover (already had some)
- some other wire 22awg for low current connections;
- some thermocouple wire (K-type).
- Spade connectors.
- 240V cable (usually butcher a spare IEC cable with a US plug).
- 3-d printing materials:
- ABS plastic
- PLA plastic
- TPU plastic
Contributions to INCS are more than welcome. I am sure there are many improvements that could be made. I am very happy to discuss ideas for improvement and how to add/remove features.
Please use the issue tracker at https://github.com/UoM-maul1609/ice-nucleation-cold-stage/issues if you want to notify me of an issue or need support. If you want to contribute, please either create an issue or make a pull request. Alternatively, come and see me in Manchester and/or lets meet for a coffee and a chat!
To be arranged.