ultra-low refrigerator specified for specimen storage

For starter, This project design had been granted patent and the project team DO NOT grant any, include but not limit to, person, orgnization, third-party, to copy, imiate or any beahavour that voliates the group's patent rights.

patent link (translated): https://patents.google.com/patent/CN205843174U/en?oq=CN205843174U

My Bio teacher, Nick Ni have a bunch of competent cell to store. However these cell requires at least -50C to store and the bio department haven't enough found for such refrigerator. So I and Nick decided to make our own based on Peltier effect

The competent cell are stored in dry ice before use, which wouldn't last long without a fridge.

for those of you who don't know Peltier effect, here is the wikipedia site for it.:

https://en.wikipedia.org/wiki/Thermoelectric_effect

for starters, we choosed a 3-level cooling plate, which can generate a tempreture difference for about 100C on between the poles.

We then 3d printed a small camber for the specimen to place, and attatching a water cooler and the cooling plate to it；

Then, we used a multi layer insulation material to keep heat outside:

from inside to out:

1. fiber glass sheet for main insulation material

2. acrylic plate for structure reinforcement

3. aluminum foil for reflect IR light

4. ABS plastic for shell

Time to test it!

this is the 1st version's test, which is not ideal.

We then filled the chamber with metal ball as heat transfer material from cooling plate to specimen, and it works way better than we expected:

We won't stop there, we need at least -50C for the specimen, so we put the whole unit into the fridge:

That's pretty much it, There's still a very vast room for upgrade, such as changing to a more beefy heatsink, or a more powereful cooling plate would all help deceeasing the tempreture.