I need to chill embryos that are in water in a 24 well microplate that is mounted on a video microscope system (system size= 18"x18"x17"), and I'm looking for some advice and suggestions on how this might be accomplished. I'm still at the 'ideas' stage so haven't thought too deeply about parts needed etc, but want to get a gauge from more experienced minds for feasibility of such a project. For context I have I'd say beginner experience with arduinos and electronics which have been predominantly centered on creating systems to heat things and controlling timing and flow of water.
Ideally, It would be great to develop a system that both heats and cools, but my immediate problem is cooling. The system has a light above the plate and the microscope below the plate, so I can't have the plate on cooling block as the bottom of the wells need to remain clear for video monitoring (and the top for light to penetrate). I am looking to get the temperature down from room temperature (~21C) to 10C. In and ideal word I would just place the system in an incubator, but we don't have one available or the funds to buy one that would be big enough, so I am looking into other options.
One thought was to actually try and construct an incubator for the system, using insulation materials (styrofoam etc) and use a peltier(s) and fans (plus associated heatsinks) to act as a mini ac unit. However, I know that peltiers are pretty inefficient and I am not sure if they would be able to achieve the level of cooling needed over the area to achieve this.
Another idea was to create a custom cooling plate /system that would wrap around (or potentially within) the plate, likely by using a water cooling system using a chiller connected to a pump to circulate cool water.
Do you think either of these would be achievable, and if so, which would you attempt first? Both have their various pros and cons, and I'd appreciate any thoughts or other suggestions. I recognize that you probably don't need an arduino for either set up if just maintaining a constant temp, but the eventual goal would be to apply fluctuating thermal regimes to the plate which may require arduino control (and I also have a bunch of arduinos from a previous project). Thanks in advance!
Thanks for your reply! Yes the peltier plate method would be much cheaper and is also probably more versatile for my needs than the circulating chiller. I've had my eye on that peltier from adafruit so I think I will purchase and have a play around to see what I can accomplish. I've read some mixed things about how much the temperature can drop when using peltiers and an additional fan to circulate the cold air in a cooler/incubator, but I think the best thing is to start experimenting and see what I find. Thanks!
You will find lots of misinformation on the web, because surprisingly few hobbyists understand how vital it is to efficiently remove the heat from the hot side of a Peltier cooler.
Do your research and don't skimp on the thermal transfer paste. The heat transfer efficiency (conductivity) of pastes sold on the market varies by a huge factor.
Thanks for the great advice! This certainly adds a lot of food for thought in terms of system efficiency. I'll make sure to do my homework for parts for the prototype.
That was a lot of words and I'm not sure exactly why you can't use a cooling plate.
However, one thing I can say for sure is that with proper heat removal as @jremington mentioned, Peltier coolers can get very cold. We had an instrument that had a refrigerated section using Peltiers and we had to be careful not to freeze samples. Use big heat sinks with fans on the Peltier coolers and you should be fine. The thing to remember is that they're heat pumps: they just move heat from one side to the other, so you have to get that heat off the hot side. Also, they are very inefficient so expect to have to use a solid power supply.
I would also monitor the temperature of the hot side so I could shut off power if it got too hot (fan failed, outlet blocked, etc.)
I have some units that were removed from one of those instruments I mentioned, and I could probably give myself frostbite in seconds if I wasn't careful!