Microscope Slide Cooler by ntdesign

Last crawled date: 3 years, 1 month ago

A poor man's microscopy cryo stage. We use this to prepare air-sensitive single crystals at low temperature in an inert atmosphere, but I don't see why it couldn't be used for other purposes such as biological samples. The idea is creating a cold upward N2 or air gradient over the sample, which is constantly replaced. The slide itself has a large contact surface with the cold gas flow, which helps maintain a constant sample temp. The gas is cooled by passing it through some sort of heat exchanger (LN2 or dry ice bath).
Slides can be slotted in and out if the sample is reasonably flat (1mm clearance).
The device is compact enough to be carried in a pocket. One crystal mounted on a standard sample holder can be held in the recess and locked in place, e.g. for mailing. In a test, we disconnected the device from the nitrogen flow, covered the inlet and outlet, slid on the lid and buried it in dry ice overnight. The next day, the device could be reconnected and manipulations continued normally with no sample damage.
You need a standard microscopy slide, a 22x22mm slide cover for the underside window (optional, but helps prevent condensation), some grease for seating the connectors and 4x M5x16 countersunk + hex nuts.
A very simple heat exchanger setup is shown in the pictures, with LN2 in the tank and very slow flow a constant temperature in the -30°C to -10°C range can be established. Temperature control is possible but very limited (maybe +/- 15° but the base temp is predetermined by the actual setup).