| abstract |
The present invention provides methods and devices for freezing drops of liquid reagent solution in a cryogenic liquid. In one embodiment, the apparatus of the present invention comprises means for dispensing uniform, precisely measured drops of a liquid reagent and a rotatable carousel positioned below the dispensing means. The upper surface of the carousel has a plurality of trays each containing a cryogenic liquid, typically liquid nitrogen, for receiving the drops of liquid reagent. An alternative embodiment of the present invention comprises a tank comprising a cryogenic liquid for receiving the drops of liquid reagent. The tank has a heat source for slightly heating a portion of the cryogenic liquid such that a convection current in the cryogenic liquid is created. The convection currents in the cryogenic liquid provide mild agitation of the liquid and prevent aggregation of the frozen drops. |