A method and apparatus for freezing a liquid droplet includes dispensing, by a liquid dispenser, a droplet of liquid into a fluid chamber containing a freezing fluid. The droplet of liquid is allowed to dwell in the freezing fluid for at least a predetermined dwell time so that the droplet of liquid freezes to a frozen droplet. The method and apparatus further includes injecting, by a gas injector, a stream of gas transversely to a surface of the freezing fluid at about where the frozen droplet is located along the surface of the freezing fluid contained in the fluid chamber so that the frozen droplet sinks in the freezing fluid.