Detecting boundary between two liquid layers medical research

摘要

An air bubble is generated at a certain device (24) within the first liquid. The device is moved towards the second liquid layer as it holds the bubble. The pressure change which occurs when the air bubble reaches the boundary is detected. The position of the boundary is detected on the basis of a position of the device at a time when the pressure change is detected. The air bubble is generated at a tip (25) of the device. The first liquid layer can consist of a floating upper layer and both liquids can be bodily fluids.