| 摘要 |
For biological sampling, a manual or automatic pipette or other suction system is used where the pressure and/or air flow can be modified. The lower end of the pipette is inserted to lie at the surface of the sample fluid for the fluid to be drawn into it by suction. Preferred Features: The pressure is set to a level where the apparatus is at rest, and the pressure is registered at the environment which differs from it to show the position of the lower end of the pipette at the surface of the fluid and/or sold sample. The suction-delivery volume is between a few nanoliters and a few microliters and/or the constant pressure variation frequency is between a few Hz and a few hundred Hz. The air flow is 10-50 (preferably 20-30) mu l/sec. The difference in the pressure, from normal levels, allows detection of an anomaly at the sampling mouthpiece, the presence of a mouthpiece at the pipette and/or the presence of at least one air bubble in or at the sample surface. It also gives detection of at least one air bubble if a pressure level is registered after an initial pressure variation, or a free surface of a fluid in the event of a second pressure variation after the first change, or the surface of a solid in the event of a pressure increase. An Independent claim is included for an apparatus with at least one pressure sensor (5) to measure the pressure when at rest or a different pressure, or a difference in pressure formed by an air flow. An evaluation unit (6) analyzes the pressure readings at the sensor (5) to determine if the free end (8) of the apparatus is at the surface (9) of the biological sample (2). A system alters the pressure or the air flow at the apparatus for its condition at rest. A system (4) to vary the pressure has a flexible tube (11) which can be compressed and decompressed regularly by alternating movements such as by a motor-powered cam or crank. The air flow (19) is generated by a pipette (3) plunger (19) which ejects air from the pipette (3). The mouthpiece opening (8) is at a disposable mouthpiece (7).
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