Locking pipette tip and mounting shaft and hand-held manual pipette

A pipetting system comprising:

• a pipette tip mounting shaft including
• a lower sealing section;
• and
• an upper locking section, the upper locking section of the mounting shaft including means for engaging, a collar of a disposable pipette tip and flexing and distorting the collar out of round when the collar is fully mounted to the mounting shaft;
• and
• a disposable pipette tip having
• a barrel comprising a lower opening through which liquid is aspirated into the barrel and dispensed from the barrel, an upper portion having an inside surface with a round circumference, and means located in the round upper portion of the barrel for sealing the pipette tip against the lower sealing section of the mourning shaft;
• and
• a collar having an inner surface with a circular circumference in its relaxed state, an upper opening for receiving the mounting shaft wherein said collar flexes and distorts out of round when the disposable pipette tip is mounted on the mounting shaft, means for maintaining roundness of the circular circumference of the inside surface of the upper portion of the barrel when the pipette tip is mounted on the mourning shaft and the collar is distorted out of round by the upper locking section of the mounting shaft, and means on the inner surface of the collar for securing the collar to the upper locking section of the mounting shaft when the collar is mounted to the mounting shaft and distorted out of round.

A hand-held manual pipette comprising:

• a disposable pipette tip having
• a barrel with a lower opening through which liquid is aspirated into the barrel and dispensed from the barrel;
• a collar having an upper opening that receives a lower end of a pipette mounting shaft, a lower end of the collar having a larger inside diameter than the inside diameter of the tipper end of the barrel;
• and
• a circumferential shelf that connects the lower end of the collar to the upper end of the barrel;
• and
• a pipette mounting shaft including
• an upper locking section, the locking section of the mounting shaft including a stop that engages the circumferential shelf of the pipette tip when the mounting shaft is fully inserted into the collar of the tip, two or more outwardly extending lobes spaced circumferentially around the locking section of the mounting shaft and located above the stop on the mounting shaft for engaging the inside surface of the collar, and recessed relief portions in the upper locking section of the mounting shaft spanning circumferentially between the lobes and recessed relative to the lobes such that the collar distorts outwardly at the lobes and inwardly at the relief portions when the pipette tip is fully mounted on the mounting shaft.