Piston seal for a pipettor

• US 6,544,479 B1
• Filed: 07/06/1999
• Issued: 04/08/2003
• Est. Priority Date: 12/29/1997
• Status: Expired due to Fees

• Current Assignee: Thomas W. Astle
• Original Assignee: Thomas W. Astle
• Inventors: Astle, Thomas W.
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): Bex, Kathryn
• Application Number:
  US09/347,565
• Time in Patent Office: 1,372 Days
• Field of Search: 422/63, 422/67, 422/68.1, 422/81, 422/100, 422/103, 436/52, 436/54, 436/180, 738/631, 738/637.3, 738/640.1, 738/641.6, 738/641.7, 738/633.2
• US Class Current: 422/501
• CPC Class Codes: B01L 3/022 Capillary pipettes, i.e. having very small bore B01L3/0224 - B01L3/0237 take precedence
• CPC Class Codes: G01N 35/1065 Multiple transfer devices
• CPC Class Codes: Y10T 436/119163 with aspirator of claimed structure
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

In a preferred embodiment, a small volume pipettor, including: a plurality of pistons; a plurality of liquid delivery needles; motive means to cause one of the pistons to move axially within one of the needles to cause a liquid to be selectively drawn into and discharged from the needle; sealing apparatus disposed around the pistons to effect sealing of upper ends of the needles; assembly apparatus in which the needles and the sealing apparatus are disposed; and apparatus to permit the assembly apparatus to be removed from the pipettor as a one-piece unit. Further provided are novel apparatus to seal upper ends of the needles around the pistons.

Claims

1. Sealing means for a pipettor of the type having at least one piston and at least one needle, with said piston being axially movable within said needle, said sealing means comprising:

(a) a cylindrical seal surrounding and in contact with said at least one piston;

(b) a first O-ring encircling said cylindrical seal to serve as a tensioning garter spring to effect a tight seal between said cylindrical seal and said at least one piston; and

(c) an upper end of said at least one needle terminates in a V-shaped form, with an upper rim of said V-shaped form engaging a lower surface of said first O-ring, with said first O-ring providing a downward force on said at least one needle.

2. Sealing means for a pipettor, as defined in claim 1, further comprising:

a second O-ring encircling said V-shaped form, with said second O-ring providing an upward force on said at least one needle.

3. Sealing means for a pipettor, as defined in claim 2, wherein:

(a) an assembly means which includes adjacent upper and lower needle mounting plates having defined therein, respectively, first and second aligned bores;

(b) said first bore has substantially disposed therein said seal and said first O-ring; and

(c) said second bore has substantially disposed therein said V-shaped form and said second O-ring.

4. Sealing means for a pipettor, as defined in claim 3, wherein:

said cylindrical seal includes an outwardly extending flange formed at an upper end of said cylindrical seal and disposed above said first O-ring.

5. Sealing means for a pipettor, as defined in claim 3, wherein:

degree of compression of said first and second O-rings is determine by an amount of material removed from an upper surface of said lower needle mounting plate and/or the lower surface of said upper needle mounting plate.

6. Sealing means for a pipettor of the type having at least one piston and at least one needle, with said piston being axially movable within said needle, said sealing means comprising:

(a) a cylindrical seal surrounding and in contact with said at least one piston;

(b) a first O-ring encircling said cylindrical seal to serve as a tensioning garter spring to effect a tight seal between said cylindrical seal and said at least one piston;

wherein;

(c) an assembly means which includes;

(i) upper and lower needle mounting plates; and

(ii) said cylindrical seal is formed in a sheet extending between said upper and lower needle mounting plates; and

(d) said cylindrical seal has a diameter less than that of said at least one piston and has a frustoconical shape when said at least one piston is not inserted through said cylindrical seal.