Blood sampling devices

• US 5,913,868 A
• Filed: 01/13/1997
• Issued: 06/22/1999
• Est. Priority Date: 07/13/1994
• Status: Expired due to Term

• Current Assignee: Owen Mumford
• Original Assignee: Owen Mumford
• Inventors: Marshall, Jeremy, Crossman, David Danvers
• Primary Examiner(s): Buiz, Michael
• Assistant Examiner(s): TRUONG, KEVIN THAO
• Application Number:
  US08/782,153
• Time in Patent Office: 890 Days
• Field of Search: 606/181, 606/182, 606/184, 606/185
• US Class Current: 606/181
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150427 Specific tip design, e.g. for improved penetration characteristics
• CPC Class Codes: A61B 5/150519 Details of construction of hub, i.e. element used to attach the single-ended needle to a piercing device or sampling device
• CPC Class Codes: A61B 5/150549 Protectors removed by rotational movement, e.g. torsion or screwing
• CPC Class Codes: A61B 5/150618 Integrally moulded protectors, e.g. protectors simultaneously moulded together with a further component, e.g. a hub, of the piercing element
• CPC Class Codes: A61B 5/150633 Protective sleeves which are axially extensible, e.g. sleeves connected to, or integrated in, the piercing or driving device; pivotable protective sleeves
• CPC Class Codes: A61B 5/15186 Devices loaded with a single lancet, i.e. a single lancet with or without a casing is loaded into a reusable drive device and then discarded after use; drive devices reloadable for multiple use

Abstract

A lancet has a needle (2) embedded in a plastics body (1), its tip (3) projecting from the forward end but being initially encased in a cap (4). This cap (4) may be integrally moulded with the body, around the needle tip (3), and be sheared away before use. The needle (2) can be pushed back in relation to the body (1) after use, conveniently by applying the cap (4) to the tip (3), until the tip is safely flush with, or set back with respect to the leading end of the body (1). The rear end of the body (1) has a structure (9) to prevent the rear end of the needle (2) being pushed forwards again. To ensure that the tip disappears, the body (1) may be formed with an intermediate, resiliently flexible bridge (19) stiff enough to remain rigid during pricking. But when the needle (2) is forced back and pressure is also applied to the part of the body forward of the bridge (19), the needle (2) and that forward part move back with respect to the rear part of the body. Then the forward part is released to move forwards, sprung by the bridge (19), leaving the needle held by the rear part.

Claims

1. A lancet for a skin pricker, the lancet comprising a needle with a tip and an elongate body with a forward end and rear end of moulded plastics material encasing most of the needle, the needle tip being initially encased by a breakaway cap integrally moulded with the body at its forward end and being exposed when the cap is removed, wherein the needle and body have co-operating formations that prevent the needle moving forwards from its initial position relative to the body, and wherein the needle is movable rearwardly with respect to the body to retract the needle tip within the body, the force required for this rearward movement being greater than the force required for the needle tip to penetrate skin.

2. A lancet as claimed in claim 1, wherein the plastics body has a forward part and a rearward part joined by a bridge which acts as a spring normally holding the parts distanced but which is compressible to allow the parts to approach, wherein the rearward part exerts a greater frictional grip on the needle than does the forward part, and wherein the expansion force of the compressed spring bridge is sufficient to overcome the frictional grip of the forward part whereby when the needle is pushed rearwardly with a pusher also acting on the forward part with a force sufficient to overcome the frictional grip of the rearward part, the forward part closes up towards the rearward part and the needle is retracted, and when the pusher is removed the rearward part holds the needle while the forward part is sprung forward relative to the needle by the bridge to shield the needle tip.

3. A lancet as claimed in claim 2, wherein the rearward part of the body is substantially longer than the forward part and thus has a much greater surface area in contact with the needle, thereby giving rise to the differential frictional grip of said parts on the needle.

4. A lancet as claimed in claim 2, wherein the bridge is provided by an aperture diametrally through the body.

5. A lancet as claimed in claim 4, wherein the diametral aperture is an enlargement of one of the apertures which are formed by elements which hold the needle while the body is moulded around it.

6. A lancet as claimed in claim 4, wherein the aperture is generally elliptical or lozenge shaped in cross section, the major axis of said section being transverse to the length of the body.

7. A lancet as claimed in claim 1, wherein a membrane is formed at the rear end of the body against which the rear end of the needle bears during skin pricking, but which can be broken when the needle is urged rearwardly by a substantial force.

8. A lancet as claimed in claim 1, wherein the hold on the needle of the rearward part is a throat is formed at the rear end of the body in which the rear end of the needle is trapped during skin pricking, but through which that rear end of the needle can be urged by a substantial force.

9. A lancet as claimed in claim 1, wherein the cap is adapated to serve as an implement for pushing the tip of the needle, after use, back into the body.

10. A lancet as claimed in claim 9, wherein the forward end of the body is recessed and the cap has a projection which can enter the recess when pushing the tip of the needle.

11. A lancet as claimed in claim 1, wherein the rear end of the body is adapted to shield the rear end of the needle when the needle is retracted.

12. A lancet as claimed in claim 1, wherein the needle formation is a forwardly facing shoulder where the needle reduces in cross section to a leading length portion projecting from the body and terminating in the tip.

13. A lancet as claimed in claim 12, wherein the needle is generally cylindrical with a flat formed over the leading length portion to make the reduced cross section.