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Contamination-resistant dispensing and metering drop forming device

  • US 5,219,101 A
  • Filed: 01/17/1991
  • Issued: 06/15/1993
  • Est. Priority Date: 06/01/1989
  • Status: Expired due to Term
First Claim
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1. A device for dispensing liquids in drop form of substantially uniform size which comprises a container having a dropper tip including a passageway for ingress of air to and egress of liquid from said device, said passageway communicating between the container and an orifice in the dropper tip;

  • means for temporarily reducing the volume of the container; and

    disposed within the dropper tip, across the passageway, a microporous composite membrane with pores of a size to resist passage of contaminants, said membrane having a liquophilic component permitting delivery of drops of a liquid to a desired location outside the container and a liquophobic component adapted to resist the passage of such liquid but to permit the passage therethrough of air, the surface area and pore size of said liquophilic component being so selected as to meter liquid being dispensed in drop form and avoid a stream of liquid from emerging from the dropper tip during normal use, said passageway being intersected by said membrane and communicating with both the liquophilic and liquophobic components.

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