{
  "patent_number": "US 3220960",
  "country": "US",
  "title": "How Soft Contact Lenses Were Invented Using Hydrogels",
  "original_title": "Cross-linked hydrophilic polymers and articles made therefrom",
  "summary": "This patent describes the chemical recipe for soft, water-absorbing plastic materials that form the basis of modern soft contact lenses.",
  "what_it_does": "The patent defines a shaped body made from a hydrogel, which is a material that holds a large amount of water. It uses a base of a water-soluble monoester (like hydroxyethyl methacrylate) mixed with a small amount of a diester to create a cross-linked structure. This cross-linking acts like a microscopic net that holds the water inside the polymer without the material dissolving. By adjusting the ratio of these ingredients, the resulting plastic remains soft and flexible while retaining its shape in an aqueous environment.",
  "what_it_does_not_cover": [
    "Does not cover rigid gas-permeable contact lenses made from non-hydrogel materials.",
    "Does not cover non-cross-linked polymers that would simply dissolve in water.",
    "Does not cover the specific manufacturing process of spinning or molding the lenses, only the chemical composition of the material itself."
  ],
  "filed": "1960-12-21",
  "granted": "1965-11-30",
  "expires": "1982-11-30",
  "status": "expired",
  "holder": "Individual",
  "holder_url": "https://patentbrief.org/company/individual",
  "inventors": [
    {
      "name": "Wichterle Otto",
      "url": "https://patentbrief.org/inventor/wichterle-otto"
    },
    {
      "name": "Lim Drahoslav",
      "url": "https://patentbrief.org/inventor/lim-drahoslav"
    }
  ],
  "times_cited": 228,
  "tags": [
    "biotech",
    "materials",
    "consumer_electronics"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/3220960/soft-contact-lens-hydrogel",
  "markdown_url": "https://patentbrief.org/patent/us/3220960/soft-contact-lens-hydrogel/md",
  "google_patents_url": "https://patents.google.com/patent/US3220960",
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}