BOSTON — While other scientists successfully shrank beakers, tubes and centrifuges into diagnostic laboratories that fit into aluminum boxes that cost $50,000, George Whitesides had smaller dreams.

The diagnostic tests designed in Dr. Whitesides’s Harvard University chemistry laboratory fit on a postage stamp and cost less than a penny.

His secret? Paper.

His colleagues miniaturized diagnostic tests so they could move into the field with tiny pumps and thread-thin tubes. Dr. Whitesides opted for a more novel approach, reasoning that a drop of blood or urine could wick its way through a square of filter paper without any help.

And if the paper could be etched with tiny channels so that the drop followed a path, and if that path were mined with dried proteins and chemically triggered dyes, the thumbnail-size square could be a mini-laboratory — one that could be run off by the thousands on a Xerox machine.