1951 – Microtiter Plates

A microtiter plate is an array of chemical test tubes called "wells", invented in 1951 by a Hungarian medical doctor.

They are used in a variety of experimental designs, most typically biochemistry assays. The picture above is an example of a colorimetric assay result. Most of the time, they are not directly interpreted visually, as in this example, but are instead put into a plate reader that measure light transmission in each well and converts it to a numerical result. See an example catalog from a vendor. Liquid handlers make it possible to create these visualizations automatically.

Sources:

1. The text above is adapted from an e-mail by Jon Hill.
2. Picture from Gould and Lashomb (2005) Bacterial Leaf Scorch of Shade Trees.
3. Wikipedia (2013) Microtiter plate.
4. Also see this blog post on how chemical reactions can be used to create bar charts.