E Ink (electronic ink) is a brand of electronic paper (e-paper) display technology commercialized by the E Ink Corporation, which was co-founded in 1997 by MIT undergraduates JD Albert and Barrett Comiskey, MIT Media Lab professor Joseph Jacobson, Jerome Rubin and Russ Wilcox.

It is available in grayscale and color and is used in mobile devices such as e-readers, digital signage, smartwatches, mobile phones, electronic shelf labels and architecture panels.

The notion of a low-power paper-like display had existed since the 1970s, originally conceived by researchers at Xerox PARC but had never been realized. While a post-doctoral student at Stanford University, physicist Joseph Jacobson envisioned a multi-page book with content that could be changed at the push of a button and required little power to use.

Neil Gershenfeld recruited Jacobson for the MIT Media Lab in 1995, after hearing Jacobson's ideas for an electronic book. Jacobson, in turn, recruited MIT undergrads Barrett Comiskey, a math major, and J.D. Albert, a mechanical engineering major, to create the display technology required to realize his vision.

The initial approach was to create tiny spheres which were half white and half black, and which, depending on the electric charge, would rotate such that the white side or the black side would be visible on the display. Albert and Comiskey were told this approach was impossible by most experienced chemists and materials scientists and had trouble creating these perfectly half-white, half-black spheres; during his experiments, Albert accidentally created some all-white spheres.

Comiskey experimented with charging and encapsulating those all-white particles in microcapsules mixed in with a dark dye. The result was a system of microcapsules that could be applied to a surface and could then be charged independently to create black and white images. A first patent was filed by MIT for the microencapsulated electrophoretic display in October 1996.

The scientific paper was featured on the cover of Nature, something extremely unusual for work done by undergraduates. The advantage of the microencapsulated electrophoretic display and its potential for satisfying the practical requirements of electronic paper were summarized in the abstract of the Nature paper:

It has for many years been an ambition of researchers in display media to create a flexible low-cost system that is the electronic analogue of paper ... viewing characteristic[s] result in an "ink on paper" look. But such displays have to date suffered from short lifetimes and difficulty in manufacture. Here we report the synthesis of an electrophoretic ink based on the microencapsulation of an electrophoretic dispersion. The use of a microencapsulated electrophoretic medium solves the lifetime issues and permits the fabrication of a bistable electronic display solely by means of printing. This system may satisfy the practical requirements of electronic paper.