Chemists Construct Squishy Memristors and Diodes

Quasi-liquid electronics might make better brain implants, scientists say

3 min read

7 December 2010— Researchers at North Carolina State University have demonstrated new "soft" electronic components, built from liquid metals and hydrogels. The scientists hope that such components—quasi-liquid diodes and memristors—will work better than traditional electronics to interface with wet squishy things, such as the human brain.

Ju-Hee So, a graduate student in chemistry at NC State, described a quasi-liquid diode at the fall meeting of the Materials Research Society in Boston last week. The device’s electrodes are made of an alloy—75 percent gallium and 25 percent indium—that is highly conductive and liquid at room temperature. The electrode is housed within a plastic casing. Sandwiched between the electrodes are two films made of agarose, a hydrogel commonly used in biochemistry that is more than 90 percent water by weight. Each film is doped with electrolytes; one contains polyacrylic acid (PAA), and the other holds polyethyleneimine (PEI), which is a base.

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The Ultimate Transistor Timeline

The transistor’s amazing evolution from point contacts to quantum tunnels

1 min read
A chart showing the timeline of when a transistor was invented and when it was commercialized.

Even as the initial sales receipts for the first transistors to hit the market were being tallied up in 1948, the next generation of transistors had already been invented (see “The First Transistor and How it Worked.”) Since then, engineers have reinvented the transistor over and over again, raiding condensed-matter physics for anything that might offer even the possibility of turning a small signal into a larger one.

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