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Nanogenerator Gets More Flexible and Transparent

Newly flexible and transparent nanogenerators could enable artificial skin and soft robots

2 min read
A transparent electronic skin for tactile sensing.
Photo: Xiong Pu

Just last week, a research team in South Korea  devised a way to improve the electrical output of the triboelectric nanogenerators (TENGs) developed by researchers at the Georgia Institute of Technology. 

Not to be outdone, a team of scientists at Georgia Tech, led by Zhong Lin (Z.L.) Wang, have improved the capabilities of their TENGs technology by making them far more flexible. In the process, the team has given the devices a new name: skin-like triboelectric nanogenerators, or STENGs. These stretchy generators should provide another flexible power source for the increasing number of flexible electronics.

In research described in the journal Science Advances, the Georgia Tech researchers combined a hybrid material made up of an elastomer and an ionic hydrogel that can harvest energy from movement and provide tactile sensing. The flexibility and tactile sensing suggests that the material could be used to make self-powered electronic skin or self-powered soft robots.

Like TENGs, STENGs harvest static electricity from friction. A typical TENG device consists of two different materials that are rubbed together. The trick is to use one material that tends to give off electrons, such as glass or nylon, so that it will donate them to materials that tend to absorb them, such as silicon or teflon. By converting this mechanical energy to electricity, the TENGs can power small electronic devices.

The major difference between STENGs and TENGs is the use of electrical conductors as the electrode. The elastomer serves as the electrification layer, and the ionic hydrogel acts as the electrode. The main benefit: The researchers report that using these new materials gave the STENGs stretch ratios of over 1000 percent. In an e-mail interview with IEEE Spectrum, Wang noted that the flexible TENG his team developed last year—dubbed the shape-adaptive TENG—could  be stretched to just 300 percent of its original length.

In addition to flexibility, the new stretchable material is highly transparent. It allows 96.2 percent of visible light to pass through it, which should help in transmitting optical data. The material is also able to cope with fairly high temperatures of 30 degrees Celsius, and with humidity as high as 30 percent. That may not offer much benefit if you’re in a tropical jungle, but it would make the STENGs suited to a lot of other climates.

Wang also points out that the material, which is biocompatible, is relatively low cost thanks to the use of fairly conventional materials that still provide high performance.

The research out of the Ulsan National Institute of Science and Technology (UNIST) in South Korea reported last week yielded a new polymer that serves as a dielectric material (or insulator) for TENG devices, and provides a 200-fold increase in the power output over traditional TENG devices.

But the new STENG devices achieved areal power densities approaching 35 milliwatts per square meter—far better than traditional TENGs—without the new polymer insulator. Wang said that the UNIST polymer could be adapted into the latest STENG devices, promising not only greater flexibility but also increased power output.

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The First Million-Transistor Chip: the Engineers’ Story

Intel’s i860 RISC chip was a graphics powerhouse

21 min read
Twenty people crowd into a cubicle, the man in the center seated holding a silicon wafer full of chips

Intel's million-transistor chip development team

In San Francisco on Feb. 27, 1989, Intel Corp., Santa Clara, Calif., startled the world of high technology by presenting the first ever 1-million-transistor microprocessor, which was also the company’s first such chip to use a reduced instruction set.

The number of transistors alone marks a huge leap upward: Intel’s previous microprocessor, the 80386, has only 275,000 of them. But this long-deferred move into the booming market in reduced-instruction-set computing (RISC) was more of a shock, in part because it broke with Intel’s tradition of compatibility with earlier processors—and not least because after three well-guarded years in development the chip came as a complete surprise. Now designated the i860, it entered development in 1986 about the same time as the 80486, the yet-to-be-introduced successor to Intel’s highly regarded 80286 and 80386. The two chips have about the same area and use the same 1-micrometer CMOS technology then under development at the company’s systems production and manufacturing plant in Hillsboro, Ore. But with the i860, then code-named the N10, the company planned a revolution.

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