Living organ-on-a-chip could soon replace animal testing

If a team of Harvard bioengineers has its way, animal testing and experimentation could soon be replaced by organ-on-a-chip technologies. Like SoCs (system-on-a-chip), which shoehorn most of a digital computer into a single chip, an organ-on-a-chip seeks to replicate the functions of a human organ on a computer chip.

In Harvard’s case, its Wyss Institute has now created a living lung-on-a-chip, a heart-on-a-chip, and most recently a gut-on-a-chip.

We’re not talking about silicon chips simulating the functions of various human organs, either. These organs-on-a-chip contain real, living human cells. In the case of the gut-on-a-chip, a single layer of human intestinal cells is coerced into growing on a flexible, porous membrane, which is attached to the clear plastic walls of the chip. By applying a vacuum pump, the membrane stretches and recoils, just like a human gut going through the motions of peristalsis. It is so close to the real thing that the gut-on-a-chip even supports the growth of living microbes on its surface, like a real human intestine.

In another example, the Wyss Institute has built a lung-on-a-chip, which has human lung cells on the top, a membrane in the middle, and blood capillary cells beneath. Air flows over the top, while real human blood flows below. Again, a vacuum pump makes the lung-on-a-chip expand and contract, like a human lung.

These chips are also quite closely tied to the recent emergence of the lab-on-a-chip (LoC), which combines microfluidics (exact control of tiny amounts of fluid) and silicon technology to massively speed up the analysis of biological systems, such as DNA. It is thanks to LoCs that we can sequence entire genomes in just a few hours — a task that previously took weeks or months.

These human organs-on-a-chip can be tested just like a human subject — and the fact that they’re completely transparent is obviously a rather large boon for observation, too. To test a drug, the researchers simply add a solution of the compound to the chip, and see how the intestinal (or heart or lung) cells react. In the case of the lung-on-a-chip, the Wyss team is testing how the lung reacts to possible toxins and pollutants. They can also see how fast drugs (or foods) are absorbed, or test the effects of probiotics.

Perhaps more importantly, these chips could help us better understand and treat diseases. Many human diseases don’t have an animal analog. It’s very hard to find a drug that combats Crohn’s disease when you can’t effectively test out your drug on animals beforehand — a problem that could be easily solved with the gut-on-a-chip. Likewise, it is very common for drugs to pass animal testing, but then fail on humans. Removing animal testing from the equation would save money and time, and also alleviate any ethical concerns.

Moving forward, the Wyss Institute, with funding from DARPA, is currently researching a spleen-on-a-chip. This won’t be used for pharmaceutical purposes, though; instead, DARPA wants to create a “portable spleen” that can be inserted into soldiers to help battle sepsis (an infection of the blood).

And therein lies the crux: If you can create a chip that perfectly mimics the spleen or liver or intestine, then what’s to stop you from inserting those chips into humans and replacing or augmenting your current organs? Instead of getting your breasts enlarged, you might one day have your liver enlarged, to better deal with your alcoholism. Or how we connect all the organ chips together and create a complete human-on-a-chip?

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ZX Spectrum: 30 years old, and still one of the cheapest computers ever made

Today is the 30th birthday of the ZX Spectrum, one of the most popular home computers ever made, and probably the single most important factor in the creation of the IT industry in the UK. The ZX Spectrum, made by Sinclair Research in Cambridge, England is usually considered the UK equivalent of the US-made Commodore 64.

Hardware-wise, the ZX Spectrum was completely unremarkable. There was an 8-bit Zilog Z80A CPU, a graphics chip capable of outputting 32 columns by 24 rows (256x192px) with 15 colors, and either 16 or 48KB of RAM. At just £125 ($200), however, the ZX Spectrum was incredibly cheap. The Commodore 64 cost $600. The BBC Micro, made by Sinclair’s arch rival Acorn Computers, cost £299. Despite costing just a fraction of its contemporaries, the ZX Spectrum had comparable functionality. All three computers had similar amounts of RAM and processing power, and all three had similar editions of the BASIC programming language.

How did Sinclair Research pull it off? Innovative design and aggressive engineering. From the very start, Sinclair Research knew that it wanted the ZX Spectrum to be as cheap as possible, and so almost every component was engineered from the ground up with penny pinching in mind. The main printed circuit board was kept as small and dense as possible, which resulted in a very lithe chassis (just 23x14x3cm, compared to the monstrous 40x21x7cm Commodore 64 and gargantuan 40x35x8cm BBC Micro). Instead of using a conventional keyboard with hundreds of moving parts, a rubber, chiclet “island” keyboard with just four or five parts was used. (In the eyes of original users, this resulted in the ZX Spectrum keyboard feeling like “dead flesh” — an early example of a tech meme.) The ZX Spectrum was wrapped in a plastic case and weighed just 550 grams (1.2lbs), compared to the metal, clunky 1.8kg (4lb) Commodore 64, and back-breaking 3.7kg (8.1lb) BBC Micro.

In short, the ZX Spectrum was simply better engineered than its contemporaries — much like iPhone, except Apple uses its engineering and supply line advantage to squeeze out higher profits, rather than slashing prices. Like the ZX Spectrum, it’s not like the iPhone uses fundamentally different silicon or materials — Apple is still limited by the state of the art — but through design, engineering, and supply line expertise, Apple simply manages to cram more tech into the same (or smaller) space — and with a cheaper bill of materials.

ZX Spectrum+, a later version that did away with the “dead flesh” keyboard

The ZX Spectrum would go on to sell five million units — not bad, when you consider there are only 30 million homes in the UK — and net Clive Sinclair, the owner of Sinclair Research, a knighthood for “services to British industry.” Curiously, Sinclair, a serial inventor, recently admitted that he doesn’t actually use computers — he prefers the telephone to email.

To this day, even after 30 years of being hammered at by Moore’s law and accounting for inflation, there are remarkably few home computers that have been sold at a lower price point than the ZX Spectrum (it would cost around $450 today). The Raspberry Pi, a British-made Linux-based PC that will be sold for around $25, is the obvious exception, and the spiritual successor of the ZX Spectrum.

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SoC vs. CPU – The battle for the future of computing

After more than 50 years at the top of the heap, the CPU finally has some competition from an upstart called the SoC. For decades, you could walk into a shop and confidently pick out a new computer based on its CPU — and now, everywhere you look, from smartphones to tablets and even some laptops, there are SoCs.

Don’t worry, though, CPUs and SoCs are actually rather similar, and almost everything you know about CPUs can also be applied to SoCs.

What is a CPU?

Despite the huge emphasis put on CPU technology and performance, it is ultimately a very fast calculator. It fetches data from memory, and then performs some kind of arithmetic (add, multiply) or logical (and, or, not) operation on that data. The more expensive/complex the CPU, the more data it can process, the faster your computer.

A CPU itself is not a personal computer, however — a whole framework of other silicon chips is required for that. There must be memory to hold the data, an audio chip to decode and amplify your music, a graphics processor to draw pictures on your monitor, and hundreds of smaller components that all have a very important task.

What is an SoC?

An SoC, or system-on-a-chip to give its full name, integrates almost all of these components into a single silicon chip. Along with a CPU, an SoC usually contains a GPU (a graphics processor), memory, USB controller, power management circuits, and wireless radios (WiFi, 3G, 4G LTE, and so on). Whereas a CPU cannot function without dozens of other chips, it’s possible to build complete computers with just a single SoC.

The difference between an SoC and CPU

The number one advantage of an SoC is its size: An SoC is only a little bit larger than a CPU, and yet it contains a lot more functionality. If you use a CPU, it’s very hard to make a computer that’s smaller than 10cm (4 inches) squared, purely because of the number of individual chips that you need to squeeze in. Using SoCs, we can put complete computers in smartphones and tablets, and still have plenty of space for batteries.

Due to its very high level of integration and much shorter wiring, an SoC also uses considerably less power — again, this is a big bonus when it comes to mobile computing. Cutting down on the number of physical chips means that it’s much cheaper to build a computer using an SoC, too.

Conventional PC motherboard (left) vs. the main iPad 3 circuit board (right). This image is roughly to scale.

The only real disadvantage of an SoC is a complete lack of flexibility. With your PC, you can put in a new CPU, GPU, or RAM at any time — you cannot do the same for your smartphone. In the future you might be able to buy SoCs that you can slot in, but because everything is integrated this will be wasteful and expensive if you only want to add more RAM.

CPUs are on the way out

Ultimately, SoCs are the next step after CPUs. Eventually, SoCs will almost completely consume CPUs. We are already seeing this with AMD’s Llano and Intel’s Ivy Bridge CPUs, which integrate a memory controller, PCI Express, and a graphics processor onto the same chip. There will always be a market for general purpose CPUs, especially where power and footprint are less of an issue (such as supercomputers). Mobile and wearable devices are the future of computers, though, and so are SoCs.

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Molybdenite threatens graphene as silicon replacement

Researchers from the Swiss Federal Institute of Technology have created integrated circuits using single-atom-thick molybdenite, a substance that’s very similar to graphene. Molybdenite logic has very similar characteristics to its silicon-based cousins, but because single sheets of the material are just 0.65nm thick it can be used to make very small, very power-efficient transistors.

Molybdenite (pronounced mol-IB-dee-nite) is a mineral of molybdenum sulfide, and looks and feels a lot like graphite. Like graphite, it has a layered crystalline form that makes it a good lubricant, and a good target for producing single-atom-thick layers. Just after graphene was famously synthesized from graphite using sticky tape, molybdenite flakes were also created using the same technique. For some reason no one has coined the term “molybdenene” — maybe I can be the first. Though, looking at it written down like that, maybe there’s a reason we don’t call it molybdenenenene…

As you know, graphene is undeniably one of the most miraculous materials ever discovered — it’s probably the answer to our battery dependency woes, amongst other things — but it lacks one very important feature that semiconductors need: a reliable bandgap. Semiconductors, by definition, sometimes insulate and sometimes conduct, depending on how much voltage you run through them. The voltage difference required to switch between insulating and conducting states is called the bandgap — and graphene doesn’t have one. Molybdenite, on the other hand, has a bandgap right in the sweet spot for everyday computer chips.

To turn it into a transistor, the Swiss researcherslaid atom-thick sheets of molybdenite onto a silicon wafer, and then attached each minuscule bit to a gold electrode using hafnium oxide (a high-k dielectric used in contemporary silicon chips). In the image at the top of the story, each of the thin tips is a tunnel field-effect transistor (pictured right).

In essence, this means that molybdenite offers a viable alternative once we reach the physical limits of silicon. As we’ve mentioned many times before, though, silicon, as the reigning incumbent, will not be unseated easily. By the time Intel & Co. are forced to look beyond silicon, which is still a few years off, graphene and carbon nanotubes — both of which are capable of operating at higher speeds and lower voltages than molybdenite — might’ve reached the necessary level of maturity. Still, it’s comforting to know that, as of today, we basically have the technology to incorporate 1nm transistors into computer chips.

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IBM creates 9nm carbon nanotube transistor that outperforms silicon

IBM has demonstrated a nine nanometer (9nm) carbon nanotube transistor (CNT) — the smallest CNT ever made, and significantly smaller than any commercial silicon transistor. At 9nm, IBM’s transistor is also smaller than the physical limit of silicon transistors, which is around 11nm.

Beyond its diminutive size, the 9nm CNT is capable of switching at very low voltages (0.5V), thus consuming less power than its silicon counterparts — but it can also carry four times as much current, meaning a better signal quality and a wider range of applications.

Carbon nanotubes, much like graphene, have long been heralded as the eventual replacement for silicon transistors due to their improved electrical qualities. There are (obviously) problems for the adoption of CNTs, though: They’re hard to mass produce (though maybe IBM should talk to Berkeley about that), and they also have to reach a maturity level that can unseat a semiconductor technology that has ruled supreme for more than 40 years. It’s not that Intel & Co. don’t want to use carbon nanotubes, but when you’re churning out billions of dollars worth of silicon chips there’s an awful lot of inertia preventing a sideways leap to a new technology.

It is this inertia that resulted in Intel’s 3D FinFET chips — a last gasp effort to squeeze a few more years out of silicon semiconductors. The question is, does Intel also have a working CNT, or does IBM now have the upper hand? Intel’s projected roadmap has an 11nm node in 2015 — but what about after that? It’s important to remember that IBM has one of the most advanced semiconductor processes in the world, along the same lines as TSMC and GloFo. If IBM is the first to market with carbon nanotube transistors, Intel might finally have a challenger.

Read more at Nano Letters (pay-walled)

[Image credit]

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Intel Ivy Bridge CPUs arriving April 2012

According to Taiwanese OEMs, April 8 will be the day that you can get your hands on desktop and mobile Ivy Bridge CPUs. These will be the first commercial chips that use a 22nm process, and — perhaps more importantly — the first silicon chips that use 3D tri-gate transistors (FinFET), instead of ye olde MOSFET that every other manufacturer and foundry are still using.

A total of 13 CPUs will be released on or around April 8: Seven desktop chips will be immediately available, all priced between $332 and $184 and targeted at the low- and mid-range market, the fastest being a Core i7-3770K. Six mobile chips spanning the entire price gamut will be available, including a high-end $1100 Core i7-3920Qm. Chipsets for both desktop and mobile will also be released, including the top-end Z77, and H77, Z75, and B75, and their mobile equivalents.

Before you get too excited, though, bear in mind that Ivy Bridge is not a performance update to Sandy Bridge. Where Sandy Bridge was the tock — new architecture — following Westmere, Ivy Bridge is the tick (die shrink) of Intel’s tick-tock release strategy. That doesn’t mean that IB isn’t faster than SB — some leaked benchmarks show a 2-8% gain — but primarily, Ivy Bridge will consume less power. According to Intel, the Core i7-3770k will have a TDP of just 77 watts, down from 95W on the current top-end i7-2700K.

This is obviously big news for the mobile sector where the CPU, along with the display and backlight, make up the bulk of a device’s power consumption. Presumably, with Intel’s 2012 focus being smartphones, ultrabooks, and the success of Medfield, almost everyone at Intel is focusing on reducing power footprints. Laptops might be by far the most dominant PC form factor, but if I can build a desktop PC that’s fast, saves power, and cuts down on CPU core temperature, I’m not going to complain. The other big change, though it probably won’t affect many ExtremeTech readers, is that Ivy Bridge chips will feature a new, slightly-less-awful integrated GPU.

The power savings, incidentally, most likely stem from the use of 3D FinFETs in Ivy Bridge, and other advances in silicon chip fabrication technologies. Medfield will have to wait until 2013 or 14 for its 3D FinFET re-work, but when it eventually happens Intel might even move ahead of ARM-based designsin terms of power consumption.

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